Lassa hemorrhagic fever is an infectious viral disease caused by the Lassa virus. In its acute form, it is characterized by malaise, fever, vomiting, muscle pains and headache, symptoms that are also associated with malaria and typhoid fever. With time, however, bleeding from orifices begins, likening this to Ebola which is also a viral hemorrhagic fever. This disease leads to low-grade fatalities which occur within two weeks of symptomatic disease and has no known vaccine. Lassa fever was first discovered in 1969 in West Africa, particularly in Nigeria’s Borno state. Since then, infections have been noted in other West African nations like Ghana, Liberia, Guinnea, and Sierra Leone. The current outbreak of Lassa fever is considered a surprising one, owing to its quicker than normal spread which is far and wide leading to a lot of deaths including the death of the health care personnel deployed to offer care to victims. It is also characterized by a high mortality rate of about 22%.
Etiology of Lassa Fever
Rodents, specifically the natal multimammate mice, are implicated in the initiation and spread of this disease. They are the carriers of the Lassa virus which belongs to the enveloped bi-segmented single-stranded RNA viruses collectively known as Arenaviridae. These rats excrete the virus in their urine and feces throughout their life. That, coupled with its high offspring rate makes exposure massive. Human beings get infected once they come into contact with the rats’ excretory products via the fecal-oral or inhalational route and from there horizontal spread begins through skin contact and contact with infected body fluids. Poor sanitation is implicated in both initiation and spread of the disease.
Signs and Symptoms Associated With Lassa Fever
Lassa fever has been known to take either a non-complicated course, which accounts for almost 80% cases, or a complicated one. It is the complicated course of Lassa fever which leads to fatalities with fever being a major manifestation. This disease affects four major organ systems. The most commonly affected is the gastrointestinal system, in which signs and symptoms are vomiting, diarrhea, nausea, constipation, and hepatitis. A lowered blood pressure, increased heart rate, hypertension, and carditis are the main signs that the cardiovascular system is affected. With the respiratory system, dyspnea and chest pain are the cardinal signs. In the patients whose nervous system has been affected by Lassa fever, they present with meningitis, seizures, and hearing defects thought to subside with time.
To properly manage Lassa fever, a proper diagnosis is very vital. Laboratory testing is used to distinguish the disease from others that are thought to exhibit similar signs and symptoms. Cell cultures are used to check for the presence of the Lassa virus, polymerase chain reaction for the viral RNA and ELISA test to check for antibodies produced against the viral RNA. Blood tests show lymphopenia and thrombocytopenia in infected persons. Elevated aspartate aminotransferase is diagnostic and so is the presence of the virus in cerebrospinal fluid.
Treatment of Lassa fever begins by isolation. Ribavirin which has both an oral and intravenous formulations has proved effective when applied synergistically with blood transfusion and fluid replacement therapy. This fever has a generally good prognosis if treated early, with the poorest being in a pregnant woman, whose mortality rate is 80%.
Considering that there is no known vaccine, the Centre for Disease Control recommends these preventive measures; rodent control, use of personal protective equipment in handling infected persons and proper sanitation.