The development of an enzyme-linked immunosorbent assay for Trypanosoma vivax and its use in a seroepidemiological survey of the Eastern Caribbean Basin

An enzyme-linked immunosorbent assay (ELISA) for IgG antibodies against a South American (New World) strain of Trypanosoma vivax was developed and used for mass screening of cattle from 20 islands in the Eastern Caribbean Basin. The sensitivity and specificity of antigens prepared from a bovine-derived field strain and a nurine-adapted laboratory strain of T. vivax, both of New World origin, were compared using an indirect fluorescent antibody (IFA) test, and an antigen prepared from murine-adapted strain was subsequently used to develop an ELISA test. The results of the ELISA test were then compared with the results of a concurrently run IFA test. There was no cross-reactivity with either test using serum from a Trypanosoma theileri-infected cow. Both tests were weakly cross-reactive with sera from a T. brucei-infected steer, and the IFA test was moderately cross-reactive with several serum samples from a T. evansi-infected steer. For bovine sera collected from herds on islands in the Eastern Caribbean region, only five of 640 tested positive with the ELISA test. Thirty five of 653 sera tested were positive by IFA although the fluorscence elicited was weak as compared to that elicited by sera from known infected animals. Sera collected from 27 cattle in a region known to be free of T. vivax (OH, U.S.A) were negative with the ELISA test, whereas seven of 30 sera from a herd in French Guiana known to be infected with T. vivax were positive. None of 45 caprine and 60 ovine sera collected from islands in the Eastern Caribbean region were positive by the IFA test, therefore an ELISA system for these species was not developed (AU)

The first autochthonous case of Chagas' disease with notes on possible vectors in Guyana

In Guyana, the first autochthonous case of Chagas' disease was discovered in the North West Region. A vector survey showed the presence of two important genera of triatomid bugs widely distributed in various habitats throughout the area (AU)

Recovery of Trypanosoma forattinii Coutinho and Pattoli from a Trinidadian rodent: research note

Recovery of Trypanosoma forattinii from natural infected Oryzomys capito velutinus from Trinidad, is reported. Negative results were obtained with attempts to infect experimentally, several laboratory animals, silvatyc rodents of the same ecological area and several species of triatomid bugs. Positive results were obtained only by using O. capito velutinus born in laboratory. (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)

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

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)

Trypanosoma cruzi infection in blood-sucking reduviid bugs in Trinidad

Wild reduviid bugs from Trinidad were examined for the presence of T. cruzi, which was found in an appreciable proportion of them. The likelihood of human infection, and its epidemiology, are discussed. Further clinical and epidemiological studies of trypanosome infection in man are in progress and will be reported later. (AU)

Trypanosome infections in British Honduras

Several species of wild mammals, collected in the Cayo District of British Honduras, have been found infected with trypanosomes; a small number of Triatoma dimidiata from the same area have also been found infected. An account was given of laboratory observations on the different strains of parasite (AU)

Parasitological studies in British Honduras. 1. A parasite resembling Trypanosoma (Schizotrypanum) cruzi in the coati, Nasua narica (Carnivora, Procyonidae), and a note on Trypanosoma legeri from the ant-eater, Tamandua tetradactyla (Edentata)

A trypanosome, morphologically indistinguishable from Trypanosoma (Schizotrypanum) cruzi, is described in the coati (Nasua narica, Carnivora, Procyonidae) from British Honduras. Although Chagas' disease has yet to be reported from British Honduras, it is known to occur in the neighbouring countries of Guatemala and Mexico. It is suggested that the disease may exist in British Honduras but has so far gone undiagnosed. Clinical and epidemiological searches for it might well be instigated. T. legeri Mesnil and Brimont, 1910, was encountered in five of 12 ant-eaters (Tamandua tetradactyla) examined in the El Cayo District of British Honduras. Attempts to culture the parasite in NNN blood-agar media were unsuccessful (Summary)