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Biomedical subjects

C H Porter

Publications and source records attributed to C H Porter.

27 records · Page 2Linked to original sources
PubMed1985

Epidemiologic study of visceral leishmaniasis in Honduras, 1975-1983.

Between 1975 and 1983, 53 patients with parasitologically proven visceral leishmaniasis (VL) and 16 patients with suspected VL were diagnosed in Honduras. The patients' ages ranged from 3 months to 10 years, but 95% were younger than 3 years old. Since 1978, when 16 patients were reported, the yearly incidence has declined, and in 1982 only 4 patients were reported. We located and interviewed the families of 57 of the 69 patients. At the onset of illness, all 57 patients lived in rural areas, and 55 lived in southern Honduras. All the patients who were discharged from the hospital alive were still living at the time of the interview. A case-control study, using age-matched neighbors as controls, showed that patients were significantly more likely to have lived in poorly constructed, wood-stick houses. We used an indirect immunofluorescence test to analyze blood samples for Leishmania antibodies from 218 family members of patients, 170 family members of controls, and 156 children living on the island of El Tigre, where 4 of the 5 most recently diagnosed patients lived. Although 15 specimens gave a positive reaction to L. donovani antigen, each gave a stronger reaction when tested against Trypanosoma cruzi antigen, suggesting that the reactions to L. donovani were false positives. A serosurvey of 279 dogs of cases and controls and from El Tigre showed that 24 had positive reactions to L. donovani antigen, but only 4 (1.4%) had higher titers to L. donovani than to T. cruzi.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1985

The gonotrophic cycle of wild Simulium ochraceum and the associated development of Onchocerca volvulus.

A total of 1,700 host-seeking Simulium ochraceum were allowed to feed to repletion on human volunteers heavily infected with Onchocerca volvulus and then were marked and released. Seventy-three (4.3%) of the flies were recaptured. The gonotrophic cycle of S. ochraceum, including the host seeking and oviposition phases, was approximately 74-97 hr in duration; however, for a few flies the cycle was up to an additional 24 hr in length. The frequency distribution of recaptured flies indicated that 2 gonotrophic cycles may be completed in 7-8 days. The large proportion of flies recaptured with sac-stage follicular dilatations indicates that S. ochraceum may begin to search for and can rapidly locate a new host almost immediately after oviposition. Larvae of O. volvulus were found in 15 (20.6%) of the recaptured flies. Early first stage larvae were present in host-seeking flies that had completed 1 gonotrophic cycle: 12 of 13 infected flies recaptured between 74 and 97 hr had early first stage larvae. Development of O. volvulus larvae to the infective stage was estimated to require approximately 11 days at the study site. During this time, S. ochraceum would normally have completed 3 gonotrophic cycles and be in the host seeking phase of a fourth at approximately 11 days after ingesting microfilariae.

Animals↗
PubMed1984

Descriptive statistics for the larval stages of Onchocerca volvulus in host-seeking Simulium ochraceum.

In four localities of Guatemala with dissimilar intensities of onchocerciasis, filarial larvae were recovered by dissection from host-seeking Simulium ochraceum. Measurements made on over 600 Onchocerca volvulus larvae were used to characterize the early first, late first, second, and third developmental stages. The numerical attributes used to characterize the third larval stage and the associated means were body length (657.3 microns); anterior body width (18.9 microns); posterior body width (20.2 microns); distance from anterior end to nerve ring (87.9 microns), to junction of muscular and glandular esophagus (137.6 microns), and to junction of esophagus and intestine (419.6 microns); and distance from anus to tip of tail (36.8 microns). Ratios to total body length were as follows: distance from anterior end to nerve ring, mean = 0.133, to junction of esophagus and intestine, mean = 0.634, and to anus, mean = 0.945. Differences between these phenotypic features and those reported for African O. volvulus appeared to be insufficient to distinguish the two forms. With very few exceptions, the filarial larvae found in host-seeking S. ochraceum were considered to be O. volvulus.

Anal Canal↗