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 in October. 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 GrandeRiver. 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% of this year’s outbreaks were located in the "Tick Free Area" outside the Quarantined Zone. Also, 65% of the infested premises have been in ZapataCounty, 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 FalconLake, 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% 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.