West Nile Fever (WNF)

Why in News?

The Health authorities have sounded a caution following suspected cases of West Nile fever (WNF) in Ernakulam.

• West Nile Fever – It is a mosquito-borne viral infection caused by West Nile Virus.
• Global Spread – It is found in Africa, Europe, the Middle East, North America, and Asia, first identified in Uganda (1937).
• Transmission – West Nile virus, a flavivirus primarily transmitted by Culex mosquitoes.
• Host – The birds are the natural hosts, whereas humans and horses are “dead-end” hosts.
• Symptoms
  • Asymptomatic – Approximately 80% of infected individuals show no symptoms.
  • Mild Infection – Approximately 20% experience fever, severe headache, body aches, joint pain, vomiting, diarrhoea, or rash.
  • Severe Infection (Neuroinvasive Disease) – Less than 1% develop severe complications, including meningitis, encephalitis, or acute flaccid paralysis.
• Risk Groups – People over 50 and immunocompromised individuals are at higher risk of severe illness.
• Duration – Mild symptoms typically last a few days; however, recovery from fatigue and weakness can last several weeks or months.
• Diagnosis – Key tests include IgM antibody ELISA, PCR for viral RNA, virus isolation in labs & via samples like blood or cerebrospinal fluid (CSF).
• Treatment – There is no specific antiviral treatment or vaccine available for humans, whereas a vaccine is available for horses.
• Supportive care – Hospitalisation, IV fluids, respiratory support, pain relief, prevention of secondary infections.
• Prevention
  • Use mosquito repellent containing DEET or picaridin.
  • Wear long-sleeved shirts and long pants, particularly at dawn and dusk.
  • Eliminate standing water around homes to reduce mosquito breeding sites

References

1. The Hindu | Suspected West Nile fever cases trigger health warning
2. WHO | West Nile Virus