From root@aspensys.com Wed Jun 21 15:28:38 1995 Date: Wed, 21 Jun 1995 18:42:12 +0500 CENTERS FOR DISEASE CONTROL AND PREVENTION HIV/AIDS PREVENTION CDC NATIONAL AIDS HOTLINE TRAINING BULLETIN ................................................................. June 19, 1995 #146 These are answers from the Centers for Disease Control and Prevention (CDC) to questions concerning the MMWR Cryptosporidiosis Workshop Report of June 15, 1995. 1. What is Cryptosporidium and how is it transmitted? Cryptosporidium is a small parasite that is found in the feces of infected humans or young animals. Humans are infected when they ingest oocysts that contaminate water, food, hands, or other objects. 2. What are the symptoms? In immunocompetent persons, Cryptosporidium infection causes diarrhea that is usually watery, lasts 1 to 2 weeks, and is often accompanied by abdominal cramps, fatigue, nausea, vomiting, and low-grade fever. People usually develop symptoms about 5-9 days after ingesting the oocysts. In persons with severely weakened immune systems, cryptosporidiosis can be chronic and severe. The watery diarrhea can be prolonged and debilitating, and may be fatal. 3. Who is at risk of severe cryptosporidiosis? Persons at risk of severe cryptosporidiosis include persons with AIDS, persons who have cancer or organ or bone marrow transplants who are taking drugs that weaken the immune system, and persons who are born with genetically weakened immune systems. 4. How much Cryptosporidium infection is there? In the general population in the United States, about 1% of stool specimens from persons with diarrhea have tested are positive for Cryptosporidium. About 15%-30% of adults in the United States have evidence of some previous infection with Cryptosporidium, based on a blood test. Cryptosporidiosis is among the most common causes of diarrhea in patients with AIDS in the United States. The actual incidence of cryptosporidiosis in AIDS patients is unknown, but we think that 5%-10% of AIDS patients will develop cryptosporidiosis each year. 5. Why is Cryptosporidium a problem in treated drinking water? Most surfaces water sources, such as lakes, rivers, and streams, contain some Cryptosporidium oocysts. The oocysts are highly resistant to chlorine and other disinfectants, which are used to kill bacteria and viruses in drinking water. In addition, the oocysts are so small (4-6 microns in diameter) that conventional municipal water treatment does not guarantee 100% removal of the oocysts. When tested repeatedly, a little over half of the public water supplies that obtain raw water from rivers, lakes, and streams have low levels of Cryptosporidium in the treated, filtered water. 6. How can I tell if there is Cryptosporidium in my drinking water? Special tests are needed to identify Cryptosporidium in water. These tests are expensive and are not very good for detecting low numbers of organisms that may be present in tap water. These tests involve filtering large volumes of water through a filter and examining the filtrate under a special microscope. 7. What is the treatment of Cryptosporidium infection? Most people get better without treatment for cryptosporidiosis because their immune system gets rid of the infection without treatment. Although some drugs seem to improve the symptoms in some patients with weakened immune systems, no safe and generally effective form of treatment for cryptosporidiosis has been identified to date. One drug, paromomycin, appears to be the most promising currently. 8. How many people in Milwaukee died from the Cryptosporidium outbreak? We don't know. The most severe cryptosporidiosis occurs in persons who are most profoundly immunosuppressed, and who are most likely to die from other infections. Undoubtedly, the debilitation and dehydration caused by this infection led to the early death of some AIDS patients, but we do not know how many persons in the Milwaukee area died as a result of infection with Cryptosporidium. It can be very difficult to differentiate dying "of" from dying "with" cryptosporidiosis. 9. If CDC knows there is some risk from drinking water, why doesn't CDC recommend that all immunocompromised persons boil or filter their drinking water or drink bottled water? Shouldn't everything possible be done to prevent these devastating infections in persons with AIDS? Short answer: CDC has not made a national recommendation for all immunocompromised persons because the risk of getting cryptosporidiosis from drinking tap water is probably very low compared to that from other sources, and because the measures required to reduce the risk from drinking water can be burdensome to the individual in terms of inconvenience and cost. Long answer: First we need to put the risk of getting cryptosporidiosis from drinking tap water into perspective. The available data suggest that in most situations, this risk is low compared with the risk associated with contact with the stools of infected animals or people, hand-to-mouth spread from surfaces that are contaminated with infected stool, or by swallowing contaminated recreational water. For example, persons with HIV infection who live in large metropolitan areas with unfiltered water sources do not appear to have increased rates of Cryptosporidium infection compared to those who live in communities with other types of drinking water (CDC, unpublished data). Second, for people whose drinking water comes from uncontaminated ground water sources and those whose drinking water comes from high quality surface sources, the risk of getting Cryptosporidium infection from drinking water is probably extremely low. A national recommendation would inappropriately target these people. Third, reducing the overall risk of cryptosporidiosis may involve major changes in lifestyle, not only in changing drinking water but in other matters as well. Drinking only boiled, filtered, or bottled water is inconvenient and can be expensive. Information point: In recent cryptosporidiosis outbreaks, people who did not use these measures for all their drinking water appeared to be at the same risk as people who never used them. In sum: To make such a national recommendation would be burdensome and expensive for individuals. In many cases these recommendations are unnecessary, and focusing on drinking water ignores the importance of other modes of transmission. 10. If CDC is not issuing a national recommendation, what is its message for immunocompromised persons in the United States? Persons who have severely weakened immune systems should be aware that Cryptosporidium infection can cause severe diarrhea, and that they can get this infection from contact with the stools of infected persons or young animals, from hand-to-mouth spread from surfaces that are contaminated with infected stool, by swallowing contaminated recreational water, by drinking contaminated tap water, or by eating contaminated foods. The report of this conference provides information on steps that can be taken to reduce the risk from water and other sources. Because the risk from water probably varies from city to city and because taking these steps can be expensive, inconvenient, or disruptive, CDC recommends that severely immunosuppressed persons discuss ways to reduce the risk of cryptosporidiosis with their health care provider. 11. Some state and local public health agencies have already recommended that immunocompromised persons drink only boiled, filtered, or bottled water. What does CDC think about this? Because we do not have national data, these decisions should be made by local public health agencies who have assessed the level of risk in their communities. Other cities and states have assessed the risk and decided that in their location, the risk of infection with Cryptosporidium from drinking water is extremely low and does not warrant such a recommendation. 12. How can I decide whether or not to take these measures? No specific criteria have been established. If you have AIDS, if you have cancer or have had an organ or bone marrow transplant and are taking drugs that weaken your immune system, or if you were born with a genetically weakened immune system, you may be at risk for severe cryptosporidiosis. CDC suggests you talk to your health care provider regarding the level of immune suppression and on ways to reduce the risk of infection. Your public health agency may be able to provide you information on the quality of water in your community. Unfortunately, assessing the risk of Cryptosporidium infection from your drinking water is difficult. Many cities do not test for Cryptosporidium in their water because testing is expensive and time-consuming, and the results are difficult to interpret. A positive test does not necessarily mean there is a risk, and a negative test does not necessarily mean there is no risk. If your drinking water comes from a surface source (lake, stream, or river) that is unfiltered, or one that is located downstream from a sewage outfall or runoff from animal waste, your water may be at increased risk of containing Cryptosporidium oocysts. 13. Besides taking these measures, what other steps should immunosuppressed persons take to avoid infection with Cryptosporidium? * Avoid drinking untreated surface water directly from lakes or streams. * Avoid swimming in lakes or municipal swimming pools. * Avoid working with large groups of diaper-aged children. * Avoid sexual practices that may result in exposure to feces. * Avoid contact with feces of all animals, particularly young farm animals such as calves. * Wash your hands thoroughly after any contact with young animals or with soil (e.g., gardening), or after changing diapers. 14. Is the U.S. water supply safe? The U.S. water supply is among the best in the world. It could be made safer, but additional improvements come at a price. Each community needs to decide how far to go to improve their water quality. 15. Why don't we know more about Cryptosporidium? 15. Cryptosporidium was first found to infect humans just over 20 years ago. As with other emerging infectious diseases, we have lacked the necessary research and diagnostic tools to adequately define the risk of infection and understand the disease. 16. Is Cryptosporidium in drinking water a new problem? Cryptosporidium has probably been in our water for many years. We have become aware of the problem much more in recent years because of the rapid growth in the number of people who are immunosuppressed and who are vulnerable to severe disease. In addition, only in the past few years have tests been developed to detect Cryptosporidium in water. On the other hand, the numbers of oocysts in the water may have increased in some communities because of increased contamination of the source water going into the water treatment plants by human sewage and animal feces. 17. What is CDC doing about Cryptosporidium in drinking water? CDC is involved in three major arenas: * Coordination of the U.S. public health response to this threat * Research to define the risk of getting Cryptosporidium infection from drinking water * Development of better methods for detecting Cryptosporidium oocysts in environmental water samples and detecting infection in humans Information Points: CDC * has been working closely with the American Water Works Association, the U.S. Environmental Protection Agency, and state health departments through the Council of State and Territorial Epidemiologists, to address public health concerns about waterborne cryptosporidiosis and to act on suggestions made by the attendees of the September conference * hosts biweekly meetings of the Working Group on Waterborne Cryptosporidiosis, a coalition of agencies and organizations concerned about cryptosporidiosis, to exchange information and to develop educational materials for immunosuppressed persons, the public, health care providers, state and local health departments, and water utility operators * continues to provide epidemiologic and laboratory assistance to state and local health departments in investigating outbreaks and assessing the magnitude of the problem (Maine apple cider; recreational water exposure in a lake in New Jersey; well water, Washington State; Las Vegas) * encouraged the Council for State and Territorial Epidemiologists to make cryptosporidiosis a nationally notifiable disease, which it did, and is working with states to make it reportable in each state * is working with manufacturers of water filters and bottled water to encourage and develop more informative labeling of these products regarding Cryptosporidium * is working with collaborators to determine how much Cryptosporidium occurs in drinking water * is developing less labor-intensive and more efficient methods for detecting Cryptosporidium oocysts in environmental water samples * is developing more accurate methods for detecting antibodies to Cryptosporidium in blood samples. Disclaimer: CDC Hotline Training Bulletins The information in the "CDC Hotline Training Bulletins" is provided by CDC and NIH for use by the CDC National AIDS Hotline in responding to general questions from the public about HIV and AIDS. The bulletins are not intended to be comprehensive discussions of the subject areas. Treatment and drug therapy options change as new research and clinical experiences broaden scientific knowledge. Therefore, persons seeking information on drug therapy should refer to the product information sheet included in all drug packages for the most current and accurate information about a particular drug, especially if the drug is new or infrequently used. HIV-infected individuals should consult their personal physician for specific concerns about their health. For persons desiring more information on a specific topic, public, medical, and university libraries can provide excellent references. The AIDS Clinical Trials Information Service (800-874-2572) can provide information about ongoing HIV/AIDS clinical trials; the HIV/AIDS Treatment Information Service (800-448-0440) can assist with information about the latest treatments for persons with HIV infection or AIDS.