The American Journal of Tropical Medicine and Hygiene - Volume 27, Issue 1, 1978

With strict adherence to ethical guidelines, a semi-immune volunteer was exposed to homologous and heterologous blood challenges with strains of Plasmodium falciparum from Vietnam and Tanzania. On both occasions infections developed, but clinical manifestations were moderated, prepatent periods increased, and parasitemias limited. Gametocytes produced by these infections failed to infect Anopheles stephensi. Possible reasons for this are discussed.

Although partial resistance (RI) of Plasmodium falciparum to quinine is common in some areas of the world, failure to obtain an initial response (RII or RIII) is unusual. Furthermore, emergence of quinine resistance during therapy of malaria infections in humans and animals is uncommon. In the current study, exposure of the Panama II strain of P. falciparum in Aotus monkeys to subcurative quinine therapy during six serial passages over 6 months resulted in a shift in the quinine responsiveness of the strain from mild insensitivity to quinine to uniform resistance of a marked degree. Treatment with quinine for 14 days of infections in 12 monkeys with the original isolate resulted in cure in 8 monkeys and RI resistance in 4. Infections with the resistant isolate (selected under quinine pressure) were uniformly resistant to cure by 14 days of quinine; resistance to quinine was RIII in 4 of 12 monkeys and was RII in 5. These results suggest that extensive usage of quinine or related drugs (e.g., mefloquine) in the field may result in decreasing sensitivity of falciparum malaria to quinine.

An indirect immunofluorescent antibody test was used to detect antibody to Babesia microti in human sera. Nine patients from Nantucket Island, Massachusetts infected with B. microti had serum titers ≥1,024. Of 84 control sera from New York City residents, 246 sera from patients with possible exposure to ticks, and 36 sera from patients with suspected or confirmed tick bites, none was reactive at titers of 1:16 or above. The within-test reproducibility was within one fourfold dilution in 95% of trials. Test-to-test reproducibility was within one fourfold dilution in 33% of trials and within two fourfold dilutions in 100% of trials. Although cross-reactions among infected patients' sera and antigens of B. argentina, B. equi, B. bigemina, Plasmodium vivax, P. falciparum, and P. brasilianum were common, titers were highest to the homologous antigen.

Norepinephrine (NE) was assayed fluorimetrically in the hearts of rats killed at different periods after inoculation with the Y strain of Trypanosoma cruzi. The levels of cardiac NE which, as reported previously, were not measurable 18, 22, and 32 days after inoculation became detectable at day 48. At day 70 these levels were around 50% of the control values and at day 97 normal values were attained in most animals. These results strongly suggest that sympathetic nerve fibers are destroyed in the acute phase of T. cruzi infection and regenerated during the chronic phase.

Sporadic cases of visceral leishmaniasis have been reported from all parts of Iran except the deserts and very arid zones in the southeast. About 120 cases have been reported up to the present time, the majority from the mountainous areas of the southwest. Most patients (76%) have been children under 10 years of age. The probable reservoirs of infection are wild carnivores, infection of man and dog being accidental. During a survey conducted in the Caspian area and northeastern part of Iran in 1970, 20 jackals and 10 foxes were shot; examination of smears from bone marrow and spleen showed the infection in a jackal (Canis aureas) and in a fox (Vulpes vulpes). On the basis of epidemiological evidence, Phlebotomus major is the probable vector of kala-azar in Iran.

A 56-year-old alcoholic developed primary meningoencephalitis and died 3 weeks later. Autopsy revealed multiple areas of necrosis and acute and granulomatous inflammation in the brain and pancreas. Trophozoites and cysts were discovered in the brain and trophozoites alone in the pancreas. Morphologic studies revealed some parasitic features described as characteristic for Naegleria, but clinical, histological and immunohistological features favored an Acanthamoeba infection. This study calls for caution in the use of pure morphological criteria for the differential diagnosis of Naegleria and Acanthamoeba in humans. Cultural characteristics, immunohistology and serologic tests are probably more reliable for differentiating these parasites.

A case of severe Strongyloides stercoralis infection is described in a patient with renal failure due to bilateral cortical necrosis. Because thiabendazole, the drug of choice in strongyloidiasis, is primarily excreted by the kidneys, alternative therapy with mebendazole was instituted. Although the patient eventually died as a result of the renal failure, successful therapy with mebendazole was well demonstrated.

An unusual outbreak of hookworm disease occurred after a game of “kabaddi” (a local game which results in much body contact with the ground) in 27 young males from one village. It was characterized by an immediate incapacitating dermatitis, followed by severe pulmonary symptoms. Progressive weakness, abdominal pain, weight loss and anemia developed within a few months. Ancylostoma duodenale was found in all except four patients who had received antihelminthic treatment. Specific treatment for hookworm resulted in complete clinical recovery. Features of the outbreak were: 1) the hitherto unrecorded mode of infection; 2) severe dermatitis; 3) pulmonary symptoms lasting more than 3 mo; 4) abdominal symptoms suggestive of subacute obstruction starting 4–6 mo after exposure; and 5) severe disability with weight loss for a period of 1 yr until specific treatment was administered.

Three strains of Culicoides variipennis (two colonized strains designated as 000 and 036 and wild flies reared from field-collected larvae) were fed on cow blood in membrane feeders containing microfilariae of Onchocerca cervicalis ranging in concentration from 5.2 to 13.0 × 104 microfilariae per ml. Flies were maintained at different temperatures during the development of parasite larvae, and infective larvae were collected by individual dissection and by feeding infective flies on horse serum. Additionally, infective flies were fed on jirds (Meriones unguiculatus). High concentrations of microfilariae (12.0 × 104 per ml blood or greater) were required to infect a high proportion of the flies and to produce many infective larvae. In the 000 and 036 strains, 5.2% and 13.2% of the flies, respectively, developed infective larvae compared to 57.1% in wild flies when fed on identical concentrations of microfilariae (12.0 × 104 per ml blood) obtained from the same horses. However, wild flies were more reluctant to feed on the membranes. Infective larvae developed 7 days after feeding in the 000 strain of flies maintained at 80 ± 2°F and 12 days after feeding in those maintained at 71 ± 2°F. In the 036 strain, 66% of infective flies fed on jirds; 86.0% of all infective larvae were shed while biting and 62.5% of the flies lost all of their larvae. Infective flies (of all strains) fed on horse serum in the membrane feeder and transmitted infective larvae into it. The application of the O. cervicalis-C. variipennis system to human onchocerciasis is discussed.

Three species of marine fish were collected from the waters around Seribu Islands, near Jakarta, Indonesia, and examined for nematode larvae of the family Anisakidae. Larvae were found in 719 (49%) of 1,459 Rastrelliger kanagurta, 445 (50%) of 884 Decapterus russelli, and 217 (41%) of 531 Sardinella sirm. Larvae from a subsample of 150 infected fish, 44 R. kanagurta, 86 D. russelli, and 20 S. sirm, were examined microscopically and only Anisakis type I and Terranova type B larvae were found. In all three species of fish the Anisakis larvae predominated. The Anisakis larvae found in these fish are a potential source of infection for humans in Indonesia; however, human anisakiasis has not yet been reported from this country.

Schistosoma mansoni and S. haematobium infections were studied quantitatively in 400 consecutive autopsies in Cairo, Egypt. Pathological findings were correlated with the presence or absence of schistosome infection as well as with the intensity of infection. The intensity of S. haematobium infection was much greater in cases with obstructive uropathy (hydroureter or hydronephrosis) than in those without; however, infection intensity was similar in cases with mild or severe obstructive uropathy; i.e., the presence, but not the degree, of obstructive uropathy was related to infection intensity. The presence of focal lesions was more important in the pathogenesis of severe obstructive uropathy than was the concentration of eggs in the ureters or bladder. The most severe cases of schistosomal obstructive uropathy were usually caused by ureteral stenosis, ureteral stones or distortion of the ureteral orifices. Pyelonephritis was of similar frequency in cases with and without schistosomiasis. Pyelonephritis occurred most often in patients with bladder outlet obstruction or distortion of the ureteral orifices. In the absence of these lesions, hydroureter did not predispose to pyelonephritis. Glomerulonephritis was not positively associated with S. haematobium infection. S. mansoni infection caused severe schistosomal colonic polyposis in three heavily infected individuals. Both S. mansoni and S. haematobium also caused less marked polyposis. Salmonella infections were infrequent and not significantly associated with schistosomiasis. In this series, schistosomiasis was rare in patients 9 yr or less of age. Among cases over 9 yr of age, schistosomiasis was considered the cause of death in 9.2% of infected cases (6.2% of all cases). Among infected cases, 2.5% of deaths were ascribed to schistosomal obstructive uropathy, 2.4% to bladder cancer associated with schistosomiasis, 3.1% to Symmers' fibrosis of the liver, 0.8% to schistosomal colonic polyposis and 0.4% to salmonellosis associated with schistosomiasis. Although we made no deliberate selection of cases for study, any hospital-based series gathers a highly selected group of patients. Our results should be applied to other infected populations with great caution. In addition, pathologic studies concentrate on serious anatomic lesions and cannot accurately evaluate the effects of other important lesions, such as schistosomal cystitis, which produce considerable morbidity.

Parameters of immunization of mice with 60Cobalt-irradiated Schistosoma mansoni cercariae are described and related to protection against subsequent challenge infection. Such immunization was found to be dependent on dose of irradiation, number of immunizing cercariae, and number and time course of infections. Low levels of resistance were obtained with low irradiation doses, in contrast to previous studies in mice. In general, resistance increased with increasing irradiation doses, up to approximately 48–56 Kr. Maximal resistance (70–80%) was induced by a single exposure to 250–500 cercariae, irradiated at a dose rate of 2 Kr/minute to a total dose of 56 Kr, administered percutaneously 4–6 wk prior to challenge. Challenge could be delayed for at least 15 wk after immunization without a decrease in resistance. The resistance obtained was not attributable to a delayed migration of challenge worms.

Schistosoma mansoni schistosomula migrate through the lungs of infected mice; peak recovery occurs 6 days following infection. When cercariae were irradiated at 60Cobalt doses of 24 to 64 Kr, the number of schistosomula recovered from lungs 6 days after infection decreased in a dose-dependent fashion. The pattern of lung migration of schistosomes irradiated at 56 Kr prior to infection was similar to that of nonirradiated schistosomes, but greatly reduced numbers were recovered. When mice were immunized by a single infection with 56 Kr attenuated cercariae 6 wk prior to challenge, the pattern of challenge migration through the lungs was altered. The number of schistosomes recovered increased rapidly between 2 and 6 days post-infection, and showed a plateau between 8 and 10 days with peak recovery occurring 10 days post-infection. This peak recovery was reduced in comparison to that of nonimmunized mice, but did not account for all of the reduction observed at the adult worm stage.

Between 1971 and 1976 approximately 20% (2,265) of the population of Sanpete County, Utah, was screened for hydatid disease (Echinococcus granulosus) by intradermal, indirect hemagglutination, and bentonite flocculation tests. Of 34 persons who had follow-up chest radiographs and radioisotope liver scans, 6 were found to have asymptomatic hepatic cysts. If a participant who had pulmonary cysts and negative screening tests were included, the prevalence of asymptomatic hydatid disease would be 3 per 1,000. During the same period, 82 (148 per 1,000) of 553 dogs successfully purged and examined had E. granulosus infections. Human cyst carriage was associated with dog ownership, particularly of infected dogs or in conjunction with sheep raising as the main livelihood. Combinations of immunodiagnostic tests were more efficacious in identifying cyst carriers than the tests used singly. Limitation of screening to high risk groups (e.g., sheep raisers with dogs) can reduce costs without reducing yield. Optimum management of the cyst carrier awaits further information on the natural history of asymptomatic hydatid disease.

Approximately 4.75% of the animals sent to slaughter from a southern California feedlot during a 9-mo period were found to be infected with the cysticercus of Taenia saginata. An investigation of possible transmission sources revealed that the feedlot was the most likely site of infection. One feedlot worker was found to be infected with T. saginata, and the pen infection patterns and other physical relationships indicated that he was the source of infection. The following recommendations were made: 1) treatment of the infected worker; 2) education of employees as to the mode of transmission and personal hygienic practices; 3) addition of sanitary facilities; 4) maintenance of animal source and destination records; 5) inauguration of a surveillance program to include parasitologic examination of employees prior to employment and periodically thereafter; and 6) restriction of unauthorized personnel from critical areas.

In March 1974 eight men in Chandpur, Bangladesh, experienced an illness characterized by severe abdominal cramps, nausea, vomiting and bloody diarrhea with onset 20 min to 9 h (median 2.5 h) after eating one of two fish dishes at a restaurant. Rectal cultures from all eight grew Kanagawa-positive strains of Vibrio parahaemolyticus (serotype O3K5) that were negative in the Sereny test for invasiveness and the Y-1 adrenal cell and infant mouse assays for enterotoxin production. The short incubation, severity of abdominal cramps and grossly bloody stools distinguish this illness from that usually associated with V. parahaemolyticus infection in the United States.

The prevalence of trachoma was studied in a representative sample of family units from a rural community. Evidence of current or previous infection was found in 82% of the total population, but there was a relatively low prevalence of intense upper tarsal disease. Most children acquire the disease within the first 3 yr of life, these primary infections having a tendency towards spontaneous cure without complications. The prevalence of active disease and potentially blinding sequelae is higher in elderly females than in males of the same age. Clinical and microbiological evidence suggests that trachoma is transmitted primarily within households in this community, the main source of infection appearing to be children of pre-school age. Chlamydiae were isolated from the eyes of children with intense upper tarsal disease, but not from elderly persons with similar clinical signs.

Two communities of Orang Asli (aborigines) in Peninsular Malaysia were observed for evidence of Rickettsia tsutsugamushi infection over periods of 1–8 mo. Sequential sera were examined for antibody by the indirect immunofluorescence test. The incidence of infection in the two self-selected populations in the two communities was calculated to be 3.9% per month and 3.2% per month.

An epidemic of jungle yellow fever occurred in Goiás State, Brazil, between December 1972 and March 1973. Laboratory confirmed cases were observed in 36 counties located in the central and southern parts of the State. Seventy-one cases were proved, of which 44 were fatal. The diagnosis was made on the basis of pathology, serology, and virus isolation. Besides yellow fever, malaria and viral hepatitis were present, and in two fatal cases there was malarial pigment in the liver in addition to the specific lesions associated with yellow fever virus infection. The fact that male patients strikingly outnumbered females (9:1) and that young adults were predominantly affected indicates that transmission occurred mainly inside or adjacent to the forests. The lack of cases in urban areas can be attributed to the absence of Aedes aegypti in these areas. Yellow fever complement-fixing antibody in high titers was found in 18 of 1,201 (1.4%) persons living in eight counties of the affected area. This finding suggests that at least 21,000 persons out of the 1.5 million rural inhabitants of the three districts where the epidemic occurred had been infected by the virus. The epidemic subsided following an intensive vaccination campaign, and the last four cases were observed in March 1973.

Sera from 12 different species of Hawaiian mammals and birds as well as from humans were examined by plaque reduction neutralization test for antibodies against encephalomyocarditis virus (EMC). The highest prevalence of antibodies was found among rats (Rattus sp.), mongooses, pigs, and cows. Lower rates were observed among humans, cats, and wild birds. The prevalence of EMC antibodies among R. rattus on four Hawaiian islands ranged from 8–86%, indicating considerable geographic variation in virus activity. Sera from selected rodent populations in Colorado, the Caroline and Philippine islands, Panama, and Iran were also tested and the results confirmed the association of EMC with members of the genus Rattus. Laboratory-reared R. rattus, R. norvegicus, and Mus musculus were fed three low-passage EMC virus strains. The frequency of infection among the exposed animals varied with rodent species and with each virus strain, suggesting differences in species susceptibility as well as in strain infectivity. Blood, urine, and stool specimens were collected from the animals for virus isolation at regular intervals after virus administration. With the exception of single blood and fecal samples collected 24 h post-feeding, no virus was recovered from any of the specimens from experimentally infected rodents. Attempts to demonstrate contact transmission among EMC-infected and control mice caged together were also negative. Infection of birds (pigeons and chickens) with EMC following parenteral inoculation was demonstrated. EMC virus did not survive in mosquitoes after intrathoracic injection.