Lassa fever is a viral disease that occurs preferentially in only some parts of West Africa. Affected countries include Nigeria, the Ivory Coast and Guinea. In Germany, only isolated cases have occurred so far. If Lassa fever is detected, notification is mandatory.
What is Lassa fever?
Lassa fever is one of the viral hemorrhagic fevers (associated with internal bleeding), which also includes Ebola, yellow fever and Marburg virus infection. According to the International Convention, the fever was named after the town of Lassa, where it was first detected. It is caused by viruses and initially progresses like the flu. The affected person suffers from fever, headache and pain in the limbs, and later there is a sore throat, a dry cough, chest pain and cramps in the abdomen. First symptoms appear after 6 to 21 days of incubation. In many cases, those who contract the disease suffer only mild symptoms, and internal bleeding does not occur in every single case. Nevertheless, the rate for the fatal course of the disease is about ten to 20 percent in pregnant women even 50 percent.
Causes
The cause of Lassa fever is Lassa virus, which is transmitted by the African wolverine rat. The virus gets onto food through the excretions of the rats (feces or urine) and from there into the human body. In some areas, the rats themselves are consumed and transmit the virus directly. The rat itself shows no symptoms of the disease. Through droplet infection, transmission of Lassa fever is also possible from person to person. Contact with the blood, saliva, semen, vomit, urine or feces of an infected person is also a possible cause of infection. Lassa fever occurs where poor sanitary conditions facilitate an ideal breeding ground for food contamination or person-to-person transmission of vitus.
Symptoms, complaints, and signs
Lassa fever often produces no or only imperceptible signs of illness. In two out of ten cases, the illness is associated with flu symptoms, such as fever, muscle, head, and joint pain, and faintness. After five to seven days, respiratory symptoms appear. These include cough, severe sore throat and swelling around the larynx, as well as inflammation of the pharyngeal mucosa and tonsils. White or yellowish coatings then form on the tonsils, giving off an unpleasant odor. Possible accompanying symptoms of Lassa fever are chest pain and a stabbing headache. In addition, the hemorrhagic fever can cause fluctuations in blood pressure 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 with internal bleeding or pericarditis develops. Edema can occur in the area of the eyelids and neck. This accumulation of water is usually associated with further pain and severe discomfort, and often there is also restriction of movement. Lassa fever can also cause gastrointestinal symptoms such as nausea, vomiting and abdominal cramps. The aforementioned symptoms occur gradually and subside quickly with expert treatment. In eight out of ten patients, the course of the disease is mild with no serious symptoms or discomfort.
Diagnosis and course
Lassa fever can be unequivocally diagnosed by detecting the causative virus in the blood, urine, throat, or tissue samples of the ill person. Specific antibodies to 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 to exclude late symptoms as far as possible, a blood test should be arranged as soon as possible if there is any suspicion. Because of the symptoms, other diseases are often suspected, especially in the early stages. Lassa fever initially shows flu-like symptoms, so that a severe flu infection may be assumed. Confusion with malaria or other hemorrhagic fevers is also possible. Typical symptoms of Lassa fever include edema of the face, conjunctivitis, protein excretion in the urine, pharyngitis, and pain behind the breastbone.If the disease is severe, bleeding of the internal organs, mucous membranes and skin will eventually occur, the consequence of which may be failure of the cardiovascular system.
Complications
Due to Lassa fever, those affected suffer from the usual symptoms of influenza. There is a strong and high fever and further also aching limbs. Also the resilience of the patients decreases due to the illness clearly, so that it comes to a tiredness and to a exhaustion. Likewise, this disease leads to sore throat and headaches. It is not uncommon for patients to suffer from pain in the abdomen or vomiting due to Lassa fever. Likewise, in many cases, the disease can be mistaken for malaria, resulting in delayed treatment of these conditions. If Lassa fever is not treated, the patient may die of heart disease. The treatment itself is carried out with the help of medication and usually leads quickly to success. Special complications do not occur, so that a positive course of the disease can be recorded. The patient’s life expectancy is not reduced if treatment is started early. Furthermore, no particular complications or complaints occur. However, those affected must not maintain contact with other people, as Lassa fever has a high risk of infection.
When should one go to the doctor?
People who come down with influenza after a stay in a country with poor sanitary conditions should see their family doctor. If cough, sore throat and other signs of Lassa fever are added, medical advice should be sought immediately. The symptoms indicate a serious illness, which must be clarified by a doctor in any case. If stabbing chest pains or headaches develop, the affected person must be taken to a hospital. In the event of circulatory failure, severe blood pressure fluctuations and other typical complications, the emergency physician should be alerted. The affected person should take it easy; in case of doubt, first aid measures must be taken. Treatment of Lassa fever is carried out by the family doctor or an internist. Depending on the symptoms, cardiologists, ophthalmologists or gastroenterologists must be consulted. Individuals who have a chronic illness or allergy are best to confer with the appropriate medical professional. If a child shows symptoms of Lassa fever, parents should call the emergency medical services. Pregnant women and the seriously ill also need to have unusual symptoms clarified immediately.
Treatment and 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 given sufficient fluids. Because of the possibility of sudden hypotension (low blood pressure), intensive medical care is often ordered. Patients are given the drug ribavirin to contain the virus. In Lassa fever, rapid diagnosis and starting treatment in the first six days after the onset of symptoms is an important factor in prognosis. In addition, the way the medication is administered plays a crucial role. The mortality rate decreases by a factor of three when treatment is started early and ribavirin is administered orally (by mouth), and by a factor of 10 when administered intravenously.
Outlook and prognosis
In most patients, Lassa fever is mild. They recover completely. A good 20 percent do not experience any symptoms at all. In all others, the typical symptoms appear with varying intensity. From the second week of illness onwards, there is a marked improvement. The mortality rate is about one to two percent in relation to all infections. It is striking that most of those affected die around the twelfth day of illness. Kidney and circulatory failure occupy a significant space. Bleeding may also occur. Lassa fever is native to the African continent. There it is detected in Nigeria, Guinea, Liberia and Sierra Leone. Diseases in industrialized countries such as Germany are almost non-existent. The virus has been imported unnoticed in individual cases. Due to the risk of infection, patients must observe precautionary measures towards other persons.While the disease phase lasts a maximum of four weeks, viruses with infectious potential can sometimes still be detected in excretion for ten weeks. Transmission is also possible via blood and saliva. If Lassa fever progresses unfavorably, the recovery period is protracted. Patients then suffer from numbness and musculoskeletal disorders. Early initiation of therapy is considered the most effective remedy for Lassa fever.
Prevention
Infection with Lassa fever can be prevented by avoiding contact with rats as well as people who are already ill, if possible, and by ensuring adequate hygiene. Lassa viruses can be excreted in urine for up to nine weeks and in seminal fluid for up to three months after the onset of the disease and can lead to infection. Antibodies are formed against Lassa fever, which preclude recurrence of the disease.
Follow-up
Often, aftercare measures for Lassa fever are severely limited. Here, those affected are primarily dependent on rapid and, above all, immediate treatment of the symptoms so that no further complications can occur. A self-healing of the disease is usually not possible, so that the affected person should see a doctor at the first signs and symptoms of this fever. As a rule, the infection is treated by taking various medications. It is important to take the correct dosage of medication on a regular basis in order to permanently alleviate and limit the symptoms. If there are any questions or uncertainties, a doctor should always be consulted first. A doctor should also be consulted first if side effects of the medication occur. Most patients are dependent on the help and care of other people during the treatment of Lassa fever, whereby care by one’s own family in particular can have a positive effect on the further course of the disease. This can also prevent depression or other psychological upsets. Possibly Lassa fever reduces the life expectancy of the affected person, although the further course of the disease is strongly dependent on the time of diagnosis.
What you can do yourself
Lassa fever is a highly contagious and therefore notifiable disease. In addition, the disorder is very dangerous and can be fatal. The risk is particularly high for pregnant women, with morbidity in this group as high as 50 percent if the disease is not immediately treated professionally. Therefore, the best self-help measures patients can take are prevention and immediate consultation with a physician if infection is suspected. Lassa fever occurs almost exclusively in West Africa. The virus that causes the disease is transmitted by rats. Therefore, rat meat should not be eaten under any circumstances. Since the animals also spread the virus by other means, for example through their feces, raw food should not be eaten either. In the case of fruit, peel fruit is preferable. Transmission can also occur from person to person by droplet infection. Contact with saliva or semen of infected persons is particularly dangerous. The incubation period ranges from a few days to up to three weeks. Anyone who shows symptoms of influenza during a stay or shortly after returning from a risk area should definitely see 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.