West Nile virus is transmitted through bite of mosquitoes. The mosquito act as a vector for the transmission of the virus. Birds are the most common species affected and they are the primary reservoir host of the virus.
West Nile virus is most commonly found in temperate parts of the world. It was first reported in Uganda in the year 1937. Although it was considered a minor risk for humans, since then it has emerged to be with a higher number of cases since last few decades. In 2012, there was a break out of WNV infection in USA where almost 300 people died.
West Nile Virus has a particular affinity for the brain in humans. Many of the patients have head ache as a prominent symptom.
West Nile virus causes following diseases patterns:
- West Nile fever: there are flu like symptoms such as malaise, nausea, sweating, drowsiness, joint pains etc.
- West Nile neuro invasive disease
- West Nile virus encephalitis
- West Nile meningitis: patient mainly has neck stiffness
- West Nile poliomyelitis: it causes polio like manifestations with muscle weakness or paralysis asymmetrically in both the limbs.
- West Nile reversible paralysis
- Skin involvement: popular rash is seen on the extremities in some of the patients.
- Heart involvement
- Kidney involvement
Increased risk of contracting WNV is seen in following patients:
- History of organ transplant
- Older age group (more than 50)
- Increased BP
- Diabetes mellitus
Diagnosis is mainly based on the clinical presentation. The patients usually have a history of a recent mosquito bite. Some of the diagnostic testing are as follows:
- Lumbar puncture: the cerebrospinal fluid is collected by lumbar puncture. The presence of WNV in the CSF can be detected with the help of ELISA technique.
- Anti- body detection: specific antibodies can be detected in blood or CSF.
- Histopathology: affected body tissue can be examined under microscope after staining methods.
- Polymerase chain reaction tests.
WNV infection has no cure. And it also doesn’t have any specific treatment. In severe cases, following supportive measures are used.
- Hospitalisation: the patient should be hospitalised and kept under observation around the clock.
- Intravenous fluids: intravenous fluids are administered to maintain electrolyte balance.
- Oxygen, Ventilators: if breathing problem occurs, patient can be put on oxygen and ventilator as per the severity.
- Anti- biotics: prophylactic anti- biotics are given to decrease the chances of secondary infections.
Although the outcome is good in case of WNV infection, the patients may have long term complications such as
- Long duration to recover
- Increased risk of kidney disease
As it is said, prevention is better than cure. Effective mosquito control is very necessary and the only preventive measure available right now to avoid west Nile virus infection. Following methods are advisable to reduce the risk of mosquito bites.
- Mosquito repellents: applying insect repellent creams on the skin. it gives a direct protection from mosquito bites.
- Wear long sleeved t shirts.
- Long pants and hats to cover the exposed skin
- Avoid roaming outdoors at dawn and dusk when mosquitoes are most active
- Using medicated bed nets.
Using all these preventive methods will give protection from the WNV.