A good part of the rainy season lies ahead; while some epicentres reported cholera cases during the dry period, the rains generally cause spikes as water sources become contaminated.
The unique Lake Chad Basin is the centre of economic activity - commerce, fishing, farming - for some 11 million people, according to an August report by the UN Children's Fund (UNICEF). Population movements for social and commercial activity are constant between areas where sanitation is poor. All this contributes to the explosion of cholera once infection starts, according to aid agencies doing prevention work in the region.
That is why a regional strategy is critical, UNICEF says. "A cross-border, decentralized approach is necessary to protect each country's population and nip outbreaks in the bud," says François Bellet, UNICEF regional water and sanitation specialist for west and central Africa.
Countless families depend on commerce, fishing and other activities in the region; at the same time cholera seriously undermines economic development, says the Chad government in an anti-cholera plan.
"Cholera hits families' revenue and brings recurrent health expenses - all of this deepens poverty and under-development."
In October 2010, health ministers of the four countries plus Benin signed the Abuja Commitment, calling for better collaboration to tackle cholera and other infectious diseases. The health ministers acknowledge that people have inadequate access to clean water and proper sanitation and that cross-border coordination mechanisms are lacking, with no formal way for health districts to share disease surveillance data.
Last year, the Lake Chad Basin region reported 58,000 cases of cholera, with 2,300 deaths, according to UNICEF - the most serious outbreak since 1991. Here is a tally of how many people have been affected this year:
Cameroon: As of 22 August, 14,730 cases; 554 deaths. Lethality rate 3.76 percent.
Chad: As of 22 August, 10,314 cases; 314 deaths. Lethality rate 3.1 percent.
Niger: As of 8 August, 976 cases; 25 deaths. Lethality rate 2.5 percent.
Nigeria: As of 1 August, 12,840 cases; 318 deaths. Lethality rate 2.5 percent.
This article was produced by IRIN News while it was part of the United Nations Office for the Coordination of Humanitarian Affairs. Please send queries on copyright or liability to the UN. For more information: https://shop.un.org/rights-permissions