Cases of human infection of West Nile virus (WNV) have been reported in Greece where 13 people have died and at least 140 have become ill, according to the Hellenic Centre for Disease Control and Prevention. Greek authorities say 32 patients are currently hospitalized. Several other countries in Europe are also affected, especially Central Europe and the Mediterranean area, according to the latest issue of Eurosurveillance. The publication adds that numerous animal cases have also been documented.

A “single probable case” was reported in Portugal in July this year. Infected horses have also been reported outside the European Union, including Morroco, Russia (Volgograd Oblast) and Israel – countries that lie in the paths of migratory birds.

The current outbreak in Greece is occurring in the north of the country. Experts believe WNV has “has probably been circulating in humans in the region of central Macedonia in northern Greece for many years.”

Eurosurveillance informs that the reported probable human WNV infection cases in Greece and Portugal confirm that the virus is present in several other countries in the European Union – experts expect more human infections during the mosquito season.

As sporadic cases have been reported in several parts of Hungary over the last few years, health authorities believe WNV is widespread in the country, and not just limited to a single area. A recent Italian study on infected organ donors concluded that the virus is more widespread in Italy than people think.

Eurosurveillance wrote:

..the case report in this issue of a Dutch traveller returning from Israel with WN infection highlights the need for awareness among physicians and laboratory staff to consider WNV infections as a differential diagnosis in cases where patients return from areas where they may have been exposed to the virus.

Eurosurveillance stresses the need for integrated multidisciplinary surveillance systems and effective response plans. It is important that doctors and veterinarians are made aware of the clinical presentation of WNV disease in humans and animals (especially horses) during the mosquito season which spans June to October.

Eurosurveillance adds:

In addition, there is a need to have a better and more precise picture of WNV risk areas in Europe and neighboring countries in order to implement appropriate control measures, especially guidelines for blood donation and organ transplants. Also, studies in Europe are required to better understand the cycle of transmission and the maintenance of WNV in the environment over the years to provide appropriate indicators for risk assessment.

West Nile Virus (WNV) is a virus of the Flaviviridae family which is spread by the bite of infected mosquitoes. The Flaviviridae virus family also includes Japanese encephalitis, dengue fever and yellow fever.

West Nile Virus mainly affects birds – but can also infect other animals, including horses, dogs, cats, bats, skunks, squirrels, chipmunks and domestic rabbits. Humans may also be infected.

Most infected humans either experience no signs or symptoms, or just a skin rash and headache. A small percentage of infected individuals, however, may develop a life-threatening illness which may include encephalitis (inflammation of the brain), myelitis (inflammation of the spinal cord), or meningitis (inflammation of tissues surrounding the brain and spinal cord). Experts say approximately 1% of infected humans develop these serious complications. Those at highest risk for serious illness are the elderly and those with lowered immune systems.

“West Nile virus: the need to strengthen preparedness in Europe”
H Zeller, A Lenglet, W Van Bortel
European Centre for Disease Prevention and Control, Stockholm, Sweden

Source: Eurosurveillance, Hellenic Centre for Disease Control and Prevention (Greece)

Written by Christian Nordqvist