What You Need To Know
West Nile Virus (WNV) has been detected in New Jersey mosquitoes earlier than expected this year, starting in mid-May. To date, mosquitoes have tested positive for WNV in 15 of NJ's 21 counties. Healthcare providers should be alert for potential cases of WNV and other mosquito-borne diseases as the summer progresses.
For many people, WNV and other arboviruses cause asymptomatic infection or mild to moderate febrile illness. People 60 years and older or with weak immune systems are at greater risk of developing severe illness, which may present as encephalitis, meningitis, or acute flaccid paralysis, and can result in death or survival with long-lasting neurological sequelae. Medical care is supportive.
CDC has posted new WNV resources for healthcare providers, including a diagnostic testing algorithm and a free continuing medical education offering.
Locally acquired mosquito-borne diseases in NJ include WNV, Eastern equine encephalitis (EEE), and Jamestown Canyon Virus (JCV). While testing for WNV is available at many commercial laboratories, testing for EEE and JCV is primarily performed at public health Laboratories.
- IgM antibody testing is recommended to detect acute infection for most arboviruses in immunocompetent persons, but molecular testing, in addition to IgM antibody testing, should be considered for immunosuppressed patients. Single specimen IgG antibody tests should not be used as they cannot distinguish between acute and prior infection.
- CDS requests that serum (and CSF if available) specimens be sent to the NJDOH Public Health and Environmental Laboratories (PHEL) for patients who are hospitalized with neuroinvasive disease (e.g., encephalitis, meningitis, acute flaccid paralysis) of unknown etiology or for patients presenting with a febrile illness of unknown etiology if an arboviral disease is suspected.
- Specimens will be tested using the PHEL arboviral panel (WNV, EEE, St. Louis encephalitis, and Powassan [tickborne] virus) with additional testing, if indicated, performed at CDC (e.g., JCV, La Crosse virus and the tickborne viruses Heartland and Bourbon).
NJ is consistently among the US states with the highest number of travel-associated mosquito-borne diseases, which include dengue, chikungunya, malaria, and Zika. Testing for these diseases is widely available at commercial laboratories, but confirmatory testing is available at PHEL, as is testing in special circumstances (e.g., novel mode of transmission, suspected local transmission, distinguishing between malaria and babesia parasites). CDS will assist healthcare providers with testing for less common travel-associated vector-borne disease pathogens at CDC based on clinical presentation and travel history.
Serological testing for vector-borne diseases is challenging as there may be persistent IgM antibodies that are not indicative of an acute infection, cross-reactivity with other viruses, seen particularly with flaviviruses, false positive results, and some tests that are non-species specific. For these reasons, tests should be ordered for persons with a compatible clinical presentation.
- NJDOH requests that laboratories send all IgM antibody-positive or equivocal test results for WNV, Chikungunya, and Zika; and IgM antibody equivocal test results for dengue to PHEL for confirmatory testing.
Action Items:
- Healthcare providers:
- Consider mosquito and tickborne arboviruses in patients presenting with neuroinvasive disease (e.g., encephalitis, meningitis, acute flaccid paralysis) of unknown etiology or with a febrile illness of unknown etiology if an arboviral disease is suspected.
- Submit specimens to NJDOH for expanded arboviral panel testing, particularly for viruses where commercial testing is unavailable (e.g., Powassan, EEE, JCV). Review online instructions for requesting arboviral testing or contact CDSVectorTeam@doh.nj.gov to discuss testing needs. Specialized vector-borne disease testing at PHEL or CDC requires CDS review/pre-approval.
- Notify your local health department immediately if you have a patient that tests positive for a travel-associated mosquito-borne disease (e.g., dengue, malaria) in the absence of a relevant international travel history.
- Review the NJ Vector-borne Disease dashboard to monitor the burden of vector-borne diseases in NJ residents, as well as what pathogens mosquitoes and ticks have tested positive for in NJ. Weekly reports that provide a snapshot of vector-borne disease activity are posted online from May-November, are sent via LINCS, and can be sent via email upon Request.
- Counsel patients who are traveling to areas with travel-associated mosquito-borne diseases to (a) take precautions to prevent mosquito bites while traveling; (b) start and complete prescribed antimalarials; and (3) continue to prevent mosquito bites for three weeks after returning to NJ to prevent the introduction of diseases like dengue and malaria into the NJ mosquito population, which could result in subsequent locally acquired cases.