USAHA News
United States Animal Health Association
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For immediate release:

TICK INCURSIONS INCREASE IN SOUTH TEXAS

        GREENSBORO, N.C., Oct. 27, 2004 -- Infestations of cattle fever ticks along the 
U.S.-Mexico border in Texas were sharply higher this year.

	This information was presented to the USAHA Committee on Parasitic Diseases at 
its meeting here this week.  Historically, there are annual incursions of cattle fever 
ticks (Boophilus annulatus and B. microplus) into south Texas when errant tick-infested 
livestock and free-ranging white-tailed deer from Mexico cross the Rio Grande River.  
Each year a variable number of such incursions result in populations of cattle fever 
ticks that infest cattle in Texas pastures that are usually near the river.

	During the first 9 months of 2004, 77 premises were quarantined after cattle 
fever tick-infested cattle were identified on them by personnel from the Cattle Fever Tick 
Eradication Program of the USDA’s Animal and Plant Health Inspection Service (APHIS).  The 
number of infestations discovered this year is almost three times the number found during 
the same period in 2003 and is seven times greater than the total number for all of 2002.

	It is noteworthy that 27 percent of this year’s outbreaks were located in the "Tick 
Free Area" outside the Quarantined Zone.  Also, 65 percent of the infested premises have 
been in Zapata County, which is located in the lower one third of the nearly 800-kilometer-long 
Quarantined Zone and which is separated from Mexico along most of its border by Falcon Lake, 
a large lake formed by a dam across the Rio Grande.  

	Past attempts to relate the prevalence of tick outbreaks to climate have generated 
inconclusive results.  Even so, a series of warmer than average winters and above-average 
precipitation in southern Texas and northeastern Mexico would favor growth of tick populations 
and seem likely to be important variables in the epidemiology of recent cattle fever tick problems.

	The committee also heard a report on efforts to eradicate the tropical bont tick 
from St. Croix, U.S. Virgin Islands.  The tropical bont tick, which can spread the organism that 
causes heartwater in cattle and other ruminants, was first found on St. Croix in 1967.  By March 
1968, the number of infested farms had increased to 11.  An aggressive eradication program was 
launched and in 1972, St. Croix was declared free of the tropical bont tick.

	In 1987, after being free for 15 years, ticks were found again.  Due to a lack of funds, 
there was no eradication program; the farm was quarantined and the animals were routinely 
sprayed with an acaracide.  By September 2003, the number of infested farms had increased to eight.

	Livestock producers in the United States and Caribbean and South American countries 
have developed an interest in the St. Croix Senepol breed of cattle.  However, the presence 
of the tropical bont tick limits the exportation of Senepol cattle.  In an attempt to encourage 
importation of Senepol cattle into the United States and other interested countries -- which 
would greatly aid the St. Croix economy -- APHIS entered into a cooperative agreement with 
St. Croix to establish a tropical bont tick eradication program on the island.

	The program is currently in the eradication stage with two teams in the process of 
performing a 100-percent premises inspection in the eastern end of St. Croix so that a dividing 
line can be established between quarantined and non-quarantined zones.  Currently, all eight 
tick-infested premises are on the western end of the island.  They will be sprayed with a tickicide 
every two weeks.  The program is designed to eliminate the ticks in 24 months, with an 18-month 
treatment period and a 6-month surveillance period.

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