With smallpox, it was regarded as the most dreaded African disease in the second half of the 19th century. In 1947 the disease killed 20000 people in Egypt, as the British evacuated people there from India. The disease again invaded Africa in the 1970s and is now considered to be endemic in the continent, with large epidemics occurring sporadically, often in refugee communities ravaged by war, as well as poverty-stricken areas. Somalia, Zambia, Rwanda and Sierra Leone have all had thousands of deaths in the 1990s, with Mozambique now regarded as being in the grips of an ongoing epidemic since 1997. The disease returned to Latin America after an absence of more than a century, with more than a million cases by 1994.
Epidemics are usually seasonal, but can be very unpredictable.
The disease has been almost eradicated in countries which were previously home to some of the biggest outbreaks. Currently, less than 20 cases in the whole country are seen each year and they tend to be isolated. His studies inspired many other scientists to study how various diseases are spread and led to the establishment of the discipline of epidemiology. The organism is a bacterium, lives in fresh water and causes disease only in humans. It looks like a comma, or sperm, under the microscope and was first cultured by Robert Koch from the gut of dead cholera victims.