EQUINE PIROPLASMOSIS - USA (02): (TEXAS)

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A ProMED-mail post

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International Society for Infectious Diseases


Date: 28 Jan 2010
Source: Caller.com [edited]



Rare horse disease affects horses in 12 states
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King Ranch, Texas, is the epicenter of a months-long outbreak of a
deadly horse disease rarely seen in the United States that kills as
many as 20 percent that it infects. As of 20 Jan 2010, 364 cases of
equine piroplasmosis had been confirmed. Of those, 289 are on King
Ranch. The rest are scattered across Texas, Alabama, California,
Florida, Indiana, Louisiana, Minnesota, North Carolina, New Jersey,
Tennessee, Utah and Wisconsin, according to the World Animal Health
Information System.

A South Texas ranch, identified by the Texas Animal Health Commission
as the outbreak's source, has sold horses with equine piroplasmosis
in 15 states since 2004. Jack Hunt, the CEO of King Ranch, confirmed
the outbreak started on the ranch.

Horses, donkeys, mules and zebras are susceptible to the disease,
which is caused by 2 parasitic organisms. More severely affected
animals can have fever, anemia, jaundiced mucous membranes, swollen
abdomens and labored breathing.

"It will kill a horse," said Mike Vickers, a Brooks County
veterinarian and commissioner on the Texas Animal Health Commission.
"It's very, very serious."

No horses have died, officials believe. The ranch's 300-plus horses
have since been quarantined. Piroplasmosis had never been seen in
Texas and rarely had been found in the United States, according to
the Texas Animal Health Commission, the state's livestock and poultry
health regulatory agency. It is prevalent in 90 percent of the world
and commonly found in Mexico.

Once a horse is infected, the parasitic organisms remain in the
horse's system permanently, making the horse a potential carrier. It
does not affect humans or other non-equine mammals. Ticks usually
transmit the disease to horses, but it also has been spread from
animal to animal by contaminated needle. There is some concern that
it might be spread by biting horse flies, Vickers said.

Hunt, who has been in the ranching business for 35 years, said he had
never heard of the disease when it was discovered in October 2009.

A total of 8 other ranches in Jim Wells, Kleberg, and Brook counties
have been quarantined and tied to the initial outbreak, said James
Lenarduzzi, a veterinarian with the Texas Animal Health Commission.
Horses from ranches adjacent to King Ranch will be tested in coming
weeks to determine if they are infected.

The 825 000-acre King Ranch includes most of Kleberg and Kenedy
counties and portions of Brooks, Jim Wells, Nueces and Willacy
counties. It is renowned for its horses, including 1946 Triple Crown
winner Assault and 1950 Kentucky Derby and Belmont Stakes winner Middleground.

Though the ranch still has a horse breeding program, no horses have
been sold since the quarantine, Hunt said.

The Texas Animal Health Commission issued its 1st directive on the
South Texas-based infection 20 Oct 2009, noting that the disease had
been confirmed on an undisclosed ranch. Canada promptly banned
imports of Texas horses, though later relaxed the restrictions. A
total of 10 states have stringent restrictions in place that call for
testing and other controls before a horse can be imported from Texas.

State Rep. Yvonne Gonzalez Toureilles, D-Alice, who chairs the House
Committee for Agriculture and Livestock, got involved this week after
several South Texas ranchers complained that King Ranch has kept its
name away from the outbreak, which started in October 2009.

Hunt said King Ranch self-reported the infection, which was required
by law, and has worked openly with state and federal agencies since.
"We are putting a lot of resources and energy into trying to figure
out a way to take care of the problem," Hunt said. "What we don't do
is cover up stuff, which we have been accused of in this case."

The state has 1 million horses. Owners, family members and volunteers
spend USD 3 billion per year attending competitive events with more
than 250 000 horses, according to a Texas A&M University report. And
horse owners have more than USD 13 billion invested in barns, towing
vehicles, trailers, tack and related equipment and spend more than
USD 2.1 billion annually to maintain their horses.

Some South Texas ranchers are angry that the state and federal
government have been tight-lipped on the disease's origin, said
Lavoyger Durham, who manages the 13 000-acre El Tule Ranch near
Falfurrias for Brown and Root heiress Nancy Brown Negley.

Lenarduzzi met with Durham and about 25 fellow South Texas ranchers
Thursday [28 Jan 2010] to discuss the disease but would not say where
it started, which Lenarduzzi said is standard operating procedure.

Gonzalez Toureilles said she will meet with Texas Animal Health
Commission officials by Monday [1 Feb 2010] to make sure the outbreak
is being handled correctly.

King Ranch also is working with the U.S. Department of Agriculture
and some of the nation's top epidemiologists on experimental
procedures to remove the parasite from a horse's system, Hunt said.
"They have sent great people to work on this project, and we have had
lots of interaction," Hunt said. "It's just a process we are all
going to have to go through. It's not pleasant for anybody affected by it."

[Byline: Jaime Powell]

--
Communicated by:
ProMED-mail


[Equine piroplasmosis results from infection by the protozoa _Babesia
caballi_ or _B. equi_ (phylum Apicomplexa). The 2 organisms may
infect an animal concurrently.

Equine piroplasmosis is a tick-borne protozoal infection of horses.
Piroplasmosis may be difficult to diagnose, as it can cause variable
and nonspecific clinical signs. The symptoms of this disease range
from acute fever, inappetence, and malaise, to anemia and jaundice,
sudden death, or chronic weight loss and poor exercise tolerance. The
disease may be fatal in up to 20 percent of previously unexposed
animals. The tick vectors exist in the United States, and epidemics
of piroplasmosis were seen in Florida in the 1960s.

The incubation period for _B. equi_ infections is 12 to 19 days, and
infections are more severe. For _B. caballi_ infections, it is 10 to 30 days.

The clinical signs of piroplasmosis are variable and often
nonspecific. In rare peracute cases, animals may be found dead or
dying. More often, piroplasmosis presents as an acute infection, with
a fever, inappetence, malaise, labored breathing, congestion of the
mucus membranes, and small, dry feces. Anemia, jaundice,
hemoglobinuria, sweating, petechial hemorrhages on the conjunctiva, a
swollen abdomen, and posterior weakness or swaying may also be seen.
Subacute cases may have a fever (sometimes intermittent),
inappetence, malaise, weight loss, signs of mild colic, and mild
edema of the distal limbs. The mucus membranes can be pink, pale
pink, or yellow, and may have petechiae or ecchymoses. In chronic
cases, common symptoms include mild inappetence, poor exercise
tolerance, weight loss, transient fevers, and an enlarged spleen
(palpable on rectal examination). Foals infected in utero are usually
weak at birth, and rapidly develop anemia and severe jaundice.

In acute cases, the animal is usually emaciated, jaundiced, and
anemic. The liver is typically enlarged and dark orange-brown. The
spleen is enlarged, and the kidneys are pale and flabby. Petechial
hemorrhages may be seen in the kidneys, and subepicardial and
subendocardial hemorrhages in the heart. There may also be edema in
the lungs and signs of pneumonia.

The differential diagnosis for piroplasmosis includes surra, equine
infectious anemia, dourine, African horse sickness, purpura
hemorrhagica, and various plant and chemical toxicities.

Equine piroplasmosis can be diagnosed by identification of the
organisms in Giemsa stained blood or organ smears. _B. caballi_
merozoites are joined at their posterior ends, while _B. equi_
merozoites are often connected in a tetrad or "Maltese cross."
Organisms can often be found in acute infections, but may be very
difficult to find in carrier animals. In carriers, thick blood films
can sometimes be helpful.

Because _Babesia_ organisms can be difficult to detect in carriers,
serology is often the diagnostic method of choice. Serologic tests
include complement fixation, indirect fluorescent antibody (IFA), and
enzyme-linked immunosorbent assays (ELISA). The IFA test can
distinguish between _B. equi_ and _B. cabali_.

Other methods of diagnosis include DNA probes, in vitro culture, and
the inoculation of a susceptible (preferably splenectomized) animal
with blood from a suspected carrier. In addition, pathogen-free
vector ticks can be fed on a suspect animal, and _Babesia_ identified
either in the tick or after the tick has transmitted the infection to
a susceptible animal.

Disinfectants and sanitation are not generally effective against the
spread of tick-borne infections. However, preventing the transfer of
blood from one animal to another is vital.

The state of Texas in the South Central United States, can be located
on the HealthMap/ProMED-mail interactive map at:


Portions of this commentary have been extracted from
.
- Mod.TG]

[see also:
Equine piroplasmosis - USA 20100129.0309
2009
----
Equine piroplasmosis - USA 20100129.0309
Equine piroplasmosis - USA (12): (NM) 20091230.4394
Equine piroplasmosis - USA (11): multi-state 20091203.4128
Equine piroplasmosis - USA (10) 20091117.3963
Equine piroplasmosis - USA (09): (NJ ex TX) 20091111.3912
Equine piroplasmosis - USA (08): (TX) alert 20091030.3749
Equine piroplasmosis - USA (07): (TX) 20091024.3675
Equine piroplasmosis - USA (06): (TX) OIE 20091022.3631
Equine piroplasmosis - USA (05): (TX) 20091021.3617
Equine piroplasmosis - USA (04): (KS, MO) resolved 20090917.3262
Equine piroplasmosis - Ireland 20090909.3183
Equine piroplasmosis - USA (03): (KS, MO) 20090729.2662
Equine Piroplasmosis - USA (02): (MO) 20090612.2172
Equine Piroplasmosis - USA: (FL) quarantine lifted 20090225.0771
2008
----
Equine Piroplasmosis - USA (04): (FL) 20080930.3088]
....................sb/tg/ejp/dk

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