Lassa fever is an acute viral hemorrhagic illness primarily found in West African countries like Nigeria, Sierra Leone, Liberia, and Guinea. Named after the town of Lassa in Nigeria where it was first identified in 1969, this disease can cause severe illness and impacts healthcare systems in endemic regions.
The Lassa Virus and Its Spread
Lassa fever is caused by the Lassa virus, a single-stranded RNA virus from the Arenaviridae family. Its primary carriers are Mastomys natalensis rodents, or multimammate rats, common in West Africa and often found near human homes. Infected rodents shed the virus in their urine and feces.
Humans typically contract Lassa fever through direct contact with rodent excreta, or by consuming food and items contaminated with infected Mastomys rat urine or feces. Inhaling contaminated dust can also lead to infection. Human-to-human transmission is possible, though less common, occurring through direct contact with an infected person’s blood, urine, feces, vomit, or other bodily secretions.
Human-to-human transmission is concerning in healthcare settings, especially when proper infection control and personal protective equipment are not used. Casual contact, such as hugging or shaking hands, does not spread the virus. While the virus can be found in bodily fluids, aerosol transmission is not a significant route.
Identifying the Symptoms
Lassa fever symptoms vary significantly; many infected individuals remain asymptomatic. For those who develop symptoms, the incubation period typically ranges from 2 to 21 days. Initial symptoms are often non-specific, resembling common illnesses like malaria or dysentery.
Early signs include a gradual onset of fever, weakness, headache, and muscle pain. As the disease progresses, individuals may experience gastrointestinal issues like nausea, vomiting, and diarrhea. Other symptoms include a sore throat, cough, and chest pain.
In severe cases, symptoms can worsen to include facial swelling, pleural effusion, and bleeding from sites like gums, nose, or injection sites. Permanent hearing loss is a long-term complication for many survivors. Pregnant women face a high risk for severe complications and miscarriage.
Diagnosis and Medical Care
Diagnosing Lassa fever is difficult because its early symptoms resemble many other common diseases in endemic regions. Healthcare providers often consider Lassa fever only after several days of symptom onset. Laboratory tests are necessary to confirm the diagnosis.
Primary diagnostic methods involve detecting the Lassa virus or antibodies against it. RT-PCR detects viral RNA, while ELISA identifies antibodies (IgM and IgG) produced in response to infection. Early diagnosis is important for effective treatment.
Medical care for Lassa fever involves supportive therapy, including hydration, fever management, and pain relief. The antiviral drug ribavirin treats Lassa fever and is effective when administered early, ideally within the first six days of symptom onset. Unfortunately, in many endemic areas, ribavirin is often administered too late due to delayed diagnosis.
Preventing Lassa Fever
Preventing Lassa fever relies on strategies focusing on controlling rodent populations and implementing hygiene practices. In homes and communities, store food in rodent-proof containers and maintain a clean environment to deter rats. Proper waste disposal also helps reduce rodent habitats.
Personal hygiene practices, such as frequent handwashing, are important. Avoiding contact with the urine, feces, or other bodily fluids of infected individuals prevents human-to-human transmission. Safe burial practices for those who have died from Lassa fever also help prevent further spread.
In healthcare settings, infection prevention and control measures are important to prevent human-to-human transmission. This includes using personal protective equipment like masks, gloves, gowns, and goggles. Sterilization of medical equipment and isolating infected patients until they are no longer contagious also play a role in preventing Lassa fever spread.