Diagnosis of a Trypanosoma lewisi-like (Herpetosoma) infection in a sick infant from Thailand

Trypanosomes were observed in a peripheral blood smear from a 45-day-old Thai infant displaying fever, anaemia, cough and anorexia. Human trypanosomiasis is not endemic to Thailand, so parasite identification was undertaken to determine likely sources of the infection. Several morphological parameters of the trypanosomes were similar to those of Trypanosoma evansi and statistically different from those of Trypanosoma lewisi-like parasites from a naturally infected indigenous rat. However, duplicate PCR assays with primers flanking trypanosome rRNA internal transcribed spacer 1 (ITS1) resulted in amplicons of approximately 623 bp that corresponded to the expected size for T. lewisi-like parasites. The ITS1 sequence from the infant's blood was 98 and 49 % identical to T. lewisi and T. evansi sequences, respectively. Based on molecular results, it was concluded that the infant was infected with a T. lewisi-like (Herpetosoma) species.

A Gambian infant with fever and an unexpected blood film

The authors describe the differential diagnosis, investigation, and management of a two-month-old infant with edema, malnutrition, and fever.

Phylogeny, taxonomy and grouping of Trypanosoma rangeli isolates from man, triatomines and sylvatic mammals from widespread geographical origin based on SSU and ITS ribosomal sequences

Phylogenetic relationships among Trypanosoma rangeli isolates from man, wild mammals and triatomine bugs from widespread geographical origin were inferred by comparison of the small subunit of ribosomal gene sequences. The phylogenetic trees indicated that the subgenus Herpetosoma is polyphyletic and strongly supported division of this group into two monophyletic lineages, one made up of T. rangeli, T. rangeli-like and allied species and other consisting of T. lewisi and related taxa. Based on phylogenetic analysis, morphology, behaviour in vertebrate and invertebrate hosts and epidemiology we propose: a) the validation of Herpetosoma as a taxon comprised only for species of group lewisi and the maintenance of T. lewisi as the type-species of this subgenus; b) the classification of T. rangeli, T. rangeli-like and allied species into a ‘T. rangeli-clade’ more closely related to Schizotrypanum than to T. lewisi or T. brucei. The phylogenetic tree disclosed at least 4 groups within the clade T. rangeli, all confirmed by polymorphism of the internal transcribed spacer, thus conferring for the first time phylogenetic support to groups of T. rangeli and corroborating the high complexity of this taxon. Grouping was independent of their mammalian host-species and geographical origin, indicating that other factors are determining this segregation.

[The cases of infection of brown rats Rattus norvegicus with Trypanosoma lewisi (Kent, 1880) Laveran i Mesnil, 1901, in the area of Warsaw agglomeration]

Two from three brown rats (Rattus norvegicus) catched in Milan6wek near Warsaw, and one catched in the centre of Warsaw were infected with Trypanosoma lewisi. The morphometric features of trypanosomes were in accordance with the features of T. lewisi gived by other authors. This is first note about infection of free living rats with T. lewisi in Poland.

An unusual morphological type of Trypanosoma (Herpetosoma) lewisi (Kent, 1880) detected in the blood of Rattus norvegicus in India

An unusual morphological type of Trypanosoma (Herpetosoma) lewisi (Kent, 1880) which was detected in Rattus norvegicus in India is reported in the present study. This type is different from known types of T. lewisi in that the kinetoplast is at a greater distance from the posterior end (P-K) than the usual type. The total length, including the free flagellum, is 35.3-39.3 microns and P-K is 11.9-15.0 as against total length of 21 to 36.5 microns in the normal form.

Isoenzyme characterization of trypanosomes of the subgenus Herpetosoma

Isoenzyme analysis was used to characterize 6 species of trypanosomes of the subgenus Herpetosoma using 13 different enzyme systems. The species studied were Trypanosoma lewisi, T. musculi, T. grosi, T. microti, T. evotomys and T. nabiasi which cannot be distinguished on morphological grounds. Extracts for thin-layer starch-gel electrophoresis were prepared from cultures of insect forms in either Schneider's Drosophila or Grace's insect tissue culture media with foetal calf serum or a nutrient agar medium. Extracts of T. lewisi and T. musculi bloodstream forms were also run for comparison. All parasites gave distinct patterns which enabled them to be differentiated on one or more enzyme systems. Two types of computer analysis were used to group the parasites; using these techniques the murine parasites T. lewisi, T. musculi and T. grosi fell into one broad group, and T. microti and T. evotomys of microtine rodents formed another. These findings are in accord with earlier observations on the behavioural characteristics of these parasites in their mammalian host and their vector (fleas). The clear differences observed provide the basis for the application of other biochemical and immunological techniques for differentiation within this subgenus of trypanosomes.