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West Nile virus infection is a mosquito-borne disease that is usually mild and often gets better without treatment. However, a few people suffer from severe complications, which can lead to costly hospitalization and loss of work.

U.S. Centers for Disease Control and Prevention (CDC) reports that the country spends millions of dollars each year in the treatment of West Nile virus disease, a condition transmitted to humans by a mosquito bite. In fact, hospitalizations and follow-ups related to the disease cost nearly $800M in healthcare expenses as well as lost productivity since 1999. This means that the United States spends about $56M annually for direct and indirect costs brought about by the mosquito-borne West Nile virus. These findings were based on research published online by the American Society of Tropical Medicine and Hygiene.

The Cost of West Nile Virus Disease

Recent research shows that being bitten by a mosquito that transmits the West Nile virus (WNV) can cost the government millions of dollars in terms of hospitalization, medications, follow-up visits, and lost work. After examining more than 37,000 WNV infections reported to the CDC (1999-2012), investigators found more than 18,000 patients were hospitalized and more than 1,500 people died from the disease. More than 16,000 individuals developed complications, such as neurologic sequelae, of which elderly patients were at high risk for severe complications. However, CDC reports that the number of patients affected by the disease may be more than the actual cases reported since 1999. Furthermore, the researchers believe that the costs calculated may have been underestimated since most of these were based on initial costs incurred and may have not included additional costs involved in the burden of the illness.

Indirect costs for lost work and reduced productivity due to the illness are significant especially for younger patients who suffered from neurological complications such as meningitis.

On the other hand, older patients were more likely to suffer from encephalitis, also affecting the brain, although most of them have retired from work.

The findings are useful but the authors believe that a more accurate estimation of costs related to direct and indirect effects of the disease will determine if spending on developing new vaccines, drugs and mosquito control measures is cost-effective.

What is the West Nile Virus?

In 1937, a mosquito-borne virus was identified in the West Nile district in Uganda. It was first recognized in 1999 in the USA, where it caused 59 New York City residents to suffer various clinical syndromes characterized by fever, encephalitis, meningitis, and paralysis. In the two years that followed, the virus rapidly spread westward, affecting 28 states. Since then, more than 30,000 patients have been affected and more than 1,200 people have died.

According to epidemiologists, WNV causes a seasonal epidemic that usually begins in summer and may continue until the fall season. 

The virus is transmitted from infected birds (usually jays and crows) to humans only through bites from certain adult mosquitoes that bite both birds and humans.

The virus is not spread through person to person contact, animal to person contact nor by eating dead animals. However, it is possible (though rare) to transmit the virus through blood transfusion, organ transplant, child birth or laboratory exposure.

Continue reading after recommendations

  • HealthDay. West Nile Virus Has Cost U.S. Nearly $800 Million: CDC.
  • American Family Physician. West Nile Virus in the United States: An Update on an Emerging Infectious Disease.
  • WebMD. West Nile Virus Overview.
  • Medicine Net. West Nile Virus.
  • CDC. West Nile Virus.
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