Lassa Fever reported in West Africa. Memories from the late 1970s.

The Nigerian Centre for Disease Control has recently reported (28 May 2024) 14 cases of Lassa fever in 3 states, Bauchi, Ondo, and Edo. There has been 1 fatality. A cluster of Lassa fever cases is not uncommon in Nigeria and 125 cases have been notified in 2024.

Attending to a hospital patient with a fever of unknown origin (PUO) is usually straightforward today.

It was certainly not in the late 1970’s if the person happened to be returning to the UK or Australia from West Africa. While we had a good grasp on personal risk (none) with the likes of malaria, leptospirosis, and typhoid our understanding of Lassa fever was only in its infancy. We accepted the unwell patient needed to be seen as soon as possible but the safety of staff also needed to be considered. Apart from infectious disease there was also the possibility of diabetic ketoacidosis, and this can be fatal if the treatment is delayed.

It's been over 50 years since the discovery of Lassa fever in 1969 and the true risk of exposure is much better understood today.

Lassa fever is an acute viral disease which is spread by rats. The virus is transmitted to humans by inhalation and ingestion. The rodents shed the virus in urine and droppings and food may be contaminated.

It can also be transmitted from human to human by secretions, blood, and excretions.

Strict adherence to standard infection prevention and control measures is necessary in preventing person to person transmission. In a study of health workers In Sierre Leone in the 1980’s it was shown that attending health staff were at a lower risk of exposure than the community if standard protocols were followed.

Apart from Nigeria, the disease is also reported in Liberia, Benin, Sierra Leone, Guinea, Togo, southern Mali, and Ghana. It is more likely to be seen during the West African dry season (December to April). The rodents invade homes in search of food.

Travel associated Lassa Fever has been recorded in the USA, Canada, UK, Netherlands, Israel, Sweden, and Germany. Despite these recorded cases, the risk of Lassa Fever in travellers is very low.

Those visiting areas of risk should be aware of the disease and how it is transmitted.