Russia warns of increase in cases of West Nile Virus: All you need to know

Russia warned on Monday of a possible increase in West Nile Virus (WNV) infections this autumn as mild temperatures and heavy precipitation create favourable conditions for the mosquitos that carry it.

"In light of favourable climatic conditions this year - an abundance of precipitation... a warm and long autumn, a high number of (virus) carriers could be observed in the autumn," Rospotrebnadzor, Russia's consumer health watchdog, said.

More than 80% of Russia's West Nile fever cases are recorded in its southwest region.

What is West Nile Virus?

WNV is an infectious disease spread by infected mosquitoes. It spreads from birds to humans with the bite of an infected Culex mosquito. It can lead to a fatal neurological disease in humans.

The virus causes West Nile fever in around 20 per cent of cases, according to World Health Organization (WHO). It is related to the Zika, dengue and yellow fever viruses.

What are the symptoms of WNV?

People who get WNV usually have no symptoms or mild symptoms. The symptoms include a fever, headache, body aches, skin rash, and swollen lymph glands. They can last a few days to several weeks, and usually go away on their own.

Where did the WNV originate?

According to WHO, WNV was first isolated in a woman in the West Nile district of Uganda in 1937. It was identified in birds (crows and columbiformes) in Nile delta region in 1953.

Before 1997, WNV was not considered pathogenic for birds, but at that time in Israel a more virulent strain caused the death of different bird species presenting signs of encephalitis and paralysis. Human infections attributable to WNV have been reported in many countries for over 50 years, the WHO said.

When is it dangerous?

If West Nile virus enters the brain, it can be life-threatening. It may cause inflammation of the brain, called encephalitis, or inflammation of the tissue that surrounds the brain and spinal cord, called meningitis.

How is WNV diagnosed?

A physical exam, medical history, and laboratory tests can diagnose it.

Who are at risk?

Older people, children and those with weakened immune systems are most at risk.

What is the cure?

There are no specific vaccines or treatments for human WNV disease. The best way to avoid WNV is to prevent mosquito bites. Treatment is supportive for patients with neuro-invasive West Nile virus, often involving hospitalization, intravenous fluids, respiratory support, and prevention of secondary infections.

Scientists have said that milder temperatures attributed to climate change could cause diseases such as the WNV to become more widespread.