Lassa Fever 101

Lassa fever is a viral disease that is prevalent in only some parts of West Africa. The countries affected include Nigeria, Ivory Coast and Guinea. So far, only isolated cases have occurred in Germany. If Lassa fever is diagnosed, there is an obligation to report.

What is Lassa fever?

In two out of ten cases, the illness is associated with flu symptoms, such as fever, muscle, headache and joint pain and fatigue. See AbbreviationFinder for abbreviations related to Lassa Fever.

Lassa fever is a viral hemorrhagic fever (associated with internal bleeding), which also includes Ebola, yellow fever and Marburg virus infection. According to an international agreement, the fever was named after the town of Lassa, where it was first detected.

It is caused by viruses and initially runs like the flu. The affected person suffers from fever, headache and body aches, later a sore throat, a dry cough, chest pains and cramps in the abdomen. The first symptoms appear after an incubation period of 6 to 21 days.

In many cases, the sufferers only suffer from mild symptoms and internal bleeding does not occur in every single case. Nevertheless, the rate for the fatal course of the disease is around ten to 20 percent, and in pregnant women it is even 50 percent.


The cause of Lassa fever is the Lassa virus, which is transmitted by the African multiteat rat. The virus gets into food via the rat’s excrement (faeces or urine) and from there into the human organism.

In some areas, the rats themselves are eaten and transmit the virus directly. The rat itself shows no symptoms of the disease. Lassa fever can also be transmitted from person to person through droplet infection .

Contact with the blood, saliva, semen, vomit, urine or faeces of a sick person is also a possible cause of infection.

Lassa fever occurs where poor sanitary conditions facilitate an ideal breeding ground for food contamination or human-to-human transmission of the vitus.

Symptoms, Ailments & Signs

Lassa fever often causes no or only imperceptible symptoms. In two out of ten cases, the illness is associated with flu symptoms, such as fever, muscle, headache and joint pain and fatigue. Respiratory symptoms appear after five to seven days.

These include coughing, severe sore throat and swelling in the area of ​​the larynx, but also inflammation of the pharyngeal mucosa and tonsils. White or yellowish deposits then form on the tonsils, which give off an unpleasant odour. Possible accompanying symptoms of Lassa fever are chest pains and stabbing headaches.

In addition, hemorrhagic fever can cause blood pressure fluctuations and occasionally lead to circulatory failure. If the pathogen is carried over, there is a risk that the internal organs will become inflamed. Then conjunctivitis develops with internal bleeding or pericarditis. Edema may appear in the eyelid and neck area.

These accumulations of water are usually associated with further pain and a strong feeling of discomfort, and there are often restricted movements. Lassa fever can also cause gastrointestinal symptoms such as nausea, vomiting and abdominal cramps. The symptoms mentioned occur gradually and subside quickly with expert treatment. In eight out of ten patients, a mild course of the disease without serious symptoms or complaints can be expected.

Diagnosis & History

Lassa fever can be clearly diagnosed by detecting the causative virus in the patient’s blood, urine, throat or tissue samples. The specific antibodies against the virus can be detected in the blood about a week after the onset of Lassa fever.

In order to achieve a good prognosis and rule out late symptoms as far as possible, a blood test should be arranged as soon as possible if there is a suspicion. Because of the symptoms, especially in the early stages, other diseases are often suspected. Lassa fever initially shows flu-like symptoms, so a severe flu infection may be assumed.

Confusion with malaria or other hemorrhagic fever diseases is also possible. Typical symptoms of Lassa fever include edema of the face, conjunctivitis, protein in the urine, sore throat and pain behind the breastbone.

In the case of a severe course of the disease, bleeding of the internal organs, mucous membranes and skin ultimately occurs, the consequence of which can be a failure of the cardiovascular system.


Because of Lassa fever, those affected suffer from the usual symptoms of influenza. This leads to a strong and high fever and also to body aches. The patient’s resilience also decreases significantly due to the disease, resulting in tiredness and exhaustion. This disease also leads to sore throats and headaches.

It is not uncommon for patients to suffer from abdominal pain or vomiting due to Lassa fever. In many cases, the disease can also be confused with malaria, resulting in delayed treatment of these symptoms. Failure to treat Lassa fever can result in cardiac death. The treatment itself is carried out with the help of medication and is usually quickly successful.

Special complications do not occur, so that a positive course of the disease can be recorded. The patient’s life expectancy will not be reduced if treatment is started early. Furthermore, there are no particular complications or complaints. However, those affected are not allowed to maintain contact with other people, since Lassa fever has a high risk of infection.

When should you go to the doctor?

People who get the flu after a stay in a country with poor hygienic conditions should see their family doctor. If cough, sore throat and other signs of Lassa fever occur, medical advice must be sought immediately. The symptoms indicate a serious illness that must be clarified by a doctor in any case. If sharp chest pains or headaches develop, the person concerned must be taken to a hospital.

In the event of circulatory failure, severe blood pressure fluctuations and other typical complications, the emergency doctor must be alerted. The person concerned should take it easy; if in doubt, first aid measures must be taken. Lassa fever is treated by the general practitioner or an internist. Depending on what symptoms are occurring, you may need a cardiologist, ophthalmologist, or gastroenterologistto be consulted. People who suffer from a chronic illness or allergy are best advised to consult with the doctor responsible. If a child shows symptoms of Lassa fever, parents should call emergency services. Pregnant women and seriously ill people must also have unusual symptoms clarified immediately.

Treatment & Therapy

Lassa fever is treated by inhibiting the multiplication of the virus as much as possible and relieving the patient’s symptoms. In addition, the affected person must be supplied with sufficient liquid. Because of the possibility of sudden hypotension (low blood pressure), intensive care is often required.

Patients receive the active ingredient ribavirin to contain the virus. In Lassa fever, prompt diagnosis and initiation of treatment within 6 days of onset of symptoms is an important prognostic factor.

The way the medication is administered also plays a crucial role. The mortality rate decreases by a factor of three with early treatment initiation and administration of ribavirin orally (by mouth) and as much as 10-fold with intravenous administration.

Outlook & Forecast

Lassa fever is mild in most patients. You make a full recovery. A good 20 percent perceive no complaints at all. In all others, the typical symptoms occur in varying degrees of intensity. From the second week of illness, a significant improvement begins. The mortality rate is about one to two percent based on all infections. It is striking that most of those affected die around the twelfth day of illness. The failure of the kidneys and the circulatory system takes up a significant space. Bleeding can also occur.

Lassa fever is native to the African continent. There it is proven in Nigeria, Guinea, Liberia and Sierra Leone. Diseases in industrialized countries like Germany are hardly present. In individual cases, the virus was imported unnoticed.

Due to the risk of infection, patients must take precautions towards other people. While the disease phase lasts a maximum of four weeks, viruses with contagious potential can sometimes be detected in the excretion for another ten weeks. Transmission is also possible via blood and saliva. If the Lassa fever takes an unfavorable course, the period of recovery drags on. Patients then suffer from deafness and disorders in the musculoskeletal system. Starting therapy early is considered the most effective remedy for Lassa fever.


Infection with Lassa fever can be prevented by avoiding contact with rats and people who are already sick and by ensuring adequate hygiene. Lassa viruses can be excreted in the urine for up to nine weeks and in the semen for up to three months after the onset of the disease and lead to infection. Antibodies are formed against Lassa fever, which rule out recurrence.


The aftercare measures for Lassa fever are often severely limited. Those affected are primarily dependent on rapid and, above all, immediate treatment of the symptoms so that no further complications can arise. Self-healing of the disease is usually not possible, so the affected person should consult a doctor at the first signs and symptoms of fever.

The infection is usually treated by taking various medications. It is important to ensure regular intake with the right dosage in order to permanently relieve and limit the symptoms. Should there be any questions or ambiguities, a doctor should always be consulted first. You should also see a doctor first if you have side effects from the medication.

Most patients are dependent on the help and care of other people during the treatment of Lassa fever, with care from their own family in particular having a positive effect on the further course of the disease. This can also prevent depression or other mental upsets. Lassa fever may reduce the life expectancy of those affected, with the further course of the disease depending heavily on the time of diagnosis.

You can do that yourself

Lassa fever is a highly contagious and therefore notifiable disease. The disorder is also very dangerous and can be fatal. The risk is particularly high for pregnant women; in this group, the morbidity is as high as 50 percent if the disease is not treated professionally immediately.

Therefore, the best self-help measures the patient can take are prevention and immediate medical attention if infection is suspected. Lassa fever occurs almost exclusively in West Africa. The virus that causes the disease is transmitted by rats. Under no circumstances should rat meat be eaten. Since the animals also spread the virus via other routes, for example their faeces, no raw food should be eaten either. When it comes to fruit, nuts are to be preferred. Transmission can also occur from person to person through droplet infection. Contact with the saliva or semen of infected people is particularly dangerous.

The incubation period is between a few days and up to three weeks. Anyone who shows symptoms of flu during a stay or shortly after returning from a risk area should definitely consult a doctor immediately and explicitly point out the possible infection with Lassa fever so that the suspicion can be clarified immediately and adequate treatment can be started promptly.

Lassa Fever

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