Kaohsiung Armed Forced General Hospital

2021.08.26
Lassa Fever
Background
Lassa fever is an acute viral hemorrhagic fever, zoonotic infectious disease and is endemic in parts of West Africa. Though the disease was firstly described in the 1950s, Lassa virus was not identified until 1969 from 2 dead healthcare workers in Nigeria. Approximately 80% of the infected people are asymptomatic or have mild symptoms, while 20% of the infected patients develop serious symptoms. Symptoms include slight fever, feeling tired and weak, headache, sore throat, muscle pain, chest pain, nausea, vomiting, diarrhea, cough, and abdominal pain. In some people, the disease may cause more serious symptoms like facial swelling, fluid in the lung cavity, bleeding, low blood pressure, shock, seizures, tremor, disorientation and coma may be developed in the later phase. The virus, a member of the family Arenaviridae, is a single-stranded RNA virus. The virus is transmitted to people from exposure to urine or faces of infected Mastomys rats, and through direct contact with the blood and bodily secretions of an infected patient. The death rate is approximately 1%. Ribavirin, an antiviral drug, has been showed effective in the treatment of Lassa fever patients.
Epidemiology
Lassa fever is mainly found in Sierra Leone, Liberia, Guinea, and Nigeria, and is spread by rats. Other neighboring countries are also at risk of transmission because Mastomys rats that carry the virus are also found throughout the West African region. In 2016, a funeral worker was diagnosed with Lassa fever due to contact with an infected corpse. The overall case fatality rate is 1%, and the observed case fatality rate among patients hospitalized with severe illness of Lassa fever is 15%. The disease is especially severe in late pregnancy, with maternal death or fetal loss occurring in more than 80% of cases during the third trimester. So far, no confirmed case has been reported in Taiwan.
Lassa Fever Surveillance in Taiwan
1.Taiwan National Infectious Disease Statistics System- Lassa Fever
2.Fever screening at international airports and seaports.
3.Self–reporting through the toll–free 1922 hotline or local public health authority.
Prevention and Control
1.Prevent rodents from entering homes. Avoid consuming rodents. Avoid food storage where rodents could reach.
2.Avoid direct contact with the patient’s blood, secretions, body fluids, organs, semen, or contaminated environment. Wear gloves and appropriate protective equipment when caring for patients. Patients should avoid all types of sex until their semen tests negative for the virus.
3.The symptoms in the early stage are not specific. Healthcare workers taking care of all patients should practice standard precautions closely.
FAQs
1.How do people become infected with the Lassa fever?
People can get Lassa fever through contact with the urine or droppings of an infected rat, consuming infected rats, inhaling tiny contaminated particles. People can also contract the disease by direct contact with a patient’s blood or body fluids, through mucous membranes, like eyes, nose, or mouth.
2.Who is at risk of Lassa fever?
People at greatest risk of Lassa virus infection are those who live in or visit endemic regions, including Sierra Leone, Liberia, Guinea, and Nigeria and have exposure to the rats. Risk of exposure may also exist in where Mastomys rats exist. Healthcare workers and those who handle bodies or work in laboratory are also risk groups.
3.Can Lassa fever be treated?
Ribavirin, an antiviral drug, has been showed effective in the treatment of Lassa fever patients. It is most effective when given soon after a patient becomes sick. Patients should also receive supportive care.
4.How can I prevent getting infected with Lassa fever?
(1) Prevent rodents from entering homes. Avoid consuming rodents. Avoid food storage in where rodents could reach.
(2) Avoid direct contact with the patient’s blood, secretions, body fluids, organs, semen, or contaminated environment. Wear gloves and appropriate protective equipment when caring for patients. Patients should avoid all types of sex until their semen tests negative for the virus.
(3) The symptoms in the early stage are not specific. Healthcare workers taking care of all patients should practice standard precautions closely.