LASSA FEVER: What you need to know.

Posted on: February 28th, 2020 under Articles

Nigeria has recorded reoccurring Lassa Fever outbreaks over the past 3 years. Lassa Fever also known as Lassa hemorrhagic fever (LHF) is an acute, life-threatening viral disease. The carrier of the virus is a very common rodent in West Africa known as the Mastomys natalensis a multimammate rat. It is one of the several viruses that the World Health Organization (WHO) has listed for urgent research to develop new diagnostic tests, vaccines, and medicines. Lassa Fever is endemic in most parts of West Africa most especially Sierra Leone, Liberia, Guinea, and Nigeria. Every year the number of reported Lassa virus infections in West Africa is estimated at 100,000 to 300,000, with approximately 5,000 deaths. An estimated 80% of people who become infected with Lassa virus have no symptoms, which increases the risk of transmitting the disease. 1 in 5 infections progresses to the severe state of the disease, where the virus affects several organs such as the liver, spleen, and kidneys.

In Nigeria, most cases of Lassa fever are reported during the dry season between November to March. The disease was first identified in Nigeria in 1969 and is named after Lassa, a town in Borno state, where the first cases occurred when a prominent expert in the disease, Aniru Conteh, died from the disease. The most severe outbreak of Lassa fever in Nigeria occurred in 2018, it spread to 18 states in the country (Anambra, Bauchi, Benue, Delta, Ebonyi, Edo, Ekiti, Federal Capital Territory,  Gombe, Imo, Kogi, Lagos, Nasarawa, Ondo, Osun, Plateau, Rivers, and Taraba). There were 1081 suspected cases and 90 reported deaths, however, only 317 cases and 72 deaths were confirmed as Lassa fever. In 2019 approximately 170 people died from the virus in Nigeria.

In 2020, 195 cases of Lassa fever have been reported with about 29 recorded deaths. 90 percent of these cases occurred in Edo, Ondo and Ebonyi states (Nigeria Centre for Disease Control, NCDC). However, there has been a decline in the fatality rate from 23.4% in 2019 to 14.8% in 2020.


An infected multimammate rat excretes the virus in its faeces and urine throughout its lifetime which results in an easy spread of the virus. Poor environmental hygiene and inappropriate disposal of waste has led to an increase in rodents cohabiting with humans and this has in turn increased the transmission of this virus. Lassa fever is transmitted to humans via the following;

  • Consumption of food contaminated with the urine or droppings of the infected rats.
  • Contact with the blood, secretions or excrements of an infected individual.
  • Inhaling of secretions from infected rats while sweeping.
  • Contact with items contaminated by rodent urine or faeces
  • Consumption of infected rats.
  • Contact with contaminated medical equipment such as reused needles


The signs and symptoms of Lassa fever typically occur 1-3 weeks after the patient comes in contact with the virus. Approximately 80% of Lassa fever virus symptoms are mild and may be taken for other common illnessesSymptoms include:

  • Fever
  • Headache
  • Weakness
  • Vomiting
  • Cough
  • Sore throat
  • Diarrhoea
  • Bleeding in gums, eyes, or nose
  • Difficulty in breathing
  • Facial swelling
  • Pain in the chest, back, and abdomen, and shock
  • In fatal cases, death can occur within 14 days as a result of multiple organ failure.

The most common complication of Lassa fever is hearing loss, which occurs in approximately 1 in 3 infected persons. Deafness caused by Lassa fever is not necessarily related to the severity, it varies in degree and is usually irreversible. The disease is particularly dangerous for women in the third trimester of pregnancy as there is a 95%   chance of losing the baby.


The symptoms of Lassa fever vary widely, and diagnosis can be difficult. Clinically, the disease can resemble other viral hemorrhagic fevers, including the Ebola virus, malaria, and typhoid. The only definitive tests for Lassa fever are laboratory-based, and the handling of specimens can be hazardous. Lassa fever is generally diagnosed by using enzyme-linked immunosorbent serologic assays (ELISA). Reverse transcription-polymerase chain reaction (RT-PCR) can also be used in the early stages of the disease.


Early diagnosis increases the chances of survival from the disease. Ribavirin an antiviral drug has proven useful in fighting the Lassa virus if prescribed early. Ribavirin is not useful for preventing Lassa fever before it occurs, and there is currently no vaccine for this disease. However, work is going on to get a vaccine for the virus. Lassa fever patients are advised to stay rehydrated, maintain normal blood pressure as well as treatment of any other complicating infections.


The main focus of the prevention of Lassa fever is maintaining community hygiene to control the rat population.

Other preventive measures include:

  • regular hand-washing
  • storing foods in rodent-proof containers
  • ensuring that foods are washed and cooked properly
  • keeping garbage away from the home
  • blocking of holes and making use of rat traps
  • avoiding blood and other bodily fluids when caring for sick relatives
  • using protective equipment in a healthcare setting, including masks and eyewear

Although Mastomys rat cannot be totally eradicated, they can be prevented from cohabiting with humans. It is important to keep the home and environment clean, cover leftover foods properly and dispose waste appropraitely as there is no vaccine for the disease presently.

At H.E.L.P Initiative, we are passionate about raising awareness and educating the public on all they need to know about the disease to help curb its further spread.

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