BOVINE TUBERCULOSIS - USA (04): (TX) CONFIRMED

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Date: 13 Jun 2009
Source: Texas Animal Health Commission News Release [edited]



Cattle Tuberculosis Confirmed in Texas
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Cattle tuberculosis (TB) has been confirmed in a west Texas dairy
that has been quarantined since April 2009 when some cattle in the
herd responded to a TB test being conducted prior to a sale. (The
sale was cancelled.) The cattle TB diagnosis was confirmed at the
National Veterinary Services Laboratory (NVSL) in Ames, Iowa, where
_M. bovis_, or cattle TB bacteria, was grown or "cultured" from
tissues that had been collected during the necropsy of the
test-positive cattle.

"The infected herd remains quarantined while the final disposition of
the herd is determined -- either slaughtering the herd, or repeatedly
testing and removing infected animals until the herd is free of
cattle TB," said Dr. Bob Hillman, Texas' state veterinarian and head
of the Texas Animal Health Commission (TAHC), the state's livestock
and poultry health regulatory agency.

"Dairy, calf-raising and dairy animal replacement operations with
epidemiological links to the infected herd are being tested to
determine both the origin and potential spread of the disease. I
encourage ranchers or accredited veterinarians to call the state of
destination prior to shipping bison, beef or dairy cattle out of
Texas," said Dr. Hillman. "Some states may impose enhanced TB entry
requirements on Texas cattle and bison. Keep in mind, too, that many
states, like Texas, have implemented cattle trichomoniasis testing
requirements, so call before you haul."

Dr. Hillman said Texas' cattle TB-free status with the U.S.
Department of Agriculture (USDA) could be in jeopardy, if the
infected dairy cannot be depopulated, or if a 2nd infected herd is
detected within 48 months.

Nebraska, in early June 2009, confirmed TB infection in a beef herd.
Currently, California and Minnesota are not cattle TB-free, and areas
in Michigan and New Mexico have specified zones that are not TB-free.
When TB-free status is lost, breeding cattle and bison moved out of a
state need a negative TB test within 60 days prior to shipment, or
animals must originate from a herd that has accredited TB-free
status, achieved through a formal testing and retesting program.

Texas initially gained TB-free status in November 2000, when all
counties except El Paso and portions of Hudspeth Counties were
declared free of the disease. (The El Paso Milk Shed had a history of
recurring infection, and eventually, the dairies were depopulated.
Dairies no longer operate in this area along the U.S.-Mexican border
near El Paso, Texas.)

In June 2002, Texas lost TB-free status after infection was detected
in a beef herd and in an operation with both beef and dairy cattle.
To regain TB-free status, 2014 Texas purebred beef herds and the
state's 818 dairies were tested for the disease from October 2003
through August 2006. One TB-infected dairy was detected and
depopulated. In September 2006, the USDA issued the coveted TB-free
status for all of Texas' 254 counties.

When exposed to cattle TB, an animal's immune system will fight the
invasion by encapsulating the bacteria. This can cause the formation
of lesions or growths in and on lymph nodes, mammary glands, lungs
and other internal organs. Although infected, the animals may appear
healthy, until the latter stages of the disease, when signs may
include weight loss, coughing or breathing difficulties. The disease
is not treatable in livestock.

"Cattle TB is a serious, transmissible disease that can spread among
herds," said Dr. Hillman. "In the early 1900s, when the national
cattle TB eradication program was initiated, more than 5 percent of
the country's herds were infected with the disease. At that time,
cattle TB posed a significant human health threat, because consumers
could become infected when they drank raw, unpasteurized milk that
had not been through heat-treatment to kill bacteria. Today,
commercially produced milk is pasteurized. While bovine TB is still
a human health threat, other forms of tuberculosis, such as the human
and avian strains, now pose the greatest risk of TB exposure to persons."

--
Communicated by:
Carla Everett


[In the previous ProMED-mail posting (20090424.1536) it was suspected
that the lesions found in a bovine were tuberculosis. This is
confirming the news of such a possibility back in April 2009.

The _Mycobacterium bovis_ organism grows slowly, both in the
laboratory and in the animal. And unfortunately there are no rapid
and reliable tests for this organism. Although there is a test for
this disease in the live animal, its accuracy is not that great and
confirmation still depends upon culturing the organism, generally
from a lesion within the animal.

One of the best weapons against this disease is inspection at the
time of slaughter.

Sadly, the issue of drinking non-pasteurized milk is again on the
rise because of a trend in promoting non-pasteurized milk as healthy.
Consumption of non-pasteurized milk can cause severe illness and
possibly death, because of such diseases as tuberculosis. - Mod.TG]

[see also:
Bovine tuberculosis - USA: (TX), susp 20090423.1536]
....................tg/ejp/dk

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