Wednesday, August 20, 2008

Piroplasmosis in Florida

There has been a report of piroplasmosis at an Ocala area Hospital. Here is an excerpt from the FAEP report.

Equine Piroplasmosis (EP) is a blood-borne parasitic disease which is caused by two

organisms, Theileria equi (formerly Babesia equi) and Babesia caballi. It is primarily

transmitted to horses by ticks; however, the disease can be spread mechanically from

animal to animal by contaminated needles. The disease was eradicated from Florida in the 1980's and the tick species generally believed to transmit this disease in other countries have not been identified in Florida in many years. This disease is not directly contagious from one horse to another but requires direct blood transfer. Human infection with equine piroplasmosis is extremely rare. Acutely affected horses can have depression, fever, anemia, jaundiced mucous membranes and low platelet counts. Equine Piroplasmosis can also cause horses to have roughened hair coats, constipation, and colic.

In its milder form, Equine Piroplasmosis causes horses to
appear weak and show lack of appetite. Some horses become chronic carriers of the disease. As EP is considered a foreign animal disease and is reportable in Florida, we are asking veterinarians to report any horses suspect for the disease. Reporting can be done Monday- Friday 8:00am-5:00pm by calling (850) 410-0900 or faxing to (850) 410-0915. After hours reporting may be done by calling (800) 342-5869 or via email to

Thus far none of the ticks tested have been found to be positive that is a good thing. The BIG question is ...where did it come from". Did the infected tick somehow make it into Florida from outside the country or is it possible that the organism was not fully eradicated 20 years ago like we thought.

As Veterinarians we must constantly be on the look-out for potential diseases such as this. It is possible that cases have gone undiagnosed that were thought to be something else. The case in Ocala presented as a Hemolytic crisis which could be caused by several diseases, fortunately someone was looking and spotted characteristic changes on a blood smear.

Since EP can look like something benign like a rough hair coat and weight loss it is important to point out changes that you see and look for the cause....don't just let it go.

Heres what you need to do.

Recommendations for Your Equine Clients: Monitor your horse for the presence of ticks. Use commercially available topical products labeled for ticks if your horse is in an area where tick infestation is a problem. Most of these products are synthetic pyrethrins. Include an avermectin product in your deworming program to provide systemic treatment for ticks. Ask your veterinarian if you are unsure.

If you find large numbers of ticks or suspect piroplasmosis, please contact your

veterinarian. Do not share needles between animals during the administration of any medication mor vaccinations. EP and other diseases can be spread by the introduction of blood cells from an infected animal into an uninfected animal during routine administration of injectable medications. Continue your normal equine activities.

Additional updates and information will be posted to the Florida Department of Agriculture and Consumer Services, Division of Animal Industry web site at:


Esther Garvi said...

Dear Dr Weldon,
What do you know about the treatment of piroplasmosis is? Our barb mare here in West Africa was just diagnosed with it today, and we suspect that our second mare may have it as well. Having lived more than 20 years in Niger, I have not encountered the disease before, until my dog suffered from it in spring 2008. Unfortunately, he passed away. Both horses are doing well as in terms of eating and general performance, but the mare who has been diagnosed with it (Sahara) has had a blood-coloured urine (not blood-stained) for the past few days as well as a decreased appetite.

Would be so happy for any feedback, as we live in a country with very little resources...

Esther Garvi
Zinder, Niger

Dr. Alan Weldon said...

It is possible that your horse has EP and I would suggest that you have them tested. If you have a good pathologist available it could be seen on a blood smear, if not then have several different serology tests done so you dont miss it. Treatment consists of Imidocarb but since it can make them sick it is best to be sure what you are treating.Identification of parasites in blood
smears provides the definitive diagnosis of equine
infection, but bears certain limitations, particularly
during apparent or chronic infection due to low
parasitaemias. Serodiagnosis by use of complement
fixation test (CFT) alone may give false negative test
results, especially in horses that are parasite carriers, and
has been shown to be less sensitive than the indirect
fluorescent antibody test (7,8). Polymerase chain reaction
(PCR) proved very useful for the detection of haemoparasites
(9), and combined with reverse line blot (RLB)
offers the possibility of simultaneous detection and
identification of different species infecting horses (10).
Imidocarb treatment (2.2mg / kg BW q 24h) of B. caballi
infected horses has been shown to eliminate the
infection (11,12), but data on the efficacy of this treatment is
scarce and more sensitive diagnostic tools have developed
over the years. Recent literature suggest that even high
dose treatment with imidocarb (4.7mg/kg BW im q 72h 5
times) may not be capable of eliminating B. caballi and T.
equi infections from healthy carriers (13). We have to keep
in mind that an infection with T. equi often results in
life-time carriers and the treatment (imidocarb 4.0 mg /
kg BW q 72h) is certainly not without risks. Colic and
death may be the consequence of treatment and complete
elimination of the parasite if often not achieved
despite treatment.

Esther Garvi said...

Thank you for your swift reply!

We sent blood samples to the lab here in Zinder, and both horses were positive of EP. I don't know exactly how they identify it, but what I am sure of is that their red blood cells are under attack. We have two mares and live in an area where EP is endemic. I bought Arwen in 2004 and now suspect she has had it ever since coming in from the bush? The horses have had no ticks during their time with us, but we can't control the horse flies, whom I have understood can be just as good a carrier of the disease as ticks.
A second opinion is to occur today; I have no idea what treatments are available in Niger, but the vet I spoke with yesterday said there are.

Apart from being diagnosed with EP, the horses are in seemingly good health, eating and playing as usual. What do you know of the chronic version?