Health Nuggets: Lassa Fever

By Aniekeme Uwah


Dear readers, welcome to the 4th edition of HEALTH NUGGETS with DR ANIEKEME ANIEFIOK UWAH. Today, we continue the series on the 41 priority diseases, conditions and events that have been listed for Integrated Disease Surveillance and Response (IDSR). We will be looking at one of the epidemic prone diseases that have been ravaging our country for some weeks now. The disease is Lassa fever.


Just as I stated in the last edition of HEALTH NUGGETS where we looked at coronaviruses, In the last 50 years, there has been an increase in the incidence of zoonotic diseases, which are diseases transmitted from animals to man. Some of these diseases include Ebola Virus Disease (EVD), Lassa fever, Rabies, Monkey pox and very recently Coronavirus.

Lassa fever is an Old-World viral hemorrhagic illness. It is an acute viral zoonotic illness. The virus was first identified in 1969 when 2 Missionary nurses died in Northern Nigeria in a town called Lassa in the present Borno State, hence the name Lassa fever.


It is endemic in West Africa [Sierra Leone, Guinea, Liberia and Nigeria]. It was first described in Sierra Leone in the 1950s. Lassa fever occurs in all age groups and in both men and women. Persons at greatest risk are those living in rural areas where the rat that transmits the virus are usually found, especially where there is poor sanitation or crowded living conditions and health workers with a poor index of suspicion. Lassa fever occurs more often in the dry season rather than in the rainy season.

The reasons for higher incidences of Lassa fever at this time of the year include ecological factors and farming practices like bush burning. As at the 26th of January 2020, there were 258 confirmed cases of Lassa fever and 41 deaths recorded in more than 21 states of the country.


Lassa fever is caused by the Lassa virus.


The Lassa virus is transmitted by rats of the family Mastomys, in particular, Mastomys natalensis. The rat themselves might show no symptoms of the disease, but they shed the virus freely in urine and droppings and secrete the virus in their saliva.


The virus is easily transmitted to humans. Transmission occurs via direct contact with rat urine, faeces and saliva via contact with excretion or secretion or infected materials or via ingestion of excretion contaminated food. There is also a high risk of human to human transmission especially amongst health care workers.


About 80% of human infections are asymptomatic. However, at onset, there is insidious fever, rigors, high temperature [up to 40 degrees Celsius,] weakness, muscle aches, headache, nausea and vomiting.
After a few days; there could be sore-throat, chest-pain, diarrhea, cough and abdominal pains.
Severe cases may progress to show facial swellings, fluid in the lung cavity, bleeding from the mouth, nose, vagina or Gastro intestinal tract (GIT) and low blood pressure. Protein may be seen in urine. It should be noted at this point that bleeding is a predictor of a significantly higher risk of death.


Is 6-21days.


Clinical diagnosis of Lassa fever is often difficult, especially in the early course of the disease because the symptoms are varied and non-specific. Lassa fever is difficult to differentiate from many other diseases like malaria, shigellosis, typhoid fever, yellow fever and other viral haemorrhagic fevers like Ebola Virus Disease etc.

Therefore, all suspected cases should be admitted to isolation facilities. Hospital transmission occurs through inadequate infection control measures. Strict isolation of cases and procedures for handling body fluids and excreta must be maintained. Treatment is usually supportive and general support includes rehydration and administration of analgesics.


To prevent and control Lassa fever, everyone is encouraged;
1.To maintain good community hygiene to discourage rodents from entering homes.
2. To store grains and other food stuffs in rodent – proof containers, disposing of gabbage far from homes.
3. To maintain good environmental hygiene and proper waste disposal.
4. To maintain good personal hygiene through regular hand washing.
5. To ensure that fruits and other food items are properly washed before consumption.
6. To maintain clean households.
7. To stop the eating of rats and other rodents.
8. To keep cats to attack rats.
9. To use traps to catch the rats.
10. Not to handle dead rats with their bare hands.
11. To stop bush burning.
I also encourage health workers to put in place adequate infection prevention measures and barrier nursing in their health facilities.


I. To detect and respond promptly and appropriately to cases and outbreak of Lassa fever taking into cognizance the fact that a single case of Lassa fever is an outbreak..
II. Immediate case based reporting of cases and deaths when an outbreak is suspected.


The Nigeria Centers for Disease Control (NCDC) and the World Health Organization (WHO) recommends that the surveillance case definition for Lassa fever be used by all health facilities for reporting suspected cases to the Local Government Area (LGA) level.
Other case definitions have been added to enable our health care workers to be more informed about the management of cases of Lassa fever.
Suspected case:
‘Any individual presenting with one or more of the following: malaise, fever, headache, sore throat, cough, nausea, vomiting, diarrhoea, myalgia, chest pain, hearing loss and either;
a. History of contact with excreta or urine of rodents
b. History of contact with a probable or confirmed Lassa fever case within a period of 21 days of onset of symptoms OR Any person with inexplicable bleeding/hemorrhagia.
Confirmed case:
‘Any suspected case with laboratory confirmation (positive IgM antibody, PCR or virus isolation) ‘
Probable case:
‘Any suspected case (see definition above) who died or absconded without collection of specimen for laboratory testing.’
‘Anyone who has been exposed to an infected person, or to an infected person’s secretions, excretions, or tissues within three weeks of last contact with a confirmed or probable case of Lassa fever .’
Active State:
‘Means where there has been at least one confirmed case, and contacts within 21 days post exposure.’


In conclusion, the prevention of the outbreak of Lassa fever in our state is a collective responsibility. This acute viral illness discovered in 1969 in a town called Lassa in Bornu State Nigeria, has caused tremendous pains and sorrows to Nigerians including health professionals whose death in most cases points to the commencement of the outbreak.
You are therefore advised to visit the health facility nearest to you if you have any of the symptoms highlighted.


For more information and enquiries, send an email to or call 08036780343

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