Abstract. Before 1999, leishmaniasis was considered an imported disease in Thailand. Since then, autochthonous leishmaniasis was reported in both immmunocompetent and immmunocompromised patients especially in human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS). A new species was identified and named as Leishmania siamensis consisting of two lineages, that is, lineages TR and PG. Analysis of isoenzymes has clarified the more commonly detected L. siamensis lineage PG as Leishmania martiniquensis (MON-229), a species originally reported from the Martinique Island, whereas the L. siamensis lineage TR has been identified as the true novel species, L. siamensis (MON-324). Both cutaneous leishmaniasis (CL) and visceral leishmaniasis (VL) have been found among Thai patients. Disseminated CL and VL could be presented in some reported patients who had HIV/AIDS coinfection. So far, only sporadic cases have been reported; thus, the true prevalence of leishmaniasis should be determined in Thailand among the high-risk populations such as people with HIV/AIDS. A recent survey among animals identified L. martiniquensis DNA in black rats (Rattus rattus) suggesting a potential animal reservoir. In addition, L. martiniquensis DNA was identified in Sergentomyia gemmea and Sergentomyia barraudi, the predominant sandfly species in the affected areas. However, further studies are needed to prove that these sandflies could serve as the vector of leishmaniasis in Thailand.

Blastocystis has a widespread distribution in a variety of animals, which is a potential source of infection for humans. However, the contribution of zoonotic transmission remains unclear due to the absence of molecular proof of these organisms being identical to those found in humans. We report herein the similar subgroup of Blastocystis isolates from humans, pigs, and a horse using a restriction fragment length polymorphism (RFLP) analysis of partial small-subunit ribosomal DNA (ssu rDNA). Additionally, sequence and phylogenic analysis of partial ssu rDNA of Blastocystis from a human, a pig, and a horse sharing a common subgroup shows that Blastocystis isolates from a pig and a horse were monophyletic and closely related to B. hominis, with 92 to 94% identity. These results suggest the possibility of zoonotic potential of Blastocystis.Blastocystis hominis is one of the most common intestinal protozoa found in humans. This organism has been recognized as a causative agent of diarrhea both in immunocompromised and immunocompetent hosts in several studies (6,8). However, its role in human disease is still intensely debated since most cases are asymptomatic (2,18,21,23). It has been reported from both developed and developing countries, with a high prevalence in tropical areas, ranging between 30 and 50% (2, 15, 21). Our knowledge of this organism in several aspects, including its transmission, is still unclear. Zoonotic transmission of B. hominis has been speculated since epidemiological studies suggested a linkage between close contact with animals and blastocystosis in humans (8,17). In addition, Blastocystislike organisms were detected in a wide range of animals (1, 4, 9, 16). However, there was no conclusive evidence demonstrating animal-to-human transmission and zoonotic potential of B. hominis. One of the difficulties is the identification of these organisms since infection with Blastocystis has been diagnosed on the basis of morphology, host of origin, and in vitro culture characteristics (4). Although the morphology of Blastocystis detected in some animals was similar to those found in humans, only few animal isolates of Blastocystis were genetically proven to be identical to human isolates (7,25). Using a restriction fragment length polymorphism (RFLP) analysis of small-subunit ribosomal DNA (ssu rDNA), Clark identified a ribodeme of Blastocystis isolated from guinea pigs similar to that found in B. hominis (7). Yoshikawa et al. also showed that the pattern of random amplified polymorphic DNA in Blastocystis isolated from a chicken was similar to that displayed by B. hominis isolate HE87-1 (25). These observations, however, were limited and lack epidemiological data to support the association. Therefore, to determine the zoonotic potential of B. hominis, we conducted a study of genotypic characterization using RFLP analysis of partial ssu rDNAs of Blastocystis isolated from humans compared to those isolated from animals. ssu rDNAs of Blastocystis isolated from a human, a pig, and a horse were also partia...

BackgroundLeishmaniasis, caused by Leishmania siamensis, is an emerging disease in Thailand. Although reported cases have been increasing, epidemiological information of the disease including host and vector aspects is not clearly known. This study was a preliminary survey of the potential vector of L. siamensis in an affected area of leishmaniasis, Trang Province, southern Thailand.MethodsThe collection of sandflies was performed around the area where a case of leishmaniasis was reported using CDC light traps. Species of sandfly were identified based on morphological characteristics according to Lewis’s key. PCR amplification and sequencing of the heat shock protein 70 gene (hsp70) was used to identify L. siamensis DNA in sandflies.ResultsA total of 146 male and female sandflies were collected in the affected areas. Of 71 female sandflies, four species were identified, i.e., Sergentomyia (Neophlebotomus) gemmea, S. (Neophlebotomus) iyengari, S. (Parrotomyia) barraudi and Phlebotomus (Anaphlebotomus) stantoni. Among these species, S. (Neophlebotomus) gemmea was the most predominant species in all areas. DNA of L. siamensis was identified in S. (Neophlebotomus) gemmea. Nucleotide sequences of PCR products using DNA extracted from S. (Neophlebotomus) gemmea showed 99.8% identity to L. siamensis.ConclusionS. (Neophlebotomus) gemmea might be a potential vector of L. siamensis in an affected area, Trang Province, southern Thailand. However further studies are needed to prove whether these sandflies can be natural vectors of leishmaniasis.

Sensitivities of DNA extraction methods and PCR methods for Giardia duodenalis were evaluated. A combination of the most sensitive methods, i.e., FTA filter paper and a PCR protocol using RH11/RH4 and GiarF/GiarR primers, showed no significant differences compared to immunofluorescence assay in terms of their sensitivities and specificities.

The root extract of Trichosanthes cucumerina L. and bryonolic acid (1), its main constituent, as well as the fruit juice and cucurbitacin B (3), its main constituent, were tested for cytotoxicity against four human breast cancer cell lines (SKBR3, MCF7, T47D, and MDA-MB435), two lung cancer cell lines (A549 and SK-LU1), and one colon cancer cell line (Caco-2). The root extract had higher IC (50) values than bryonolic acid (1) against three breast cancer cell lines (MCF7 = 267/121, T47D = 316/124, MDA-MB435 = 140/90 microL/mL) and one lung cancer cell line (A549 = 106/100 microL/mL). The fruit juice also had higher IC (50) values than cucurbitacin B (3) against the four breast cancer cell lines (131/73, 375/35, 249/60, and 156/26 microL/mL, respectively) and one lung cancer cell line (141/41 microL/mL) as shown above, as well as against the colon cancer cell line (101/1.5 microL/mL). However, the root extract inhibited SK-LU1 more strongly than did the fruit juice, cucurbitacin B (3), and bryonolic acid (1) (149/169/180/>500 microL/mL, respectively). The root extract inhibited the two lung and three breast cancer cell lines (SKBR3, MDA-MB435, and MCF7) more strongly than the fruit juice. Bryonolic acid (1) inhibited MDA-MB435 somewhat better than the other tested human cancer cell lines. The fruit juice inhibited the colon cancer cell line (Caco-2) more strongly than the root extract. Cucurbitacin (3) inhibited human cancer cell lines, especially Caco-2, much more strongly than bryonolic acid (1). In addition to bryonolic acid (1), bryononic acid (2), cucurbitacin B (3), and dihydrocucurbitacin B (4) also were isolated from the root extract.

BackgroundAutochthonous cutaneous and visceral leishmaniasis (VL) caused by Leishmania martiniquensis and Leishmania siamensis have been considered emerging infectious diseases in Thailand. The disease burden is significantly underestimated, especially the prevalence of Leishmania infection among HIV-positive patients.MethodsA cross-sectional study was conducted to determine the prevalence and risk factors associated with Leishmania infection among patients with HIV/AIDS living in Trang province, southern Thailand, between 2015 and 2016. Antibodies against Leishmania infection were assayed using the direct agglutination test (DAT). DNA of Leishmania was detected by ITS1-PCR using the buffy coat. Species of Leishmania were also identified.ResultsOf 724 participants, the prevalence of Leishmania infection was 25.1% (182/724) using either DAT or PCR assays. Seroprevalence of Leishmania infection was 18.5% (134/724), while Leishmania DNA detected by the PCR method was 8.4% (61/724). Of these, 24.9% (180/724) were asymptomatic, whereas 0.3% (2/724) were symptomatic VL and VL/CL (cutaneous leishmaniasis). At least five species were identified: L. siamensis, L. martiniquensis, L. donovani complex, L. lainsoni, and L. major. Multivariate analysis showed that CD4+ levels <500 cells/μL and living in stilt houses were independently associated with Leishmania infection. Those who were PCR positive for Leishmania DNA were significantly associated with a detectable viral load, whereas non-injection drug use (NIDU) and CD4+ levels <500 cells/μL were potential risk factors of Leishmania seropositivity.ConclusionsA magnitude of the prevalence of underreporting Leishmania infection among Thai patients with HIV was revealed in this study. Effective public health policy to prevent and control disease transmission is urgently needed.

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BackgroundVisceral leishmaniasis (VL) caused by Leishmania siamensis is an emerging disease continuously reported in six southern provinces of Thailand. To date, the phylogenetic relationships among Leishmania isolates from Thai patients and other Leishmania species are still unclear and the taxonomic diversity needs to be established. In this study, the phylogenetic inference trees were constructed based on four genetic loci (i.e., SSU-rRNA, ITS1, hsp70, and cyt b), using DNA sequences obtained from autochthonous VL patients from southern Thailand and reference sequences of reported Leishmania isolates from other studies deposited in GenBank.ResultsPhylogenetic analyses of hsp70 and cyt b loci supported a clade comprised of L. siamensis isolates, which is independent to the other members in the genus Leishmania. In combination with genetic distance analysis, sequence polymorphisms were observed among L. siamensis isolates and two different lineages could be differentiated, lineages PG and TR. Phylogenetic analysis of the cyt b gene further showed that L. siamensis lineage TR is closely related to L. enrietti, a parasite of guinea pigs.ConclusionThe finding of this study sheds further light on the relationships of L. siamensis, both in intra- and inter-species aspects. This information would be useful for further in-depth studies on the biological properties of this important parasite.