2009 Alerts and Updates...

Tick-Transmitted Horse Disease Detected
on South Texas Ranch

A tick-borne disease known as equine piroplasmosis has been confirmed
on a ranch in South Texas.  Additional testing is being conducted to
determine the extent of infection.  Horses on the ranch are quarantined
to their premises, and a thorough disease investigation is underway.  

Equine piroplasmosis can affect horses, donkeys, mules or zebras and
cause clinical signs common to many diseases, including poor appetite and
weight loss. Death losses can occur.  Some infected equine animals may
exhibit few or no signs of disease.  Those animals that  survive the acute
phase of infection may  continue to carry the parasite, which has been
identified as Theileria equi (formerly known as Babesia equi), for long
periods of time.  

“Although equine piroplasmosis is not considered to be endemic in the U.
S., cases have been detected on occasion,” said Dr. Bob Hillman, Texas’
state veterinarian and head of the Texas Animal Health Commission, the
state’s livestock and poultry health regulatory agency.  “In June, equine
piroplasmosis was detected in Missouri, with a related case found in
Kansas.  In 2008, the infection was detected in Florida.  These cases have
been closed.”

“As many as 15 tick species are capable of carrying and transmitting the
blood parasite responsible for causing equine piroplasmosis,” Dr. Hillman
explained.  “At this time, we do not know which species of tick is
responsible for transmitting infection on the South Texas ranch.  
Additional blood and tick samples are being collected and will be
submitted for analysis to the National Veterinary Services Laboratory
(NVSL) in Ames, Iowa.”

Dr. Hillman said there is no vaccine for equine piroplasmosis, and
treatment generally is not effective against this tick-borne infection.  To
avoid spread of the disease, it is important to eliminate contact with ticks
and to prevent the transfer of blood from one equine animal to another.

“Equine owners may want to consult with their veterinarians for
recommendations on preventing tick infestation,” said Dr. Hillman. “If
equine animals exhibit signs of illness, a veterinarian should be contacted,
so appropriate samples may be collected for laboratory testing.  
Currently, we have no indication that this tick transmitted disease has
occurred at other sites in Texas, but maintaining vigilance for this blood
parasite is necessary in determining the extent of this disease situation.”


Texas Animal Health Commission
Box l2966 * Austin, Texas 78711 * (800) 550-8242 * FAX (512) 719-0719
Bob Hillman, DVM * Executive Director
For info, contact Carla Everett, information officer, at 1-800-550-8242,
ext. 710, or ceverett@tahc.state.tx.us