Shigella Dysenteriae

The History of a Human Pathogenic Bacterium:

Shigella Dysenteriae

Gloria Agwegwe

Biology 295

Dr. Curtis Greene

July 22, 2010

The History of a Human Pathogenic Bacterium:

Shigella Dysenteriae

Shigella dysenteriae type 1(or bacillary dysentery) is the only cause of epidemic dysentery. It is the most virulent out of the four subgroups of Shigella. This organism is generally found in the stool of infected individuals, as well as in contaminated water supplies. It is known to be able to survive on soiled linens for up to seven weeks, in water supplies for 5-11 days, and in kitchen waste for 1-4 days. Shigella can even survive in dust particles for six weeks at room temperature.

Infected humans act as host for this particular organism, as well as primates. The infections caused by this organism are generally seen in developing countries and areas of poor sanitation. Transmission occurs via direct or indirect contact with individuals who are infected by ingesting contaminated water, or food, as well as contact with fecal material. It can cause foodborne or waterborne epidemics. Water may become infected if someone who has Shigellosis swims in it. Crops can be infected with the bacteria if they are watered with contaminated water. This will cause major problems if these contaminated crops are then distributed over a large region, exposing anyone who eats the crops to infection.

The bacterium Shigella dysenteriae was discovered by Japanese bacteriologist Kiyoshi Shiga in 1897. At the time, Dr. Shiga was working as a research assistant in the Institute for Infectious Disease under the direction of Dr. Shibasaburo Kitasato, the famous Japanese scientists who cultivated Clostridium tetani and studied plague bacteria in Hong Kong. Dr. Kitasato directed Shiga's attention to an investigation of a sekiri (dysentery) outbreak. The Japanese word sekiri means "red diarrhea," a more accurate description of the disease than the generic term dysentery used to describe a...