What is Lassa fever?

 Lassa fever is an infectious disease that occurs mainly in West Africa. It is triggered by the Lassa virus, which is transmitted to humans by rodents . Most of those affected experience a mild course of the disease. The disease is mild in most people affected . However, it can also be fatal. However, it can also be fatal. For this reason, timely recognition and treatment of Lassa fever is life-saving.

How widespread is Lassa fever?

Lassa fever is particularly endemic in the African regions of Sierra Leone, Guinea, Nigeria and Liberia . Here, the viruses cannot be removed and therefore occur permanently. In the case of Lassa fever, the infections are localised, since the viruses can only be transmitted to humans by the African multitasker rat. In these areas, all rats living there carry the virus in . However, it is impossible to eliminate all of them.

According to estimates , about 300,000 people are infected with the virus every year. At , the disease runs mildly and/or completely without symptoms in about 80 percent of those affected. In some cases, however, the course of the disease is very severe and about 2 percent of those infected die of Lassa fever.

Only very rarely can diseases caused by Lassa fever be detected in areas outside the endemic region . This usually happens through travellers who have previously stayed in African regions and bring the virus with them on their return journey . The Lassa virus has already been detected in Switzerland, Austria and Germany.

What are the symptoms of Lassa fever?

As already described, not all infected persons develop symptoms. For the others, most symptoms appear about 6-21 days after infection. The first symptoms are usually similar to a flu as follows:

• Fever,
• Fatigue,
• Headache and aching limbs,
• Muscle aches,
• Pain behind the breastbone,
• Nausea and vomiting,
• Cough,
• Conjunctivitis.

These symptoms are familiar from normal flu infections. However, a painful inflammation with ulcers in the throat is indicative of Lassa fever. Sometimes the mucous membrane of the larynx is also swollen. In some cases, there is also a skin rash, which rises above the skin and can be felt.

If the course is severe, the following symptoms usually appear from the second week onwards:

• Oedema of the face and eyelids,
• Bleeding in the mucous membranes,
• Accumulation of fluid in the pericardium and the pleura,
• Drowsiness of consciousness,
• Low blood pressure and slow heartbeat.

In the further course of a severe case of Lassa fever, kidney failure and circulatory failure may occur . It is not uncommon for severe bleeding to occur. In addition, the brain can also be affected by the virus , resulting in encephalopathy. This often manifests itself in drowsiness, convulsions. In many cases, those affected fall into a coma.

How is Lassa fever diagnosed?

Since the symptoms of Lassa fever are very similar to those of a flu-like infection or other febrile infections, such as malaria, dengue fever, typhoid and Ebola, it is difficult for a doctor to make the diagnosis quickly and unequivocally. Therefore, at the anamnesis interview, the doctor will mainly focus on the recent travel destinations. Among other things, the following questions will be asked:

• Do you suffer from fever?
• Have you been abroad in the past three weeks? If so, where exactly were you?
• Have you been in contact with people who are also ill?

After this conversation, the doctor will examine the patient thoroughly. The temperature and blood pressure will be taken and the doctor will not only palpate the abdomen, but also listen to the lungs and heart.

However, in order for Lassa fever to be detected without any lingering doubt and diagnosed , a blood test will be necessary. For this purpose, blood is taken from the patient, which is then examined in a laboratory under the highest safety standards. Thanks to a molecular genetic test of the genetic make-up, an infection can be detected directly . In addition, the blood of the person affected is searched for corresponding antibodies against the virus. These are only present in the body if there has been contact with the viruses. A number of different blood values can also provide information about how the course and severity of the infection is to be assessed . If the kidneys and pancreas are involved , this will be shown by the creatinine and lipase values in the blood.

How is Lassa fever treated?

Lassa fever can be fatal. In view of this, it is essential that a therapy with the right means is carried out in time. However, it must be said that at present there are no drugs approved for the treatment of Lassa fever either in Germany or in Switzerland or in Austria. However, if one disregards the official approvals , the active substance ribavirin is often used at the beginning of the disease. This drug has the property of inhibiting the multiplication of viruses. The sooner this drug is used, the better it can show its effect. Lassa fever patients are monitored on an isolation ward for 24 hours. However, the main focus here is on treating the symptoms. The aim of the isolation measures is to prevent other people from becoming infected with the virus.

What is the prognosis for Lassa fever?

If the right treatment is given, most patients show a clear improvement from about the second week after the onset of the disease. However, after Lassa fever has been cured, most of those affected still feel weak for some time. This is because the body needs some time to recover. If the course of Lassa fever is severe, most patients die around the twelfth day of the disease. The main causes of death are kidney failure and circulatory failure. Likewise, severe haemorrhage and, above all, the development of encephalopathy significantly worsen the prognosis.

Is there an obligation to report Lassa fever?

In order to prevent the spread of Lassa fever, it is subject to compulsory notification in Austria, Switzerland and Germany. Only the suspected case must be reported by doctors by name to the responsible health authority.