US Economic Impact Of West Nile Virus Nears $800M: CDC Report
February 11, 2014

US Economic Impact Of West Nile Virus Nears $800M: CDC Report

Lawrence LeBlond for - Your Universe Online

A mosquito-borne disease that has been plaguing the US since it was first detected in New York in 1999, has left a greater economic dent than had previously been estimated, according to a new study from the US Centers for Disease Control and Prevention.

Published in The American Journal of Tropical Medicine and Hygiene (AJTMH), the CDC report has found that since West Nile virus (WNV) was first detected in the US, it has cost the country about $778 million. While previous studies have looked at hospitalizations and treatments associated with this disease, the CDC report is the first to also factor in long-term productivity losses and other extended needs of patients suffering from the effects of WNV, such as repeat doctor visits and extended drug prescriptions.

In the 14 years since the virus was first detected in the US, more than 37,000 people have been sickened and at least 1,500 people died from infection. The virus causes fever and achy joints and other flu-like symptoms in about 20 percent of those who are infected. About one in 150 cases will go on to develop a serious nervous system illness such as encephalitis or meningitis.

Little is known about the much longer long-term health needs of individuals affected by WNV or the total economic cost due to the relative newness of the disease here in the US. However, the CDC report authors looked at the costs of initial hospitalizations and the direct and indirect costs in the five years following their initial hospitalization – from follow-up visits and medications to how much downtime from school or work occurred.

"We believe that previous costs associated with West Nile virus disease have been underestimated because they've predominantly focused on the costs of the initial illness," study lead author J. Erin Staples, MD, PhD, a medical epidemiologist at CDC in Fort Collins, Colorado, said in a statement. "Many hospitalized patients will incur additional medical and indirect costs, and these need to be figured into the burden of WNV disease. Only with accurate figures can public health, academic, and industry officials determine the cost effectiveness of local mosquito control measures or of developing new drugs and vaccines."

For the study, the team looked at 80 cases of WNV that occurred during a 2003 outbreak in Colorado. The team then calculated costs of additional related medical care and missed work incurred in the five years following each patient’s initial infection and hospitalization. To estimate the total cost of the disease to the country, the team extrapolated those costs to the total number of hospitalized cases of WNV disease reported to the CDC since 1999. Based on their results, the annual cost of WNV to the nation is $56 million.

The CDC report also calculated the costs of each specific “clinical syndrome” linked to the WNV: fever, meningitis, encephalitis and acute flaccid paralysis (AFP). The team found that the short-term and long-term costs for individuals hospitalized with WNV disease varied widely and depended on which syndrome they encountered.

"We broke down costs by clinical syndrome and were surprised by what we found. While patients with meningitis had shorter hospital stays than others with neurological syndromes, they were also younger and more likely to miss work, which translated to a higher economic cost in lost productivity," Staples said. "Encephalitis patients tended to be older, with many of them retired, so the cost associated with lost productivity was lower."

The team found that those hospitalized with AFP had the largest initial and long-term medical costs – median $25,000 and $22,000, respectively. Patients hospitalized for meningitis or fever incurred similar costs of initial hospitalization – median $7,500. Most of these patients did not require long-term medical care.

For the patients in the study, the average age of diagnosis was 55 years; about a quarter of the patients were over 65 years old. Hospitalized patients were absent from work or school for an average of 42 days due to their illness.

The economic impact of WNV may be reduced exponentially if countermeasures and intervention strategies can be developed to efficiently combat this virus, according to Alan D. T. Barrett, PhD, a tropical disease expert at the University of Texas Medical Branch, Galveston.

"There are a number of candidate vaccines and antiviral drugs in development, and the figures for economic burden reported in this paper will aid policy makers and pharma to assess the economics of vaccine and drug development," Barrett said in an accompanying editorial to the CDC paper.

Several potential vaccines for WNV are currently being tested, but none are yet available to vaccinate the general public.

"Understanding the economic impact of disease is an increasingly important data point for the public health community and policy makers," said Alan J. Magill, MD, FASTMH, strategy leader for the Bill & Melinda Gates Foundation and president of the American Society of Tropical Medicine and Hygiene, which publishes the journal. "As we all strive for the most efficient and effective use of scarce resources, studies like this offer decision makers facts that will help them make sound funding and policy decisions."