Updated: Jan 27, 2020
Lassa fever is a zoonotic disease, meaning that humans become infected from contact with infected animals.
The animal reservoir, or host, of the Lassa virus, is a rodent. "The infected rodent do not become ill, but they can shed the virus in their urine and feces", the World Health Organization says.
Because the clinical course of the disease is so variable, detection of the disease in affected patients has been difficult. Lassa virus infections can only be diagnosed definitively in the laboratory using the following tests:
Reverse transcriptase-polymerase chain reaction (RT-PCR) assay
Antibody enzyme-linked immunosorbent assay (ELISA)
Antigen detection tests
Virus isolation by cell culture.
Between January 1 and 24, 2020, Nigeria have recorded 163 confirmed cases and 24 deaths from nine states across the country. These were obtained from the NCDC website (www.ncdc.gov.ng).
Currently, there is no vaccine to protect against Lassa fever.
Symptoms of Lassa fever
According to the World Health Organization, “the incubation period of Lassa fever ranges from 6–21 days”. The onset of the disease, when it is symptomatic, is usually gradual, starting with;
General weakness, and
After a few days;
Cough and abdominal pain may follow.
In severe cases, facial swelling, fluid in the lung cavity, bleeding from the mouth, nose, vagina or gastrointestinal tract and low blood pressure may develop.
Protein may be noted in the urine. Shock, seizures, tremors, disorientation, and coma may be seen in the later stages. Deafness occurs in 25% of patients who survive the disease. In half of these cases, hearing returns partially after 1–3 months. Transient hair loss and gait disturbance may occur during recovery.
Death usually occurs within 14 days of onset in fatal cases. The disease is especially severe late in pregnancy, with maternal death and/or fetal loss occurring in more than 80% of cases during the third trimester.
Prevention and Control
Prevention of Lassa fever relies on promoting good “community hygiene” to discourage rodents from entering homes. Effective measures include;
Storing grain and other foodstuffs in rodent-proof containers
Disposing of garbage far from the home
Maintaining clean households.
Family members should always be careful to avoid contact with blood and body fluids while caring for sick persons.
Health-care workers caring for patients with suspected or confirmed Lassa fever should apply extra infection control measures to prevent contact with the patient’s blood and body fluids and contaminated surfaces or materials such as clothing and bedding.
Laboratory workers are also at risk. Samples taken from humans and animals for investigation of Lassa virus infection should be handled by trained staff and processed in suitably equipped laboratories under maximum biological containment conditions.
General public should rely on strengthening measures such as ensuring proper sanitation, “these measures also depend on personal responsibility as we all have a role to play in preventing the spread of Lassa fever”, said, Director-General of the Nigeria Centre for Disease Control (NCDC), Dr. Chikwe Ihekweazu while commenting on recent outbreak and efforts by the agency to contain the situation.
Treatment and prophylaxis
The antiviral drug ribavirin seems to be an effective treatment for Lassa fever if given early on in the course of clinical illness. There is no evidence to support the role of ribavirin post-exposure prophylactic treatment for Lassa fever, the World Health Organization says.
Source: The WHO and NCDC