Lassa Fever and Rats


Lassa Fever is a type of disease caused by a virus called Lassa virus. It is Zoonotic meaning that “it can be transmitted by infected animals like rats”.

Humans contract the illness through contact with food or household items contaminated with rodent urine or faeces. Humans can also be infected with contact with the blood, faeces or bodily secretions of a person infected with Lassa Fever.

Sexual transmission has also been reported. Lassa fever is endemic in African countries like Benin, Ghana, Guinea, Liberia, Mali, Sierra Leone and Nigeria. It occurs in areas where rats are predominant. It occurs in all age groups and both sexes.


Symptoms usually occur between six to twenty-one days. Some of these symptoms include;

· Fever

· Headache

· Sore throat

· Muscle pain

· Chest pain

· Nausea

· Diarrhea

· Cough

· Abdominal pain

In severe cases,

· Facial swelling


· Fluid in the lung cavity

· Bleeding from mouth and nose

· Coma

· Death occurs 14 days of onset in fatal cases.


A medical doctor should be seen for an effective diagnosis if these symptoms are present. Some of these symptoms manifest in other diseases transmitted through blood, for example, yellow fever, shigellosis, malaria and ebola. Proper diagnosis is made in the medical laboratories.


An antiviral drug called Ribavirin is an effective treatment for Lassa fever if given earlier in the course of the infection.

Prevention and Control

There is no vaccine used to prevent Lassa fever. Major control strategies can be used to eradicate and avoid rats that help to transmit the disease.

· Good personal hygiene and environmental sanitation should be practised.

· Storing foodstuffs in covered containers or rodent-proof containers to avoid contamination by rats.

· Disposing waste far from home.

· Keeping cats in homes.

· Samples of sick persons in hospitals should be taken carefully, using hand gloves and other personal protective equipment to avoid contact with bodily fluids.

· Rats can be controlled and eradicated by the use of rodenticides (chemicals that kill rodents) and rat poisons. Setting rat traps at strategic rat locations, and using ‘Exclusion’ (closing openings or blocking access in buildings big enough for rats to enter).

Written By Ms. Chijioke, BSc Parasitology

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