Everything you wanted to know about West Nile fever

This year we are seeing a large number of cases of West Nile fever, which appeared within several weeks, earlier than in previous years (the disease generally appears towards the end of summer-beginning of fall). Since the start of the year, 19 cases of West Nile fever have been identified in the National Central Laboratory, most this past June. Most of the patients reside in central Israel and were hospitalized at hospitals in the areas where they live. Since the beginning of the year, no West Nile fever patients have been diagnosed yet at Hillel Yaffe Medical Center. The Director of the Infectious Diseases Unit at Hillel Yaffe, Dr. Regev Cohen, explains a bit about the symptoms of the disease and the possibility of preventing it.

West Nile fever is a zoonotic disease - a disease that is passed to humans from animals, particularly by being bitten by the female Culex mosquito, although also by the female Asian Tiger mosquito (Aedes).

Most of the people who are infected with the virus, approximately 80%, will not experience any symptoms at all. If symptoms appear, they will manifest as high fever, headaches and general fatigue, much like the flu. Some patients will develop a rash. In rare cases (approximately 1% of those infected), the disease may lead to various neurological effects such as meningitis, inflammation of the brain or spinal cord. The appearance of neurological symptoms is more typical in people in their 60s and older. In extreme cases, the disease may lead to death, particularly in the elderly and those who have severe chronic diseases.

The incubation period of the disease, from the mosquito bite to onset of the disease, ranges from 2-14 days. It is important to emphasize that the disease is not transmitted from person to person, but only by mosquito bites. Person-to-person transmission is possible only in cases of organ transplants or transfusion of contaminated blood.

How can the disease be identified?

Diagnosis of the disease is done by blood test to identify antibodies and, in some cases, also by lumbar puncture to find remnants of the virus or associated antibodies. However, a person may have a mild case of the disease, not develop any neurological symptoms and heal on their own. In other words, it is important to pay attention to fevers, particularly in the summer, and see how they develop in order to prevent the condition from deteriorating.

What are the complications of the disease?

As noted, the main complications of the disease may occur as a result of damage to the nervous system (neurological symptoms). These effects may lead to the development of meningitis, brain inflammation and inflammation of the spinal cord with mild paralysis of the limbs.

What is the treatment?

Treatment of the disease is symptomatic, primarily administration of fluids and fever-reducing medications. There are reports of administration of antibodies against the virus, but they are few and do not show uniform results.

Can the disease be prevented?

The main effort against this disease should be focused on prevention. Mosquitoes need standing water to breed and eradication of pools of water - even small ones, which appear insignificant, such as plants - are essential in the struggle to reduce the risk of being infected with the disease. Make sure to take personal protection measures to prevent mosquito bites such as using approved mosquito repellents (including those containing DEET or picaridin. If you put on sunscreen, apply mosquito repellent on top of it. Wear long clothing when outside the home and install screens on your windows and doors.

The Regional Health Offices are responsible for spraying against mosquitoes and treating pools of standing water. Therefore, inform the authorities when there are a large number of mosquitoes where you live.