American trypanosomiasis (Chagas' disease) in the Caribbean

This article presents a brief review of American trypanosomiasis (Chagas' disease) in the Caribbean, an area generally considered non-endemic for the infection (AU)

Educación para el control de la enfermedad de Chagas / Educational approach in the control of Chags' disease

La enfermedad de Chagas constituye un problema de salud grave y lamentable que afecta a varios millones de personas de América Latina. Dado que la infección se propaga casi exclusivamente por insectos redúvidos hematófagos que habitan en las viviendas humanas, la mejor manera de combatirlos consiste en romper este medio de cohabitación. Por consiguiente, se requieren amplios programas de educación a largo plazo para advertir a las poblaciones rurales sobre el peligro, fomentar medidas preventivas básicas y ofrecer información sobre la manera de mejorar las condiciones de la vivienda. Por el momento estos son los instrumentos disponibles más apropiados para combatir ese azote de la humanidad (AU)

A revision of trypanosoma (schizotrypanum) cruzi strains from British Honduras, and the importance of strain characteristics in experimental chemotherapy of Chagas' disease

The characteristics of 10 strains of Trypanosoma cruzi from British Honduras are reviewed and discussed. The strains were isolated from the faeces of wild-caught Triatoma dimidiata and all proved to be highly pathogenic to white mice and rats and to certain species of wild rodents. All the strains were characterized by a high cardiotropism, which did not diminish even after prolonged passage in further animals. A variable degree of neurotropism, characterized by parlysis of the limbs, produced by the strains was observed in many laboratory animal as well as in some of the experimentally infected wild rodents. Histological studies of organs from several of the paralized animals failed to provide definitive clues as to the origin of the paralysis. A wide range of dimorphism was observed in the blood-forms of T. cruzi from each of the isolated strains; this dimorphism and the mean nuclear index number changed during each passage. The morphogenisis of the parasites in tissues, in the insect vector, and in NNN culture medium, was found to include amastigote, sphaeromastigote, epimastigote and transitional trypomastigote forms, all leading to the formation of the infective trypanosome form. The importance of co-ordinated studies on the biological and physiological characteristics of T. cruzi strains from man, animal reservoirs, and triatomine insect vectors, from the regions where Chagas' disease is endemic, is emphasized as one of the fundamental requirements for the experimental chemotherapy of Chagas' disease (AU)

American trypanosomiasis in British Honduras: XI. Observation on the viability and morphology of Trypanosoma sigmodoni Culbertson 1941, in vitro

The viability and morphology of Trypanosoma sigmodoni from artificial media are described. Although the parasites in vitro transformed into amastigote, sphaeromastigote and epimastigote stages, they failed to multiply, or to complete their development to trypomastigote form. It is suggested that the forms of T. sigmodoni seen in the cultures may be morphologically similar to the stages of the parasite that may occur in the (as yet unknown) invertebrate host.(Summary)

American trypanosomiasis in British Honduras: X. Natural habitats and ecology of Triatoma dimidiata (Hemiptera, Reduviidae) in the El Cayo and Toledo Districts, and the prevalence of infection with Trypanosoma (Schizotrypanum) cruzi in the wild-caught bugs

The natural habitats and ecology of Triatoma dimidiata in the El Cayo and Toledo districts of British Honduras are described, and the results are recorded of an investigation into the prevalence of infection with Trypanosoma (Schizotrypanum) cruzi in the wild-caught bugs. In the El Cayo District 1,390 bugs were caught, of which 256 (18.41 percent) were found to be carrying a gut infection with T. cruzi. In Toledo District 402 were caught, of which 105 (26.11 percent) were found to be similarly infected. In both districts most of the insects were collected in various outdoor ecotopes. A few were caught inside houses, but their numbers were very small and their presence in human dwellings is considered to be accidental. There is at present no evidence that the bugs are domestic in British Honduras. T. dimidiata appears to be well established in at least two districts of British Honduras. The importance of the insects in the epidemiology of Chagas' disease throughout the country can only be determined by further investigations.(Summary)

American trypanosomiasis in British Honduras: IX. Development of Trypanosoma (Schizotrypanum) cruzi in Triatoma dimidiata (Hemiptera, Reduviidae), and a note on the occurrence of dividing trypomastigote forms in the gut of some of the naturally infected bugs

The life-cycle and morphogenesis of Trypanosoma (Schizotrypanum) cruzi in the insect vector Triatoma dimidiata are described. It is confirmed that the morphogenesis of British Honduras strains of T. cruzi in the insect vector proceeds on lines similar to those observed in the mammalian host and in vitro, and includes the amastigote, sphaeromastigote, epimastigote and trypomastigote stages. The presence of dividing trypomastigote forms and the unequal development of the parasites in a single daughter cell, seen in the faeces of some naturally infected Triatoma dimidiata, are also described and discussed.(Summary)

American trypanosomiasis in British Honduras: VIII. The morphogenesis of Trypanosoma (Schizotrypanum) cruzi in the tissues of animals experimentally infected with British Honduras strains of the parasite

The cycle is described of the intracellular development of British Honduras strains of Trypanosoma (Schizotrypanum) cruzi in the tissues of experimentally infected animals. From studies and observations on a considerable amount of material it is concluded that the morphogenesis of T. cruzi in tissues includes the amastigote, sphaeromastigote, epimastigote and transitional trypomastigote forms, leading to the formation of the bloodtype trypnosome. It is suggested that, in order to clarify the long-standing controversy on the morphogenesis of the parasite, more detailed studies are required on the characteristics and variations of T. cruzi strains from other geographical localities where Chagas' disease is epidemic.(Summary)

American trypanosomiasis in British Honduras. VII. A natural infection in a wild cotton rat Sigmodon hispidus (Rodentia, Cricketidae) with a trypanosome morphologically resembling Trypanosoma sigmodoni culbertson, 1941

A description is given of a natural infection in a wild cotton rat (Sigmodon hispidus) from British Honduras with a trypanosome morhologically similar to Trypanosoma sigmodoni Culbertson, 1941, isolated in Florida. Slight morphological differences between the trypanosome from British Honduras and the one described from Florida are not considered to be of importance, since it is known that variations are common in lewisi-type trypanosomes. The trypanosomes produced an infection when inoculated into another cotton rat, but they failed to infect white mice. The discovery of this species of trypanosome in British Honduras is of importance. Its presence must be taken into account in investigations of wild animals as natural reservoirs for infection with T. cruzi. (AU)

American trypanosomiasis in British Honduras. V. Development of Trypanosoma (Schizotrypanum) cruzi in animals infected with strains isolated in the El Cayo District, and the occurrence of crithidia forms in the tissues

The morphology is described of the tissue stages of Trypanosoma cruzi observed in strains isolated in British Honduras. The persistent presence of crithidia forms of the parasite in infected vertebrate tissues suggests that T. cruzi strains found in British Honduras differ from strains described from other geographical areas. It is suggested that such strains may be suitable for studies on trypanocidal drugs in vivo and for comparative studies on the morphology of reproduction in tissues. (AU)

American trypanosomiasis in British Honduras. VI. A natural infection with Trypanosoma (Schizotrypanum) cruzi in the opossum Didelphis marsupialis (Marsupialia, Didelphoidea), and experimental investigations of different wild-animal species as possible reservoirs for the parasite

The occurrence is described of a natural infection with Trypanosoma (Schizotrypanum) cruzi in the common opossum, Didelphis marsupialis, captured in El Cayo District, British Honduras. The identity of the parasite was established from histological sections if the heart muscle, which showed pseudocysts filled with leishmania forms. Seven species of wild animal were experimentally infected with T. cruzi. Rats of the species Heteromys desmarestianus, Ototylomys philotis, Tylomys nudicaudus and Oryzomys sp. were all highly susceptible to the parasite and developed a fatal illness. It ie concluded that these species are unlikely to act as natural reservoirs for T. cruzi, but that they may prove useful in further experimental studies on the parasite and for the passage of strains. A rat of the species Nyctomys sumichrasti showed a high resistance to the infection; only scanty intracellular forms of T. cruzi were found in heart-muscle smears, and chagastic pseudocysts were present in small numbers in histological sections of the heart muscle. Results similar to those obtained with the Nyctomys rat were observed in a coati (Nasua narica), which also showed a high resistance to the challenge . No intracellular forms of T. cruzi were found in the heart muscle, but they were present in small numbers in the liver and spleen; they were morphologically identical to those seen in the heart muscle smears from the Nyctomys rat. No infection developed in two young grey foxes (Urocyon cinereo-argenteus) when challenged with a highly virulent strain of T. cruzi. It is concluded that these animals are unlikely to act as natural reservoirs for the parasite in British Honduras. It is believed that, although experimental inoculation of wild animals with T. cruzi may be prejudiced by their possible previous contact with the parasite, the results may give some indication of the nature of possible reservoir-hosts. (AU)

A survey for intestinal parasites in two communities in British Honduras, Central America

A survey of intestinal parasites in two communities in British Honduras is described. Infection rates with the two species of parasitic helminths and protozoa were found to be high, and in need of further investigation. The reasons for the high parasitic infection rates are attributed to lack of hygiene, to ignorance of the dangers involved and to the absence of preventive and curative facilities.(Summary)

The incidence of intestinal parasites in two communities in British Honduras

During studies on American trypanosomiasis and Chagas' disease, a small scale survey for intestinal parasites was made in two communities in the western part of British Honduras. In one, 7.7 percent of the population were studied, and of these 70.7 percent were positive for intestinal parasites, while in the other community 20.6 percent of the population were investigated and of these 78.6 percent were infected. Multiple infections were common, but ascaris and trichiuris were the most frequent parasites. It is suggested that poor hygiene, ignorance and absence of preventive and curative facilities contribute to this high infection rate (AU)

American trypanosomiasis in British Honduras IV -Laboratory observations on Triatoma dumidiata (Hemiptera Reduviidae) and its efficiency as a vector of Chagas' disease in British Honduras

Wild-caught and laboratory-bred Triatoma dimidiata were studied in British Honduras. Newly hatched nymphs were very reluctant to feed in the laboratory, but later instars fed readily. Armadillos and rabbits were the most acceptable hosts; man was unattractive even to starved insects. Nymphs and adults of laboratory fed T.dimidiata were fed on white rats infected with Trypanosoma (Schizotrypanum) cruzi and all acquired gut infections and remained infective for life. T. dimidiata does not defaecate during or immediately after feeding, and it is suggested that infection by direct faecal contamination is most unlikely; the infective faecal material may be carried to a wound, to the conjunctiva of the eye or to the oral or nasal mucosa after the insect has been squashed on the human body.(Summary)

American trypanosomiasis in British Honduras III - Unusual morphology in a strain of trypanosoma (Schizotrypanum) cruzi from a white mouse infected with the gut contents of a wild-caught Triatoma dimidiata (Hemiptera, Reduviidae)

A strain of Trypanosoma cruzi from British Honduras is described which shows a variation in size of the kinetoplast and nucleus in two different hosts.(Summary)

American trypanosomiasis in British Honduras: I. Isolation of a strain of Trypanosoma (Schizotrypanum) cruzi from a triatomine bug, Triatoma dimidiata (Hemiptera, Reduviidae)

An infection with flagellates in the gut of a wild triatomine bug, Triatoma dimidiata, caught in Mountain Pine Ridge, Cayo District, British Honduras, is described. The flagellates on subsequent inoculation into white rats and mice produced an infection with a trypanosome identical with Trypanosoma cruzi. Tissue stages (Leishman-Donovan bodies and developing forms) were seen in the heart muscle of all the infected animals. Clean laboratory-bred nymphs of T. dimidiata were infected by feeding on the parasitized animals, and the faeces from these nymphs proved infective to white rats and mice. The experimental evidence collected during these investigations shows that the infection in the wild reduvid bug, as well as those in all the subsequently infected animals, was due to T. (Schizotrypanum) cruzi

American trypanosomiasis in British Honduras. II. The prevalence of Chagas' disease in Cayo district

An account is given of a survey for Chagas' disease which was carried out in Cayo District, British Honduras, in July and August 1966. Serological tests were carried out on 750 serum samples; 20 (2.7 percent) showed a positive reaction. Of 750 persons questioned, 131 (24.1 percent) recognised Triatoma dimidiata. Some of the persons examined clinically showed cardiac signs compatible with, but not specific for, Chagas' disease. Suggestions are made for further investigations of Chagas' disease in British Honduras.(Summary)

Trypanosoma (schizotrypanum in British Honduras)

Previously, the various trypanosome infections detected in the blood of wild-caught mammals and triatomid bugs collected in British Honduras could be referred to as Trypanosoma cruzi-like, because neither pseudocysts nor Leishman Donovan bodies were found in the organs of the infected animals. since June 1966, three strains of trypanosome have been isolated from wild-caught Triatoma dimidiata. All strains were pathogenic to white rats and mice, killing them in 21-25 days after inoculation. In all animals infected with any of these three strains of parasites, pseudocysts and leishmanoid forms were found in heart muscle and in one white rat tissue stages of T.cruzi were found in a smear of the diaphragm. All three strains have been transmitted to clean triatomine bugs, and the infections have been transmitted from the bugs to further clean laboratory animals. A trypanosome can be classified as trypanosoma (Schizotrypanum) cruzi if it fulfills four conditions: (a) the trypanosome is morphologically and biometrically identical with T.cruzi; (b) the parasites are pathogenic to healthy laboratory-bred animals; (c) pseudocysts and Leishman Donovan bodies can be detected in the tissues of the infected animals; (d) the parasites are transmissible, either by blood inoculation or through clean triatomine bugs, to healthy animals. The strains of trypanosome isolated in 1966 all fulfill these conditions and it is quite clear that strains of T.cruzi which are highly virulent to experimental animals, exist in British Honduras. It is possible that there is little man-vector contact in the country, and that human T.cruzi infections are purely accidental. Alternatively, the strains of parasite, propagated among while mammalian hosts, may not be very pathogenic to man, thus accounting for the relative absence of patients with acute symptoms of Chagas' disease (AU)