West Nile virus Encephalitis is a mosquito-borne viral disease, which can cause an inflammation of the brain and can be a serious, even fatal, illness.
West Nile virus is common in Africa, West Asia, the Middle East and Europe and experts believe it is now established as a seasonal epidemic in North America.
West Nile virus appears in summer in North America and outbreaks often carry on into autumn - in 1999 the virus was confirmed in the New York metropolitan area during the summer and fall, it survived the winter and has since then been present in humans, horses, certain birds, and mosquitoes.
West Nile virus is most often spread by the bite of an infected mosquito - mosquitoes become infected when they feed on infected birds - the infected mosquitoes can then spread the virus to humans and other animals when they bite.
West Nile virus is not spread through touching or through casual contact such as touching or kissing a person with the virus, but in a few cases it has been spread through blood transfusions, organ transplants, breastfeeding and even during pregnancy from mother to baby.
Since 1999, West Nile virus has spread rapidly across the United States following the pattern of migratory birds and has emerged in all states except Maine and Washington and into parts of Canada, Mexico, Central America, and South America.
West Nile virus is a potentially serious illness for which there is no human vaccine and it is important that the public has information that can help them recognize and prevent West Nile virus.
While 80% of West Nile virus infections produce no symptoms in people, or symptoms which are mild or moderate, about 20% of cases produce mild symptoms including fever, headache, and body aches, often with skin rash on the chest, stomach and back, vomiting, and sometimes and swollen lymph glands - these symptoms generally last a few days, although some healthy people have reported having the illness for several weeks.
A few victims, less than 1% of cases, will however have more severe infections marked by headache, high fever, neck stiffness, muscle weakness, stupor, disorientation, convulsions, paralysis, coma, and, rarely, death - these symptoms may last several weeks, and the neurological effects may be permanent.
Those over 50 years of age have a higher risk of developing a more severe infection, as do people with weaker or compromised immune systems and people with chronic diseases, such as cancer, diabetes, alcoholism, or heart disease - they are at greater risk of developing symptoms and health effects that are more serious, including meningitis, encephalitis and acute flaccid paralysis.
Meningitis is inflammation of the lining of the brain or spinal cord - Encephalitis is inflammation of the brain itself and Acute flaccid paralysis is a polio-like syndrome that can result in the loss of function of one or more limbs - these conditions can be fatal.
Symptoms typically develop between 3 and 14 days after a person has been bitten by an infected mosquito.
Those who spend more time outdoors either working or playing are also more at risk as they stand more chance of being bitten by an infected mosquito.
Risk through medical procedures is very low as all donated blood is checked for West Nile virus before being used and the risk of getting West Nile virus through blood transfusions and organ transplants is very small, and should not prevent people who need surgery from having it.
Pregnancy and nursing do not increase the risk of becoming infected with West Nile virus and the risk that West Nile virus may infect a fetus or an infant through infected breast milk is still being evaluated - those with concerns should discuss them with their care provider - there are no reported adverse events following use of repellents containing DEET in pregnant or breast-feeding women - pregnant women and nursing mothers are encouraged to talk to their doctor if they develop symptoms that could be West Nile virus.
There is no specific treatment for West Nile virus infection and in most people with milder symptoms such as fever and aches, these will pass on their own without medical attention. In more severe cases, people are often hospitalized where they can receive supportive treatment including intravenous fluids, help with breathing and nursing care.
The simplest and most effective way of preventing a West Nile virus infection is to avoid being bitten by mosquitoes - this is done by using an insect repellent containing an EPA-registered active ingredient when outdoors, especially at dusk and dawn when many mosquitoes are most active - wearing long sleeves and pants at these times or staying indoors during these hours - and ensuring there are good screens on windows and doors to keep mosquitoes out.
The Centers for Disease Control and Prevention (CDC) recommends using products that have been shown to work in scientific trials which contain active ingredients which have been registered with the US Environmental Protection Agency (EPA) for use as insect repellents on skin or clothing - EPA registration ensures a repellent has been evaluated for efficacy and safety and the potential effects on human beings and the environment.
EPA registration means that EPA does not expect a product, when used according to the instructions on the label, to cause unreasonable adverse effects to human health or the environment. Of the active ingredients registered with the EPA, the CDC believes that two have demonstrated a higher degree of efficacy. These products contain active ingredients which provide longer-lasting protection than others and they are :- DEET (N,N-diethyl-m-toluamide) and Picaridin (KBR 3023).
Also registered with EPA is Oil of lemon eucalyptus [active ingredient: p-menthane 3,8-diol (PMD)], a plant- based repellent - recent research has found it provided protection similar to repellents with low concentrations of DEET. These products are available as lotions, creams, gels, sprays, and towelettes.
It is also important to rid yards and garden areas of potential mosquito breeding sites by emptying standing water from flower pots, buckets and barrels, regularly changing the water in pet dishes and bird baths, emptying out any containers which might inadvertently store water such as tyres, toys and garden equipment, blocked gutters, poorly maintained pools, and any type of receptacle with decaying organic matter.
West Nile virus does not usually cause illness in dogs and cats and there is no evidence that a dog or cat can transmit the virus to humans or other animals, horses are however more susceptible to West Nile virus and closely related viruses but fortunately, there is an effective West Nile virus vaccine for horses.
To date the West Nile virus has been detected in 35 mammal species including domestic cattle, reindeer, harbor seal, little brown bat, rhesus macaque, Asian elephant and gray squirrel - the virus has also been identified in two reptile species, American alligators and crocodile monitors.
Although other birds can become infected with the West Nile virus, the mortality rate is much higher in crows than in other birds - in the crow family crows, jays, ravens, and magpies, tend to become sick and die - and crows' susceptibility to the virus makes them very useful sentinels in monitoring viral activity.
While there is no evidence that a person can contract the virus from handling live or dead infected birds, experts recommend that it is always best to avoid barehanded contact when handling any dead bird or animal - for disposal, they advise the wearing of gloves and the careful placing of the bird in double-plastic bags.
Local health department officials will assist with specific instructions for storage if the dead bird is suitable for testing.
Though West Nile virus is NOT transmitted from person-to-person, some evidence exists that crow-to-crow transmission is possible without mosquito vectors.
Blood and/or cerebrospinal fluid samples from suspected West Nile virus patients with clinical symptoms are sent to a registered laboratory for an Enzyme-Linked Immunosorbent Assay (ELISA) test that detects West Nile virus antibodies - sometimes a follow-up sample is needed to confirm diagnosis, and in rare cases, samples are sent to the CDC for definitive confirmation.
It is mandatory for commercial labs to report all positive results for West Nile virus to the DHSS for confirmatory testing and a patient can only be diagnosed as a certified case after the Public Health and Environmental Laboratory (PHEL) tests the blood and confirms them to be positive.
The CDC is working with state and local health departments, the Food and Drug Administration and other government agencies, as well as private industry, to prepare for and prevent West Nile virus.
The CDC is coordinating a nation-wide electronic database where states share information about West Nile virus and is also helping states develop and carry out improved mosquito prevention and control programs by developing better, faster tests to detect and diagnose West Nile virus - they are also improving education and programs for the media, the public, and health professionals.
New testing laboratories for West Nile virus are being set up and work carried out on the development of vaccines to deal with the virus.
The West Nile virus surveillance plan is coordinated among a number of state and local agencies and involves the Department of Environmental Protection (DEP), the Office of Mosquito Control and Coordination, NJ Department of Health and Senior Services (DHSS), Department of Agriculture, Division of Animal Health, Rutgers University and 21 county mosquito control agencies, local health departments, physicians and hospitals, along with the national Centers for Disease Control and Prevention (CDC) and other states in the region.