The American Journal of Tropical Medicine and Hygiene - Volume 16, Issue 6, November 1967

Studies to assess the potential causal prophylactic value of chlorguanide, pyrimethamine, and primaquine against a strain of chloroquine-resistant P. falciparum, the Thailand (JHK) strain, indicated that daily administration of chlorguanide, weekly administration of pyrimethamine, or weekly administration of primaquine may prove far from uniformly effective.

A case of low-grade Plasmodium vivax parasitemia and severe anemia associated with the serologic stigmata of autoimmune disease, a positive Coombs test, positive serologic test for syphilis, positive rheumatoid factor, and slight elevation of the serum gamma globulin fraction is described. Coombs-positive hemolysis has not been previously reported in untreated malaria. The possible significance of the Coombs test and the mechanism of anemia in malaria are discussed.

Furamide® T/c, a combination of diloxanide furoate, tetracycline hydrochloride, and chloroquine phosphate, was tested under conditions of poor sanitation in 50 patients with intestinal protozoal infections. There was a follow-up period of 90 days after termination of therapy.

The combination was active against eight species of intestinal ameba and flagellate, clearing the stools, in most cases, within 48 hours of cessation of treatment, of both cysts and trophozoites.

Long-term investigations of this combination are warranted.

In rhesus monkeys and in a human volunteer typical cercarial dermatitis was observed, which subsided by the end of 1 week after exposure to the cercariae of Heterobilharzia americana.

H. americana evidently did not produce a patent infection in these primates; no eggs were passed in the stools of a rhesus monkey kept for observation over 5 months after exposure to the cercariae or in the stools of the human volunteer. Young schistosomules were recovered from the liver of a rhesus monkey at necropsy 21 days after exposure to the cercariae, whereas preadults were still alive in monkeys at necropsy 45 days after the onset of the infection.

In the liver there was a slight to moderate portal-tract and interlobular-space infiltration, and there were necrotic lesions with early fibroepithelial pseudotubercle organization. Inflammatory infiltration was also observed in the lung.

In these monkeys the infection was accompanied by a moderate eosinophilia, starting about the 4th day after exposure to the cercariae, and continuing for several weeks, after which the eosinophil count returned to about normal.

Detectable levels of antibodies were demonstrated in the sera of these monkeys at the end of the 1st week after exposure and lasted until 94 days, when the experiment was terminated.

A total of 3,836 tropicorbid snails, Biomphalaria obstructa, from 13 localities in Louisiana collected between 1959 and 1966 proved to be nonsusceptible to infection with a Puerto Rican, a Brazilian (Minas Gerais), and a St. Lucian strain of Schistosoma mansoni. Among these were snails collected from the same locality where susceptible snails had been found in earlier studies in 1945 through 1953. It is possible that the snails found at present in these lakes have been recently introduced from a nearby drainage system (Mississippi River) and that the susceptible snails may still exist in other parts of the same drainage system (Amite River), but none has yet been found.

With a method by which the penetration of cercariae of Schistosoma mansoni can be quantitated separately from their subsequent development into worms, a comparative study was performed in the hamster, mouse, guinea pig, rabbit, and rat. Cercarial penetration was almost identical in the five species of rodent. Four weeks after exposure, in relation to the number of cercariae that penetrated, the maturation of the worms was 50% in the hamsters, between 36 and 39% in the mice, guinea pigs, and rabbits, and 26% in the rats. The infection remained constant in the hamsters and mice for at least 16 weeks, but diminished gradually in the rabbits and guinea pigs. The rats rapidly eliminated the schistosomes.

Ninety-two cases of larval anisakiasis in the gastrointestinal tract of Japanese people, usually with a clinical diagnosis of gastric tumor or acute condition of the abdomen, were studied clinicopathologically, including 19 cases encountered by the authors. Two of these cases are presented, in one of which an intact Anisakis-like larva was found in an eosinophilic phlegmon of the intestine after surgical excision because of abdominal symptoms. On the basis of morphologic comparison with Anisakis larvae collected from mackerel, the worm from the lesion was identified as an Anisakis-like larva. In Japanese people, the infection probably is acquired by eating raw marine fish and squid.

The hypothesis that the mean length of the precipitates produced in the circumoval precipitin reaction (COP) depends on the mean amount of antiegg antibody present in the serum of animals or man infected with the parasite S. mansoni was tested during the course of infection, and of treatment and treatment-withdrawal, in experimental schistosomiasis. Results indicate that measurement of the mean length of the circumoval precipitates may be useful in the evaluation of drugs against infection with S. mansoni.

In this review, the phenomenon of delayed hypersensitivity is characterized briefly, and, based on recent reports, its apparent demonstration in immunity to Trichinella spiralis, Trichostrongylus colubriformis, Ancylostoma caninum, Fasciola hepatica, and Hymenolepis nana is presented. The prominent role of this phenomenon in the mechanism of immunity to adult T. spiralis is explained, and then consideration is given separately to each of the other parasites to offer by speculation an explanation for the reported results.

In this study, over one-half of the specimens of stool submitted by South Vietnamese labor applicants were positive for intestinal nematodes. Nearly all positive specimens contained eggs of either Ascaris lumbricoides or hookworm. The comparatively low prevalence of Trichuris may be due to the relatively low numbers and resistance of its eggs or to the little moisture in the soil during part of the study. Multiple infections with nematodes were not rare. It is suggested that a significant portion of the adult South Vietnamese population harbors, in a relatively asymptomatic manner, enteric nematodes in a balanced hostparasite relation.

In vitro adsorption of globulins onto the cuticle of a nematode was originally reported by Soulsby, who demonstrated this with larvae of Ascaris suum incubated in antisera from animals infected with this parasite. Coombs et al. also demonstrated that globulin adsorbed onto the cuticle of the free-living nematode Turbatrix aceti after exposure to normal human and rabbit sera. In both studies, this was demonstrated with an indicator system of human erythrocytes of Group O sensitized to human gamma globulin, then exposed to antihuman gamma globulin prepared in rabbits. The agglutinated erythrocytes adhered to the cuticle of the worm. These investigators suggested that the globulin responsible for the reaction is possibly antibody in nature.

The red-cell-adhesion reaction observed by Soulsby and Coombs was observed in the present study when larvae and adults of Trichinella spiralis were incubated in rabbit antisera and tested by the same indicator system.

Live adults and larvae were obtained from rats according to methods described elsewhere.

Histoplasmin skin tests were done on 1,021 persons in eight communities in western Colombia; reactor rates varied from 0 to 74%. Reported cases of histoplasmosis and other studies of histoplasmin sensitivity in Colombia are reviewed, and these suggest that the disease is endemic in the Pacific coastal plain, the Cauca and Magdalena valleys, and the eastern lowlands. The areas of high prevalence are characterized by altitudes below 5,000 feet, constant warm to hot temperatures, moderate to very heavy rainfall, and tropical or subtropical forest vegetation. It is suggested that low annual rainfall in the north coast and continual cool temperatures at altitudes above 6,000 feet are unfavorable for the growth of H. capsulatum and thus explain the low prevalence of histoplasmin sensitivity in these areas.

Infection of young Montana livestock—a donkey, two goats, and two calves—with Rickettsia prowazekii is reported. The maximum rise in antibody titer occurred between the 20th and 30th days. Despite use of the epidemic agent to infect our animals, complement-fixation tests on their serum did not adequately differentiate the two forms of typhus, though toxin neutralization did specifically identify the epidemic form. The donkey showed the highest and most persistent serologic conversion. Both types of antibody were still present in this animal after 452 days, but had disappeared by 124 days in the goats and calves. Overt signs of disease were practically absent, and rickettsemia was not demonstrated by periodic transfer of blood to guinea pigs.

Forty young men were inoculated with live, attenuated VEE virus vaccine, and as evidenced by a significant increase in hemagglutination-inhibiting antibody titers, all were infected. However, viremia was demonstrated in only 13. The level of viremia was low, varied with time, and occurred between 60 hours and 12 days after vaccination. All subjects were evaluated closely from clinical, laboratory, virologic, and serologic standpoints. Some degree of reaction was seen in 37.5% of these persons, 10% of them having a 3+ reaction, of a possible 4+. Viremia was demonstrated in 32.5%. Transient electrocardiographic abnormalities were noted in 47.5%, and 40% had transient leukopenia. Eight men followed with daily electroencephalographic tracings demonstrated no significant change subsequent to vaccination. There was no consistent positive or negative correlation between any of these responses or combination of responses.

During the course of a study designed to evaluate the clinical syndrome produced in man by immunization with the attenuated strain of Venezuelan equine encephalomyelitis virus, the opportunity was taken to study, in a prospective manner, whole-blood amino acids and the applicability of fluorescent-antibody techniques to the diagnosis of infection following immunization with live, viral vaccine.

Twenty healthy men were immunized at 0800 hours on day 0 by subcutaneous injection; another 20, at 2000 hours. The quantity of virus utilized for immunization in both groups was 5,000 guinea-pig intraperitoneal immunizing doses50 of live, attenuated VEE virus vaccine. Whole-blood amino acids and fluorescent-antibody studies were performed upon specimens obtained at 0800 and 2000 hours daily.

A significant serologic response verifying infection was demonstrated in each vaccinated man. The number immunized at 0800 hours who became ill was not statistically different from those immunized at 2000 hours. Likewise, no statistical difference was noted in the duration or severity of illness between the two groups. The normal amino-acid diurnal periodicity was changed after immunization in every man regardless of time of inoculation. This disturbed rhythm was noted on days 1 through 4 in the group inoculated at 0800 hours and on days 2 through 8 in the group immunized at 2000 hours. In addition, significant increases in proline and glutamic acid and decreases in glutamine were noted in samples obtained from men immunized at 2000 hours.

The presence of fluorescing particles in white blood cells was demonstrated in 85% of those vaccinated. The presence of these particles reached a peak in specimens obtained on day 2 after immunization in the group inoculated at 0800 hours and on day 6 in the group immunized at 2000 hours.

The more pronounced changes manifested by the group immunized at 2000 hours suggest that the greater or lesser effect of an infectious micro-organism upon the human host may be dependent to some degree upon the time of exposure.

The significance of these findings in relation to the pathogenesis of this viral disease is discussed.

Guaroa virus was isolated on six occasions from Anopheles (Kerteszia) neivai collected in the area of the Raposo River in the Pacific lowlands of Colombia, twice from mosquitoes collected in 1962 and four times from mosquitoes taken in 1964. The virus was not detected in A. neivai taken in 1963 and 1965. A. neivai was the only mosquito from which Guaroa virus was isolated although many thousands of mosquitoes of other species, collected at the same times and in the same localities, were processed for virus.

The rhesus monkey is susceptible to experimental infection with chikungunya and Mayaro viruses as evidenced by a febrile reaction and high levels of circulating virus. These animals appeared refractory to infection with O'nyong-nyong virus. Infection with either Chikungunya or Mayaro virus protects these animals against infection with the heterologous virus. These results clearly show that the Asian rhesus monkey is a suitable laboratory animal for the serologic and immunologic study of selected group A arboviruses.

The comparative immunogenicities of experimental formalin-inactivated chikungunya (CHIK) vaccines prepared in chick-embryo (CE), suckling-mouse-brain (SMB), and green-monkey kidney-cell (GMKC) tissue culture with the CHIK 168 virus have been described. Tests of protection in mice revealed that CE vaccine was markedly inferior to either SMB or GMKC vaccine. Both SMB and GMKC vaccine were highly effective in protecting mice against an intracerebral challenge. However, the potentially encephalitogenic properties of SMB vaccines seriously limit their use in practice, so further evaluation of this vaccine was not now pursued. Results of plaque-inhibition tests revealed that GMKC vaccine elicited significant levels of serum-neutralization (N) antibody in mice to heterologous African E-103, Asian BAH-306, and Indian C-266 strains as well as the homologous 168 strain of CHIK virus. To correlate these findings with actual protection a vaccine trial was performed in rhesus monkeys, with these strains of the CHIK virus in the challenge procedure. After three doses of GMKC vaccine, high levels of N antibody developed in monkeys, and in most instances, CF and HI antibody were present in low titers to the challenge viruses. The immunogenic potency of GMKC vaccine was clearly defined by the complete absence of viremia in the vaccinated monkeys and no appreciable stimulation of N, complement-fixation, or hemagglutination-inhibition antibody subsequent to challenge. In contrast, the control monkeys, with one exception, had viremia, and responded with high levels of N, CF, and HI antibody after challenge.

A semisynthetic medium that promotes growth of Biomphalaria glabrata under axenic conditions is described. This medium, when enriched with vitamin E, promotes reproduction of the mollusk. The snail was reared over three consecutive generations under germ-free conditions. The sterilization temperature of the medium is critical: when sterilized at higher temperatures than 110°C, the medium does not promote growth.

Diapause and estivation were studied in an albino strain of Biomphalaria glabrata. A group of small lamellate B. glabrata showed a persistent tendency, for an average duration of 29 days, to climb out of the water. These snails subsequently produced 36% lamellate offspring, 64% of which showed a spontaneous tendency to climb out of the water. Results suggested that genetic factors influenced the morphologic and physiologic changes that adapted some small B. glabrata for diapause and prolonged estivation.

Lamellate snails survived 10 months out of water, and immature Schistosoma mansoni survived in snails 7 months out of water. S. mansoni larvae remained dormant in snails during estivation. In snails remaining in water after exposures to both S. mansoni and Angiostrongylus cantonensis, both infections developed. A. cantonensis developed to third-stage larvae in estivating snails.

Estivation provides B. glabrata a survival mechanism against both drought and chemical molluscicides.