Hunting the disease that could spark a new pandemic

As rich countries slash foreign aid, scientists in West Africa are preparing the continent to fight deadly illnesses that can spread undetected across borders.

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It all starts with a fever.

It's the first signal that an outbreak of disease could be moving silently through the population.

At a health centre in a busy area of the Senegalese capital, Dakar, no cases of dengue had been detected before 2023. In the following nine months, more than 200 cases were spotted. The illness had always been there - in homes and clinics, people were developing the warning signs of intense pain in the joints and bones that lend the mosquito-borne disease its nickname of “breakbone fever”. But these cases were invisible until a surveillance site, set up by the Institut Pasteur de Dakar (IPD), brought them under the microscope.

Although it was founded almost 100 years ago and became known for medical testing and research, it is only in the past couple of years that the institute has grown to become the control room of a network of listening posts across 11 West African countries, primed to spot clusters of disease before they become uncontrollable outbreaks. It is trying to expand these efforts further across Africa in the face of deep funding cuts by rich countries, as many shift their resources towards defence.

At the more than 40 surveillance sites making up this network, health workers take swabs from the nose or throat of any patient who comes in with a temperature higher than 37.5C.