The American Journal of Tropical Medicine and Hygiene - Volume 26, Issue 4, July 1977

This study was designed to investigate the use of primaquine in malaria control in the Khmer Republic (Cambodia). Blood was drawn from 106 male Khmer Air Force troops for analysis of hemoglobin E and glucose-6-phosphate (G-6-PD) deficiency. A test group of 15 men with G-6-PD deficiency and a group of 31 normal controls were given 15 mg of primaquine each morning for 14 days. The patients were followed for hemoglobinuria and changes in hematocrit. Primaquine induced a significant, but not a dangerous, hemolysis in G-6-PD-deficient Khmer troops. The G-6-PD deficiency seen in Khmer Air Force subjects was G-6-PD Mahidol. Statistically, G-6-PD Mahidol was linked to hemoglobin E.

Fluorescent antibodies were detected in 89% of 288 Orang Asli (Malaysian aborigines) with Plasmodium falciparum antigen and in 62% with P. brasilianum (for P. malariae) antigen. Blood films from 18 donors were positive for P. falciparum; 2 of them had mixed infection with P. vivax. Seven of the P. falciparum-positive blood films were from children in the 2- to 9-year age group. Of 17 sera from cord blood, 16 had significant levels of P. falciparum antibody and 14 of P. malariae antibody, the levels being the same as those of the mothers. None of these babies had congenital malaria. A higher percentage of male donors reacted to both antigens. There was an age dependent increase in the number positive and the maximum titers.

Three morphologically different, true-breeding phenotypes have been isolated from a strain of Anopheles albimanus from Lake Apastepeque, El Salvador. Studies with coindigenous strains of Plasmodium vivax and P. falciparum show that these phenotypes differ significantly in their susceptibility to malaria parasites. This difference is apparent both in the number of mosquitoes that become infected and the level of infection obtained. Variations in malaria susceptibility are markedly greater with P. vivax than with P. falciparum. The significance of genetic variants within a local vector population with respect to the epidemiology of malaria is discussed.

This report summarizes the results of a comparative study of the virulence of the “S-M,” H, and C strains of P. knowlesi for Indian rhesus monkeys (Macaca mulatta) and cynomolgus monkeys [M. irus (fascicularis)] of Malayan (West Malaysia) and Philippine origins. Each of the above strains produced fulminating, uniformly fatal infections in the rhesus monkey and mild, chronic infections, characterized by relatively low level parasitemias in cynomolgus monkeys of Philippine origin. In striking contrast, the H and C strains produced infections in cynomolgus monkeys of Malayan origin which were indistinguishable in severity from infections produced in M. mulatta. The circumstances of the study precluded evaluation of the virulence of the “S-M” strain for M. irus of Malayan origin. Even so, the available data make it necessary to qualify the long-held belief that infections with P. knowlesi in M. irus invariably follow a benign course.

Because the presence of Trypanosoma rangeli in Argentina and Brazil has not been confirmed, a search was carried out in man and triatomine insects. Fifty-nine of 207 persons (28.5%) were infected when studied with one or more xenodiagnosis (40 Triatoma infestans/xenodiagnosis); 0.1% to 13% of 7,821 bugs' feces and 4% of 875 dissected midguts showed T. cruzi in Giemsa stained smears. One of 6,980 hemolymph samples and 1/875 salivary glands showed few flagellates which may have originated in the gut. They were not found in stained smears. Thirteen percent of 188 wild-caught domiciliary T. infestans showed only T. cruzi in the gut and feces. Although the presence of T. rangeli could not be demonstrated, the study indicates that examination of pooled hemolymph and random samples of salivary glands and midguts can be carried out together with the usual examination of extracted feces in any species of triatomine, including those with salivary glands lacking the pink color present in the genus Rhodnius. Unless this procedure is widely used it will not be possible to differentiate T. rangeli and other possible trypanosome infections from those of T. cruzi nor to determine, therefore, the true prevalence of Chagas' disease in a given human population.

Two cousins from a large Spanish-American family were simultaneously diagnosed as having amebic liver abscesses. Survey of 183 extended-family members revealed that 45.7% of 162 had a positive amebiasis indirect hemagglutination test and 12.6% of 111 had cysts or trophozoites of Entamoeba histolytica demonstrated in a single stool examination. A total of five family members had had liver abscesses; two deaths had occurred. In a random sample survey of the remainder of the community, only one person (0.3%) had a positive serologic test. Within the extended family, person-to-person appeared to be the predominant mode of transmission. Water supplies were not contaminated. Both community and extended family homes had the same source of water. Type and source of food supply were not correlated with infection and there was no evidence to implicate an infected food handler. Clustering of seropositivity occurred in homes without indoor toilets. Homes of the extended family were more crowded and significantly fewer of them had indoor toilets. Endemic foci of amebiasis continue to exist in the United States. Follow-up of family and other close contacts of persons with amebiasis will frequently identify other cases.

A new compound, 4-isothiocyanato-4′-nitrodiphenylamine (C.9333-Go/CGP 4540), was tried in 39 hospitalized patients with hookworm infection, using several treatment schedules. At effective dose schedules (125 mg × 3 given 4-hourly; 250 mg × 3, 8-hourly; 1,000 mg × 3, 12-hourly), the egg reduction was 96% to 100%; the zero egg-counts were confirmed by coproculture for larvae. The compound was very well tolerated. Transient and mild side effects—giddiness, diarrhea and sweating—were observed in only three patients. No toxic effects were seen as judged by serial organ function tests, except a transient and mild asymptomatic elevation of transminases in one patient.

Rhabditiform larvae, and in two cases eggs, of Strongyloides spp. identified in the stools of Zambian patients were cultured to the free-living adult stage. Free-living adults of S. fülleborni, a parasite common in primates in Africa and Asia, were present in cultures from 13 (9.9%) of 131 cases of stronglyoidiasis. In three of these cases, both S. fülleborni and S. stercoralis free-living adults were found.

We document six cases in which tissues were invaded by Enterobius vermicularis. These cases illustrate several mechanisms whereby the worms form granulomata in ectopic sites. In three cases, the worms passed through pre-existing breaches in the intestinal mucosa. In one case, a gravid worm migrated via the female genital tract to the peritoneal cavity. In two other cases, male worms were found on the outer surface of the intestine, suggesting active penetration of the intestinal wall.

Autopsies of two patients with onchocerciasis in the Republic of Zaïre are reported. In one patient with elephantiasis who died following diethylcarbamazine therapy there were large numbers of microfilariae of Onchocerca volvulus in the kidney, liver, pancreas, and lung. In the second patient, who also had leprosy and hyperinfection strongyloidiasis, we found an encapsulated adult O. volvulus in the wall of the thoracic aorta.

Recent investigations of infections with Onchocerca volvulus in Guatemala presented the opportunity to study some aspects of complement fixation (CF) antibody titers. An extract of adult O. volvulus obtained from nodules excised from patients was used as antigen. Serum was procured from individuals whose intensity of infection was determined by skin snip counts of microfilariae. In general there was an inverse relationship between intensity of infection and CF titers. This correlation was significant in men 40 years and older. The CF titer of women was greater than that of men with the same intensity of infection.

Ultrastructural studies on Onchocerca volvulus disclosed intracellular organisms within the lateral chords of adult worms and of the larval stages. In the females the organisms were also present in the oogonia, oocytes, developing eggs and microfilariae. The organisms, found within vesicles of host (filarid) membrane and limited to the cytoplasm of infected cells, appeared to have a developmental cycle consisting of three morphologically distinct forms: a small spheroidal form up of 0.3 µm in size, a bacillary form up to 1.5 µm in length and 0.7 µm in diameter, and a third form, intermediate in size between the former and the latter, characterized by a dense inclusion. The intravesicular location and the developmental cycle consisting of three distinct forms are the two characteristics which suggest that these organisms are more similar to the chlamydiae than to the rickettsiae, in spite of their being transovarially transmitted. The significance of these findings with respect to the host-parasite relationship and pathogenesis of onchocerciasis is presently unknown and will require further study.

Loa loa, also known as the African eye worm, is a common parasite in the central part of West Africa. As Chrysops silacea and C. dimidiata, the only important vectors of loaiasis, are found exclusively in the tropical rain forests of West Africa, the parasite's transmission is confined to this region. References by early writers to the extraction of Loa loa from the eye of a man on the Island of Ormus (today known as Hormuz or Hormus) in the Persian Gulf apparently were based on a misinterpretation of an illustration by de Bry (1598) of the blinding of a royal relative.

Surgical repair of an inguinal hernia in a 19-year-old man in Honduras revealed massive numbers of small granulomata containing trematode eggs on the omentum and other peritoneal surfaces. The eggs resembled those of Achillurbainia recondita Travassos, 1942, a species found in the maxillary sinuses of the opossum, Didelphis marsupialis. Species of Achillurbainia (syn. Poikilorchis Fain and Vandepitte, 1957) have been reported in retroauricular cysts or abscesses in residents of West Africa and Southeast Asia.

Menichlopholan, a biphenyl compound, in a single dose of 2 mg/kg body weight, gave a 73%–90% cure rate in the treatment of pulmonary infections due to Paragonimus uterobilateralis at two centers in Nigeria. Ninety-five patients were followed up for 4 months, and 58 for 1 year. Side effects of the drug included sweating and body pains, but there was no significant biochemical or hematological evidence of damage to the internal organs. The advantages of single dose therapy are likely to make menichlopholan the treatment of choice for paragonimiasis in Africa, and probably elsewhere.

Thirty consecutive patients who were treated for Schistosoma mansoni infection with antimony sodium dimercaptosuccinate (Astiban) during the 1960s, and who had not visited an endemic area since the treatment, were reexamined 11 to 17 (average 13) years after the last presumed exposure. Seven of them (23%) still had active infections, six being chronic infections of which only one had been treated in an acute stage. None of the patients with chronic S. mansoni infection had signs of changes in liver, gut, or other organs, and all were able to work at full capacity. Living eggs were found in rectal biopsy specimens from all cases, but in only two cases in stool specimens. Serological reactions were positive in three cases and also in two of the egg-negative cases. Skin tests gave immediate positive reactions in 6 of 7 egg-positive and in 11 of 23 egg-negative patients.

Four hundred consecutive autopsy cases were examined in Cairo, Egypt. Sixty percent of cases had Schistosoma haematobium eggs in the tissues and 25% also were infected with S. mansoni. Only a quarter of S. haematobium infections were active, while nearly two-thirds of S. mansoni cases remained active. Adult S. haematobium and S. mansoni were effectively recovered from the mesenteric circulation by a combination of perfusion and dissection. Quantitative recovery from the genitourinary system was reasonably complete, although small numbers of worms were missed in the dissection of these organs.

Adult Schistosoma haematobium and S. mansoni were recovered at autopsy. The number of eggs of both species present in the tissues and passed in the excreta was related to the number of female worms (worm pairs) recovered. Only 26% of S. haematobium infections were active at the time of necropsy. Forty-seven percent of S. haematobium females were in the mesenteric circulation and 52% were in genitourinary organs. S. haematobium worm pairs were sedentary, laying eggs in single sites for prolonged periods. In addition, the worm pairs seemed to be clustered in active genitourinary lesions. S. haematobium eggs calcified and accumulated in the tissues, and a geometric mean of 600,000 eggs per worm pair was found. Large numbers of eggs remained in inactive cases. There was a significant increase in eggs per female worm in older persons. The relative contribution of egg accumulation (increasing the numerator) and worm death (decreasing the denominator) to this phenomenon are not known. In contrast, S. mansoni eggs were not retained in the tissues to the degree exhibited by S. haematobium. There was an apparent equilibrium between egg deposition and egg excretion or destruction. A geometric mean of 15,900 eggs per worm pair was present, and did not change with age. The total number of eggs per female worm and the relative proportion of eggs in the lungs, liver, and intestines were similar to those seen in Brazilian cases of S. mansoni infection. The number of eggs per female worm found in the feces was lower than that noted in Brazil. S. haematobium infections were much heavier in cases also infected with S. mansoni than in those with pure S. haematobium infection. No pure S. mansoni infections were seen. S. mansoni infection appeared unaffected by S. haematobium infection, except for calcification and accumulation of S. mansoni eggs in the genitourinary system.

Elution of complexed immunoglobulins was carried out on renal tissue obtained at autopsy from schistosomiasis mansoni and control cases. Substantial amounts of IgG were found in acid eluates of 2 of 5 schistosomiasis cases and 2 of 3 controls. The IgG from schistosomiasis cases produced specific indirect immunofluorescence reactions in gut and tegument of sections of adult Schistosoma mansoni; no reactivity was present against egg granulomas, cercariae, or mouse liver tissue. Control case eluates produced no fluorescence with S. mansoni antigens.

Plasma samples obtained from patients with well defined Schistosoma mansoni infections, or control subjects, were passively transferred to CF1 mice. Three, 12, or 24 hours after passive transfer, the recipient and control mice were challenged with either 200 or 600 live cercariae, and the adult worm burdens or schistosomula lung recoveries, respectively, were determined 7 weeks or 6 days after challenge. None of the human plasmas afforded the recipient mice protection against the development of schistosomes. Worm and larval yields were equivalent in all cases, even though many of the patient plasmas were shown, as assessed by an in vitro eosinophil-dependent cytotoxic antibody assay, to contain high levels of antischistosomular antibody.