Pathogen News archives:

From 04/09: Cholera Outbreak in Zimbabwe, Anwar Huq and Rita R. Colwell

Cholera is a waterborne diarrheal disease caused by ingestion of water contaminated with the pathogenic bacterium, Vibrio cholerae, a naturally occurring species in the aquatic environment. The infection is dose dependent and approximately 106 bacteria will cause full blown disease; however, as few as 103 bacteria can also cause diarrhea.  Most susceptible are malnourished children and the immune-suppressed.  The disease spreads from person to person under conditions of poor hygiene and poor sanitation.  Nevertheless, cholera is a disease that can easily be treated by replacement of body fluids (oral rehydration therapy) and, for severe cases, an antibiotic like tetracycline.

Zimbabwe is an unfortunate victim of infrastructure degradation. According to the World Health Organization, low level outbreaks of cholera occurred in Zimbabwe throughout 2008, with the current full-blown epidemic beginning in August, 2008. This country is now experiencing a drastic decline in public health and water systems, as the country goes through an economic meltdown, with concomitant severe deterioration in living conditions.  In Zimbabwe today, 80% of the population does not have access to safe drinking water, and most lack proper sanitary facilities, conditions conducive to transmission of cholera.  The situation is exacerbated by the closing of major hospitals because of a shortage of staff and medical supplies.

On Wednesday, December 17, 2008, the United Nations reported 1,111 people dead from cholera and 20,581 suspected cases reported.  The WHO reported 18,413 cases as of December 15, 2008.  The New York Times at about the same time cited 16,000 cases and 780 deaths. Although the country’s president claims the epidemic has ended, health experts are warning that the number of cases could surpass 60,000, with half of the country’s 12 million inhabitants at risk.  The epidemic has spread into the neighboring countries, notably South Africa and Botswana.

Cholera is an imminently preventable disease since boiling water before drinking will kill the bacteria.  In 1973, Distinguished University Professor Rita Colwell began her research program at the University of Maryland to understand the ecology of V. cholerae. In 1996, Dr. Colwell and Dr. Anwar Huq, Professor of Maryland Pathogen Research Institute, developed a method of simple filtration of surface waters with four layers of folded sari cloth that effectively removes 99% of the cholera bacteria in surface water in Bangladesh, since cholera bacteria in the natural environment are attached to copepods and other plankton, copepods being a natural host. A field trial conducted in Bangladesh showed 50% reduction of cases of cholera in the villages in Bangladesh that used sari filtration to filter natural water for domestic purpose including drinking. The team is now working to develop a similar filtration procedure, using inexpensive material available in African countries. In addition, the Colwell team is also extensively working on developing a predictive model for cholera, based on satellite remote sensing for global prediction, to assist public health officials in preparing for future epidemics of cholera.

REFERENCES AND LINKS
ColwellSariPNAS2003.pdf
HuqSariFiltAEM1996.pdf
LobitzPNAS2007.pdf
http://www.who.int/hac/crises/zwe/zimbabwe_cholera_epi_bulletin1_15dec2008.pdf
http://www.who.int/mediacentre/news/releases/2008/pr49/en/index.html
http://edition.cnn.com/2008/WORLD/africa/12/18/zimbabwe.cholera/index.html?eref=edition#cnnSTCText
http://www.nytimes.com/2008/12/12/world/africa/12cholera.html?_r=1

Dr. Rita Colwell is a Distinguished University Professor at the University of Maryland at College Park and at Johns Hopkins University Bloomberg School of Public Health. Her interests are focused on global infectious diseases, water and health, and she is currently developing an international network to address emerging infectious diseases and water issues, including safe drinking water for both the developed and developing world. Dr. Colwell served as the 11th Director of the National Science Foundation from 1998-2004. Before going to NSF, Dr. Colwell was President of the University of Maryland Biotechnology Institute and Professor of Microbiology and Biotechnology at the University Maryland.

Dr. Anwar Huq is a Research Professor at the Maryland Pathogen Research Institute. His laboratory research focuses on the isolation, identification and characterization of important enteric bacterial agents using conventional, immunological and genetic methods.  Specific research interests include: mode of transmission of medically important pathogens and measures for the prevention of the disease,  environmental pollution, its implication and questions related to microbiology in the areas of public health and hygiene, impact of global climate change in the ecology of pathogens responsible for causing epidemic, use of remote sensing in human health applications to predict epidemics, and application of wireless technology in the detection of pathogens in combination with space science technology.

From 9/08: Multidrug Resistant TB (XDR-TB)

MDR-TB (Multidrug Resistant TB) describes strains of tuberculosis-causing bacteria that are resistant to at least the two main first-line TB drugs - isoniazid and rifampicin. XDR-TB, or Extensive Drug Resistant TB (also referred to as Extreme Drug Resistance) is MDR-TB that is also resistant to three or more of the six classes of second-line drugs.

Resistance to anti-TB drugs in populations is a phenomenon that occurs primarily due to poorly managed TB care. Problems include incorrect drug prescribing practices by providers, poor quality drugs or erratic supply of drugs, and also patient non-adherence.

Recent findings from a survey conducted by WHO and CDC on data from 2000-2004 found that XDR-TB has been identified in all regions of the world but is most frequent in the countries of the former Soviet Union and in Asia.

From 03/2008: E coli O157:H7 outbreaks
A recent hamburger meat recall from the giant manufacturer Cargill has again heightened public awareness to the serious health risks associated with E. coli O157:H7. Since first being identified in 1982 as the causative agent of an outbreak of bloody diarrhea from improperly cooked contaminated hamburgers, E. coli O157:H7 has been identified as the disease-causing agent in a number of outbreaks from contaminated salami, apple cider, spinach, water and other vegetables. These continuing reports of illness caused by this pathogen, or disease-causing organism, reinforce the necessity of the public’s appropriate handling of food.

E. coli organisms are commonly found in the intestine and the environment and do not usually cause disease. However, E. coli strains have acquired genes that enable the bacteria to attach to and colonize cells lining the large intestine and a toxin, Stx, that specifically inhibits protein synthesis. These factors can cause severe damage to the intestinal lining.

People generally become ill two to eight days after becoming infected with E. colit O157:H7Most infected people resolve the illness in a few days and antibiotics are not recommended as they worsen disease. In rare cases, the toxin spreads to affect the kidneys and cause the complication hemolytic uremic syndrome.

Precautions to prevent E. coli O157:H7 infections include:

• Eat only ground beef and hamburger that are thoroughly cooked.
• Avoid spreading harmful bacteria in your kitchen. Keep raw meat separate from ready-to-eat foods. Wash hands, counters, and utensils with hot soapy water after they touch raw meat.
• Wash all fruits and vegetables under running water, especially those that will be eaten raw.
• Drink water that has been treated with chlorine or another effective disinfectant.
• Avoid swallowing lake or pool water while swimming. (For more information, see the CDC Healthy Swimming website.)
• Wash hands carefully with soap after diaper changing or bowel movements to reduce the risk of spreading infection.

related links:
U.S. Centers for Disease Control

From 10/07: Spread of Superbugs
MRSA: Antibiotic-resistant Staph Infection
News of the recent death of a high school student in southern Virginia has brought public attention to a serious infectious bacteria, Methicillin-resistant Staphylococcus aureus, or MRSA. MRSA is a bacterium that does not respond to certain antibiotics. Most staphylococcal bacteria are very common and can colonize in the nose, throat and skin without causing infection. But if it gets into the body, typically through a cut or scrape, it can cause potentially serious infections.

In the past, these staph infections were readily treatable with beta-lactam antibiotics, such as Methicillin and Penicillin. This family of antibiotics kills certain types of bacteria by interfering with cell wall synthesis as the organisms divide. However, bacteria can often multiply very quickly and mutate to adapt to harsh surroundings. MRSA is an example of a pathogen, or infectious disease-causing agent, that has acquired the ability to resist the standard antibiotic resistance, which has become a worrisome public health issue nationwide. Basic research to study “superbug” pathogens is ongoing at the Maryland Pathogen Research Institute.

The U.S. Centers for Disease Control and Prevention recommends vigorous and frequent hand-washing as the most effective way to stop MRSA transmission.

related links:
National Institutes of Health
U.S. Centers for Disease Control