West Nile fever is an infectious disease that is usually harmless. Medical measures usually serve only to control the symptoms.
What is West Nile fever?
West Nile fever is an infectious disease caused by viruses. West Nile fever owes its name to the West Nile district, which is located in Uganda, Africa. In 1937, the first evidence of infection with the causative virus of West Nile fever was found here. Since symptoms are absent in many cases of West Nile fever, it is almost impossible to state the worldwide incidence of West Nile fever. However, West Nile fever occurs primarily in warm climates such as parts of Africa, India, and Southeast Asia. In addition, an epidemic caused by West Nile fever also occurred in North America during the summer months of 2002. In humans, an infection with West Nile fever is not subject to compulsory notification. However, if animals are infected with the virus that causes West Nile fever, it is an animal disease that is notifiable.
Causes
The cause of West Nile fever is infection with a virus called West Nile virus (WNV). Carriers of the virus responsible for West Nile fever include insects and, in particular, mosquitoes. Since West Nile fever is transmitted from animals to humans, the viral infection is called a zoonosis: wild birds are often initially affected by West Nile fever; mosquitoes that have had contact with animals suffering from West Nile fever can then transmit the virus to humans. West Nile fever can also be caused by human-to-human infection: Such transmission can occur, for example, during organ transplants or blood transfusions. It is also possible that transmission of the virus responsible for West Nile fever can occur from nursing mothers to their infants.
Typical symptoms and signs
- Fever
- Headache
- Pain in the limbs
- Diarrhea
- Nausea
- Vomiting
- Lymph node swelling
- Skin rash
Diagnosis and course
West Nile fever can hardly be diagnosed on the basis of symptoms present. This is due in part to the fact that possible symptoms are nonspecific and West Nile fever is also often completely asymptomatic. A reliable diagnosis of West Nile fever is therefore possible primarily with the help of blood samples: In affected persons infected with West Nile fever, the pathogen is usually detectable in the blood. Antibodies that form in the blood or cerebrospinal fluid when West Nile fever is present also enable a diagnosis to be made. The incubation period for West Nile fever is usually a few days. If West Nile fever is accompanied by symptoms, these are usually similar to the symptoms of a mild flu illness. In most cases, West Nile fever is self-limiting, which means that the symptoms resolve on their own within a few days. In a clear majority of those affected, West Nile flu progresses without complications. Risk factors for the occurrence of complications in West Nile fever are, for example, other physical illnesses or a high age.
Complications
In most cases, West Nile fever is unproblematic and resolves after about seven days. Certain factors play a role in the course of the disease, such as the age of the patient, the immune system, and physical illness and psychological factors. Complications are rather rare, and if they do occur, it is mostly older or immunocompromised people who are affected. In these people, heart muscle inflammation, meningitis or paralysis can occur. In the event of a severe course, it makes sense for patients to be treated as inpatients so that the course can be better monitored. This applies especially to elderly people or people with immune deficiency, because the disease can be life-threatening in them. Deaths are rare, but some patients retain late effects for a long time after surviving the disease, especially if the brain was also affected. But even people with an unproblematic course can still suffer from limb pain, concentration and memory problems and fatigue months after West Nile fever.
When should you go to the doctor?
If a stay abroad is planned, it is generally recommended to obtain sufficient information about the conditions there. The person concerned should build up knowledge about the health risks and, if necessary, consult the attending physician. The state of hygiene should be ascertained in good time and the likelihood of certain diseases should be inquired about. In some cases, vaccinations are recommended so that the organism can adequately defend itself against the pathogens. West Nile fever occurs only in people who stay in the African, Southeast Asian or Indian area. For this reason, appropriate precautions to maintain health are advised before traveling to this region. In general, however, the infectious disease does not pose an increased risk of serious illness. Nevertheless, a doctor should be consulted as soon as health impairments become apparent. In case of fever, headache, digestive tract disorders or swelling of the lymph, a visit to the doctor is advisable. A feeling of illness, general malaise, nausea and vomiting indicate a health disorder that should be diagnosed and treated. Changes in skin appearance, irregularities in locomotion, and an increase in existing symptoms should be discussed with a physician. Medical treatment is necessary to provide relief from symptoms as soon as possible. Itching and swelling of the skin should also be evaluated by a physician.
Treatment and therapy
In the majority of cases, West Nile fever does not require medical treatment. Cure usually occurs within a few days. If West Nile fever is accompanied by severe symptoms, a sensible measure may be, among other things, the observance of bed rest by the affected person. In the case of severe West Nile fever, the symptoms can be alleviated in consultation with the attending physician; appropriate measures may include fever reduction and/or an adequate supply of fluids. Only in very rare cases does West Nile fever require specialist care in the context of hospitalization; such a step may be useful, for example, if there is a greatly increased risk of complications in connection with West Nile fever (such as the risk of suffering inflammation of the brain or heart). Targeted drug preparations to combat West Nile fever are not currently available to the medical community.
Prevention
West Nile fever can be prevented only to a limited extent, because no vaccines exist yet that can be used against West Nile fever in humans. Measures that can serve as individual prophylaxis against West Nile fever are aimed at avoiding mosquito bites in areas affected by West Nile fever: For example, applying anti-mosquito sprays can be useful for this purpose. And wearing long clothing can also help to avoid mosquito bites and thus West Nile fever.
Aftercare
Follow-up care for West Nile fever is based on the symptoms that the patient shows and the course of the disease. If the course is positive, the symptoms resolve within three to fourteen days. The patient must then visit the doctor again, who will perform a routine examination. In addition, a clarification of the symptoms is necessary. Antibiotic medication can then be discontinued. A medical history is also taken as part of the follow-up care. Furthermore, measures must be taken to prevent a recurrence of the infection. If the symptoms occur after a trip abroad, any fellow travelers should also be examined. The same applies to family members who have had contact with the infected person. The therapy itself is completed after seven days. It is limited to alleviating the symptoms by means of rest and sufficient sleep. Treatment and follow-up care should take place in an inpatient hospital so that a rapid response can be made in the event of complications. Follow-up care is provided by the internist in charge or the family doctor. If the course is severe, other specialists must be consulted. If permanent damage is to be expected, psychological care is often also necessary for the patient.
What you can do yourself
The flu-like symptoms of West Nile fever usually subside within a week, even without treatment.In order for the body to fight the infection successfully, it needs a lot of rest: Sick people should take it easy during this time and avoid sports and heavy physical work. A light diet rich in vitamins supports the immune system, and foods that are easy on the stomach, such as rusks, gruel or a vegetable porridge made from boiled carrots and potatoes, help with nausea and vomiting. In herbal medicine, ginger is successfully used against nausea as a spice, tea or in the form of capsules from the pharmacy. Fever can be lowered by simple home remedies such as calf compresses, but this should be avoided in the case of chills. Heavy sweating causes a lot of fluid to be lost: to prevent circulatory problems, it is extremely important to drink enough fluids. Unsweetened herbal teas or a lightly salted chicken broth are best for this purpose. Lime blossom and elderflower tea are known for their diaphoretic and anti-inflammatory effects, while willow bark tea can relieve pain. If the symptoms do not improve within a week or if symptoms of an incipient meningitis appear (severe headache, photophobia, neck stiffness), further self-treatment should be avoided and a doctor should be consulted immediately. Prophylactically, consistent protection against mosquito bites in endangered regions is recommended by using insect repellent and appropriate clothing.
