Sunday, July 30, 2006
Rocky Mountain Spotted Fever
Rocky Mountain spotted fever was first recognized in 1896 in the Snake River Valley of Idaho and was originally called "black measles" because of the characteristic rash. It was a dreaded and frequently fatal disease that affected hundreds of people in this area. By the early 1900s, the recognized geographic distribution of this disease grew to encompass parts of the United States as far north as Washington and Montana and as far south as California, Arizona, and New Mexico.
In response to this severe problem, the Rocky Mountain Laboratory was established in Hamilton, Montana. This facility is now a part of the National Institute of Allergy and Infectious Diseases, National Institutes of Health. Laboratory and epidemiologic studies were also carried out by the Communicable Disease Center (now the Centers for Disease Control and Prevention, or CDC) and are still conducted by scientists in the Viral and Rickettsial Zoonoses Branch, Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, CDC.
Howard T. Ricketts was the first to establish the identity of the infectious organism that causes this disease. He and others characterized the basic epidemiologic features of the disease, including the role of tick vectors. Their studies found that Rocky Mountain spotted fever is caused by the bacterium, Rickettsia rickettsii. This species is maintained in nature in a complex life cycle involving ticks and mammals; humans are considered to be accidental hosts and are not involved in the natural transmission cycle of this pathogen. Tragically, Dr. Ricketts died of typhus (another rickettsial disease) in Mexico in 1910, shortly after completing his remarkable studies on Rocky Mountain spotted fever.
The name Rocky Mountain spotted fever is somewhat of a misnomer. Beginning in the 1930s, it became clear that this disease occurred in many areas of the United States other than the Rocky Mountain region. It is now recognized that this disease is broadly distributed throughout the continental United States, as well as southern Canada, Central America, Mexico, and parts of South America. Between 1981 and 1996, this disease was reported from every U.S. state except Hawaii, Vermont, Maine, and Alaska.
Rocky Mountain spotted fever remains a serious and potentially life-threatening infectious disease today. Despite the availability of effective treatment and advances in medical care, approximately 3% to 5% of individuals who become ill with Rocky Mountain spotted fever still die from the infection. However, effective antibiotic therapy has dramatically reduced the number of deaths caused by Rocky Mountain spotted fever; before the discovery of tetracycline and chloramphenicol in the late 1940s, as many as 30% of persons infected with R. rickettsii died.The Organism
Rocky Mountain spotted fever is caused by Rickettsia rickettsii, a small bacterium that grows inside the cells of its hosts. These bacteria range in size from 0.2 x 0.5 micrometers to 0.3 x 2.0 micrometers. They are difficult to see in tissues by using routine histologic stains and generally require the use of special staining methods.
In the human body, rickettsiae live and multiply primarily within cells that line small- to medium-sized blood vessels. Spotted fever group rickettsiae can grow in the cytoplasm or in the nucleus of the host cell. Once inside the host the rickettsiae multiply, resulting in damage and death to these cells. This causes blood to leak through tiny holes in vessel walls into adjacent tissues. This process causes the rash that is traditionally associated with Rocky Mountain spotted fever and also causes damage to organs and tissues.
Taxonomy
The genus Rickettsia is included in the bacterial tribe Rickettsieae, family Rickettsiaceae, and order Rickettsiales. This genus includes many other species of bacteria associated with human disease, including those in the spotted fever group and in the typhus group. More than 20 species are currently recognized in genus Rickettsia but not all are known to cause disease in humans. Other genotypes are also known but they have not been classified yet as valid species and new agents are being discovered in many areas of the world.
Signs and Symptoms
Rocky Mountain spotted fever can be very difficult to diagnose in its early stages, even by experienced physicians who are familiar with the disease.
Patients infected with R. rickettsii generally visit a physician in the first week of their illness, following an incubation period of about 5-10 days after a tick bite. The early clinical presentation of Rocky Mountain spotted fever is nonspecific and may resemble a variety of other infectious and non-infectious diseases.
The classic triad of findings for this disease are fever, rash, and history of tick bite. However, this combination is not always detected when the patient initially presents for care.
Initial Signs and Symptoms
Initial symptoms may include fever, nausea, vomiting, severe headache, muscle pain, lack of appetite.
The rash first appears 2-5 days after the onset of fever and is often not present or may be very subtle when the patient is initially seen by a physician. Younger patients usually develop the rash earlier than older patients. Most often it begins as small, flat, pink, non-itchy spots (macules) on the wrists, forearms, and ankles. These spots turn pale when pressure is applied and eventually become raised on the skin.
Later Signs and Symptoms
Later signs and symptoms include rash, abdominal pain, joint pain, diarrhea.
The characteristic red, spotted (petechial) rash of Rocky Mountain spotted fever is usually not seen until the sixth day or later after onset of symptoms, and this type of rash occurs in only 35% to 60% of patients with Rocky Mountain spotted fever. The rash involves the palms or soles in as many as 50% to 80% of patients; however, this distribution may not occur until later in the course of the disease. As many as 10% to 15% of patients may never develop a rash.
Abnormal Laboratory FindingsAbnormal laboratory findings seen in patients with Rocky Mountain spotted fever may include thrombocytopenia, hyponatremia, or elevated liver enzyme levels. See Laboratory Detection for more information on laboratory confirmation of Rocky Mountain spotted fever.
Hospitalization
Rocky Mountain spotted fever can be a very severe illness and patients often require hospitalization. Because R. rickettsii infects the cells lining blood vessels throughout the body, severe manifestations of this disease may involve the respiratory system, central nervous system, gastrointestinal system, or renal system. Host factors associated with severe or fatal Rocky Mountain spotted fever include advanced age, male sex, African-American race, chronic alcohol abuse, and glucose-6-phosphate dehydrogenase (G6PD) deficiency. Deficiency of G6PD is a sex-linked genetic condition which occurs with highest frequencies in people of African, Middle Eastern, and Southeast Asian origin; it affects approximately 12% of the U.S. African-American male population; deficiency of this enzyme is associated with a high proportion of severe cases of Rocky Mountain spotted fever. This is a rare clinical course that is often fatal within 5 days of onset of illness.
Long-term Health Problems
Long-term health problems following acute Rocky Mountain spotted fever infection include partial paralysis of the lower extremities, gangrene requiring amputation of fingers, toes, or arms or legs, hearing loss, loss of bowel or bladder control, movement disorders, and language disorders. These complications are most frequent in persons recovering from severe, life-threatening disease, often following lengthy hospitalizations.
Laboratory Detection
Although it is technically feasible, specific rapid laboratory confirmation of early Rocky Mountain spotted fever is rarely done. Therefore, treatment decisions should be based on epidemiologic and clinical clues, and should never be delayed while waiting for confirmation by laboratory results. Fundamental understanding of the signs, symptoms, and epidemiology of the disease is crucial in guiding requests for tests for Rocky Mountain spotted fever, sample collection and submission, and interpretation of laboratory results.
Routine clinical laboratory findings suggestive of Rocky Mountain spotted fever may include abnormal white blood cell count, thrombocytopenia, hyponatremia, or elevated liver enzyme levels (see Glossary for definitions of terms). Serologic assays are the most widely available and frequently used methods for confirming cases of Rocky Mountain spotted fever. The indirect immunofluorescence assay (IFA) (see figure) is generally considered the reference standard in Rocky Mountain spotted fever serology and is the test currently used by CDC and most state public health laboratories, but other well validated assays including ELISA, latex agglutination, and dot immunoassays can be used.
IFA can be used to detect either IgG or IgM antibodies. Blood samples taken early (acute) and late (convalescent) in the disease are the preferred specimens for evaluation. Most patients demonstrate increased IgM titers by the end of the first week of illness. Diagnostic levels of IgG antibody generally do not appear until 7-10 days after the onset of illness. It is important to consider the amount of time it takes for antibodies to appear when ordering laboratory tests, especially because most patients visit their physician relatively early in the course of the illness, before diagnostic antibody levels may be present. The value of testing two sequential serum or plasma samples together to show a rising antibody level is very important in confirming acute infection with rickettsial agents because antibody titers may persist in some individuals for years after the original exposure to any of a number rickettsial agents. IgG antibodies are more specific and reliable since other bacterial infections can also cause elevations in riskettsial IgM antibody titers.
The most rapid and specific diagnostic assays for Rocky Mountain spotted fever rely on molecular methods like PCR which can detect DNA present in 5-10 rickettsiae in a sample. While organisms can be detected in whole blood samples obtained at the acute onset of illness in a few hours, rickettsial DNA is most readily detected in fresh skin biopsies like those used in immunostaining procedures. PCR can also be done on the fixed tissues used in immunostaining, but it is less sensitive than with unfixed tissues. PCR methods can be R. rickettsii-specific but are usually confirmed by DNA sequencing of the amplified gene fragments. Consequently, this procedure is more specific than antibody-based methods which are often only genus or spotted fever group-specific. Specified diagnosis can also be confirmed by isolation of R. rickettsii from clinical samples like whole blood and biopsies. Materials can be shipped unfrozen or frozen and on dry ice to ensure optimal chances of isolation at the CDC. Isolation may require several weeks, but isolates are very important for investigating differences in the pathogenic properties and antimicrobial resistance of rickettsiae which cause disease in different parts of the United States.
Another approach to Rocky Mountain spotted fever diagnostics is immunostaining. This method is used by taking a skin biopsy of the rash from an infected patient prior to therapy or within the first 48 hours after antibiotic therapy has been started. Because rickettsiae are focally distributed in lesions of Rocky Mountain spotted fever, this test may not always detect the agent. Even in laboratories with expertise in performing this test, the sensitivity is only about 70% on biopsied tissues because of the scarcity of organisms in some samples. This assay may also be used to test tissues obtained at autopsy and has been used to confirm Rocky Mountain spotted fever in otherwise unexplained deaths (see figure). Immunostaining for spotted fever group rickettsiae is offered by the CDC, a few state health departments, and some university-based hospitals and commercial laboratories in the United States.
Treatment
Appropriate antibiotic treatment should be initiated immediately when there is a suspicion of Rocky Mountain spotted fever on the basis of clinical and epidemiologic findings. Treatment should not be delayed until laboratory confirmation is obtained.
If the patient is treated within the first 4-5 days of the disease, fever generally subsides within 24-72 hours after treatment with an appropriate antibiotic (usually in the tetracycline class). In fact, failure to respond to a tetracycline antibiotic argues against a diagnosis of RMSF. Severely ill patients may require longer periods before their fever resolves, especially if they have experienced damage to multiple organ systems. Preventive therapy in non-ill patients who have had recent tick bites is not recommended and may, in fact, only delay the onset of disease.
Doxycycline (100 mg every 12 hours for adults or 4 mg/kg body weight per day in two divided doses for children under 45 kg [100 lbs]) is the drug of choice for patients with Rocky Mountain spotted fever. Therapy is continued for at least 3 days after fever subsides and until there is unequivocal evidence of clinical improvement, generally for a minimum total course of 5 to 10 days. Severe or complicated disease may require longer treatment courses. Doxycycline is also the preferred drug for patients with ehrlichiosis, another tick-transmitted infection with signs and symptoms that may resemble Rocky Mountain spotted fever.
Tetracyclines are usually not the preferred drug for use in pregnant women because of risks associated with malformation of teeth and bones in unborn children. Chloramphenicol is an alternative drug that can be used to treat Rocky Mountain spotted fever; however, this drug may be associated with a wide range of side effects and may require careful monitoring of blood levels.
Prevention and Control
Limiting exposure to ticks is the most effective way to reduce the likelihood of Rocky Mountain spotted fever infection. In persons exposed to tick-infested habitats, prompt careful inspection and removal of crawling or attached ticks is an important method of preventing disease. It may take extended attachment time before organisms are transmitted from the tick to the host. Currently, no licensed vaccine is available for prevention of Rocky Mountain spotted fever.
Personal Protection Against Ticks
It is unreasonable to assume that a person can completely eliminate activities that may result in tick exposure. Therefore, prevention measures should emphasize personal protection when exposed to natural areas where ticks are present:
Wear light-colored clothing which allows you to see ticks that are crawling on your clothing.
Tuck your pants legs into your socks so that ticks cannot crawl up the inside of your pants legs.
Apply repellents to discourage tick attachment. Repellents containing permethrin can be sprayed on boots and clothing, and will last for several days. Repellents containing DEET (n, n-diethyl-m-toluamide) can be applied to the skin, but will last only a few hours before reapplication is necessary. Use DEET with caution on children. Application of large amounts of DEET on children has been associated with adverse reactions.
Conduct a body check upon return from potentially tick-infested areas by searching your entire body for ticks. Use a hand-held or full-length mirror to view all parts of your body. Remove any tick you find on your body.
Parents should check their children for ticks, especially in the hair, when returning from potentially tick-infested areas. Ticks may also be carried into the household on clothing and pets and only attached later so both should be examined carefully to exclude the ticks.
To Remove Attached Ticks:1. Use fine-tipped tweezers or notched tick extractor, and protect your fingers with a tissue, paper towel, or latex gloves (see figure). Persons should avoid removing ticks with bare hands.
2. Grasp the tick as close to the skin surface as possible and pull upward with steady, even pressure. Do not twist or jerk the tick; this may cause the mouthparts to break off and remain in the skin. (If this happens, remove mouthparts with tweezers. Consult your health care provider if illness occurs.)
3. After removing the tick, thoroughly disinfect the bite site and wash your hands with soap and water.
4. Do not squeeze, crush, or puncture the body of the tick because its fluids may contain infectious organisms. Skin accidentally exposed to tick fluids can be disinfected with iodine scrub, rubbing alcohol, or water containing detergents.
5. Save the tick for identification in case you become ill. This may help your doctor make an accurate diagnosis. Place the tick in a sealable plastic bag and put it in your freezer. Write the date of the bite on a piece of paper with a pencil and place it in the bag.
Rocky Mountain Spotted Fever
Prevention and Control
Limiting exposure to ticks is the most effective way to reduce the likelihood of Rocky Mountain spotted fever infection. In persons exposed to tick-infested habitats, prompt careful inspection and removal of crawling or attached ticks is an important method of preventing disease. It may take extended attachment time before organisms are transmitted from the tick to the host. Currently, no licensed vaccine is available for prevention of Rocky Mountain spotted fever.
Personal Protection Against Ticks
It is unreasonable to assume that a person can completely eliminate activities that may result in tick exposure. Therefore, prevention measures should emphasize personal protection when exposed to natural areas where ticks are present:
Wear light-colored clothing which allows you to see ticks that are crawling on your clothing.
Tuck your pants legs into your socks so that ticks cannot crawl up the inside of your pants legs.
Apply repellents to discourage tick attachment. Repellents containing permethrin can be sprayed on boots and clothing, and will last for several days. Repellents containing DEET (n, n-diethyl-m-toluamide) can be applied to the skin, but will last only a few hours before reapplication is necessary. Use DEET with caution on children. Application of large amounts of DEET on children has been associated with adverse reactions.
Conduct a body check upon return from potentially tick-infested areas by searching your entire body for ticks. Use a hand-held or full-length mirror to view all parts of your body. Remove any tick you find on your body.
Parents should check their children for ticks, especially in the hair, when returning from potentially tick-infested areas. Ticks may also be carried into the household on clothing and pets and only attached later so both should be examined carefully to exclude the ticks.
To Remove Attached Ticks:
Removal of an embedded tick using fine-tipped tweezers
1. Use fine-tipped tweezers or notched tick extractor, and protect your fingers with a tissue, paper towel, or latex gloves (see figure). Persons should avoid removing ticks with bare hands.
2. Grasp the tick as close to the skin surface as possible and pull upward with steady, even pressure. Do not twist or jerk the tick; this may cause the mouthparts to break off and remain in the skin. (If this happens, remove mouthparts with tweezers. Consult your health care provider if illness occurs.)
3. After removing the tick, thoroughly disinfect the bite site and wash your hands with soap and water.
4. Do not squeeze, crush, or puncture the body of the tick because its fluids may contain infectious organisms. Skin accidentally exposed to tick fluids can be disinfected with iodine scrub, rubbing alcohol, or water containing detergents.
5. Save the tick for identification in case you become ill. This may help your doctor make an accurate diagnosis. Place the tick in a sealable plastic bag and put it in your freezer. Write the date of the bite on a piece of paper with a pencil and place it in the bag.
Tick Removal
Folklore Remedies Don't Work!
Folklore remedies, such as the use of petroleum jelly or hot matches, do little to encourage a tick to detach from skin. In fact, they may make matters worse by irritating the tick and stimulating it to release additional saliva or regurgitate gut contents, increasing the chances of transmitting the pathogen. These methods of tick removal should be avoided.
Tick Control
Strategies to reduce populations of vector ticks through area-wide application of acaricides (chemicals that will kill ticks and mites) and control of tick habitats (e.g., leaf litter and brush) have been effective in small-scale trials. New methods being developed include applying acaricides to animal hosts by using baited tubes, boxes, and feeding stations in areas where these pathogens are endemic. Biological control with fungi, parasitic nematodes, and parasitic wasps may play supportive roles in integrated tick control efforts. Community-based, integrated, tick-management strategies may prove to be an effective public health response to reduce the incidence of tick-borne infections. However, limiting exposure to ticks is currently the most effective method of prevention of tick-transmitted diseases.
CDC Information Section
Saturday, July 22, 2006
Bacteria Enzyme May Help Regrow Spinal Cords
HealthDayBy Robert PreidtTuesday, July 18, 2006
TUESDAY, July 18 (HealthDay News) -- A treatment that promotes the regrowth of injured spinal cord nerves has proven successful in rats, U.S. researchers report.
A team at Johns Hopkins University in Baltimore and the University of Michigan in Ann Arbor used an enzyme called sialidase -- isolated from bacteria -- to treat a group of rats with nerve injuries. Within four weeks, the treated rats had grown twice as many new nerve fibers as untreated rats with the same kind of injury.
"We have established that the enzyme sialidase, which destroys one of the molecules that inhibits nerve regeneration, is sufficient to robustly improve nerve fiber outgrowth from the spinal cord," study director Ronald Schnaar, a professor of pharmacology and neuroscience at Hopkins' Institute of Basic Biomedical Sciences, said in a prepared statement.
As reported in the July 18 issue of the journal Proceedings of the National Academy of Sciences, the injury in the rats was similar to an injury that can occur in humans during childbirth or in a violent accident -- such as a motorcycle crash -- when the arm is pulled violently away from the body. This kind of injury causes nerves to be yanked out of the spinal cord, which results in a loss of feeling and muscle tone in the arm.
Surgery can be used to re-attach the yanked nerves to the spinal cord, but the results are often unsatisfactory. Unlike other nerves in the body, brain and spinal cord nerves fail to grow new nerve fibers because they're surrounded by signals from other cells in the injured area that tell the nerves to stop growing.
The next step in this research is to test whether this nerve regrowth helps restore muscle function. The scientists are also studying whether treatment with sialidase helps nerve regeneration in other types of spinal cord injuries.
Helicobacter pylori linked to circulatory disease
Common bacteria linked to circulatory disease
Reuters HealthWednesday, July 19, 2006
By David Douglas
NEW YORK (Reuters Health) - Infection by Helicobacter pylori, a bacteria associated with peptic ulcers and gastric cancer, also appears to increase the risk of diseases of the circulation, also referred to as "vascular disease," according to an analysis by Italian researchers.
Lead investigator Dr. Vincenzo Pasceri told Reuters Health that "clinical studies on the association between H. pylori and vascular diseases have produced conflicting results. While some studies have shown a significant association, these results have not been confirmed in others.
In the June issue of the American Heart Journal, Pasceri of San Filippo Neri Hospital, Rome, and colleagues report on their review of 17 studies that looked at the role of cytotoxin-associated gene A (CagA)-positive strains of H. pylori in patients with vascular disease of the heart and brain. More than 6,000 patients were included.
Overall, 13 studies found a statistically significant relationship between positive strains of CagA and heart disease. However, this relationship was not seen in CagA-negative strains. In 4 other studies, there was a significant association between brain disease and CagA-positive strains of H. pylori and, again, no association with negative strains.
Infection with CagA-positive H. pylori strains is associated with a modest but significant risk of vascular heart disease, continued Dr. Pasceri.
"Even a modest increase in cardiovascular risk may have great clinical importance," he concluded, "since chronic infection by virulent strains of H. pylori may be present in 20 percent to 40 percent of the population in Western countries."
Am Heart J 2006;151:1215-1222.
http://www.nlm.nih.gov/medlineplus/news/fullstory_36239.html
Sunday, July 16, 2006
Salmonella
Division of Bacterial and Mycotic Diseases
Center for Disease Control and Prevention
What is salmonellosis?
Salmonellosis is an infection with a bacteria called Salmonella. Most persons infected with Salmonella develop diarrhea, fever, and abdominal cramps 12 to 72 hours after infection. The illness usually lasts 4 to 7 days, and most persons recover without treatment. However, in some persons the diarrhea may be so severe that the patient needs to be hospitalized. In these patients, the Salmonella infection may spread from the intestines to the blood stream, and then to other body sites and can cause death unless the person is treated promptly with antibiotics. The elderly, infants, and those with impaired immune systems are more likely to have a severe illness.
What sort of germ is Salmonella?
The Salmonella germ is actually a group of bacteria that can cause diarrheal illness in humans. They are microscopic living creatures that pass from the feces of people or animals, to other people or other animals. There are many different kinds of Salmonella bacteria. Salmonella serotype Typhimurium and Salmonella serotype Enteritidis are the most common in the United States. Salmonella has been known to cause illness for over 100 years. They were discovered by a American scientist named Salmon, for whom they are named.
How can Salmonella infections be diagnosed?Many different kinds of illnesses can cause diarrhea, fever, or abdominal cramps. Determining that Salmonella is the cause of the illness depends on laboratory tests that identify Salmonella in the stools of an infected person. These tests are sometimes not performed unless the laboratory is instructed specifically to look for the organism. Once Salmonella has been identified, further testing can determine its specific type, and which antibiotics could be used to treat it.
Are there long term consequences to a Salmonella infection?
Persons with diarrhea usually recover completely, although it may be several months before their bowel habits are entirely normal. A small number of persons who are infected with Salmonella, will go on to develop pains in their joints, irritation of the eyes, and painful urination. This is called Reiter's syndrome. It can last for months or years, and can lead to chronic arthritis which is difficult to treat. Antibiotic treatment does not make a difference in whether or not the person later develops arthritis.
How do people catch Salmonella?
Salmonella live in the intestinal tracts of humans and other animals, including birds. Salmonella are usually transmitted to humans by eating foods contaminated with animal feces. Contaminated foods usually look and smell normal. Contaminated foods are often of animal origin, such as beef, poultry, milk, or eggs, but all foods, including vegetables may become contaminated. Many raw foods of animal origin are frequently contaminated, but fortunately, thorough cooking kills Salmonella. Food may also become contaminated by the unwashed hands of an infected food handler, who forgot to wash his or her hands with soap after using the bathroom. Salmonella may also be found in the feces of some pets, especially those with diarrhea, and people can become infected if they do not wash their hands after contact with these feces. Reptiles are particularly likely to harbor Salmonella and people should always wash their hands immediately after handling a reptile, even if the reptile is healthy. Adults should also be careful that children wash their hands after handling a reptile.
What can a person do to prevent this illness?
There is no vaccine to prevent salmonellosis. Since foods of animal origin may be contaminated with Salmonella, people should not eat raw or undercooked eggs, poultry, or meat. Raw eggs may be unrecognized in some foods such as homemade hollandaise sauce, caesar and other homemade salad dressings, tiramisu, homemade ice cream, homemade mayonnaise, cookie dough, and frostings. Poultry and meat, including hamburgers, should be well-cooked, not pink in the middle. Persons also should not consume raw or unpasteurized milk or other dairy products. Produce should be thoroughly washed before consuming.
Cross-contamination of foods should be avoided. Uncooked meats should be keep separate from produce, cooked foods, and ready-to-eat foods. Hands, cutting boards, counters, knives, and other utensils should be washed thoroughly after handling uncooked foods. Hand should be washed before handling any food, and between handling different food items.
People who have salmonellosis should not prepare food or pour water for others until they have been shown to no longer be carrying the Salmonella bacterium.
People should wash their hands after contact with animal feces. Since reptiles are particularly likely to have Salmonella, everyone should immediately wash their hands after handling reptiles. Reptiles (including turtles) are not appropriate pets for small children and should not be in the same house as an infant.
How common is salmonellosis?
Every year, approximately 40,000 cases of salmonellosis are reported in the United States. Because many milder cases are not diagnosed or reported, the actual number of infections may be thity or more times greater. Salmonellosis is more common in the summer than winter. Children are the most likely to get salmonellosis. Young children, the elderly, and the immunocompromised are the most likely to have severe infections. It is estimated that approximately 600 persons die each year with acute salmonellosis.
What else can be done to prevent salmonellosis?
It is important for the public health department to know about cases of salmonellosis. It is important for clinical laboratories to send isolates of Salmonella to the City, County, or State Public Health Laboratories so the specific type can be determined and compared with other Salmonella in the community. If many cases occur at the same time, it may mean that a restaurant, food or water supply has a problem which needs correction by the public health department. Some prevention steps occur everyday without you thinking about it. Pasteurization of milk and treating municipal water supplies are highly effective prevention measures that have been in place for many years. In the 1970s, small pet turtles were a common source of salmonellosis in the United States, and in 1975, the sale of small turtles was halted in this country. Improvements in farm animal hygiene, in slaughter plant practices, and in vegetable and fruit harvesting and packing operations may help prevent salmonellosis caused by contaminated foods. Better education of food industry workers in basic food safety and restaurant inspection procedures, may prevent cross-contamination and other food handling errors that can lead to outbreaks. Wider use of pasteurized egg in restaurants, hospitals, and nursing homes is an important prevention measure. In the future, irradiation or other treatments may greatly reduce contamination of raw meat.
What is the government doing about salmonellosis?
The Centers for Disease Control and Prevention (CDC) monitors the frequency of Salmonella infections in the country and assists the local and State Health Departments to investigate outbreaks and devise control measures. CDC also conducts research to better identify specific types of Salmonella. The Food and Drug Administration inspects imported foods, milk pasteurization plants, promotes better food preparation techniques in restaurants and food processing plants, and regulates the sale of turtles. The FDA also regulates the use of specific antibiotics as growth promotants in food animals. The US Department of Agriculture monitors the health of food animals, inspects egg pasteurization plants, and is responsible for the quality of slaughtered and processed meat. The US Environmental Protection Agency regulates and monitors the safety of our drinking water supplies.
How can I learn more about this and other public health problems?You can discuss any medical concerns you may have with your doctor or other heath care provider. Your local City or County Health Department can provide more information about this and other public health problems that are occurring in your area. General information about the public health of the nation is published every week in the "Morbidity and Mortality Weekly Report", by the CDC in Atlanta, GA. Epidemiologists in your local and State Health Departments are tracking a number of important public health problems, investigating special problems that arise, and helping to prevent them from occurring in the first place, or from spreading if they do occur.
What can I do to prevent salmonellosis?
Cook poultry, ground beef, and eggs thoroughly before eating. Do not eat or drink foods containing raw eggs, or raw unpasteurized milk.
If you are served undercooked meat, poultry or eggs in a restaurant, don't hesitate to send it back to the kitchen for further cooking.
Wash hands, kitchen work surfaces, and utensils with soap and water immediately after they have been in contact with raw meat or poultry.
Be particularly careful with foods prepared for infants, the elderly, and the immunocompromised.
Wash hands with soap after handling reptiles or birds, or after contact with pet feces.
Avoid direct or even indirect contact between reptiles (turtles, iguanas, other lizards, snakes) and infants or immunocompromised persons.
Don't work with raw poultry or meat, and an infant (e.g., feed, change diaper) at the same time.
Mother's milk is the safest food for young infants. Breast-feeding prevents salmonellosis and many other health problems.
Date: October 13, 2005
Content source: Coordinating Center for Infectious Diseases / Division of Bacterial and Mycotic Diseases
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Sunday, July 09, 2006
Cholera
Centers for Disease Control and Prevention - Division of Bacterial and Mycotic Diseases
In January 1991, epidemic cholera appeared in South America and quickly spread to several countries. A few cases have occurred in the United States among persons who traveled to South America or ate contaminated food brought back by travelers.Cholera has been very rare in industrialized nations for the last 100 years; however, the disease is still common today in other parts of the world, including the Indian subcontinent and sub-Saharan Africa. Although cholera can be life-threatening, it is easily prevented and treated. In the United States, because of advanced water and sanitation systems, cholera is not a major threat; however, everyone, especially travelers, should be aware of how the disease is transmitted and what can be done to prevent it.
What is cholera?
Cholera is an acute, diarrheal illness caused by infection of the intestine with the bacterium Vibrio cholerae. The infection is often mild or without symptoms, but sometimes it can be severe. Approximately one in 20 infected persons has severe disease characterized by profuse watery diarrhea, vomiting, and leg cramps. In these persons, rapid loss of body fluids leads to dehydration and shock. Without treatment, death can occur within hours.
How does a person get cholera?
A person may get cholera by drinking water or eating food contaminated with the cholera bacterium. In an epidemic, the source of the contamination is usually the feces of an infected person. The disease can spread rapidly in areas with inadequate treatment of sewage and drinking water. The cholera bacterium may also live in the environment in brackish rivers and coastal waters. Shellfish eaten raw have been a source of cholera, and a few persons in the United States have contracted cholera after eating raw or undercooked shellfish from the Gulf of Mexico. The disease is not likely to spread directly from one person to another; therefore, casual contact with an infected person is not a risk for becoming ill.
What is the risk for cholera in the United States?
In the United States, cholera was prevalent in the 1800s but has been virtually eliminated by modern sewage and water treatment systems. However, as a result of improved transportation, more persons from the United States travel to parts of Africa, Asia, or Latin America where epidemic cholera is occurring . U.S. travelers to areas with epidemic cholera may be exposed to the cholera bacterium. In addition, travelers may bring contaminated seafood back to the United States; foodborne outbreaks have been caused by contaminated seafood brought into this country by travelers.
What should travelers do to avoid getting cholera?The risk for cholera is very low for U.S. travelers visiting areas with epidemic cholera. When simple precautions are observed, contracting the disease is unlikely.
All travelers to areas where cholera has occured should observe the following recommendations:
Drink only water that you have boiled or treated with chlorine or iodine. Other safe beverages include tea and coffee made with boiled water and carbonated, bottled beverages with no ice.
Eat only foods that have been thoroughly cooked and are still hot, or fruit that you have peeled yourself.
Avoid undercooked or raw fish or shellfish, including ceviche.
Make sure all vegetables are cooked avoid salads.
Avoid foods and beverages from street vendors.
Do not bring perishable seafood back to the United States.
A simple rule of thumb is "Boil it, cook it, peel it, or forget it. "
Is a vaccine available to prevent cholera?
A recently developed oral vaccine for cholera is licensed and available in other countries (Dukoral from SBL Vaccines). The vaccine appears to provide somewhat better immunity and have fewer adverse effects than the previously available vaccine. However, CDC does not recommend cholera vaccines for most travelers, nor is the vaccine available in the United States . Further information about Dukoral can be obtained from the manufacturers:
Dukoral ® SBL Vaccin AB, SE-105 21 Stockholm, Swedentelephone +46-8-7351000,e-mail: info@sblvaccines.se
website:
Can cholera be treated?
Cholera can be simply and successfully treated by immediate replacement of the fluid and salts lost through diarrhea. Patients can be treated with oral rehydration solution, a prepackaged mixture of sugar and salts to be mixed with water and drunk in large amounts. This solution is used throughout the world to treat diarrhea. Severe cases also require intravenous fluid replacement. With prompt rehydration, fewer than 1% of cholera patients die. Antibiotics shorten the course and diminish the severity of the illness, but they are not as important as rehydration. Persons who develop severe diarrhea and vomiting in countries where cholera occurs should seek medical attention promptly.
How long will the current epidemic last?
Predicting how long a Cholera epidemic will last is difficult. The cholera epidemic in Africa has lasted more than 30 years. In areas with inadequate sanitation, a cholera epidemic cannot be stopped immediately, and, although far fewer cases have been reported from Latin America and Asia in recent years, there are no signs that the global Cholera pandemic will end soon. Major improvements in sewage and water treatment systems are needed in many countries to prevent future epidemic cholera.
What is the U.S. government doing to combat cholera?
U.S. and international public health authorities are working to enhance surveillance for cholera, investigate cholera outbreaks, and design and implement preventive measures. The Centers for Disease Control and Prevention investigates epidemic cholera wherever it occurs and trains laboratory workers in proper techniques for identification of V. cholerae. In addition, the Centers for Disease Control and Prevention provides information on diagnosis, treatment, and prevention of cholera to public health officials and educates the public about effective preventive measures. The U.S. Agency for International Development is sponsoring some of the international government activities and is providing medical supplies to affected countries. The Environmental Protection Agency is working with water and sewage treatment operators in the United States to prevent contamination of water with the cholera bacterium. The Food and Drug Administration is testing imported and domestic shellfish for V. cholerae and monitoring the safety of U.S. shellfish beds through the shellfish sanitation program. With cooperation at the state and local, national, and international levels, assistance will be provided to countries where cholera is present, and the risk to U.S. residents will remain small.
Where can a traveler get information about cholera?
The global picture of cholera changes periodically, so travelers should seek updated information on countries of interest. The Centers for Disease Control and Prevention maintains a travelers' information telephone line on which callers can receive recent information on cholera and other diseases of concern to travelers. Data for this service are obtained from the World Health Organization. The number is 877-FYI-TRIP (394-8747) or check out :
CDC.Gov/travel
Centers for Disease Control and Prevention
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Cholera - General Fact Sheet from World Health Organization
Cholera
Cholera is an acute intestinal infection caused by the bacterium Vibrio cholerae. It has a short incubation period, from less than one day to five days, and produces an enterotoxin that causes a copious, painless, watery diarrhoea that can quickly lead to severe dehydration and death if treatment is not promptly given. Vomiting also occurs in most patients.
Most persons infected with V. cholerae do not become ill, although the bacterium is present in their faeces for 7-14 days. When illness does occur, more than 90% of episodes are of mild or moderate severity and are difficult to distinguish clinically from other types of acute diarrhoea. Less than 10% of ill persons develop typical cholera with signs of moderate or severe dehydration.
Background
The vibrio responsible for the seventh pandemic, now in progress, is known as V. cholerae O1, biotype El Tor. The current seventh pandemic began in 1961 when the vibrio first appeared as a cause of epidemic cholera in Celebes (Sulawesi), Indonesia. The disease then spread rapidly to other countries of eastern Asia and reached Bangladesh in 1963, India in 1964, and the USSR, Iran and Iraq in 1965-1966.
In 1970 cholera invaded West Africa, which had not experienced the disease for more than 100 years. The disease quickly spread to a number of countries and eventually became endemic in most of the continent. In 1991 cholera struck Latin America, where it had also been absent for more than a century. Within the year it spread to 11 countries, and subsequently throughout the continent.
Until 1992, only V. cholerae serogroup O1 caused epidemic cholera. Some other serogroups could cause sporadic cases of diarrhoea, but not epidemic cholera. Late that year, however, large outbreaks of cholera began in India and Bangladesh that were caused by a previously unrecognized serogroup of V. cholerae, designated O139, synonym Bengal. Isolation of this vibrio has now been reported from 11 countries in South-East Asia. It is still unclear whether V. cholerae O139 will extend to other regions, and careful epidemiological monitoring of the situation is being maintained.
Transmission
Cholera is spread by contaminated water and food. Sudden large outbreaks are usually caused by a contaminated water supply. Only rarely is cholera transmitted by direct person-to-person contact. In highly endemic areas, it is mainly a disease of young children, although breastfeeding infants are rarely affected.
Vibrio cholerae is often found in the aquatic environment and is part of the normal flora of brackish water and estuaries. It is often associated with algal blooms (plankton), which are influenced by the temperature of the water. Human beings are also one of the reservoirs of the pathogenic form of Vibrio cholerae.
Treatment
When cholera occurs in an unprepared community, case-fatality rates may be as high as 50% -- usually because there are no facilities for treatment, or because treatment is given too late. In contrast, a well-organized response in a country with a well established diarrhoeal disease control programme can limit the case-fatality rate to less than 1%.
Most cases of diarrhoea caused by V. cholerae can be treated adequately by giving a solution of oral rehydration salts (the WHO/UNICEF standard sachet). During an epidemic, 80-90% of diarrhoea patients can be treated by oral rehydration alone, but patients who become severely dehydrated must be given intravenous fluids.
In severe cases, an effective antibiotic can reduce the volume and duration of diarrhoea and the period of vibrio excretion. Tetracycline is the usual antibiotic of choice, but resistance to it is increasing. Other antibiotics that are effective when V. cholerae are sensitive to them include cotrimoxazole, erythromycin, doxycycline, chloramphenicol and furazolidone.
Epidemic control and preventive measures
When cholera appears in a community it is essential to ensure three things: hygienic disposal of human faeces, an adequate supply of safe drinking water, and good food hygiene. Effective food hygiene measures include cooking food thoroughly and eating it while still hot; preventing cooked foods from being contaminated by contact with raw foods, including water and ice, contaminated surfaces or flies; and avoiding raw fruits or vegetables unless they are first peeled. Washing hands after defecation, and particularly before contact with food or drinking water, is equally important.
Routine treatment of a community with antibiotics, or "mass chemoprophylaxis", has no effect on the spread of cholera, nor does restricting travel and trade between countries or between different regions of a country. Setting up a cordon sanitaire at frontiers uses personnel and resources that should be devoted to effective control measures, and hampers collaboration between institutions and countries that should unite their efforts to combat cholera.
Limited stocks of two oral cholera vaccines that provide high-level protection for several months against cholera caused by V. cholerae O1 have recently become available in a few countries. Both are suitable for use by travellers but they have not yet been used on a large scale for public health purposes. Use of this vaccine to prevent or control cholera outbreaks is not recommended because it may give a false sense of security to vaccinated subjects and to health authorities, who may then neglect more effective measures.
In 1973 the WHO World Health Assembly deleted from the International Health Regulations the requirement for presentation of a cholera vaccination certificate. Today, no country requires proof of cholera vaccination as a condition for entry, and the International Certificate of Vaccination no longer provides a specific space for recording cholera vaccinations.
Trade in food products coming from cholera-infected regions
The publication "Guidelines for Cholera Control", available through WHO's Distribution and Sales Unit, states the following:
"Vibrio cholerae 01 can survive on a variety of foodstuffs for up to five days at ambient temperature and up to 10 days at 5-10 degrees Celsius. The organism can also survive freezing. Low temperatures, however, limit proliferation of the organism and thus may prevent the level of contamination from reaching an infective dose.
"The cholera vibrio is sensitive to acidity and drying, and commercially prepared acidic (ph 4.5 or less) or dried foods are therefore without risk. Gamma irradiation and temperatures above 70 degrees Celsius also destroy the vibrio and foods processed by these methods, according to the standards of the Codex Alimentarius, and
"The foods that cause greatest concern to importing countries are seafood and vegetables that may be consumed raw. However, only rare cases of cholera have occurred as a result of eating food, usually seafood, transported across international borders by individuals.
"...Indeed, although individual cases and clusters of cases have been reported, WHO has not documented a significant outbreak of cholera resulting from commercially imported food."
In summary, although there is a theoretical risk of cholera transmission with international food trade, the weight of evidence suggests that this risk is very small and can normally be dealt with by means other than an embargo on importation.
WHO believes that the best way to deal with food imports from cholera-affected areas is for importing countries to agree, with food exporters, on good hygienic practices which need to be followed during food handling and processing to prevent, eliminate or minimize the risk of any potential contamination; and to set up arrangements to obtain assurance that these measures are adequately carried out.
At present, WHO has no information that food commercially imported from affected countries has been implicated in outbreaks of cholera in importing countries. The isolated cases of cholera, that have been related to imported food, have been associated with food which had been in the possession of individual travellers. Therefore, it may be concluded that food produced under good manufacturing practices poses only a negligible risk for cholera transmission. Consequently, WHO believes that food import restrictions, based on the sole fact that cholera is epidemic or endemic in a country, are not justified.
For more information contact:
WHO Media centre Telephone: +41 22 791 2222
E-mail: mediainquiries@who.int
World Health Organization: Cholera
Saturday, July 01, 2006
Listeria Infections
Listeria infections (known as listeriosis) are caused by the bacterium Listeria monocytogenes. Infection is rare, but when it does occur it most frequently affects pregnant women in their last trimester, newborns, and children and adults whose immunity is weakened by diseases such as cancer or AIDS. People who have had various types of transplants are also more at risk for listeriosis.
Listeria bacteria can be transmitted through soil and water. A person can also ingest listeria by eating certain foods, such as deli meats and cold cuts, soft-ripened cheese, milk, undercooked chicken, uncooked hot dogs, shellfish, and coleslaw made from contaminated cabbage. Many cases of infection, however, have no identifiable source.
Listeria infections may create symptoms such as fever, vomiting, diarrhea, lethargy, difficulty breathing, and poor feeding. Pregnant women who develop listeriosis may experience only mild flu-like symptoms, although they are at risk for premature delivery, miscarriage, and stillbirth. People who have weakened immune systems are at particular risk for developing other more serious illnesses from listeriosis, including pneumonia, meningitis, and sepsis. Cases of listeriosis are relatively rare. In 2004, just 120 cases were reported in the United States.
In all cases, the earlier listeriosis is detected and treated, the better. And particularly if you are pregnant or in one of the other high-risk groups, avoiding certain foods and beverages can reduce your risk of contracting this infection.
Treating Listeriosis
Listeriosis is usually treated with antibiotics administered in the hospital through an intravenous catheter (IV). Typically, treatment lasts for about 10 days but that can vary depending on the body's ability to fight off the infection.
Children whose immune systems are compromised by illness or infection, such as cancer or AIDS, are more likely to develop severe listeriosis infections and may require additional treatment.
Preventing Listeriosis
Although there are no vaccines against the bacteria that cause listeriosis, you can help reduce the risk for yourself and your family by taking certain food safety precautions:
Always cook food (especially meat and eggs) thoroughly to the proper internal temperature.
Wash fruits and vegetables thoroughly before eating.
Only drink pasteurized milk, and make sure that milk is refrigerated at the appropriate temperature, which is less than 40 degrees Fahrenheit (4 degrees Celcius).
Avoid foods made from unpasteurized milk.
If you're in a high-risk group, avoid soft cheeses such as feta, Brie, Camembert, blue-veined and Mexican-style cheeses unless they have labels that clearly state they are made from pasteurized milk.
Reheat precooked, prepackaged foods - such as deli meats or hot dogs - to steaming hot temperatures, especially if you're pregnant.
When to Call Your Child's Doctor
Call your child's doctor immediately if your child develops rapid or labored breathing, fever, poor feeding, vomiting, a high-pitched cry, excessive sleepiness (lethargy), or irritability. If your child has listeriosis, the doctor can rule out any other illnesses and start treatment.
Reviewed by: Kate Cronan, MD
Date reviewed: November 2005
Originally reviewed by: Joel Klein, MD
KidsHealth
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Listeriosis
Listeriosis, a serious infection caused by eating food contaminated with the bacterium Listeria monocytogenes, has recently been recognized as an important public health problem in the United States. The disease affects primarily pregnant women, newborns, and adults with weakened immune systems. It can be avoided by following a few simple recommendations.
What are the symptoms of listeriosis?A person with listeriosis has fever, muscle aches, and sometimes gastrintestinal symptoms such as nausea or diarrhea. If infection spreads to the nervous system, symptoms such as headache, stiff neck, confusion, loss of balance, or convulsions can occur.
Infected pregnant women may experience only a mild, flu-like illness; however, infections during pregnancy can lead to miscarraige or stillbirth, premature delivery, or infection of the newborn.
How great is the risk for listeriosis?In the United States, an estimated 2,500 persons become seriously ill with listeriosis each year. Of these, 500 die.
At increased risk are:
Pregnant women - They are about 20 times more likely than other healthy adults to get listeriosis. About one-third of listeriosis cases happen during pregnancy.
Newborns - Newborns rather than the pregnant women themselves suffer the serious effects of infection in pregnancy.
Persons with weakened immune systems
Persons with cancer, diabetes, or kidney disease
Persons with AIDS - They are almost 300 times more likely to get listeriosis than people with normal immune systems.
Persons who take glucocorticosteroid medications
The elderly
Healthy adults and children occasionally get infected with Listeria, but they rarely become seriously ill.
How does Listeria get into food?
Listeria monocytogenes is found in soil and water. Vegetables can become contaminated from the soil or from manure used as fertilizer.Animals can carry the bacterium without appearing ill and can contaminate foods of animal origin such as meats and dairy products. The bacterium has been found in a variety of raw foods, such as uncooked meats and vegetables, as well as in processed foods that become contaminated after processing, such as soft cheeses and cold cuts at the deli counter. Unpasteurized (raw) milk or foods made from unpasteurized milk may contain the bacterium. Listeria is killed by pasteurization and cooking; however, in certain ready-to-eat foods such as hot dogs and deli meats, contamination may occur after cooking but before packaging.
How do you get listeriosis?
You get listeriosis by eating food contaminated with Listeria. Babies can be born with listeriosis if their mothers eat contaminated food during pregnancy. Although healthy persons may consume contaminated foods without becoming ill, those at increased risk for infection can probably get listeriosis after eating food contaminated with even a few bacteria. Persons at risk can prevent Listeria infection by avoiding certain high-risk foods and by handling food properly.
Can listeriosis be prevented?
The general guidelines recommended for the prevention of listeriosis are similar to those used to help prevent other foodborne illnesses, such as salmonellosis.
How can you reduce your risk for listeriosis?
General recommendations:
Thoroughly cook raw food from animal sources, such as beef, pork, or poultry.
Wash raw vegetables thoroughly before eating.
Keep uncooked meats separate from vegetables and from cooked foods and ready-to-eat foods.
Avoid unpasteurized (raw) milk or foods made from unpasteurized milk.
Wash hands, knives, and cutting boards after handling uncooked foods.
Consume perishable and ready-to-eat foods as soon as possible.
Recommendations for persons at high risk, such as pregnant women and persons with weakened immune systems, in addition to the recommendations listed above:
Do not eat hot dogs, luncheon meats, or deli meats, unless they are reheated until steaming hot.
Avoid getting fluid from hot dog packages on other foods, utensils, and food preparation surfaces, and wash hands after handling hot dogs, luncheon meats, and deli meats.
Do not eat soft cheeses such as feta, Brie, and Camembert, blue-veined cheeses, or Mexican-style cheeses such as queso blanco, queso fresco, and Panela, unless they have labels that clearly state they are made from pastuerized milk.
Do not eat refrigerated pâtés or meat spreads. Canned or shelf-stable pâtés and meat spreads may be eaten.
Do not eat refrigerated smoked seafood, unless it is contained in a cooked dish, such as a casserole.
Refrigerated smoked seafood, such as salmon, trout, whitefish, cod, tuna or mackerel, is most often labeled as "nova-style," "lox," "kippered," "smoked," or "jerky." The fish is found in the refrigerator section or sold at deli counters of grocery stores and delicatessens. Canned or shelf-stable smoked seafood may be eaten.
How do you know if you have listeriosis?
There is no routine screening test for susceptibility to listeriosis during pregnancy, as there is for rubella and some other congenital infections. If you have symptoms such as fever or stiff neck, consult your doctor. A blood or spinal fluid test (to cultivate the bacteria) will show if you have listeriosis. During pregnancy, a blood test is the most reliable way to find out if your symptoms are due to listeriosis.
What should you do if you've eaten a food recalled because of Listeria contamination?
The risk of an individual person developing Listeria infection after consumption of a contaminated product is very small. If you have eaten a contaminated product and do not have any symptoms, we do not recommend that you have any tests or treatment, even if you are in a high-risk group. However, if you are in a high-risk group, have eaten the contaminated product, and within 2 months become ill with fever or signs of serious illness, you should contact your physician and inform him or her about this exposure.
Can listeriosis be treated?
When infection occurs during pregnancy, antibiotics given promptly to the pregnant woman can often prevent infection of the fetus or newborn.Babies with listeriosis receive the same antibiotics as adults, although a combination of antibiotics is often used until physicians are certain of the diagnosis. Even with prompt treatment, some infections result in death. This is particularly likely in the elderly and in persons with other serious medical problems.
What is the government doing about listeriosis?
Government agencies and the food industry have taken steps to reduce contamination of food by the Listeria bacterium. The Food and Drug Administration and the U. S. Department of Agriculture monitor food regularly. When a processed food is found to be contaminated, food monitoring and plant inspection are intensified, and if necessary, the implicated food is recalled. The National Center for Infectious Diseases (NCID) is studying listeriosis in several states to help measure the impact of prevention activities and recognize trends in disease occurrence. NCID also assists local health departments in investigating outbreaks.
Early detection and reporting of outbreaks of listeriosis to local and state health departments can help identify sources of infection and prevent more cases of the disease.
Date: October 12, 2005
Content source: Coordinating Center for Infectious Diseases / Division of Bacterial and Mycotic Diseases
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