Mosquitoes! Mosquitoes everywhere, given a chance these small creatures hang out anywhere in and around your house. A small broken pot or broken half of a ball filled with little water is enough for them to increase their family. Apart from the job of spreading malaria, mosquitoes are also involved in spreading another virus called West Nile Virus (WNV), which can infect birds, humans, horses and of course mosquitoes, which spreads the virus. All mosquitoes are not infected and not everyone who is bitten by a mosquito gets this infection.
Infection from WNV is commonly found in Africa, West Asia and Middle East. However, now the virus has spread its wings in almost about 48 countries. In US the risk of being infected by WNV increases during the month of July to September but in many other countries the risk prevails the whole year.
Mode of infection
West Nile virus spreads when a Culex species mosquito bites an infected bird and then transfers the virus to human or animals by bite. The risk of the disease decreases as the temperature goes down. The infection is not contagious; it doesn’t spread by touching or spending time with the infected person. WNV of course can infect your pet also, but you do not get infected from your pet. The infection spreads only through mosquito bite.
Other rare possible modes of infection are
- Through blood transfusion or organ transplantation
- From mother to baby during pregnancy or during breast feeding.
Symptoms of WNV
Once the virus is in the bloodstream, it starts replicating and travels to other part of the body. The incubation period of the virus is about 5-15 days. Usually 80% of the people infected with West Nile viral don’t show any sign or symptoms. In few who exhibit few signs, usually shows a flu-like symptoms with:
- Fever
- Headache
- Muscle ache
- Nausea or vomiting
- Sore throat
- Neck and back stiffness
- Fatigue
- Joint pain
- Swollen glands
- Rash
- Disorientation
- Coma
- Tremor
- Paralysis
- Numbness
- Vision loss
If the travelling virus manages to reach the brain it can cause serious complications like inflammation of the brain called Encephalitis, or inflammation of the brain and the surrounding membrane called meningoencephalitis. Encephalitis very rarely can be fatal. Sometimes, it might also result in infection and inflammation of the membrane covering the brain and spinal cord, a condition called meningitis. Symptoms of WNV infection last for several weeks but the neurological damage remains forever. It is estimated that 1 out of every 150 people infected can develop more severe form of the disease.
Risk factors
Risk for getting infected by West Nile virus depends on the many factors. As West Nile virus has been reported to be found mostly in Africa, West Asia and Middle East people living there are at higher risk of being infected with the virus. Many people from US are also reported with the infection. The virus spreads more actively during the warmer weather during the months of July to September. In addition, more time spent outdoor during warmer seasons increases the risk of being infected.
Old age is in itself a greater risk. Adults with weak immune system who has recently undergone a blood transfusion or organ transplantation are at higher risk. Pregnancy alos increase the risk of getting infected with WNV. Virus can be transferred to baby during pregnancy or breast feeding. These are just risk factors that you should take care of; however, people from these locations are very unlikely to fall ill due to a mosquito bite.
People who get infected form WNV usually do not develop any symptoms and complications. Less than 1% of the infected people develop severe illness and almost all of them recover fully after treatment. Therefore deaths due to WNV infection are very rare. It was reported that in US, in the year 2007 about 127 people died due to fatal WNV infection and in 2008 about 44 died and in 2009, 30 deaths were reported.
Diagnosing WNV
As signs do not appear in most infected people, and if at all symptoms show up its similar to flu symptoms, therefore it is difficult to diagnose WNV by simple physical examination. Few tests to identify the virus are
- Complete blood test
- Magnetic resonance imaging of the head
- Computer tomography of the head
- Lumbar puncture & Cerebrospinal fluid test
The most reliable test is detecting antibodies against the virus in cerebrospinal fluid.
Treating WNV
Unfortunately, there is no specific treatment for West Nile viral infection. In milder cases, the fever and flu-like symptoms goes away on their own. In severe cases, you might require a hospital care for supportive treatment like intravenous fluid injection or breathing support. Antibiotics are of no use as the infection is caused by virus, and not bacteria. Research is going on to check whether anti-viral drug used for treating hepatitis-C are effective against WNV. There is no vaccination for WNV.
Preventive methods
Prevention is the best method to deal with the WNV. Keep yourself away from mosquito bites. Few simple and easy ways can be adopted to prevent a WNV infection. Avoid going out in the evening when the mosquitoes are active. If you have to go, use mosquito repellant when you move out in the evening and wear proper fully covered clothing. Protect your home, close windows and doors and use a mosquito net. Keep your home and surrounding clean and get rid of mosquito breeding sites.
Water in the pet bowl should be replaced regularly and any stagnant water should be cleaned up. Immediately report to the local authorities, if you find a dead bird. Insist your local authority to organize a mosquito control program.
Don’t ignore mosquitoes
Prevention is the best bet against spreading of WNV. Don’t ignore mosquitoes, thinking them to be another nuisance. Mosquitoes can be harmful to your health, if you do not protect yourself. If you suspect or notice any of the symptoms of WNV after a mosquito bite is it important that you consult your doctor.
