- Lassa fever is an acute viral haemorrhagic illness with 2-21 days incubation period. It is transmitted to humans through contact with food or household items contaminated with rat (Mastomys Natalensis) urine or faeces. Person-to-person infections also occur, particularly in hospitals lacking adequate infection prevention and control measures. Contaminated medical equipment or item can also be a source of infection.
- 80% of infections are asymptomatic, and overall case-fatality rate is 1%, while observed case-fatality rate among patients hospitalized with severe cases of Lassa fever is 15%. The virus affects key organs of the body such as the liver, spleen and kidneys.
- Onset of symptoms is usually insidious, starting with fever, general weakness, malaise, headache, sore throat, muscle pain, chest pain, nausea, vomiting, diarrhea, cough, and abdominal pain. In severe cases facial swelling, fluid in the lungs, bleeding from the mouth, nose, vagina or gastrointestinal tract and low blood pressure may follow.
- Some severe symptoms in later stages include; shock, seizures, tremor, disorientation, and coma.
- Complications in patients who survive include; deafness in 25% of patients (In half of these cases, hearing returns partially after 1–3 months), transient hair loss, and gait disturbance.
- Death commonly occurs within 14 days of onset in fatal cases. The disease is especially severe in late pregnancy, with maternal death and/or fetal loss occurring in more than 80% of cases during the third trimester.
Supporting Laboratory Evidence
- Proteinuria and/or microscopic hematuria
- Elevated urea ≥ 45 mg/dl or creatinine ≥ 2 mg
- Elevated transaminases (liver enzymes, ALT & AST)
- Reduced platelets count ≤ 90,000 cells/ml3
Please not that absence of this laboratory evidence, does not rule out Lassa fever
Recommendation
1. Maintain very high index of suspicion especially in patients presenting with fever during the peak incidence months of December to April, in most Lassa fever endemic countries.
2. Seek information on contact with probable or confirmed case, or travel to outbreak areas
3. Exclude malaria and other common causes of fever, then probe further about the possibility of Lassa fever case.
4. Consistent practice of Standard precautions must be applied at all times and to all patients. This requires that health care workers assume that blood and other body fluids of all patients are potential sources of infection, regardless of the diagnosis, or presumed infectious status. Standard precautions includes;
- Hand hygiene,
- Respiratory hygiene,
- Use of personal protective equipment (PPE) such as hand gloves and gown,
- Safe injection practices,
- Environmental cleaning,
- Proper waste management,
- Proper linen management
5. Safe Laboratory practices
6. Safe burial practices must be applied to those with fatal outcome
7. In case of any suspected Lassa fever patient in your health facility, transfer to holding bay or isolation unit, then call;
- Health Facility Infection Prevention and Control Focal Person
- Chairman Medical Advisory Committee (If Applicable)
- Disease Surveillance and Notification Officer (DSNO)
- State Epidemiologist
