A Message From the Maryland State Vet

Arboviral surveillance season has begun, and we are writing to provide updated guidelines for equine arboviral surveillance in Maryland in 2010 and to remind you that equine neurologic syndromes and any of the equine encephalitides, including West Nile virus (WNV), are reportable to the Maryland Department of Agriculture (MDA) Animal Health Program. The Maryland Department of Health and Mental Hygiene (DHMH) offers laboratory testing of equine specimens for WNV and other arboviruses, and we encourage you to make use of this service.

Arboviral disease continues to have an impact on both the human and animal populations in Maryland.  Since the emergence of West Nile virus in the State in 1999, there have been 172 human WNV cases, 274 equine cases, 351 positive mosquito pools, and 1250 positive birds reported in Maryland. Reported equine WNV cases increased from 30 in 2002 to 234 in 2003 and have declined sharply since that time, with only one equine WNV infection reported in Maryland in 2004, two in 2008 and one in 2009. In addition, Eastern equine encephalitis (EEE) virus has been detected in Maryland horses (2003 and 2009) as well as in mosquitoes and, less frequently, ratites (2003, 2005, and 2008).

As in previous years, the Maryland Department of Health and Mental Hygiene (DHMH) will work with the Maryland Department of Agriculture (MDA) to conduct equine surveillance. From June 1 – October 31, 2010, the DHMH Laboratories Administration will accept serum, brain, and/or CSF samples from horses exhibiting clinical signs consistent with arboviral disease for testing.

In addition to the services offered by the DHMH Laboratories Administration, equine necropsies are also available for a fee at the MDA Frederick Animal Health Diagnostic Laboratory.  The Frederick laboratory can be contacted at 301.600.1548.

As always, regular vaccination of equines is encouraged. Two vaccines are currently available: the Fort Dodge Innovator™ West Nile Virus equine vaccine, a killed virus vaccine, and the RECOMBITEK® vaccine, developed using recombinant DNA technology by Merial.  Each of these vaccines should be administered according to manufacturer instructions. It is also recommended that horses be vaccinated annually against rabies and EEE.

Information about arboviral and other infectious diseases in equines can be obtained from the Animal Health section of the MDA at www.mda.state.md.us/animal_health/diseases/reportable.php. General information on WNV and other arboviruses (including fact sheets and brochures) is available on the Maryland West Nile Virus web page at www.edcp.org/html/west_nile.html and from the Centers for Disease Control and Prevention at www.cdc.gov/ncidod/dvbid/westnile.