Studies were conducted to evaluate fecal shedding of Escherichia coli O157:H7 in a small group of inoculated deer, determine the prevalence of the bacterium in free-ranging white-tailed deer, and elucidate relationships between E. coli O157:H7 in wild deer and domestic cattle at the same site. Six young, white-tailed deer were orally administered 10 8 CFU of E. coli O157:H7. Inoculated deer were shedding E. coli O157:H7 by 1 day postinoculation (DPI) and continued to shed decreasing numbers of the bacteria throughout the 26-day trial. Horizontal transmission to an uninoculated deer was demonstrated. Although E. coli O157:H7 bacteria were recovered from the gastrointestinal tracts of deer necropsied from 4 to 26 DPI, attaching and effacing lesions were not apparent in any deer. Results are similar to those of inoculation studies in calves and sheep. In field studies, E. coli O157 was not detected in 310 fresh deer fecal samples collected from the ground. It was detected in feces, but not in meat, from 3 of 469 free-ranging deer in 1997. In 1998, E. coli O157 was not detected in 140 deer at the single positive site found in 1997; however, it was recovered from 13 of 305 dairy and beef cattle at the same location. Isolates of E. coli O157:H7 from deer and cattle at this site differed with respect to pulsed-field gel electrophoresis patterns and genes encoding Shiga toxins. The low overall prevalence of E. coli O157:H7 and the identification of only one site with positive deer suggest that wild deer are not a major reservoir of E. coli O157:H7 in the southeastern United States. However, there may be individual locations where deer sporadically harbor the bacterium, and venison should be handled with the same precautions recommended for beef, pork, and poultry.

Evidence is presented for the existence of male-produced attachment pheromones in the tick Amblyomma cajennense (F). Unfed males and females attached significantly faster to shaved sides on bovine hosts where preattached males were present than did adult ticks released in control areas. Attached ticks did not form clusters around the preattached males as described for other species of Amblyomma. They attached in areas under bags where they had been released, but were not necessarily close to the feeding males. Males apparently required at least 4 d of feeding before producing the pheromones. Males that fed for < 3 d failed to induce attachment. A significant increase in attachment of newly introduced males and females was observed only on day 4 after the feeding of the preattached male started. This response increased on days 5 and 6 after feeding had commenced. An evolutionary trend in the production of tick pheromones was suggested.

From January 1998 through September 1999, 324 dogs in three northwestern Georgia counties were examined for ticks. Six species of ticks were recovered. The three most commonly collected ticks were the American dog tick, Dermacentor variabilis (Say) (310 male male, 352 female female; prevalence, 97%; mean intensity 2.1); the brown dog tick, Rhipicephalus sanguineus (Latreille) (118 male male, 119 female female, 38 nymphs; prevalence, 22%; mean intensity, 3.8); and the lone star tick, Amblyomma americanum (L.) (8 male male 26 female female, 2 nymphs; prevalence, 5%; mean intensity, 2.4). Other ticks recovered were Ixodes cookei Packard (3 female female); the Gulf Coast tick, Amblyomma maculatum Koch (2 female female); and the blacklegged tick, Ixodes scapularis Say (1 female). Another adult female specimen of I scapularis was recovered from a cat, further reinforcing that this medically important tick is present in northwestern Georgia.

Aggregation-attachment pheromones are produced only by male ticks of the genus Amblyomma that have imbibed blood for at least 8 d from their mammalian hosts. This report demonstrates that production and release of aggregation-attachment pheromones by Amblyomma maculatum (Koch) males can be induced in vitro by using nonblood media, artificially introduced through capillary tubes, into the male ticks. The presence of these pheromones is demonstrated by using both biological observations on bovine hosts and in vitro experimentation with petri dishes. The attraction of unfed female ticks to the artificially fed males (using the petri dish method) was significantly higher (P < 0.001) than the attraction of unfed females to unfed males. Similarly, attraction and attachment were recorded on bovine hosts. Only 62.8 +/- 17.5% of the females released attached to the bovine host. Of these, 61.9 +/- 19.37% attached around artificially fed males that were placed on the bovine 24 h earlier. This percentage did not differ significantly from the 81.4 +/- 7.1% of the total that attached around males that fed naturally for 8 d. In comparison, only 33.3 +/- 21.9% of the total number of females placed on the host did so after being fed 1 d (control group). The possibility of using capillary feeding as a new tool for investigating the physiology and reproductive behavior of blood-sucking arthropods is discussed.