Ecological investigations of the lone star tick, Amblyomma americanum (L.), were conducted in 3 adjacent 60-m2 plots, located in Noxubee National Wildlife Refuge, Noxubee County, Mississippi. Ticks were collected weekly from July 1992 to July 1993 by flagging randomly selected lanes. During the year, larval ticks were collected first in early July, with peak numbers in September, and they were collected no later than late October. Nymphal ticks were collected from mid-March to late October, with peak numbers occurring in mid-May and early August. Adult ticks were found initially in early March, with peak numbers from mid-May to mid-June and were no longer collected by late August. Analyses of meteorological data indicated that the most influential parameter on tick activity was humidity.
Rocky Mountain spotted fever (RMSF), a tick-borne illness that has its highest incidence in the south central and southeastern United States, is often a diagnostic challenge, as patients frequently present with nonspecific symptoms during the early stages of illness. RMSF has a high case fatality rate among untreated individuals, and the median time from onset of symptoms to death is only eight days, making early recognition and treatment of RMSF crucial. In two Mississippi public health districts, 148 primary care physicians were randomly selected and mailed surveys regarding RMSF diagnosis, treatment, and prevention. Eighty-four of the 148 (57%) physicians responded. Responses from different specialties and different health districts were compared using chi square statistics. Almost all (99%) physicians correctly identified doxycycline as the antibiotic agent of choice for treating adults and adolescents. However, only 21% of family practice physicians, and 25% of emergency medicine physicians correctly identified the antibiotic of choice for treating children with RMSF. Twenty-three percent of physicians responded that waiting for the development of a rash before prescribing antibiotics is an appropriate treatment strategy. The current standard of care-doxycycline as the agent of choice among children 8 years of age or younger with suspected RMSF-has not been effectively communicated to all physicians caring for children. Also, many physicians are not familiar with the rationale underlying initiation of antibiotic therapy prior to the development of rash in patients with suspected RMSF. Continuing education efforts should focus on antibiotic selection in pediatric patients and initiation of therapy prior to the onset of rash in appropriate patients.
Infestations of Tyrophagus putrescentiae (Schrank; Sarcoptiformes: Acaridae), known as the ham mite, may occur on dry cured hams during the aging process. The fumigant methyl bromide is currently used to control mite infestations, but it will eventually not be available for use since it contributes to the depletion of the ozone layer. The use of ham nets treated with xanthan gum, carrageenan, propylene glycol alginate, and propylene glycol food-grade ingredients on mite orientation to or oviposition on treated or untreated ham cubes, and mite reproduction and population growth over a 10-wk period was evaluated. Behavioral tests indicated that more than 95% of the mites oriented to the ham cubes that were wrapped in untreated nets when compared to treated nets and no eggs were laid on the latter. The reproduction assays demonstrated that there were fewer (P < 0.05) T. putrescentiae produced over a 2-wk period on ham cubes covered with both gum and propylene glycol treated nets, when compared to the untreated or gum-only treated nets over the 10-wk storage period of the experiment. Medium and high concentrations of propylene glycol treatments showed the lowest reproductive rates of mites. No more than 4 mites could be found on each of these treatments in comparison to 200 to 300 mites that were recorded on the untreated hams. This study demonstrated efficacy of using the nets treated with food-grade ingredients during ham aging to control mite infestations on a laboratory scale. Further research will be conducted to determine the effectiveness of the same treated nets on whole hams in commercial aging rooms.
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