Lassa fever is a serious viral hemorrhagic disease caused by the Lassa virus, which is part of the arenavirus family.
Humans typically acquire the virus through contact with food or household items contaminated by the urine or feces of infected Mastomys rats, which are prevalent in some parts of West Africa.
The disease is common in several West African nations, including Benin, Ghana, Guinea, Liberia, Mali, Sierra Leone, Togo, and Nigeria, and possibly other countries as well.
It can also spread through person-to-person transmission or laboratory exposure, particularly in healthcare settings lacking proper infection control measures.
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Early diagnosis and treatment are essential for improving outcomes.
The overall fatality rate is approximately 1%, but it can rise to 15% in patients with severe symptoms who are hospitalized.
Early treatment with rehydration and supportive care can enhance survival rates.
About 80% of those infected with the Lassa virus show no symptoms, but in 20% of cases, the disease becomes severe and affects vital organs such as the liver, spleen, and kidneys.
Symptoms
The incubation period for Lassa fever typically ranges from 2 to 21 days.
When symptoms begin, they tend to start gradually with fever, fatigue, and general discomfort.
Within a few days, other symptoms such as headache, sore throat, muscle and chest pain, nausea, vomiting, diarrhea, cough, and abdominal pain may appear.
In severe cases, facial swelling, fluid in the lungs, bleeding from the mouth, nose, vagina, or gastrointestinal tract, and low blood pressure may occur. Protein may also be found in the urine.
As the disease progresses, more serious complications like shock, seizures, tremors, disorientation, and coma may develop.
About 25% of those who survive Lassa fever experience hearing loss, although in half of these cases, hearing improves partially within 1–3 months.
Other recovery symptoms may include temporary hair loss and coordination difficulties.
Fatal cases usually result in death within 14 days.
The disease is particularly dangerous during late pregnancy, with maternal death or fetal loss occurring in more than 80% of third-trimester cases.
Because of the wide range of symptoms and their similarity to other conditions, diagnosing Lassa fever can be challenging, especially in the early stages.
It is also difficult to distinguish from other viral hemorrhagic fevers like Ebola or other diseases such as malaria, shigellosis, typhoid fever, and yellow fever.
Treatment
Currently, there is no approved vaccine for Lassa fever, although several candidates are under development.
While the antiviral drug ribavirin has been used to treat Lassa fever in some countries, it is not officially licensed for this use, and its effectiveness is not fully proven.
There is an ongoing need for safe and effective treatments, and various options, including immune and drug therapies, are being evaluated.
Preventing Lassa fever primarily involves promoting good hygiene practices to keep rodents out of homes.
This includes storing food in rodent-proof containers, disposing of waste away from living areas, maintaining cleanliness, and keeping cats to control rodent populations.
Due to the widespread presence of Mastomys rats in affected areas, complete eradication is not possible.
Family members caring for those infected should avoid direct contact with blood and bodily fluids.
Lassa fever is endemic in certain regions, and health workers treating suspected cases should consult with local and national experts for guidance and arrange for laboratory testing.
Healthcare workers must adhere to strict infection prevention and control measures to prevent further transmission.