The American Journal of Tropical Medicine and Hygiene - Volume 31, Issue 2, March 1982

The epidemiologic features of Strongyloides stercoralis infection in Kentucky were studied by an analysis of clinical cases at the University of Kentucky Medical Center (UKMC); by an analysis of parasitologic records of the Kentucky Bureau for Health Services (KBHS); and by a prospective stool survey of school children in Clay County, located in southeastern Kentucky, an area of the state previously found to be highly endemic for intestinal parasites. S. stercoralis was the most common parasitic infection diagnosed at UKMC. The patients were predominantly white male adults who were over 50 years old, had an associated chronic or debilitating medical illness, were of low socioeconomic background, and resided in southeastern Kentucky. S. stercoralis was a common parasitic infection at KBHS and the patients showed a similar geographic distribution. Of 561 Clay County children surveyed, 23.7% harbored one or more intestinal parasite pathogens and 3.0% had S. stercoralis. Thus, S. stercoralis remains highly endemic in Kentucky and may cause disease even in geriatric patients.

A cross-sectional survey for Schistosoma haematobium infection in 5,998 individuals, representing 31,803 persons in six rural villages of the Qena governorate, Upper Egypt, was completed. There were 2,223 persons (37.1%) excreting S. haematobium eggs identified by the nuclepore membrane filtration technique of a single urine specimen. Prevalence of infection ranged from 23.9% to 64.0% among the six villages. Quantitatively the overall geometric mean egg-count was 48.1 eggs/10 ml urine. A survey of proximal canals was conducted and 9 of 4,312 Bulinus snails were infected with schistosomes (0.21%). The stools of 2 of 507 adolescent males were positive for S. mansoni. No Biomphalaria snails were found. When these findings are compared to past studies, S. haematobium prevalence appears to have substantially increased.

It has previously been shown that Salmonella paratyphi A associates with adult Schistosoma mansoni worms in animal models and in patients with schistosomiasis, resulting in Salmonella infections that are difficult to manage unless the helminthic parasite is eliminated. In the present study, characteristics of this association were explored. In vitro, fresh serum, but not heat-inactivated (56°C, 30 minutes) serum, from normal hamsters (NH) and schistosome-infected hamsters (SIH) equally inhibited bacterial growth. When either group of animals was given S. paratyphi A intracardially, there was a decline in recoverable bacteria in the blood for 3 days, but after the third day, the number of bacteria increased in SIH whereas NH blood became sterile. Co-cultivation of S. paratyphi A in Earle's medium with live worms yielded more bacterial growth than occurred in the medium without worms, suggesting that nutritional factors are involved in the relationship. An intimate association in vivo of bacteria and trematodes was confirmed by culturing Salmonella from both worm surfaces and homogenized worms, with more bacteria being recovered from female worms. Although the bacterial infection induced a significant hepatic shift of adult worms in SIH, oogram analyses were normal and no lethal effect of bacteria on worms was noted.

We describe media and a cultural system that routinely supports development in vitro of plaques of several types of cells derived from adult Schistosoma mansoni. The results permit description of several types of cells observed in cultures and of criteria developed for the comparative evaluation of the supportive capacity of different media. Methods for the harvesting of worms, of their preparation for culture, and of the maintenance of cultures are detailed. The evolutionary development of the supportive media is summarized with comments on selected variables.

A serum-free medium which supports miracidial development in some eggs deposited by adult Schistosoma mansoni in vitro is described. Derivation of the medium involved examination of the supportiveness of nine chemically defined media, selection of one promoting the highest degree of worm oviposition, and supplementation of the latter with various serum fractions. The serum fraction supporting egg maturation was nondialyzable, and precipitated at 50–60% ammonium sulfate saturation. This fraction could be replaced by bovine serum albumin; however, the supportive activity disappeared if this material was delipidated. Addition of soybean lecithin, or stearic acid, to fatty-acid-free, albumin-supplemented media yielded intermediate results, while similar addition of other nonesterified fatty acids proved non stimulatory. A fatty acid mixture, rich in stearic acid, was then developed which, when added to delipidated-albumin supplemented media, supported a degree of egg development comparable to that obtained with media supplemented with 8% newborn calf serum.

A case of human proliferative sparganosis, the first in the southern hemisphere, is reported. The patient had multiple nodular, papular, acne-like lesions, gynecomastia, and large subcutaneous abscesses. Laboratory findings showed that he also had severe anemia of the type associated with infection and chronic diseases, leukocytosis, eosinophilia, and severe hypoalbuminemia and hypergammaglobulinemia. His cellular and humoral immune responses were unaltered. New aspects on the functional repercussion of the parasitism of the human host by Sparganum proliferum are discussed. Treatment with mebendazole was ineffective; the patient's tolerance for the newer drug praziquantel was extremely poor.

An enzyme-linked immunosorbent assay (ELISA) for the detection of antibody to cysticerci of Taenia solium has been developed that employs a pork muscle antigen control for the cysticercus test antigen, somewhat improving the serological distinction between infected and uninfected subjects. Serum antibody to cysticercus was detected in 79% of classical neurocysticercosis patients from Mexico, and in 61% of a group of cysticercosis patients with an unusually rapid invasion of the central nervous system in an endemic focus of disease in Irian Jaya. Antibody was absent in a group of healthy American laboratory personnel, and in residents of a non-endemic region of Papua New Guinea. Additional tests on sera from patients with other parasitic diseases showed that cross-reactivity may occur in some patients with schistosomiasis, echinococcosis, and possibly angiostrongyliasis; however, these parasites are not known to cause human infection in Irian Jaya.

We report the fifth case of subcutaneous zygomycosis caused by Basidiobolus haptosporus in Brazil. The lesion appeared as a tumor in the right mandibular area mimicking Burkitt's lymphoma of the jaw. In this patient evaluation of cellular immunity with the lymphoblastic transformation test yielded normal results.

In a study conducted over a 5-month period (September 1979 to January 1980), rotaviruses were detected by counterimmunoelectrophoresis in the feces of 16 (13.8%) of 116 infants and young children between 1 and 48 months old with acute, sporadic gastroenteritis, at Ife, Nigeria. The highest frequency of rotavirus infection was found in the 7- to 12-month age-group (18.9%). Males constituted 61% of the sample and excreted rotavirus at a significantly higher rate than did females (P < 0.01). Rotavirus infection was higher in the drier months of November–January (19.3%) than during the rainy months of September and October (8.5%).

The micro enzyme-linked immunosorbent assay (ELISA) was used to specifically identify bloodmeal sources of Aedes triseriatus Say and Aedes vexans Meigen collected at a site endemic for La Crosse (LAC) encephalitis virus. Deer were the source of 65% of Ae. triseriatus and 94% of Aedes vexans bloodmeals, respectively. Chipmunks and tree squirrels, which are considered to be the major vertebrate amplifying hosts of LAC virus, were the sources of 8% and 16%, respectively, of the bloodmeals of Ae. triseriatus, the vector of LAC virus. The relatively small proportion of vector bloodmeals taken from the amplifying hosts raises further doubts as to the significance of vertebrate amplification in perpetutation of La Crosse virus in nature, i.e. whether vertebrate amplification alone is sufficient to make up for the shortfall of virus infection that occurs during vertical transmission.

California encephalitis (CE) virus was transmitted transovarially by its natural vector, Aedes melanimon. Vertical transmission rates ranged from 13–26% in geographical populations of Ae. melanimon infected with CE virus by intrathoracic inoculation. No consistent pattern of transmission rates was detected for location or time of year mosquito collection. Vertical transmission rates ranged from 9–29% in Aedes dorsalis inoculated with CE viral strains isolated from Ae. melanimon collected in California. The month or year of viral isolation had no effect on the efficiency of vertical transmission. However, a viral strain isolated from the Owens Valley was less efficiently transmitted than strains from the Sacramento Valley, and strains from the San Joaquin Valley were intermediate in efficiency. Filial infection rates were highest in first ovarian cycle progency and declined with increasing ovarian cycles in both Ae. dorsalis and Ae. melanimon.

Ten species of mosquitoes became sensitive to CO2 following intrathoracic (i.t.) inoculation of California encephalitis (CE) virus. These included field-collected Aedes melanimon, Aedes nigromaculis and Culiseta incidens and laboratory-clonized strains of Aedes dorsalis, Aedes triseriatus, Anopheles freeborni, Culex peus, Culex pipiens pipiens, Culex pipiens quinquefasciatus and Culex tarsalis. Another California serogroup virus, Jerry Slough (=Jamestown Canyon) (JS), also induced CO2 sensitivity in nearly 100% of infected female Ae. dorsalis, Ae. melanimon and Cx. tarsalis. Sensitivity to CO2 developed in Ae. dorsalis and Cx. tarsalis within 3 days after i.t. inoculation of CE virus, remained at a high level through day 10 after inoculation and decreased gradually with time until by 30 days postinoculation nearly all mosquitoes were nonsensitive. In contrast, Ae. dorsalis infected transovarially with CE virus were not CO2 sensitive. There was homologous but no heterologous interference to the development of CO2 sensitivity when Ae. dorsalis infected transovarially with CE virus were inoculated with CE or JS viruses.

Two other bunyaviruses, Main Drain and Turlock, produced CO2 sensitivity in 3–10% and 0%, respectively, of infected Ae. dorsalis, Ae. melanimon and Cx. tarsalis. Two togaviruses, St. Louis encephalitis and western equine encephalomyelitis, did not induce CO2 sensitivity in Ae. dorsalis and Cx. tarsalis.

The strains of Rickettsia tsutsugamushi found in naturally infected, laboratory-reared Leptotrombidium (Leptotrombidium) arenicola and L. (L.) fletcheri chiggers were characterized by direct immunofluorescence (FA) and by mouse and monkey virulence tests. The strains existing in the L. (L.) arenicola chiggers consisted of different combinations of TA716, TA763, TA686, Karp, and Kato. In addition to these five strains, Gilliam was found in the L. (L.) fletcheri chiggers. Results indicate that individual chiggers can be simultaneously infected with several antigenic strains of R. tsutsugamushi. Although these antigens appear to remain stable within familial lines when several generations were viewed, the antigenic patterns observed in two succeeding generations did not always correlate. This variable expression of antigens was considered to be due to a quantitative fluctuation from one generation to the next in the strains of rickettsiae combined with a lack of sensitivity of the direct FA test in detecting small numbers of antigenically different rickettsiae. Phenotypic variation was considered to be a less probable explanation. Morbidity and mortality were minimal in ICR mice fed upon by individual chiggers of either species, but infection rates were 85–99%. Tissue suspensions prepared from mice infected by L. (L.) arenicola produced higher mortality and longer duration of illness in mice than those prepared from L. (L.) fletcheri-infected mice. Silvered leaf and cynomolgus monkeys were fed upon by the two species of chiggers or inoculated with the mouse tissue suspensions. In both cases, minimal clinical responses were observed.

The Japanese encephalitis vaccine virus (JE 2–8) and its parent virus (JE SA 14) strains were compared for their ability to infect, to replicate in, and to be transmitted by Culex tritaeniorhynchus mosquitoes. Both viruses replicated in the mosquitoes after intrathoracic infection. The JE 2–8 vaccine was transmitted to 1/36 (3%) of suckling mice bitten by intrathoracically infected mosquitoes; however, the parent JE SA 14 strain was transmitted to 46/46 (100%) of the mice bitten. In oral infection trials, only 4/36 (11%) of the Cx. tritaeniorhynchus mosquitoes ingesting the vaccine JE 2–8 strain became infected, whereas 19/19 (100%) of those ingesting the parent JE SA 14 strain became infected. The vaccine JE 2–8 strain did not revert to virulence during passage in mosquitoes.

Acute renal failure with prolonged oliguria was observed in a patient following the bite of a Russell's viper (Vipera russellii siamensis). Renal biopsy revealed interstitial nephritis in addition to tubular necrosis and mesangial proliferation usually noted. There was no deposition of immunoglobulins. The finding expands the spectrum of renal changes in snake bite.

Adult treehole mosquitoes were collected by vacuum-sweeping of vegetation in urban, suburban, and rural woodlots in northern Indiana. The sibling species Aedes triseriatus and Ae. hendersoni were identified by polyacrylamide gel electrophoresis. Blood meals were identified by the modified precipitin method. Ae. triseriatus fed predominantly on chipmunks and deer, and Ae. hendersoni fed mainly on tree squirrels and racoon. The relative rates of feeding on the major hosts were variable depending on the location of collection, and probably reflected differences in host density. No blood-feeding on humans was detected.

Precocene II is a botanically derived chemical that inhibits the production of juvenile hormone (JH) in insects. The effects of this anti-JH compound on molting and growth by Rhodnius prolixus and Triatoma dimidiata and reproduction in R. prolixus were tested and the efficacy of precocene II as a fumigant was assessed. Precocene II induced precocious metamorphosis in both species when applied by either contact exposure or fumigation, and this effect could be prevented by juvenile hormone replacement therapy. The dosage effective in inducing precocious metamorphosis in T. dimidiata was similar to the EC50 previously reported for R. prolixus. The morphology of precocious adultoid T. dimidiata of different instars was similar to Rhodnius adultoids of corresponding instars. However, T. dimidiata was more sensitive than Rhodnius to the molt-inhibiting effects of precocene II. Rhodnius nymphs were fully susceptible to the anti-JH action of precocene when exposed for 24 hours one week before feeding. Precocene II was highly toxic to adult female Rhodnius and treatment of newly emerged females prevented oogenesis.

To the Editor:

In a recent report by Rose and Hay, a case of lobomycosis was described as the first to be diagnosed in Guyana. I wish to point out, however, that an extraordinarily severe case of that disease of 56 years' duration in a lifetime resident of Guyana was described in 1976 by Jag Bhawan et al. In addition, the cases of lobomycosis that have been diagnosed by several investigators among dolphins (Tursiops truncatus) occurred in Florida waters off the Atlantic and Gulf of Mexico coasts, not in the Caribbean sea as stated by Rose and Hay.