The West Nile Fever
The West Nile fever is an infectious disease transmitted by mosquitoes to humans. Its pathogen, the West Nile virus, occurs in Africa, North America and southeastern Mediterranean countries. Often the infection remains asymptomatic. Some patients suffer from flu-like symptoms.
The West Nile fever is an infectious disease caused by the West Nile virus. It is endemic in Africa, India, Israel, Turkey and North America. Endemic is a region in which a pathogen is permanently found and cannot be removed. The virus is always responsible for epidemic-like outbreaks in which the disease is very frequent.
West Nile Fever Symptoms
The West Nile fever remains asymptomatic in nearly 80 percent of cases. Doctors also speak of a clinically silent infection. About 20 percent of patients have sudden but mild symptoms. These resemble a flu.
The West Nile fever begins after an incubation period of 2 to 14 days. This corresponds to the time between the contagion with the pathogens and the outbreak of the West Nile virus symptoms.
West Nile Fever symptoms include:
- Fatigue, feeling of illness
- Back pain
About half of the patients who have West Nile Virus symptoms have a so-called maculopapular rash on the trunk. This is what doctors call a knotty-spotted rash. The symptoms last for an average of three to six days.
Severe course of West Nile Fever
Less than one percent of the patients who have been infected with the West Nile virus suffer a serious illness. These patients develop brain inflammation (encephalitis) or meningitis (meningitis). It manifests itself with the following symptoms:
- Very high fever
- Stiff neck
- Disturbances of consciousness
- Epileptic seizures (convulsions)
- Visual and hearing disorders
- Patients with severe West Nile fever may fall into a coma and die. Symptoms may persist for weeks or even persist. In rare cases, the heart or liver is also affected
West Nile Fever Causes and Risk Factors
The causative agent of the West Nile fever is the West Nile virus (WNV). It belongs to the flaviviruses and consists of the genome (RNA) as well as a cover in which various proteins (proteins) are incorporated.
The WNV is transmitted by mosquitoes to humans. The genus of the mosquitoes, which most frequently transmits the West Nile fever is called Culex. Other insect species such as Aedes or Mansonia can also transmit the West Nile virus to humans.
Birds serve as a reservoir for the West Nile fever. But also horses and cats can be infected. If a mosquito stings one of these animals, these animals get this viruses over their trunks.
In rare cases, the pathogen of the West Nile fever can also be transmitted by blood transfusions or organs. During pregnancy and lactation, the mother can transmit the virus to the fetus or infant.
West Nile Fever Investigations and Diagnosis
If you feel discomfort during or after a trip to endemic areas and get high fever, look for a doctor. It is not easy to diagnose West Nile fever as there are many diseases with similar symptoms. In the preliminary interview, your doctor will ask you, among other things, the following questions:
- Since when do you feel sick?
- What is your fever?
- What other symptoms do you have?
- Have you recently been abroad, for example in Africa?
- Have you noticed an insect sting?
- Do people in your environment have similar symptoms?
West Nile fever physical examination
Your doctor then examines you physically. First doctor inspects your skin. Then, doctor will pay attention to possible insect bites or a suspicious rash. He also scans your lymph nodes for swelling. He hears the lungs, heart and abdomen and checks whether you are suffering from neck stiffness. For this he tends his head forward on your chest.
Doctor also examines the function of your brain nerves by testing your vision and hearing, as well as the movement of your facial muscles and tongue. Finally, doctor tests the muscle strength of your arms and legs, which you should move against a resistance, as well as your reflexes.
West Nile Fever laboratory diagnostics
The diagnosis of West Nile fever can only be clarified by chemistry laboratory. For this, either blood or cerebrospinal fluid (CSF) is required. This is obtained by means of a lumbar function, in which a needle is carefully pushed between the vertebral bodies up into the spinal canal.
The blood or CSF sample is tested in the laboratory either for antibodies against the West Nile virus or on genetic material (RNA) of the WNV. The so-called ELISA test with which antibodies against the West Nile virus are sought in the patient’s blood can also be falsely positive. This is due to the fact that there are many similar flaviviruses.
Therefore, after a positive ELISA test, a confirmation test is carried out to ensure that the antibodies are specifically directed against the WNV.
In the first days after the contagion, the genome of the West Nile virus can also be detected in the blood or cerebrospinal fluid. For this purpose, a so-called polymerase chain reaction (PCR) is used in the laboratory.
West Nile fever similar diseases
The diagnosis of West Nile fever is not easy for your doctor. This is because the West Nile virus symptoms can also occur in many other diseases. These include:
- Flu (influenza)
- Dengue fever
- Yellow fever
The treatment of West Nile Fever
The West Nile fever is symptomatically treated. This means that the individual complaints that patients have are treated. West Nile virus can not be treated because there is still no suitable drug for this virus. Antibiotics also do not help, since they only act against bacteria, but not against viruses.
The fever is most effectively treated with antiperspirant drugs such as ibuprofen or paracetamol. Relax a lot and give your body time to relax. In addition, you should drink a lot to prevent fluid deficiency.
If you feel sick or vomit, you can take medication that suppresses the vomiting. This includes, for example, dimenhydrinate. In addition, you should eat all sorts of food such as rusks or brussels.
If you are suffering from a severe course of West Nile fever, your GP will take you to a hospital. There, the therapy can be intensified, for example, by administering fluid via the vein (infusion).
West Nile Fever Prevention
To prevent a disease of West Nile fever, you should protect yourself against mosquito bites in risk areas. The following helps:
- Wear long clothes!
- Sleep under a mosquito net!
- Cover doors and windows with fly screens!
- Spray yourself and your clothes with repellents (anti-mosquito sprays)!
- Vaccination against the West Nile fever is currently only available for horses
West Nile Fever Prognosis
The West Nile fever usually has a good prognosis, especially in children. Persons over 50 years of age are more likely to develop a severe course of West Nile fever. The same applies to patients with diabetes mellitus or immune deficiency.
About half of the patients who are suffering from encephalitis will be left with late consequences. These manifest themselves in neurological damages such as paralysis or visual disturbances. The West Nile fever encephalitis ends in 15 to 40 percent of cases fatal.