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An entomophagous wasp (Hunterellus hookeri Howard) parasitizes about a third of the host-seeking nymphal Ixodes dammini Spielman et al. ticks on Naushon Island in Massachusetts (U.S.A.) where the agents of Lyme disease (Borrelia burgdorferi Johnson et al.) and human babesiosis (Babesia microti Franca) are enzootic. Following blood-feeding, wasp-parasitized ticks are destroyed by the developing wasp. The prevalence of either human pathogen in host-seeking ticks collected in wasp-infested sites is nearly 40% lower than that found in other sites. Nymphal ticks, collected early in their season of activity, are more frequently parasitized by the wasp and less frequently by the Lyme disease spirochaete than those collected later in the summer. Spirochaetes never infected wasp-infected ticks, and few wasp-infected ticks were concurrently infected by the Babesia piroplasm. Taken together, these correlations indicate that the wasp may render the tick inhospitable to both pathogens. The presence of the wasp may have reduced risk of human infection on the island by either pathogen by as much as a third.

Primarily in order to facilitate future studies on venereal transmission of La Crosse encephalitis virus by Aedes triseriatus, tests were conducted to identify conditions that maximize insemination rates in caged populations of Ae. triseriatus derived from field-collected eggs. All tests were conducted at 21 degrees C +/- 1 degree C, which is approximately the mean temperature during July and August in southwestern Wisconsin where La Crosse virus is endemic. Non-bloodfed females exposed on their 5th through 8th day of adult life showed little sexual receptivity to either 5- to 6-day-old males or 8- to 9-day-old males. F1 females were no more receptive than their mothers had been at a similar age. Mean insemination rates did not exceed 32.6% in any of these age combinations at sex ratios ranging from 4 males: 1 female-1 male: 4 females. Mean insemination rates ranged as high as 89.0% when non-bloodfed females were exposed on their 9th through 12th day of adult life to 5- to 6-day-old males in a 4 male: 1 female ratio. In females given a bloodmeal on their 4th day of life and exposed on their 5th through 8th day to 5- to 6-day-old males, mean insemination rates ranged as high as 91.7% at a ratio of 2 males: 1 female.

Fibrin formed on endothelial cells has previously been shown to have deleterious effects on the cells. Additionally, substances that cause endothelial cell damage have been reported to induce cultured endothelial cells to synthesize prostacyclin and tissue plasminogen activator (t-PA). The present studies were undertaken to determine whether fibrin formed on cultured human umbilical vein endothelial cells would alter synthesis of prostacyclin and t-PA by the cells. Fibrin was found to increase synthesis of both prostacyclin and t-PA in a dose and time dependent manner. Stimulation of prostacyclin synthesis was completely inhibited by indomethacin; partially inhibited by actinomycin D, cycloheximide, and trifluoperazine; and not affected by cytochalasin D or vinblastine. In contrast, stimulation of t-PA synthesis was completely inhibited by actinomycin D and cycloheximide; partially inhibited by cytochalasin D, vinblastine, and trifluoperazine; and not affected by indomethacin. Fibrin I, formed with Reptilase, caused only slight stimulation of t-PA production, but virtually no stimulation of prostacyclin synthesis. Neither collagen polymerization on the cells nor thrombin added in concentrations that did not induce fibrin polymer formation stimulated production of either substance. Furthermore, soluble fibrin II generated in the presence of the fibrin polymerization inhibitor gly-pro-arg-pro also failed to stimulate either prostacyclin or t-PA production. The presence of platelets in the plasma from which the fibrin was formed did not affect the amount of stimulation of the cells. Fibrin-induced stimulation of endothelial cell production of prostacyclin and t-PA could act to limit vascular occlusion in vivo by inhibiting platelet function and by stimulating fibrinolysis via t-PA.

We report a case of bilaterally absent superior rectus muscles presenting clinically as a double elevator palsy. This patient is unique due to paradoxical ocular movements on attempted upgaze and the absence of other major craniofacial anomalies. Successful surgical correction was accomplished using a modified Jensen procedure where the superior halves of the horizontal rectus muscles were united using synthetic absorbable sutures. Congenital absence of the superior rectus muscles should be suspected in patients with severe elevation deficiency associated with paradoxical ocular movements.

We compared the relative infectivity to vector ticks of gray catbirds (Dumetella carolinensis) and white-footed mice (Peromyscus leucopus) for the Lyme disease spirochete (Borrelia burgdorferi). Of 28 catbirds captured in a site enzootic for this agent, 18 were infested by immature Ixodes dammini, the tick vector. By comparison, each of 32 mice sampled concurrently from the same site was infested, and by about 10 times as many ticks as were found infesting the 3 most commonly netted bird species. Although 76% of noninfected larval ticks placed on these mice in a xenodiagnosis became infected, none of the ticks similarly placed on 12 catbirds did so. Spirochetes were detected in ticks derived from 2 Carolina wrens (Thryothorus ludovicianus) and a common yellowthroat (Geothlypis trichas), but these species' potential contribution to infecting ticks does not compare with that of mice. Thus, although birds may help establish new foci of ticks, catbirds, at least, do not appear to contribute as reservoirs of infection.

We determined the prevalence of Babesia microti and Borrelia burgdorferi in four populations of Ixodes dammini in eastern Massachusetts. The Feulgen's reaction was more sensitive than the Giemsa method for detecting salivarian Babesia. A combination of darkfield and direct-fluorescent-antibody examination proved more sensitive than either method alone for detecting spirochetal infection. The prevalence of spirochetes was greater than the prevalence of Babesia in each of the tick populations studied. Overall, 24% of nymphs and 47% of adults examined were infected with spirochetes; in contrast, 11% of nymphs and 14% of adults were infected with Babesia. The difference between the spirochetal and babesial prevalence was greatest in the most recently infested site. The rising incidence of Lyme disease, as compared to the stable incidence of human babesiosis, may result from the relatively greater abundance of Bo. burgdorferi infected I. dammini ticks in newly infested locations.

Host blood source was found to affect both the fecundity and the duration of te gonotrophic cycle of Aedes triseriatus. Mosquitoes were fed on restrained deer, chipmunks, squirrels, humans and suckling mice. Results showed that mosquitoes fed on chipmunks or squirrels, the major La Crosse virus vertebrate amplifier hosts, had greater fecundity but longer gonotrophic time intervals (approximately 2 more days per ovarian cycle) than mosquitoes fed on deer, which is a non-amplifier species. Results were similar for both first and second mosquito gonotrophic cycles. Application of these data to a model determining differential reproductive capacity showed a 24% reduction in the number of second cycle eggs laid by Ae. triseriatus taking the initial blood meal on amplifier species as compared to those taking the initial blood meal from deer. As only those uninfected mosquitoes that feed on an amplifier species have a chance of becoming orally infected and producing infected eggs, this reduced reproductive capacity reduces correspondingly the potential number of vertical infections that can be established during the amplification process.

To test the possibility that immature deer ticks (Ixodes dammini) may concentrate in the nests of their mouse hosts, we recorded their pattern of detachment. In laboratory experiments, most engorged larvae (greater than 90%) and nymphs (greater than 80%) detached from hamsters between 1200-2000 hours when the 14-hr photophase began at 0600 hours. Time of drop-off was similar regardless of when ticks attached to hosts, but attachment late in the day delayed drop-off by one full day. Ticks detached similarly from naturally-infested Peromyscus leucopus. A post-attachment cue or cues appeared to regulate time of detachment. Such synchronous diurnal detachment may serve to concentrate ticks in the nests of their nocturnal mouse hosts, thereby enhancing pathogen transmission.

To determine whether deer may serve as reservoir hosts for the Lyme disease spirochete, we sought evidence of infection in nymphal Ixodes dammini derived from larvae that had engorged on white-tailed deer. A total of 19 deer were shot in two Lyme disease foci in Massachusetts during September 1986, the season in which larvae were most abundant. An average of 342 larval ticks of this species were collected from each deer. Of those that developed to the nymphal stage, the gut contents of 185 were examined for Borrelia burgdorferi by a direct fluorescent antibody test. Spirochetes were detected in about 1% of these nymphs, a rate of infection attributable to transovarial transmission. In contrast, infection was detected in 23% of 39 field-swept nymphal ticks of the same cohort that were collected during the following season. Although deer may be infested by numerous larval I. dammini, such ticks appear not to become infected by Lyme disease spirochetes.

We investigated whether concurrent ingestion of dengue 2 virus and microfilariae of Brugia malayi would increase viral infection and dissemination rates in Aedes aegypti. Infection rates were similar in mosquitoes that ingested virus alone or both virus and microfilariae concurrently. However, viral dissemination rates, as determined by recovery of dengue virus from both legs and bodies separately, were significantly greater in mosquitoes that ingested both agents concurrently than in those that ingested virus alone. This study confirms that vectorial capacity of a natural vector of an arbovirus may be enhanced by the concurrent ingestion of microfilariae.

If intraoperative visualization is impossible when placing a secondary Jones tube, the presence of tube drainage may confirm correct intranasal positioning. A simple suction method is presented to evaluate the intranasal position of the Jones tube in the anesthetized or uncooperative patient.

Permethrin-treated cotton, intended as rodent nesting material, was distributed in wooded sites in which the agents of Lyme disease and babesiosis were enzootic, in order to kill immature Ixodes dammini, the ticks that transmit these human pathogens. Such ticks feed most abundantly on white-footed mice (Peromyscus leucopus), apparently the main reservoir hosts of these agents, and tend to concentrate in mouse burrows. Mice captured after permethrin-treated cotton was distributed, were infested by a tenth as many ticks as were those captured in adjacent nontreated sites, a difference that continued throughout the 4-month period of observation. On average, 72% of all mice captured in treated sites were free of ticks, while virtually all mice captured in nontreated sites were infested. Voles (Microtus pennsylvanicus), however, were tick-infested, regardless of site of capture. Laboratory-reared I. dammini failed to attach to mice captured in treated sites, and most such exposed ticks died. Distribution of permethrin-treated cotton appears to be a means for preventing transmission of the pathogens that cause human babesiosis and Lyme disease.