Lassa Fever

–           Is a disease that causes generalized bleeding of the body when severe and it is caused by a germ called Lassa virus.

–           It is a disease of animals. Humans become infected from contact with infected animals.   

–           Lassa fever was first described in Nigeria in 1969 at Lassa Village in Borno State.

–           The lassa virus resides in a rodent or rat called Mastomys rat.  Usually the Mastomys rat does not become ill but it regularly sheds the virus in its urine, faeces and other secretions.

–           The rats spread the lassa virus when they feed on food items, urinate or defaecate on food items or household items that are later eaten or handled by humans respectively.

–           Humans can also get the disease when they are contaminated by the urine, blood or faeces of the rat while killing or processing the meat for food.

–           About 80% of people who become infected with Lassa virus have no symptoms and 1 out 5 infections result in severe disease that affects several organs of the body.  About 1-20% of affected patients usually die if prompt treatment is not given.

–           The disease can affect both male and female, young or old.  Health professionals and relations of affected patients are at greater risk of infection as they care for the latter because the disease is also transmitted from person to person through contamination by the body fluids of patients.

–           Women in late pregnancy are usually affected severely resulting in death in more than 80% of cases.

–           Recent update shows 13 States of Nigeria, namely:-  Bauchi, Nasarawa, Niger, Taraba, Kano, Rivers, Edo, Oyo, Abuja, Gombe Plateau, Imo and Ekiti States have been affected.

–           About 95 suspected cases and 14 confirmed cases have been reported with 43 deaths including a Medical Doctor who attended to an infected patient in Port- Harcourt.


             Symptoms usually develop within 5 – 21 days after the virus has been introduced into the body.  The symptoms of lassa fever are usually non specific when they occur.  Only about 20% of victims show symptoms such as:- gradual onset of fever, generalised body weakness, malaise, headache, sore throat, muscle pain, chest pain, nausea, vomiting, diarrhea, cough, and abdominal pain.  In severe cases, bleeding can occur in different parts of the body like mouth, nose, vagina and anus resulting in low blood pressure and shock.

            Seizures, disorientation, abnormal gait and coma may also occur,  Deafness occurs in about 25% of cases that survive the disease which may be partial or permanent.

            Usually, death occurs within 14 days of onset in fatal cases.


      This is usually difficult because the symptoms are non-specific and resemble that of other diseases like malaria, typhoid, influenza, ebola, yellow fever etc.

     Where facilities are available, lassa fever can be diagnosed by specific methods (Elisa, RT-PCR, viral culture) which are very expensive and not widely available.


    Ribavirin, an antiviral drug has been found to be effective in the treatment of lassa fever if given early on in the course of the illness.

     There is no vaccine for lassa virus disease for now.


–           This is mainly by good personal/community hygiene.

–           Limiting the entry of rodents/rats into houses, food stores, and kitchen.

–           Avoiding the drying of food on roads where rats can easily have access to the food.

–           Maintaining a clean environment including prompt and effective disposal of refuse because rats breed in  dirty places.

–           Covering of food to securely prevent rats from gaining access to the food.

–           Food already nibbed by rats should not be eaten but destroyed.

–           Family members should avoid contact with body fluids (e.g. blood, urine, saliva, vomit etc) of sick persons.

–           High level of aseptic technique should be practiced by health workers at all times.

–           Cases of suspected lassa fever infections must be isolated and report made to the Federal/State Ministries of Health.

–           Hand washing with running water and soap is very essential.    

–           Lassa virus can be transmitted through sexual intercourse hence use of condom is recommended.

Please let us all adhere to a high level of personal and environmental hygiene.

Thank you.


Ref:  Lassa Fever update, FMOH, (14/01/16.)