On dermal leishmaniasis in british honduras.
01 Jan 1965-Transactions of The Royal Society of Tropical Medicine and Hygiene (No longer published by Elsevier)-Vol. 59, Iss: 1, pp 64-71
TL;DR: A study of human cases of dermal leishmaniasis shows that the infection is not confined to “high bush” but may be present in bush of any type, and the advisability of employing prophylactic vaccination under certain conditions is worth considering.
Abstract: A study of human cases of dermal leishmaniasis shows that the infection is not confined to “high bush” but may be present in bush of any type. The advisability of employing prophylactic vaccination under certain conditions is worth considering. A rat was found to be infected with Leishmania mexicana, but there was no Leishmania among parasites obtained from lizards. 14 species of Phlebotomus were found, and preliminary observations were made on age changes and other features. Attempts to ascertain the natural infection rate, by inspection and by injection into hamsters, gave negative results, and possible reasons for this are discussed.
Citations
More filters
TL;DR: The following paper deals with the better known human leishmaniases of the New World, and some new ones, and discusses the major historical events in the laborious task of elucidating their ecology and epidemiology.
Abstract: As the first species of Leishmania encountered were the agents of human visceral and cutaneous leishmaniasis, it is understandable that studies on these parasites for a long time concentrated on those organisms commonly causing disease in man. Epidemiological studies over the past 20 years or so, however, have led to the inescapable conclusion that the genus Leishmania is comprised of numerous species of well adapted parasites, in a wide range of mammals, throughout most of those tropical and subtropical regions of the world where phlebotomine sandflies exist (Diptera: Psychodidae). Many of the leishmanias probably never gain entrance into man: due either to an incapacity to survive in his tissues, or (more likely) because the natural sandfly vectors do not feed on him. The leishmanias that do infect man are, nevertheless, among the greatest protozoological scourges of mankind, and a better understanding of their life-cycles may well help in future prevention or control of the diseases they cause. With few exceptions the leishmaniases are zoonoses, with a major source of infection in wild or domestic animals. In the Americas, the disease is essentially a rural one, and most commonly acquired by those penetrating forested or wooded regions. The following paper deals with the better known human leishmaniases of the New World, and some new ones, and discusses the major historical events in the laborious task of elucidating their ecology and epidemiology.
260 citations
TL;DR: It is concluded that Lutzomyia flaviscutellata is the major vector of the Leishmania sp.
Abstract: During observations on a focus of enzootic leishmaniasis of rodents in the Utinga Forest, Belem, Para, Brazil, active infections were encountered in 16 (17·98%) of 89 Oryzomys capito examined. Cutaneous lesions were restricted to the tails of these animals, and spontaneous recovery leaves characteristic scarring. Taking such scars into account, it is estimated that as many as 70% of the Oryzomys population may experience infection at some time during their lives. Leishmania were isolated from 3 specimens of Proechimys guyannensis captured in the same forest area. In addition to obvious lesions on the tail and foot, parasites were isolated from apparently normal ear tissue. The strains of Leishmania from Oryzomys and Proechimys appear to be identical. Insect traps were baited with Oryzomys, Proechimys and other rodents. During a period of 4 months they captured 2,774 phlebotomine sandflies, of which 2,731 were Lutzomyia flaviscutellata Mangabeira. In contrast, only 5 specimens (0·69%) of Lu. flaviscutellata were encountered among 724 sandflies caught of human bait during the same period, in the same area. Leptomonads were found in 8 of 2,706 Lu. flaviscutellata dissected (0·29%). Inoculation of these flagellates into hamsters produced typical leishmanial lesions in 6 cases. We conclude that Lutzomyia flaviscutellata is the major vector of the Leishmania sp., among Oryzomys and Proechimys in the Utinga Forest area of the Lower Amazon Region. Similarities are noted between this parasite of Brazilian rodents and Leishmania mexicana of rodents and man in Central America.
128 citations
TL;DR: This is the first report of autochthonous human leishmaniasis caused by L. braziliensis group organisms as far north as latitude 16 degrees N.
Abstract: 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.
87 citations
79 citations
TL;DR: Model the environmental requirements of the principal North and Central American phlebotomine species and analyze three niche characteristics over future climate change scenarios to provide an increased opportunity for the geographic expansion of NCA sand flys' ENM and human exposure to vectors of Leishmaniases.
Abstract: Ecological niche models are useful tools to infer potential spatial and temporal distributions in vector species and to measure epidemiological risk for infectious diseases such as the Leishmaniases. The ecological niche of 28 North and Central American sand fly species, including those with epidemiological relevance, can be used to analyze the vector's ecology and its association with transmission risk, and plan integrated regional vector surveillance and control programs. In this study, we model the environmental requirements of the principal North and Central American phlebotomine species and analyze three niche characteristics over future climate change scenarios: i) potential change in niche breadth, ii) direction and magnitude of niche centroid shifts, iii) shifts in elevation range. Niche identity between confirmed or incriminated Leishmania vector sand flies in Mexico, and human cases were analyzed. Niche models were constructed using sand fly occurrence datapoints from Canada, USA, Mexico, Guatemala and Belize. Nine non-correlated bioclimatic and four topographic data layers were used as niche components using GARP in OpenModeller. Both B2 and A2 climate change scenarios were used with two general circulation models for each scenario (CSIRO and HadCM3), for 2020, 2050 and 2080. There was an increase in niche breadth to 2080 in both scenarios for all species with the exception of Lutzomyia vexator. The principal direction of niche centroid displacement was to the northwest (64%), while the elevation range decreased greatest for tropical, and least for broad-range species. Lutzomyia cruciata is the only epidemiologically important species with high niche identity with that of Leishmania spp. in Mexico. Continued landscape modification in future climate change will provide an increased opportunity for the geographic expansion of NCA sand flys' ENM and human exposure to vectors of Leishmaniases.
77 citations
References
More filters
TL;DR: In the sandfly gut the growth pattern and morphology of the leptomonads in natural infections are similar to those of sandflies fed on hamster lesions produced by both Panamanian human strains and a wild-caught sandfly strain.
92 citations
TL;DR: Dermal leishmaniasis in British Honduras is clearly indicated 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.
Abstract: 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.
81 citations
TL;DR: An intensive and prolonged search for the larvae of Phlcbotomus sand flies in a variety of natural habitats in Panama resulted in the collection of 2258 larvae belonging to at least 15 of the 60-odd species now known from the area.
Abstract: An intensive and prolonged search for the larvae of Phlcbotomus sand flies in a variety of natural habitats in Panama resulted in the collection of 2258 larvae belonging to at least 15 of the 60-odd species now known from the area. A number of the species are quite specific in their habitat requirements, some living on the surface of fallen dead leaves on the forest floor while others burrow an inch or more beneath the soil surface. Methods used include a sugar solution notation technique, which is described, and simple searching of likely habitats. The scanty published information is reviewed.
76 citations
TL;DR: It is concluded that dermal leishmaniasis in British Honduras is a zoonosis, with wild animals acting as a source of infection for man and evidence presented to indicate that transmission among the wild animals, and to man, is by the agency of Phlebotomus species biting at ground level.
Abstract: 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.
67 citations
TL;DR: 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.
Abstract: 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.
47 citations