Lassa fever Public Health Advisory, 08 December 2019.
Lassa fever is an acute viral haemorrhagic fever (VHF) caused by the Lassa virus. The natural reservoir for the virus is the Mastomys natalensis rodent (commonly known as the multimammate rat). Other rodents have also been identified who carry the virus.
Lassa fever remains a major public health challenge in West Africa with Nigeria bearing the highest burden. Lassa fever occurs throughout the year but more cases are recorded during the dry season i.e. November through May.
Lassa fever is spread through:
1. Direct contact with urine, faces, saliva or blood of infected rats.
2. Contact with objects, household items and surfaces or eating food, contaminated with urine, faeces, saliva or blood of infected rats.
3. Person to person transmission by contact with blood, urine, faeces, vomitus, and other body fluids of an infected person.
Signs and symptoms of Lassa fever:
Lassa fever presents initially like any other febrile illness such as malaria. Its symptoms include fever, headache, sore throat, general body weakness, cough, nausea, vomiting, diarrhoea, muscle pains, chest pain, and in severe cases, unexplainable bleeding from ears, eyes, nose, mouth and other body openings.
The time between an infection and appearance of symptoms of the disease is 3 to 21 days. Early treatment and diagnosis increases the chances of survival. People most at risk are:
- People of all age groups who come in contact with the urine, faeces, saliva or blood of rats
- People living in rat infested environments which increases their chances of coming in
contact with rats
- People who consume potentially contaminated food stuff especially those left open overnight or dried outside in the open
- People who handle or process rodents for consumption
- People who do not perform hand hygiene when appropriate
- Relatives who care for sick person with unexplained illnesses at home
- Health care workers including:
- - Doctors, nurses and other health workers providing direct patient care in the
absence of standard precautions.
- - Hospital staff who clean and disinfect contaminated surfaces, materials and
supplies without adequate protective gear
- - Laboratory staff who handle blood samples of suspected Lassa fever patients
without appropriate precautions
- - Medical or support staff who prepare and or handle dead bodies without
To reduce the risk of Lassa fever, the Nigeria Centre for Disease Control (NCDC) offers the
• Ensure proper environmental sanitation – i.e. keep your environment clean at all times, block all holes in your house to prevent rats from entry.
• Cover your dustbins and dispose refuse properly. Communities should setup dump sites very far from their homes to reduce the chances of having rodents within homes
• Store foodstuff like rice, garri, beans, corn/maize etc. containers which are well covered with tight fitting lids
• Avoid drying food stuff outside on the floor, roadside where it will be exposed to contamination
• Avoid bush burning which can lead to displacement of rats from bushes to human dwellings
• Eliminate rats in homes and communities by setting rat traps and other means
• Practice good personal hygiene by frequent washing hands with soap under running water/or use of hand sanitisers when appropriate
• Visit the nearest health facility if you notice any of the signs and symptoms of Lassa fever as mentioned earlier, avoid self-medication
• Healthcare workers are advised to practice standard precautions at all times: i.e. wearing gloves while handling patients or providing care to an ill patient/relative.
• Healthcare workers should maintain a high index of suspicion for Lassa fever i.e. be vigilant and lookout for signs and symptoms of Lassa fever.
Any febrile illness that has not responded to 48 hours use of anti-malaria or antibiotics should raise an index of suspicion for Lassa fever! Please if your healthcare worker suspects Lassa fever, advise him or her to contact your local government disease surveillance and notification officer to access care in Nigeria.
NCDC Toll-Free Number: 0800-970000-10