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Lassa fever

The fever of Lassa is a hemorrhagic fever caused by the homonymous virus. It is transmitted to people through contact with rodents of the genus Moastomys , as well as with household items contaminated with the feces and urine of these animals. This disease can also be transmitted between humans, which happens especially in hospitals without any hygiene or infection control measures.

Currently Nigeria is facing the biggest outbreak of Lassa fever in its history. Since January 1, a total of 114 deaths and 365 confirmed cases have been recorded in the African country. The World Health Organization indicates that there are around 400,000 cases of Lassa fever each year, almost all of them located in West Africa.

What is Lassa fever?

Lassa fever is a zoonotic disease; that is, people become infected with it through infected animals, rodents of the genus Mastomys. It is worth noting that rats infected by this virus do not become ill since they eliminate it through feces and urine.

The clinical course of the disease varies greatly from one patient to another; it depends on a large selection of factors. Even so, when the presence of the virus is confirmed, it is essential to isolate the patient and maintain good protection and hygiene practices to avoid its transmission.

The fatality rate for Lassa fever is 1%; however, in the case of hospitalized patients it can increase up to 15%.


Lassa fever is a relatively recent illness. The first time it was described was in the mid-20th century, although the truth is that it was not isolated until the late 1960s. Its name is because it first appeared in Lassa, Nigeria. The countries most affected by this disease are Guinea, Liberia, Sierra Leone and Nigeria. There were also some cases in Europe in 2009.

How is it transmitted?

Lassa fever is transmitted to humans through exposure to the urine or feces of Mastomys rats infected with this virus. The disease can also be transmitted between humans; For this, a person must be in direct contact with any type of body secretion of another person affected by this disease.

The contagion can also occur through contaminated medical supplies. Cases of sexual transmission of Lassa virus have also been recorded. To date, no studies have been able to prove that Lassa fever can be transmitted through the air between humans.

The truth is that it is a disease that can occur in people of all races, genders and age groups. However, there are certain population groups that are more likely to be infected with this virus: people who live in rural areas where there are these types of rats and hygiene and sanitation conditions are scarce.

Lassa fever symptoms

The incubation period for this disease is between 2 and 21 days. The initial symptoms are very similar to those of the flu , such as weakness, tiredness and general malaise; sometimes they are accompanied by migraine headaches , sore throat, nausea, and vomiting. This is one of the reasons why Lassa fever in the vast majority of cases is not diagnosed until the condition is in more advanced stages.

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If the disease is not treated in its early stage, the symptoms in the most severe cases can have very negative consequences for health both in the short and long term: facial swelling, lung effusion, hypotension, seizures and even coma.

Lassa fever becomes especially severe during the last trimester of pregnancy; maternal and / or fetal death occurs in more than 80% of cases. In the rest of the patients, one of the most common consequences of this condition is deafness; 25% of patients suffer from it after their recovery, and around 50% of them recover their hearing after three months. There may also be other consequences such as hair loss.

Diagnosis and treatment of Lassa fever

In the vast majority of cases of Lassa fever, the diagnosis is complicated since the symptoms are very varied and, in addition, they are sometimes associated with a possible flu. Once the disease progresses, the symptoms are also often mistaken for other viral hemorrhagic fevers, such as Ebola virus disease.

The definitive diagnosis is established after an analysis carried out in specialized laboratories ; samples should be handled with great care. The laboratory tests to be carried out are the following: polymerase chain reaction with reverse transcriptase, ELISA, antigen detection tests and virus isolation in cell cultures.

Once Lassa fever is confirmed, the most common treatment is the administration of the antiviral ribavarin.


Generally, Lassa fever sufferers take 7-31 days to recover after symptoms begin . For patients with severe multisystem disease, the mortality rate ranges from 16 to 45 percent.

The main complications of Lassa fever occur during pregnancy; the mortality rate for pregnant women is between 50 and 92 percent. The main complications are twofold: pregnancy loss and mortality.

Prevention tips

Prevention of this disease involves maintaining good hygiene at home , trying to prevent rats from entering homes by all means. It is essential to store all food in containers that rodents cannot access and garbage should always be kept as far away from the home as possible.

The health personnel should pay the maximum preventive measures and hygiene in relation to Lassa fever. This happens to maintain the basic hygiene of the hands, as well as of the respiratory system ; and, of course, properly use personal protective equipment.

In addition, those health professionals who care for Lassa fever patients must apply a series of additional measures in order to avoid the slightest contact with the patients’ body fluids, as well as with any type of contaminated surface.

To this day, there is no type of vaccine that protects people from getting Lassa fever .

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Hello Readers, I am Nikki Bella a Psychology student. I have always been concerned about human behavior and the mental processes that lead us to act and think the way we do. My collaboration as an editor in the psychology area of ​​Well Being Pole has allowed me to investigate further and expand my knowledge in the field of mental health; I have also acquired great knowledge about physical health and well-being, two fundamental bases that are directly related and are part of all mental health.

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