Trypanosome evolution under the microscope.
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Animals↗
Biomedical subjects
H Noyes
Publications and source records attributed to H Noyes.
A revised classification for Leishmania and Endotrypanum.
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Animals↗
Higher penalties for failing to pay child support. A look at medical license revocation.
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American Medical Association↗
Leishmania chagasi: genotypically similar parasites from Honduras cause both visceral and cutaneous leishmaniasis in humans.
In the Mediterranean region Leishmania infantum causes both visceral and cutaneous leishmaniasis. These two pathologies tend to be caused by distinct parasite zymodemes. We have studied 33 isolates of Leishmania, 2 from sandflies, 5 from visceral cases, and 26 from cutaneous cases in Honduras, to determine if there is a correlation between pathology and parasite type in the New World similar to that in the Mediterranean region. Nine of the 26 cutaneous cases were caused by L. mexicana parasites, which have not been previously reported from Honduras; the remaining 17 cutaneous cases were due to L. chagasi. Only minor differences were found between the Honduran L. chagasi parasites by random amplified polymorphic DNA, differential display, pulsed-field gel electrophoresis, and schizodemes. This suggests that in Honduras the parasite type may not be the only factor determining the clinical outcome of L. chagasi infections.
Adolescent↗
Leishmania and Sauroleishmania: the use of random amplified polymorphic DNA for the identification of parasites from vertebrates and invertebrates.
We used the RAPD-PCR method for distinguishing the main Old World Leishmania parasites Leishmania tropica, L. major, and L. infantum and applied it to Sauroleishmania species from Iran. Twelve out of 21 tested primers were suitable for identification of these parasites. The Jaccard similarity index was 0.30 for L. tropica and L. infantum as well as for L. major and L. infantum. The similarity coefficient for L. major and L. infantum was 0.22 and for L. tropica and L. major it was 0.26. These data agree well with established phylogenetic/ taxonomic classification. The index between different isolates derived from various hosts and sandfly vectors for the same Leishmania species was 1, indicating that this method is suitable for epidemiological analysis.
Animals↗
Comparison of the sex-pheromone components of Lutzomyia longipalpis (Diptera:Psychodidae) from areas of visceral and atypical cutaneous leishmaniasis in Honduras and Cost Rica.
The terpene components of extracts prepared from male Lutzomyia longipalpis (Diptera: Psychodidae) collected from four sites in Honduras and one in Costa Rica were analysed by high-performance liquid chromatography, gas chromatography and coupled gas chromatography--mass spectrometry. The terpene components of Lu. longipalpis from other regions of South America have previously been shown to be sex pheromones. The flies from the four areas of Honduras, where Leishmania chagasi infection may lead to visceral or atypical cutaneous leishmaniasis, were found to be homogenous, all producing 9-methylgermacrene-B. Three types of terpene (9-methylgermacrene-B, a novel homosesquiterpene and a small amount of diterpene) were detected in pools of flies from Liberia, Costa Rica, where only atypical cutaneous leishmaniasis has been found. These results indicate that there are probably at least two and possibly three distinct populations of Lu. longipalpis in this region. The clinical manifestation of Leishmania chagasi infection does not appear to be dependent on which population of Lu. longipalpis transmitted the parasite.
Animals↗
Molecular techniques in the characterization of Leishmania isolates from Central America.
The public-health problems caused by leishmaniasis in most countries in Central America are becoming more severe. This is partly because of the increasing size of the human populations that are at risk and their migratory patterns. Annual incidence of the disease in Costa Rica, Honduras, Guatemala, Panama and Nicaragua is estimated to be as high as 20,000 cases. Regional changes in the epidemiology of the various Leishmania spp. present have emphasized the need for innovative, sensitive and accurate diagnostic tools. PCR and isoenzyme, monoclonal antibody, schizodeme, DNA-probe and random-amplified, polymorphic DNA analyses have been tested. Preliminary indications that Leishmania chagasi was present in Costa Rica and Honduras and that interspecific hybrids occurred in Nicaragua have been confirmed using these methods. The distribution of the mexicana complex was also found to be broader and more heterogeneous than initially expected. Overall, there was 87% concordance between the results produced using the different techniques.
Animals↗
An outbreak of cutaneous leishmaniasis in an Afghan refugee settlement in north-west Pakistan.
Cutaneous leishmaniasis (CL) due to Leishmania tropica appears to be an emerging disease in parts of north-east Afghanistan and north-west Pakistan. Timargara, an Afghan refugee camp of 17 years' standing, in the district of Dir, North West Frontier Province of Pakistan, experienced a major outbreak of CL in 1997 for the first time. As part of the investigation, each section of the camp was surveyed for CL. Around 38% of the 9200 inhabitants bore active lesions and a further 13% had scars from earlier attacks. According to interview statements, 99% of earlier infections had healed within the previous 2 years. To confirm the diagnosis, a sample of current CL lesions was examined parasitologically. Amastigotes were detectable by microscopy in only 36% of lesions. However, 48% of slide-negative cases produced positive cultures and some cases negative to both microscopy and culture were positive by PCR. Overall detection rate was about 80%. The sandfly Phlebotomus sergenti, a known vector of L. tropica, was captured within the camp, indicating local transmission. CL has not been reported from this area of Pakistan before. Although the majority of refugees left Afghanistan 2 decades ago, cross-border movement of men is common. The Afghanistan capital, Kabul, is currently experiencing a major epidemic of CL; infected migrant carriers from Kabul are probably the source of the outbreak in Timargara.
Adolescent↗
Implications of a Neotropical origin of the genus Leishmania.
The hypothesis of a Neotropical origin of the Leishmania/Endotrypanum clade is reviewed. The position of the L. (Sauroleishmania) external to the subgenus L. (Leishmania) is not consistent with the Neotropical origin of the latter subgenus. It is suggested that this may be a consequence of a faster evolutionary rate in the L. (Sauroleishmania). The implications for the classification of the phlebotomine sandflies of the hypothesis for a Neotropical origin of the Leishmania is also considered. The classification of Galati (1995) is proposed to be most consistent with the hypothesis of a Neotropical origin of the Leishmania, whilst classifications which place the New and Old World species in separate taxa are inconsistent with this hypothesis.
Animals↗
The evolution of trypanosomes infecting humans and primates.
Based on phylogenetic analysis of 18S rRNA sequences and clade taxon composition, this paper adopts a biogeographical approach to understanding the evolutionary relationships of the human and primate infective trypanosomes, Trypanosoma cruzi, T. brucei, T. rangeli and T. cyclops. Results indicate that these parasites have divergent origins and fundamentally different patterns of evolution. T. cruzi is placed in a clade with T. rangeli and trypanosomes specific to bats and a kangaroo. The predominantly South American and Australian origins of parasites within this clade suggest an ancient southern super-continent origin for ancestral T. cruzi, possibly in marsupials. T. brucei clusters exclusively with mammalian, salivarian trypanosomes of African origin, suggesting an evolutionary history confined to Africa, while T. cyclops, from an Asian primate appears to have evolved separately and is placed in a clade with T. (Megatrypanum) species. Relating clade taxon composition to palaeogeographic evidence, the divergence of T. brucei and T. cruzi can be dated to the mid-Cretaceous, around 100 million years before present, following the separation of Africa, South America and Euramerica. Such an estimate of divergence time is considerably more recent than those of most previous studies based on molecular clock methods. Perhaps significantly, Salivarian trypanosomes appear, from these data, to be evolving several times faster than Schizotrypanum species, a factor which may have contributed to previous anomalous estimates of divergence times.
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