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New, More Virulent Cholera Strain Caused Guinea Outbreak

Girls fill plastic basins at a free water tap in a neighborhood where houses with indoor plumbing rarely receive water, in Bissau, Guinea-Bissau, March 6, 2009. Contaminated drinking water leads to yearly cholera epidemics, particularly in remote rural re
Scientists say the cholera outbreak that struck more than 7,000 people in Guinea this year was caused by a more toxic and more contagious generation of the bacteria. Researchers suspect the same strain killed nearly 300 people and struck more than 22,000 others in neighboring Sierra Leone.

Through genetic sequencing of the cholera bacteria found in Guinea, epidemiologists working with the United Nations Children's Fund have identified them as atypical variants of the O1 El Tor strain.

Cholera, a preventable and treatable disease, causes watery diarrhea and vomiting. It can dehydrate a victim so rapidly that it can kill within hours if left untreated.

Virulent strain

The strain found in Guinea causes more violent symptoms and is more contagious than other strains, which is dangerous in a region where lack of access to safe water and proper sanitation make people especially vulnerable to infectious disease.

University Hospital of Marseilles epidemiologist Stanislas Rebaudet has studied the cholera strain in collaboration with UNICEF.

He said it is thought that with this generation of the El-Tor strain, people sick from cholera excrete more bacteria and are more contagious. Therefore there is a risk of more serious epidemics, and governments and agencies working to fight cholera must take that into account.

That makes it all the more important that governments and aid agencies step up prevention and response efforts, said water and sanitation specialist François Bellet, who is with UNICEF’s regional office for West and Central Africa.

Inreased vigilance

He said this discovery raises the alert level, requiring stronger epidemiological surveillance, preparedness and response to cholera outbreaks in Guinea and throughout the region.

Cholera, caused by contaminated food or drink, is completely preventable. According to the World Health Organization, though, the illness kills at least 100,000 people every year.

Aid workers say cholera is believed to have arrived in Guinea this year from neighboring Sierra Leone, which saw its biggest cholera outbreak in years with some 22,000 cases. Specimens from Sierra Leone are under analysis. This year’s epidemic started in coastal villages, where people regularly move between the two countries as part of their daily activities.

Rebaudet said atypical El Tor strains are not completely new; they were first detected in Bangladesh some 20 years ago and have made their way to Africa during the past decade, in Mozambique, Zimbabwe and the Lake Chad region. The same strain also is currently implicated in Haiti.