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RESEARCHFigure 2. Comparison of surveillance indices in states reportingneed for additional staff with those not reporting a need by type ofstaff needed, United States, 2012. A) Epidemiologists; B) Laboratorystaff; C) Mosquito surveillance staff. WNV, West Nile virus; CSF,cerebrospinal fluid. Values in parentheses are number of states.WNV testing capacity. All are reporting WNV and otherarbovirus activity to ArboNET.Second, the ability to detect the early signs of an outbreakof WNV and other arboviruses that can threatenlarge human populations has been compromised since2004. Endemic arboviruses that have caused outbreaksof severe illness and death in densely populated areascontinue to pose annual threats, and emerging diseases,such as dengue and chikungunya, pose new ones (14,15–17,22). Knowledge of local vector mosquito populationsand early detection of arbovirus activity in these vectors,animals, and humans are essential to guide public healthaction ranging from health advisories to mosquito control.Many fewer states now conduct any form of active surveillancethat enables rapid detection of the first sentinelhuman cases of arbovirus disease. Most states have cutback on support for mosquito surveillance. Some statesand large metropolitan areas, including some with previouslylarge WNV outbreaks, lack the necessary mosquitosurveillance information to anticipate a surge in WNVinfection. Most lack the resources to map the distributionand size of either Ae. aegypti or Ae. albopictus mosquitopopulations to enable risk evaluation or to mount an effectiveresponse to identification of local transmission ofdengue or chikungunya viruses.Third, in addition to the decreased ability to monitorvector mosquito populations, testing for arbovirusesother than WNV, SLE virus, and EEE virus is patchy andinadequate to detect or monitor their presence in manystates. Some endemic arboviruses that cause either encephalitisor acute systemic or febrile disease (e.g., Powassan,LaCrosse, Colorado tick fever, and Heartland viruses)have not been included in systematic public healthsurveillance, and their ecology and epidemiology mightbe changing.For example, Powassan virus spreads to humans fromanimal reservoirs by the same tick genus (Ixodes) thattransmits Lyme disease and babesiosis. Although Lymedisease and babesiosis have increased dramatically in incidenceand geographic distribution in the United Statesin the past decades, there is still a poor understanding ofPowassan virus epidemiology >50 years after its discovery.Most state health department laboratories do not testfor Powassan virus when they test for WNV or other arboviruses,and few clinicians order commercial tests specificallyfor this virus. Powassan, LaCrosse, and Colorado tickfever viruses were tested for in only 8%, 32%, and 4% ofstate laboratories, respectively, in 2012. However, a higherpercentage of specimens were positive for Powassan andLaCrosse virus infections than for SLE and for Coloradotick fever than EEE or WEE. These results support surveillancefor these viruses in jurisdictions with relevant vectorswhen routinely testing for WNV. If their epidemiologywere better understood, estimates of their disease burdencould be improved, and the public could be better informedof the risk for infection.Fourth, state laboratory capacity is essential to enableLHDs to monitor virus activity through mosquito, aviandeath, or sentinel-chicken surveillance. The ability of ArboNETto synthesize and report useful surveillance informationis possible only because of efforts made at eachstate and local health department to conduct the nationallyrecommended level of surveillance to meet surveillanceobjectives. This assessment documents, that as resourceshave decreased, LHDs dependent on state laboratoriesto conduct testing for them have reduced or eliminatedmosquito-based surveillance to the point where 15% ofstates no longer provide support for LHDs and one third ofresponding LHDs in areas with a high incidence of WNVno longer conduct mosquito-based surveillance.In 2004, all states approached full capacity for 2 ofthe 3 criteria for full arbovirus surveillance capacity usedin this report: ability to complete a standard case report1164 Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 21, No. 7, July 2015