What are the signs and symptoms of Lassa fever?

There have been outbreaks of Lassa fever in some states of the country, and it is still spreading to others. Permit me a space in your weekly health column to ask about the signs and symptoms of the disease and how to prevent and control it. Abashiyya V.   Thanks, Abashiyya for your question. Lassa […]

There have been outbreaks of Lassa fever in some states of the country, and it is still spreading to others. Permit me a space in your weekly health column to ask about the signs and symptoms of the disease and how to prevent and control it.

Abashiyya V.

 

Thanks, Abashiyya for your question. Lassa fever according to the World Health Organisation (WHO) is an acute viral haemorrhagic illness caused by the Lassa virus, a member of the arenavirus family of viruses.

What are the signs and symptoms?

The incubation period of Lassa fever ranges from 2–21 days. The onset of the disease, when it is symptomatic, is usually gradual, starting with:

• Fever, general weakness, and malaise.

• After a few days, headache, sore throat, muscle pain, chest pain, nausea, vomiting, diarrhoea, 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, tremor, disorientation, and coma may be seen in the later stages.

• Deafness occurs in 25% of patients who recover from 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.

How transmission occurs?

• Humans usually become infected with Lassa virus from exposure to urine or faeces of infected Mastomys rats.

• Lassa virus may also be spread between humans through direct contact with the blood, urine, faeces, or other bodily secretions of a person infected with Lassa fever.

• There is no epidemiological evidence supporting airborne spread between humans.

• Person-to-person transmission occurs in both community and health-care settings, where the virus may be spread by contaminated medical equipment, such as re-used needles.

Who are at risk?

• Lassa fever occurs in all age groups and both sexes.

• Persons at greatest risk are those living in rural areas where Mastomys are usually found, especially in communities with poor sanitation or crowded living conditions.

• Health workers are at risk if caring for Lassa fever patients in the absence of proper barrier nursing and infection prevention and control practices.

How to make a diagnosis?

• Lassa fever is difficult to distinguish from other viral haemorrhagic fevers such as Ebola virus disease, as well as from other diseases that cause fever, including malaria, shigellosis, typhoid fever and yellow fever.

• Definitive diagnosis requires testing that is available only in reference laboratories. Laboratory specimens may be hazardous and must be handled with extreme care. Lassa virus infections can only be diagnosed definitively in the laboratory.

How to prevent and control?

Prevention of Lassa fever relies on doing the following:

1. Promoting good “community hygiene” to discourage rodents from entering homes.

2. Effective measures include storing grains and other foodstuffs in rodent-proof containers

3. Disposing of garbage far from the home and maintaining clean households and keeping cats.

4. Family members should always be careful to avoid contact with blood and body fluids while caring for sick persons.

5. In health-care settings, staff should always apply standard infection prevention and control precautions when caring for patients, regardless of their presumed diagnosis.

6. These include basic hand hygiene, respiratory hygiene, use of personal protective equipment (to block splashes or other contact with infected materials), safe injection practices and safe burial practices.

7. 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. When in close contact (within 1 meter) of patients with Lassa fever, health-care workers should wear face protection (a face shield or a medical mask and goggles), a clean, non-sterile long-sleeved gown, and gloves (sterile gloves for some procedures).

8. Laboratory workers are also at risk. Samples taken from humans and animals for investigation of Lassa virus infection should be handled by trained staff.