West Nile Virus (WNV) is a mosquito-borne virus that may cause serious illness, like meningitis and encephalitis, or sometimes death.

It is spread to humans through the bite of an infected mosquito, which first got the infection from biting a bird carrying the virus. Nevertheless, WNV does not spread through body-to-body contact.

Although in the outbreak last year, people that were infected with the virus did not have illness or did not show symptoms. They only exhibited mild forms of illness before recovering fully. This is usually the case with most people infected.

Sometimes symptoms are so mild that they do not get easily noticed or are undetected. These mild cases include flu-like symptoms which may be in the form of fever, headaches and body aches. Mild rash or swollen lymph glands may also develop in some people.

But as soon as the infection causes the illness, symptoms are expected to appear in a span of two to fifteen days. The extent and severity of the symptoms may also vary from person to person. The overall risks of WNV to the overall health of each person increase with age.

Individuals that have weaker immune systems have greater risks of developing more serious symptoms. People that have higher risks of serious health effects are those suffering from chronic diseases and those that require medical treatment, like chemotherapy, that weakens the immune system.

WNV can cause severe infections which may lead to diseases affecting brain tissues. Moreover its most serious conditions may cause permanent neurological damage and may prove to be fatal. Such damages include meningitis (the inflammation of the lining of the brain or spinal cord) or encephalitis (the inflammation of the brain itself).

The symptoms for encephalitis are high fever, rapid onset of severe headache, stiff neck, loss of consciousness or coma, and weakness of the muscles. In some instances, death may occur.

Anyone who experiences the sudden onset of the abovementioned conditions should seek medical attention immediately. It is estimated that one in every 150 persons infected with WNV will develop more severe forms of the disease. Although there is still no treatment for viral infections, such symptoms should be treated and given immediate care.

WNV can bring severe complications to people of any age and health status. It is highly important to minimize the risks of getting bitten by mosquitoes. Exposure to mosquitoes in areas where WNV has been detected should be avoided so as to prevent the risks of infection.

The primary cause of the West Nile virus can be traced back to mosquitoes. These insects seem to be the main source of virus transmission to humans. Although the virus may have been carried from place to place by birds, it is the mosquitoes that eventually transfer the virus to humans. A mosquito that bites a bird infected by the West Nile virus becomes a carrier. Once an infected mosquito bites a human, the virus is then transferred into humans.

The best way of avoiding the transmission of the virus is by avoiding mosquitoes from biting you. Although banishing them might prove to be an impossible task, avoiding getting bitten and making your home mosquito-free might be able to do a lot in curbing down the spread of the West Nile virus.

In trying to prevent mosquitoes from biting, you can always depend on a number of effective mosquito repelling lotions that are available in the market. Try to choose a mosquito repellant that contains DEET. A mosquito repellant containing about 24 percent DEET is effective in protecting you from mosquito attacks for an average of five hours. The percentage of DEET in a mosquito repellant has got to do more with its staying power than with its effectiveness in trying to repel mosquitoes.

Mosquito repellants containing high concentrations of DEET may not be considered for use in children. A repellant with about ten percent DEET may be more favorable for use in children but avoid having them apply it on themselves. Adult supervision should always be on hand when using mosquito repellants on children. Such repellants with DEET should not be used on infants or toddlers.

Another way of trying to avoid being bitten by mosquitoes is by trying to limit outdoor activities during dawn to dusk and even early evenings. This is the usual time when the mosquitoes are out and active. Try also to wear light colored clothing in order to become less attractive to mosquitoes. Some studies have shown that mosquitoes are attracted to dark colored. Wearing long sleeved shirts coupled with pants is also suggested if you usually go out in mosquito infested areas. If it won’t be too bothersome, you may also try wearing mosquito netting over your face as protection.

Another good way of preventing the spread of the West Nile virus is by preventing your home from becoming a possible mosquito breeding ground. Mosquitoes usually breed in damp areas. Mosquitoes usually deposit their eggs in stagnant water until they hatch and develop into a new generation of mosquitoes. Any area outside your home with stagnant water can easily become a potential mosquito breeding ground.

It is wise to get rid of these water deposits in order to prevent mosquitoes from breeding in them. Such common areas around the home which may contain stagnant water include bird baths and outdoor pet dishes. Flower pots as well as gutters may also become potential breeding ground for mosquitoes. Even swimming pools, ponds and puddles in the yard can be big enough to host another generation of mosquitoes. The best way to avoid making your home a potential breeding ground is by regularly getting rid of the water fond in these potential mosquito breeding grounds around your home.

Since the West Nile virus outbreak may still be considered a fairly new threat, it has already been a cause of alarm in the US as well as in other parts of North America. It has also have become quite a dangerous disease that has been affecting a number of Americans since 1999.

The year that the West Nile virus was documented in the US saw about 62 diagnoses of the infection that led to seven deaths.

In the year 2000, the documented number of people infected with the West Nile virus decreased to 21 known diagnoses that led to two deaths. But in 2001, the number of diagnosed West Nile virus infections went up to 66 known cases and resulted to nine deaths.

2002 was even more serious as there was an incredible increase in known West Nile virus infections. The Center for Disease Control and Prevention listed a total of 4156 cases of West Nile virus infections that resulted in 284 deaths.

2003 showed a bleaker picture as the incidence of infection more than doubled to 9862 cases and 264 deaths. As the experts are becoming aware and started educating the public in the prevention of the West Nile disease, the incidence of cases went down in 2004 with the number of recorded cases diagnosed with the West Nile virus infection listed at 2539 and only 100 deaths.

In 2005, the cases of infection were 3000 with 119 deaths. The latest figures at 2006 saw the incidence slightly increasing at 4269 cases of infection with 177 deaths.

Other facts worth knowing about the West Nile virus are that people over 50 are on a higher risk of getting the severe illness by the infection. This might indicate that a lower disease resistance may help bring about the rapid progression of the infection.

That is why it is important to have people over 50 take a lot more care in protecting themselves from mosquito bites especially during the summer when the incidence of West Nile virus are high.

People who find themselves outside more are a higher level of risk from getting infected. This is especially true during the summer. The more time spent outdoors can mean that one is more likely to get bitten with an infected mosquito that may lead to virus transmission.

Avoiding mosquito bites is a must. If going outdoors cannot be prevented, trying to use over the counter mosquito repellants every time can greatly help in keeping away the mosquitoes.

People should also know that the West Nile virus infection can have different effects on people, especially when it comes to the symptoms they display. About one in 150 people will display severe symptoms when infected by the virus.

Up to 20 percent of people infected by the virus experience milder symptoms such as headaches, rashes nausea and swollen lymph glands. 80 percent of those infected by the virus will not show the usual symptoms at all.

There are more than 2,500 species of mosquitoes around the world, about 200 of which can be found in North America. Meanwhile, 45 mosquito species are known to carry the West Nile virus, but some of the mosquitoes are more common carriers than others.

Here are some of the common mosquito carriers of the West Nile virus in US and Canada.

Culex pipiens – These species can be found in central and eastern United States except in Florida. Known as the northern house mosquito, they are common in urban and suburban areas as well as on rural communities. The culex pipien also carries several other diseases such as filariasis, Japanese encephalitis, St. Louis encephalitis, and avian malaria.

Although normally this specie feeds on birds, some urban strains are also prone to target humans. Its presence indicates signs of polluted water in the vicinity. These mosquitoes usually breed in storm sewer catch basins, clean and polluted ground pools, and other sites that are either clean or polluted with organic wastes.

Culex quinquefasciatus – Known as the southern house mosquito, they are generally active only during the winter months. They are known to attack humans towards the middle of the night both indoors and outdoors, although they also tend to attack birds as well. Just like the culex pipiens, they harbor deadly diseases like St. Louie encephalitis and filariasis, as well as often laying their eggs in slightly to very polluted waters.

Culex restuans – Known as the white-dotted mosquito, the restuans are distributed from central Canada to Mexico. They are very common in eastern and central United States, while very widespread in New Jersey. Just like any culex, the restuans breed on polluted waters, sometimes even on temporary ground pools or just about anywhere where water tends to become collected.

Aedes albopictus – The Asian tiger mosquito or forest day mosquito is characterized by its black and white striped legs and small, black and white body. It was native to Southeast Asia, but has since spread to southern USA since 1985, in Nigeria since 2002, and in New Zealand and eastern Canada since 2007.

In the United States, the Asian tiger mosquito has been spread to 678 counties in 25 mainland states, mostly in the southeast. Aside from West Nile virus, they also carry over 20 other arboviruses.

Aedes vexans – The inland floodwater mosquito is one of the most widespread mosquito species in the world. They are found in both warm and cold environments from New Zealand to western Africa to Iceland.

In North American, this specie is common in southern Canada and throughout the United States except Hawaii. The females are persistent biters and most active in the early evening. The adults are known to fly great distances and tend to get attracted to light.

The West Nile virus quickly spread across North America after its introduction in 1999. It is theorized that the infection was introduced accidentally by an air traveler who was infected before he arrived in New York.

The disease spread quickly through infected bird, as the mosquitoes spread the disease to mammals including humans. As of 2007, 47 of 48 mainland states in the US have cases of West Nile virus infections, 12 of which had greater than 10% mortality rates in certain years.

West Nile virus was at its deadliest in the United States in 2003, with close to 10,000 cases of infections, 264 of which were fatal. However, cases of infection seem to have dwindled recently, largely due to increased awareness and improved immunity (although it can be said that there are a lot of mild cases of West Nile infection that go undiagnosed).

Aside from bites from infected mosquitoes, some mild cases of infection were discovered during blood donation screenings. There were 30 cases of West Nile virus infection from blood transfusion in the United States, majority of which were acquired from 2002 before blood screening was instituted.

In September 2002, American researchers reported the first polio-like paralysis stemming from West Nile virus. Infectious disease specialists in Ontario, Canada, began seeing West Nile patients hooked up to ventilators as they are unable to move or breathe. Such cases of West Nile virus infection affect the central nervous system and infects neurons and brain stem regions within the individual.

The October 2002 issue of New England Journal of Medicine shows results of research by the US Centers for Disease Control and Prevention. They say that for every five people infected with West Nile virus, one has a mild illness that usually lasts for three to six days.

Meanwhile, meningitis or encephalitis would occur in one in 50 people infected with the virus, more commonly in those over age 50. The researchers suggest severe muscle weakness as a common symptom that may offer doctors a diagnostic clue.

West Nile virus may be rare but its danger cannot be ignored. Even if you are infected with the virus, your risk of developing a serious illness is extremely small. Less then one percent of people who are bitten become severely ill, and most people who do become sick recover quite quickly.

However, your risk of getting infected by the West Nile Virus increases according to the following factors:

Older adults – As we get older, especially over 50, our immune system becomes weaker.

Weakened immune system – Aside from old age, you are also prone to the infections carried West Nile virus if your immune system has been weakened by HIV/ AIDS, long-term steroid use, as well as chemotherapy drugs, or anti rejection drugs following transplant surgery.

Pregnant women – A woman’s immune system tends to lower its defenses during pregnancy to ensure that the unborn child is not rejected by the body. Unfortunately, this allows pregnant women to become more susceptible to illnesses than they would be otherwise.

Time of year – In temperate regions, the virus follows a seasonal pattern that begins in late spring, with the peak time for infection occurring in late summer and early fall-usually between August and September. If you live in southern climates, you may run the risk of infection year-round.

Spend more time outdoors – West Nile virus is commonly acquired through mosquito bites. If you work or spend large amounts of time outdoors, you have a greater chance of being bitten by an infected mosquito.

Geographic region – Visiting or living in areas where mosquito-borne viruses are common increases your risk of exposure to the West Nile virus. In the United States, only one mainland state–Maine–as well as Hawaii and Alaska, have yet to have a reported case of West Nile virus infection.

People with certain genetic mutations – A recent study shows that people who are highly resistant to HIV virus because of possessing two copies of the mutated CCR5delta32 gene are actually more prone of getting infected with the West Nile virus.

There are a lot of diseases transmitted by mosquitoes, and one of them is the West Nile virus or WNV. The virus belongs to the family of Flaviviridae, the same family the dengue virus belongs to, and can be found in the tropics as well as in the temperate regions.

The virus is more common in birds, but every now and then the virus has been known to be transmitted to humans and in animals like horses, dogs, cats, bats, and domestic rabbits. 

The Culex species of mosquito is responsible for spreading the disease to humans, although infection can be relatively low compared to other diseases. In the US, the Culex pipiens is the primary species that can spread the disease in the Eastern part of the country, Culex tarsalis in the Midwest and West, and Culex quinquefasciatus in the Southeast region.

The mosquitoes get the virus by feeding on infected birds. The virus spread through our bloodstream and have varying effect, the most serious of which is encephalitis in the brain.

It is more common that infections of the West Nile virus result to mild illnesses such as skin rash, swollen glands, fever, headaches, and body aches. Usually the symptoms are gone within 7-10 days from the first signs of the symptoms.

Although rare, there’s still a chance that infection from the West Nile virus develops into West Nile meningitis or encephalitis, which is a neuroinvasive disease that affects the whole nervous system.

At first, infected individuals manifest the same symptoms of headaches, rash, fever, and headaches. But later on, high fevers, neck stiffness, disorientation, and sometimes convulsions began to appear. Then finally the patient will experience a weakened level of consciousness, some even nearing a state of coma.

No specific treatment exists for West Nile encephalitis. What we can do is subject the patient to supportive therapy which basically means early detection, hospitalization, intravenous fluids, and providing respiratory support. There’s no vaccine available to date nor treatment with antibiotics will work.

The best way is to prevent infection. Avoid areas where and when mosquitoes are active. Protect your home with screen doors and windows. If it is necessary to go outdoors, long sleeve shirts or jackets should be worn to limit skin exposure. Remove area near your home where mosquito are most likely to breed.

West Nile virus infections have been identified to occur in Africa, Europe, the Middle East, west and central Asia, Oceania, and North America.

An outbreak of West Nile virus encephalitis in humans occurred in Algeria in 1994, then two years later i happened in Romania. In 1997 the Czech Republic had to deal with a similar outbreak and in Congo in 1998. Russia faced the same problems in 1999, as well the US from 1999 to 2003.

In 2006, the Centers for Disease Control and Prevention (CDC) verified that the West Nile virus infected about 4,000 Americans throughout the country, 149 of those cases ended with death.

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