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West Nile virus surveillance declining in US
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Surveillance of West Nile virus in the United States has declined since 2004 and may now be insufficient in many states to detect outbreaks and aid in rapid responses, according to recent findings.
In 2013, the Council of State and Territorial Epidemiologists (CSTE) conducted an assessment of state and local health departments (LHDs) to measure their surveillance and staffing capabilities for tracking West Nile virus (WNV) as well as other arboviruses. Researchers examined surveillance efforts in 2012 using a survey based on an assessment tool from 2004, when the last evaluation of WNV surveillance capability was conducted, and compared results from the two time periods. CSTE received online survey results from 50 state health departments — 6 epidemiology and laboratory capacity-supported LHDs and 15 LHDs without such support.
Results indicated that in 2012, “nearly all states (98%) conducted surveillance for human WNV disease,” but fewer used WNV-related surveillance for equine disease (90%), mosquitoes (80%) and avian deaths (39%). Fewer than 60% of jurisdictions contacted specialists to promote reporting of suspected WNV cases, and less than one third conducted active surveillance for humans. While only 80% of states participated in mosquito surveillance, 90% gathered information about mosquito surveillance from LHDs in their state. Overall, 94% of states had some level of information regarding mosquito populations. Fewer jurisdictions in 2012 vs. 2004 conducted WNV-related surveillance activities.
Lyle Petersen
In 2004, nearly all states and LHDs had well-developed animal, mosquito and human surveillance systems in place to track WNV activity and prepare for outbreaks. By 2012, many health departments had diminished mosquito monitoring and laboratory testing resources, and lacked systematic disease-based surveillance for other arboviruses.
According to researchers, arbovirus surveillance systems in many U.S. states might no longer be adequate for the timely detection and information dissemination needed to fully respond to WNV outbreaks and threats from other arboviruses such as dengue or chikungunya.
Study researcher and Infectious Disease News Editorial Board member Lyle R. Petersen, MD, MPH, director of the division of vector-borne diseases at the CDC, said there has never been a greater need for a strong arbovirus surveillance system in the country.
“Large regional West Nile virus outbreaks are now part of our permanent infectious disease landscape, as demonstrated by substantial outbreaks centered in Texas in 2012 and California in 2014,” he said. “While accumulating evidence indicates that prompt intervention can greatly mitigate these outbreaks, this response is predicated on effective and timely human and mosquito surveillance. Thus, erosion of these surveillance and response capacities is particularly worrisome, especially when surveillance must rapidly respond to an ever-increasing array of new threats such as the chikungunya and Zika viruses. These capacities took years to develop and once gone, cannot instantly be redeveloped.”
Disclosure: The researchers report no relevant financial disclosures.
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