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In spring 1991, Belizian health officials expressed concern about a possible hepatitis outbreak in a banana farming district. A study was designed to identify cases and to address the serological prevalence of hepatitis virus markers. Three populations were studied: (i) persons meeting a clinical case definition for hepatitis; (ii) designated banana workers; and (iii) people in a random sample of households in the community. Information was collected using questionnaires and sera were collected for laboratory testing. This report presents the preliminary results of a study conducted in June 1991. Among people who met the clinical case definition, 24% of 42 tested had immunoglobulin M antibody to hepatitis B virus (HBV) core antigen (anti-HBc IgM). In the worker and household survey populations, 284 and 280 people, respectively, were tested for anti-HBc IgM. In each group, 4% were positive. HBV surface antigen was found in 37% of 43 clinical cases, 18% of workers, and 13% of people in the household survey. Among the 3 study populations, the prevalence of HBV core antibody (anti-HBc) ranged from 73% to 81%. Almost all tested persons had evidence of prior hepatitis A virus infection. Evidence of prior infection with hepatitis viruses A and B was widespread, but an aetiology could not be established for most of the clinical cases. However, the prevalence of hepatitis B markers in this population was very high compared to other reports from the Caribbean.

Thirty-four cases of cutaneous leishmaniasis contracted by British soldiers in Belize were studied. Pre- and post-treatment biopsies were taken from all patients. The range of histological appearances is described and the value of histological examination (including Giemsa staining and immunohistochemistry), cytological preparations and microbiological culture in diagnosis and clinical management assessed. Histology and culture were found to be complementary techniques in reaching a positive diagnosis, whilst cytological preparations were of no additional value. Histological examination of post-treatment biopsies merely confirmed the clinical impression of healing or non-healing whilst culture identified viable organisms in apparently healed lesions, which were subsequently re-treated.

In a search for leptospirosis in Belize, at least one current case was diagnosed among 11 febrile hospital patients examined in a 2-week period in mid-1984. Sera from 440 survey subjects in 6 schools, 4 urban communities and 9 rural communities were examined for leptospiral antibodies by the microscopic agglutination test. 20 of 174 (11.5%) school pupils, 19 of 88 (22%) urban community subjects and 66/178 (37%) rural community subjects were positive at titres greater than or equal to 1:50, and 7.5%, 17% and 26%, respectively, were positive at greater than or equal to 1:100. Among all groups of survey subjects, serological reactions to antigens in the Australis serogroup predominated. Up to 81% of 155 sera from cattle in various areas of Belize were positive at titres greater than or equal to 1:100. Serological reactions to serogroup Sejroe predominated (43%), followed by Pyrogenes (16%) and Australis (15%). 20 of 71 (28%) pig sera were positive at greater than or equal to 1:100, predominantly to serovars in the Australis serogroup (51%). Of 162 sheep or goat sera examined, 65 (40%) were positive at greater than or equal to 1:100, mainly to serogroup Autumnalis (25%), followed by Australis (15%).

Leishmanial organisms were cultivated from cutaneous lesions of British military personnel returning from Belize. Isoenzyme profiles of the freshly isolated organisms and 'marker' strains of New World Leishmania spp. were compared using 10 enzymes (ALAT, ASAT, ME, GPI, MPI, PGM, SOD, 6-PGDH, G-6-PDH and MDH), by starch gel electrophoresis. 19 of the 22 new isolates from Belize were isoenzymically indistinguishable from Leishmania braziliensis braziliensis (10 out of 10 enzymes) and clearly differentiated from L. b. guyanensis and L. b. panamensis (different in 6 out of 10 enzymes) and from L. mexicana mexicana and L. m. amazonensis (9 out of 10 enzymes). Two isolates closely resembled L. m. mexicana and one could not be positively identified. This is the first report of autochthonous human leishmaniasis caused by L. braziliensis group organisms as far north as latitude 16 degrees N.

READY & LAINSON (1982) referred to speculation over the identity of the sand fly which first experimentally transmitted a neotropical Leishmaniu by bite (STRANGWAYS-DIXON & LAINSON, 1962; 1966). Previously published comments on this fly’s identity (WILLIAMS, 1970; WILLIAMS & COELHO, 1978) were based on examinations of the actual specimen and after comparing it with other species of the same subgenus. The Department of Entomology, British Museum (Natural History), which received the specimen in December 1967, recently loaned me the material. In addition to studies on the fly made at the Gorgas Memorial Laboratory, Panama, and at BM(NH), it has now been possible to compare the fly with specimens in the Belo Horizonte reference collection of Phlebotominae. For simnlicitv’s sake. the fly in question is, herein, called “the Belize specimen”. It is impossible to identify the Belize specimen to specific level because it lacks spermathecae, spermathecal ducts and the genital fork. However, from the appearance of certain non-sexual features, the Belize specimen cannot belong to two species of the same subgenus Psychodopygus collected in Belize between 1963 and 1969 (WILLIAMS, 1970), and some species mentioned by READY & LAINSON (1982) can be eliminated. Thoracic pigmentation: The mesoscutum, mesoscutellum and postnotum of the Belize specimen are moderately but distinctly infuscated, and clearly contrast with the paleness of the thoracic pleura. It is unlikely that this colour contrast is an artefact due to distortion of the thorax. The pigment contrast on the thorax of the Belize specimen is similar to that of Lutzomyia (Psychodop$us) panamensis, L. (Ps.) geniculata (= L. (Ps.) guyanensis of some authors) and L. (Ps.) bispinosa, the three species of the subgenus collected in Belize in 1963-69. The Belize specimen, with a pale pronotum, differs from L. (Ps.) bispinosa, in which the uronotum is weaklv infuscate. The orocoxae of the Belize suecimen are as nale as the thoracic pleura. For this reason, the specimen cannot be identified as L. (Ps.) hirsuta nicaramrensis which has darkened procoxae in both sexes(FAIRCHILD & HERTIG, 1961.; YOUNG, 1979). Because of the contrast in thoracic pigmentation, the Belize specimen most certainly cannot be identified as L. (Ps.) carreirai thuZa (= Ps. -pessoanus of READY & LAINSON, 1982). In snecimens of L. (Ps.) carreirai thula. material from Panama and Colombia having been’examined, the entire thorax is pale, or almost so, and there is no noticeable difference in thoracic pigmentation. On the basis of thoracic pigmentation, it can be deduced that the Belize specimen cannot be L. (Ps.) carreirai thula, L. (Ps.) hirsuta nicaraguensis or L (Ps.) bispinosa. Cibarium: The cibarial arch in the Belize specimen and L. (Ps.) pana memis is well defined and complete. In L. (Ps.) geniculata and L. (Ps.) bispinosa, the cibarial arch is not well defined but appears to be complete. The cibarial arch of L. (Ps.) carreirai thula is so weakly defined that it is best described as incomplete. The cibarial pigment patch in the Belize snecimen. L. (Ps.) panamensis and L. (Ps.) geniculata is fairlv ‘well‘ defined and annears as a’ “m it seems to be triangular in shape. The salivary pump in the Belize specimen, L. (Ps.) panamensis and L. (Ps.) bispinosa is roughly circular in optical section and smaller than the pump in L. (Ps.) geniculata and L. (Ps.) carreirai thula, both having an oval-shaped pump along a distal-proximal axis. From the general appearance of the cibarium, it can be concluded that the Belize specimen cannot be identified as L. (Ps.) carreirai thula. L. (Ps.) eeniculata or L. (Ps.) bispinosa. I ~ , ”

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 paralysis of the limbs, produced by the strains was observed in many laboratory animals as well as in some of the experimentally infected wild rodents. Histological studies of organs from several of the paralysed 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 morphogenesis 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's disease is endemic, is emphasized as one of the fundamental requirements for the experimental chemotherapy of Chagas's disease.

In British Honduras (Belize), Leishmania mexicana is mainly a parasite of small forest rodents, in which the infection is usually apparent as a non-ulcerated, discrete lesion near the base of the tail. All infected rats have been captured in forest. The rat most frequently infected with L. mexicana is Ototylomys phyllotis , the most abundant and most successful rodent in forest in British Honduras. It is a strictly forest-dwelling animal with scansorial habits. L. mexicana also occurs in Heteromys desmarestianus , a ground-dwelling forest rat that occasionally extends into savanna, farmland and houses. Accidental rodent hosts of L. mexicana are Sigmodon hispidus , a rat of savanna that sometimes invades forest, and Nyctomys sumichrasti , a forest-dweller with arboreal habits. Man is an accidental host for L. mexicana . A survey revealed that 10·8% of the populations of certain rural communities in British Honduras gave positive responses to Montenegro antigen. Positive reactions were more frequent in men (18·1%) than in women (3·7%). The incidence of human leishmaniasis is highest in the central part of British Honduras, occurring among persons with past or present association with the forest extending eastwards from El Peten Department of Guatemala; L. mexicana infections are rare or absent from the north and south of British Honduras. An account is given of the development of L. mexicana lesions on man, and selected cases of human leishmaniasis are described briefly. Evidence of the role of phlebotomine sandflies in the dissemination of American cutaneous leishmaniasis is reviewed. Details are given of phlebotomine sandflies caught in British Honduras between 1963 and 1969; 3 species of Brumptomyia and 22 species of Lutzomyia were collected. Notes are given of the species of phlebotomines taken on human bait, with rat-baited oil traps, with C.D.C. miniature light traps and from resting-places such as the buttressed roots of trees, beneath decaying leaves on the forest floors, and the walls of caves. Geographical distribution and abundance, vertical zonation and biting rhythms of phlebotomines in British Honduras are discussed and observations on the distribution of sandfly bites on the human body are reported. A description is given of the techniques used to examine phlebotomines for flagellate infections and of methods used to identify such infections. Trypomastigote or epimastigote infections or both were found in specimens of Lu. cruciata, Lu. steatopyga, Lu. shannoni and Lu. trinidadensis . Promastigote infections were discovered in Lu. cruciata, Lu. ovallesi, Lu. olmeca, Lu. panamensis and Lu. permira . Only promastigotes isolated from Lu. olmeca gave rise to characteristic L. mexicana lesions when inoculated into hamsters. Transmission of leishmaniasis to rodents by Lu. olmeca is discussed. A theory is presented to explain how Lu. olmeca , a species not attracted to take blood meals on man, could be responsible for the transmission of L. mexicana to man. It is suggested that leishmaniasis in British Honduras is acquired when the daytime resting places of Lu. olmeca (decaying leaves on the forest floor) are disturbed during hours of daylight. Evidence is offered to show that when man disturbs leaves on the forest floor in the hour or so after dawn, he runs the same risks as a susceptible rat of being bitten by a female Lu. olmeca infected with L. mexicana .

1. 1) During a 3-year study on the epidemiology of dermal leishmaniasis in British Honduras, about 150 human cases were seen among which 46 were examined in detail. The parasite, Leishmania mexicana , was isolated in NNN cultures in 27 instances. 2. 2) Race, sex, age and physical condition of the individual appear to have little bearing on the susceptibility of human beings to the disease which is strictly sylvatic in origin and principally restricted to chicleros, mahogany hunters, and other forest workers. 3. 3) The disease is almost always limited to a single dermal lesion. No evidence could be found of any cutaneous spread of infection or visceral involvement. The ear is the most commonly affected part of the body (40 per cent. of the 50 lesions studied), but the hands and arms are also frequently involved (28 per cent.). Lesions on the torso and legs are uncommon. This differential distribution of lesions is thought due to a combination of at least three main factors: firstly the head and arms are the most frequently exposed parts of the body, secondly there is a marked tendency for body lesions to heal spontaneously, and finally L. mexicana appears to proliferate more readily in ear tissue than in that of other parts of the body. 4. 4) Development of the human lesion is described from a study of experimental insect transmission by Phlebotomus , natural infections of known duration and syringe-induced infections in volunteers. The incubation period following the introduction of leptomonads into the skin varied from 2 to 4 weeks. An account of the histology of the developing lesion is given. 5. 5) Three men with infections of short duration resisted attempts to super-infect them with massive intradermal inoculations of leptomonads of L. mexicana . This early premunition contrasts with the much more slowly developed immunity in the case of L. tropica infection. 6. 6) The culture of material from lesions in NNN medium proved the most reliable method of diagnosis. Hamsters and white mice are readily infected both with leptomonads from cultures and L.D. bodies taken directly from human lesions. In one instance the Montenegro skin-test was shown to give equally good reactions with antigens prepared from leptomonads of L. mexicana and L. tropica . 7. 7) Three human volunteers were readily infected with strains of L. mexicana isolated from the wild forest rodents, Ototylomys, Nyctomys and Heteromys species. 8. 8) Sixteen human cases of “Bay-Sore” were successfully treated with Stibophen (pentasodium antimony-biscatechol-3: 5-disulphonate). 9. 9) The medical and economic importance of dermal leishmaniasis in British Honduras is discussed. Two-thirds of the Colony is still under forest from which the main natural resources of chicle, timber and some agricultural products are derived, and one-third of the working population is employed in forest work of some kind. As we have clearly indicated dermal leishmaniasis in British Honduras to be a zoonosis, with the infected animals acting as reservoirs for the human disease, it follows that a large proportion of the population will remain constantly exposed to infection.

1. 1) Fifty cases of chiclero's ulcer or bay sore are reported from British Honduras, and the epidemiology of the disease is discussed. Infection is strictly limited to people living inside the forest for prolonged periods. 2. 2) The causative organism, and its behaviour in animals, is described. Inoculation of a culture of a local strain into the spleen of hamsters resulted in a widespread systemic infection and produced by fatty degeneration of the RE cells. Akinetoplastic organisms developed in some of the subcutaneous lesions. At present the organism is best called a special “nosodeme” of L. brasiliensis. 3. 3) There is little doubt that bay sore in British Honduras is a zoonosis, though examination of the following animals gave negative results:—armadillos, pacas, wild rodents, opossums, dogs and a fox. 4. 4) Fourteen species of Phlebotomus were found in British Honduras, eight of which were taken on man, including P. cruciatus Coquillett, which is believed to transmit cutaneous leishmaniasis in Mexico, and two species closely related to P. whitmani Antunes and Coutinho, a vector in Brazil. Their habits are briefly described. No leptomonads were found in a small number dissected. 5. 5) It is suggested that “control measures” for leishmaniasis in British Honduras might be by the use of attenuated vaccine, and an attempt was made to immunize hamsters. 6. 6) Thirteen species of Simulium were found, of which two, S. quadrivittatum Loew and S. metallicum Bellardi, attack man in large numbers. The occurrence of human onchocerciasis in Guatemala raises the question of its possible spread into British Honduras, and this is discussed. 7. 7) Many other organisms are recorded or discussed, including new species of parasitic protozoa, microfilariae of the toucan, some mosquitoes, midges and other insects, and larval ticks.

A survey of 14 villages in British Honduras was made to estimate the incidence of dermal leishmaniasis; diagnosis of past or present infection with L. mexicana was made by using the Montenegro skin test. Infection was found throughout the whole country, highest in the central areas, and lowest in the most southern Indian villages and in the coastal villages. No infection was found among the Blue Creek Mennonites, although mestizos who had worked there claimed to have been infected. The possible role of clothes and insect-free dwellings is discussed. A male-female ratio of 5·3:1 of infection was found; probably because women spend less time in the bush. The highest prevalence was in the 36–50-year age group. The low antigenicity of L. mexicana is suggested as the reason for the absence of an immune response in the children. The ear is confirmed as the commonest site of infection; the elbow is second. Possible reasons are discussed. The presence of subclinical infection is suggested because of the large number of people with positive skin tests, who denied ever having had bay sore. The presence of “doubtful” reactions to the skin test may also be significant in this context.

A survey in 1967 of mosquitoes taken by human bait and trap catches in British Honduras along a transect from the coast near Belize City to riverine terrain and upland forest 45 miles inland yielded 65 species— Chagasia (1), Anopheles (8), Trichoprosopon (2), Wyeomyia (5), Limatus (2), Sabethes (2), Mansonia (2), Coquillettidia (2), Uranotaenia (5), Aedomyia (1), Psorophora (8), Aedes (9), Haemagogus (2), Culex (15), Deinocerites (1). Mosquito densities are very low in the dry season (April–May), rapidly increasing with the main rains which begin about late May–June, and continuing probably considerable until the following April–May dry season. Diurnal, crepuscular and nocturnal activity, and vertical distribution in forest, resembled findings from elsewhere in Middle America. The coastal pest, Aedes taeniorhynchus , occurred in small numbers as far inland as 45 miles. The Aedes terrens group includes a new species, Ae. bertrami Schick 1970. Mansonia dyari and Ae. cozumelensis first described, respectively, from Jamaica in 1970 and from the Yucatan in Mexico in 1966, were taken, and also Ae. vexans , common in North America. Differentiation within C. (Mel.) opisthopus/taeniopus is still inconclusive, available larvae and ♂ genitalia being assigned to C. (Mel.) n. sp. near paracrybda. Ae. aegypti was not found, following an eradication programme. The anopheline and culicine species include, respectively, vectors of malaria and of arboviruses. As a result of a malaria eradication campaign, few cases of malaria occur. In 1967, equines had VEE antibodies and VEE virus was isolated, by other workers, in sentinel hamsters near Belize City but the human population which showed NT-antibodies to VEE, SLE and Ilheus appears on the whole to have escaped any major infections, in recent years. There was no conclusive evidence for arbovirus infections of British garrison troops. Up to early October 1971, British Honduras escaped, although several competent vectors occur, the severe wave of epizootic VEE in equines, with also human cases, which occurred in other Central American countries from 1969 to September 1971. In 1969 and, particularly in 1971, precautions were taken by vaccination of horses in a buffer zone along the borders of the adjacent, and severely affected, territories of Mexico and Guatemala.

1. 1) Dermal leishmaniasis (“Bay-sore”) in British Honduras is restricted to people who penetrate the forested regions. This suggests the disease to be a zoonosis, with wild animals acting as a source of infection for man. 2. 2) A variety of wild and laboratory animals were tested for susceptibility to Leishmania mexicana in attempts to indicate potential reservoir-hosts. Of the wild animals, only the cotton-rat (Sigmodon hispidus) was readily infected. Among laboratory animals the most susceptible were hamsters, mice, gerbils and rats, in that order. It was concluded, therefore, that the reservoir-hosts of L. mexicana would best be sought among the sub-Order Myomorpha of the Order Rodentia. 3. 3) A focus of infection in the forest was pin-pointed by the isolation of L. mexicana from a batch of sand-flies trapped in a selected area. About 300 insects were triturated together in Locke's solution and inoculated into the skin of a hamster. A lesion containing LD bodies developed at the inoculation site. 4. 4) L. mexicana was isolated from three different species of forest rodents trapped in this same area: the incidence of infection was as follows: The “tree-rat”, Ototylomys phyllotis Merriam (Cricetidae, Rodentia), eight of 20 (40 per cent.) examined. The “spiny-pocket-mouse”, Heteromys desmarestianus Gray (Heteromyidae, Rodentia), six of 58 (10.34 per cent.). The “vesper-rat”, Nyctomys sumichrasti Saussure (Cricetidae, Rodentia), one of eight (12.5 per cent.). No infections could be found in a variety of other mammalian species from this and other areas of the forest. 5. 5) Infection of the reservoir-hosts appeared to be purely cutaneous and restricted to lesions on the tails. Abundant LD bodies were usually evident in stained smears from such lesions and the histology of the lesions is described. 6. 6) In all respects the strains of L. mexicana from the three rodent species appear identical with the parasite causing the human disease. Leptomonads inoculated into human volunteers produced long-lasting, cutaneous lesions containing abundant LD bodies. 7. 7) It is concluded that dermal leishmaniasis in British Honduras is a zoonosis. L. mexicana is primarily a parasite of forest rodents among which Ototylomys phyllotis, Heteromys desmarestianus and Nyctomys sumichrasti figure prominently. Other rodent species are probably also involved. Man is to be regarded as an accidental host. 8. 8) Evidence is presented to indicate that transmission among the wild animals, and to man, is by the agency of Phlebotomus species biting at ground level. 9. 9) The need is indicated for further research on the distribution and life histories of the reservoir-hosts throughout the forests. In particular a study must be made of their nesting habits to determine the possibility of a specific Phlebotomus—rodent association within the nests. 10. 10) The significance of the present findings is discussed with regard to cutaneous leishmaniasis in other parts of Central and South America. Similar investigations should be made on the epidemiology of muco-cutaneous leishmaniasis, due to L. braziliensis. There are a number of apparently distinct clinical forms of cutaneous and muco-cutaneous leishmaniasis in the New World. The possibility is considered that these might be due to infection of man with different leishmanial parasites which are normally found in different wild animal hosts.

Minist?rio da Sa?de. Funda??o Servi?os de Sa?de P?blica. Instituto Evandro Chagas. Bel?m, PA, Brasil.

Minist?rio da Sa?de. Funda??o Servi?os de Sa?de P?blica. Instituto Evandro Chagas. Bel?m, PA, Brasil.