Lassa fever is a very serious and insidious disease caused by a virus that we cannot defend ourselves against. Lassa fever belongs to a heterogeneous group of diseases commonly referred to as hemorrhagic fever. What are the symptoms of this infectious disease and is it possible to treat it?
Lassa feverwas first recognized in 1969 in the Nigerian city of Lassa. This is where its name comes from. It all started with an epidemic in the mission hospital. The disease has since appeared in many West African countries, including Ghana, Mali, and Sierra Leone.
Lassa fever - causes
The Lassa fever virus belongs to the arenavirus family. It is a virus of zoonotic origin and is spread to humans by rodents called the natal mice. These small, mouse-like mammals are common in West Africa. These rodents only appear where humans live. They are very rare in uninhabited areas. In addition to the Lassa fever virus, they are carriers of four other arenaviruses that are not harmful to humans.
Rodents infiltrate homes and contaminate anything they encounter with their faeces. But the problems with spreading viruses don't stop there. The risk of falling ill is increased by the fact that these rodents are a delicacy for approx. 90% of the inhabitants of equatorial Africa. The virus can also be present in the air.
Lassa fever can also spread from person to person. Most people become infected by contact with anything that is contaminated, such as urine, faeces or saliva with active virions (a virion is a single and complete virus cell that can survive outside the cell). The disease can spread through the body fluids of infected people, such as blood, urine, semen, and saliva.
It is also important that the Lassa virus can survive in the feces for many weeks - in feces and urine for 3 to 9 weeks and in semen for up to three months.
Lassa fever - symptoms
In 80% of cases the disease is asymptomatic, in 20% of the remaining cases there are serious he alth complications. It is estimated that the virus is responsible for around 5,000 deaths annually. Deaths in hospitals, regardless of the region, are found in 10-16% of cases.
After an incubation period (6 to 21 days), the disease gets worseand affects the entire body, but different people may have different symptoms. However, the most common symptoms of Lassa fever are:
- face swelling
- general weakness
- conjunctivitis
- mucosal bleeding
When the virus attacks internal organs, symptoms appear from the digestive, respiratory, nervous, cardiovascular and urinary systems.
- digestive system - nausea, bloody vomiting, bloody diarrhea, abdominal pain, constipation, difficulty swallowing and hepatitis
- circulatory system - you may develop pericarditis, hypertension or hypotension, and tachycardia, i.e. increased heart rate
- respiratory system - coughing, chest pains, shortness of breath, pharyngitis and pleurisy
- nervous system - develops encephalitis, meningitis, unilateral or bilateral hearing loss
- urinary system - blood in urine
The virus replication happens very quickly. The virus attacks every tissue in the body. It starts with the mucosa, then the intestines, lungs and urinary tract are involved. The next target of the virus is blood vessels that are destroyed, which results in haemorrhages that are difficult to stop.
Lassa fever - diagnosis
In addition to the external symptoms that occur in infected people, laboratory tests are necessary for the diagnosis of the disease. An Elisa test is performed for the IgM antibody antigen, which has 88% sensitivity and 90% specificity for the presence of infection.
Lassa fever - treatment
Ribavirin is used to treat Lassa fever. The drug is twice as effective when given intravenously rather than orally. Ribavirin affects the metabolism of the virus and stops it from replicating. Blood transfusion and hypothermia are also used for therapeutic purposes.
It is also extremely important to isolate the sick and follow the rules of hygiene. The method of removing the excrements of infected people is also important.
About 15% -20% of Lassa patients die. The mortality rate of treated Lassa fever is only 1%, but in the event of an epidemic it reaches 50%. The death rate has been steadily declining with ribavirin treatment.
About the author
Anna Jarosz A journalist who has been involved in popularizing he alth education for over 40 years. Winner of many competitions for journalists dealing with medicine and he alth. She received, among others The "Golden OTIS" Trust Award in the "Media and He alth" category, St. Kamil awarded on the occasion of the World Day of the Sick, twice"Crystal Pen" in a nationwide competition for journalists promoting he alth and many awards and distinctions in competitions for the "Medical Journalist of the Year" organized by the Polish Association of Journalists for He alth.