The genomic basis of host and vector specificity in non-pathogenic trypanosomatids

The ability of trypanosome parasites to survive and sustain infections is dependent on diverse and intricate immune evasion mechanisms. Pathogenic trypanosomes often have broad host niches that preclude identification of host specific adaptations. In contrast, some non-pathogenic species of the genus Trypanosoma have highly specific hosts and vectors. Trypanosoma theileri, a non-pathogenic parasite of bovines, has a predicted surface protein architecture that likely aids survival in its mammalian host, distinct from the dominant variant surface glycoprotein coat of pathogenic African trypanosomes. In both species, their surface proteins are encoded by genes which account for ~10% of their genome. A non-pathogenic parasite of sheep, Trypanosoma melophagium, is transmitted by the sheep ked and is closely related to T. theileri. To explore host and vector specificity between these closely related species, we sequenced the T. melophagium genome and transcriptome and an annotated draft genome was assembled. T. melophagium was compared to 43 kinetoplastid genomes, including T. theileri. T. melophagium and T. theileri have an AT biased genome, the greatest bias of publicly available trypanosomatids. This trend may result from selection acting to decrease the genome nucleotide cost. The T. melophagium genome is 6.3Mb smaller than T. theileri and large families of proteins, characteristic of the predicted surface of T. theileri, were found to be absent or greatly reduced in T. melophagium. Instead, T. melophagium has modestly expanded protein families associated with the avoidance of complement-mediated lysis. The genome of T. melophagium contains core genes required for development, glycolysis, RNA interference, and meiotic exchange, each being shared with T. theileri. Comparisons between T. melophagium and T. theileri provide insight into the specific adaptations of these related trypanosomatids to their distinct mammalian hosts and arthropod vectors.

Diseases Caused by Amoebae in Fish: An Overview

Parasitic and amphizoic amoebae are ubiquitous and can affect a huge variety of hosts, from invertebrates to humans, and fish are not an exception. Most of the relationships between amoebae and fish are based on four different types: ectocommensals, ectoparasites, endocommensals and endoparasites, although the lines between them are not always clear. As ectocommensals, they are located specially on the gills and particularly the amphizoic Neoparamoeba perurans is the most relevant species, being a real pathogenic parasite in farmed salmon. It causes amoebic gill disease, which causes a progressive hyperplasia of epithelial cells in the gill filaments and lamellae. Nodular gill disease is its analogue in freshwater fish but the causative agent is still not clear, although several amoebae have been identified associated to the lesions. Other species have been described in different fish species, affecting not only gills but also other organs, even internal ones. In some cases, species of the genera Naegleria or Acanthamoeba, which also contain pathogenic species affecting humans, are usually described affecting freshwater fish species. As endocommensals, Entamoebae species have been described in the digestive tract of freshwater and marine fish species, but Endolimax nana can reach other organs and cause systemic infections in farmed Solea senegalensis. Other systemic infections caused by amoebae are usually described in wild fish, although in most cases these are isolated cases without clinical signs or significance.

Prevalence of intestinal parasite among patients attending two hospitals in French Guiana: A 6-year retrospective study

Introduction Intestinal parasitic diseases are a global health problem. Due to its equatorial climate, vast territory with isolated areas and the precariousness of its population, intestinal parasitosis is considered to be a major issue in French Guiana but only few data are available and these mainly focus on specific population. We aimed at determining the parasitic index and at describing the characteristics of these infections in order to develop preventive strategies. Material and methods We retrospectively analysed all the parasitological samples recorded in the register of the two main laboratories of French Guiana between 2011 and 2016. The parasitic index was the percentage of parasitised patients in comparison with the total number of subjects studied. A patient who underwent several positive parasitological examinations was considered only once in the analysis at the time of the first sampling. Results A total of 15,220 parasitological samples of 9,555 patients were analysed and 2,916 were positive in 1,521 patients. The average infestation rate and parasitic index were 19.2% and 16.0%, respectively. The parasitic index remained stable between 2011 (18.2%) and 2016 (18.3%). The patients were mainly men (66.4%), with a median age of 33.0 years (26.3% of patients were under 18 years of age) and lived mainly in the Central Agglomeration (48.2%) and in West Guiana (37.4%). Hookworms were the most common parasite (25.2%) followed by Entamoeba coli (13.3%), Strongyloides stercoralis (10.9%) and Giardia intestinalis (10.8%). Among the infected patients, 31.0% presented mixed infections and 67.5% of them had at least one pathogenic parasite. The patients aged from 0 to 18 years presented significantly more polyparasitism (30.9%) than monoparasitism (24.3%, p<0.001). Ancylostoma sp and Strongyloides stercoralis were mainly diagnosed during the rainy season (59.5% and 64.7% respectively), in men (78.6% and 81.1% respectively) and in patients aged from 18 to 65 years (86.6% and 76.6% respectively) whereas, Giardia intestinalis infected mostly children under 5 years (59.5%) of age. Conclusion Although it may not be representative of the entire Guyanese population, the parasitic index remained high and stable from 2011 and 2016 and it justifies the need for an active prevention program as it was already done in the other French overseas departments such as Martinique and Guadeloupe.

Blastocystis hominis: A Pathogenic Parasite

Background: Blastocystis hominis is recognized as a common intestinal parasite. Some studies have reported the effect of phenotypic, serologic, and biochemical indices on the parasites’ pathogenic characteristics. Objectives: This study aimed to introduce B. hominis as a pathogen, trying to change views about this parasite and introduce it as a parasite important in medical sciences. Methods: An open-ended, language-restricted (English) search was conducted in MEDLINE (PubMed), CINAHL, Scopus, and the Cochrane Library databases (from 1990 to 2018) using specific search criteria to identify Blastocystis spp. Results: The search of the literature retrieved 158 published articles on Blastocystis spp. Among these articles, the ones related to the pathogenicity of B. hominis were selected for further investigations. Results obtained in this study showed that the number of articles within five-year periods had an increasing trend. Also, studies of B. hominis have mainly investigated its pathogenic characteristics, accounting for 37.34% of the studies. Conclusions: This study showed comprehensive reasons for proving the pathogenesis of the parasite. It is hoped that further studies would fill the existing gaps regarding this parasite and identify its true identity as a medically important parasite.

Ultra-structural analysis and morphological changes during the differentiation of trophozoite to cyst in Entamoeba invadens

Entamoeba Histolytica, a pathogenic parasite, is the causative organism of amoebiasis and uses human colon to complete its life cycle. It destroys intestinal tissue leading to invasive disease. Since it does not form cyst in culture medium, a reptilian parasite Entamoeba invadens serves as the model system to study encystation. Detailed investigation on the mechanism of cyst formation, information on ultra-structural changes and cyst wall formation during encystation are still lacking in E. invadens. Here, we used electron microscopy to study the ultrastructural changes during cyst formation and showed that the increase in heterochromatin patches and deformation of nuclear shape were early events in encystation. These changes peaked at ~20h post induction, and normal nuclear morphology was restored by 72h. Two types of cellular structures were visible by 16h. One was densely stained and consisted of the cytoplasmic mass with clearly visible nucleus. The other consisted of membranous shells with large vacuoles and scant cytoplasm. The former structure developed into the mature cyst while the latter structure was lost after 20h, This study of ultra-structural changes during encystation in E. invadens opens up the possibilities for further investigation into the mechanisms involved in this novel process.

Vulvar flap morphology of Haemonchus contortus in naturally infected slaughtered goats in Northern area of Bangladesh

Background: Haemonchus contortus is regarded as one of the most prevalent and highly pathogenic parasite of ruminants. Vulvar flap morphology of female Haemonchus worms is useful to understand the biology of this nematode. Traits of vulvar morphology are considered as markers of ecological adaptation. A study was carried out to determine the types of vulvar flap present in female Haemonchus worms in naturally infected slaughtered goats in Northern area of Bangladesh. Methods: Abomasa of 520 goats (260 from Rajshahi and 260 from Noagon District) collected from January, 2013 through December, 2013 from different slaughter houses of northern area of Rajshahi, Bangladesh. Female Haemonchus worms were collected under a dissecting microscope and then washed under tap water to remove adhered feed residues from their body. All Haemonchus worms from each animal were preserved in 70% ethanol inside individually labeled universal bottles, until they were examined for the types of their vulvar flap. The statistical package SPSS 19 for Windows was used for data analysis. Parameters such as major vulvar morphotypes of Haemonchus spp were compared by Chi-square test in both study areas. Results: The major vulvar morph types was knobbed like (46.1%) followed by linguiform (33.5%) and smooth (20.4%). Out of 260 adult female Haemonchus worms collected from goats of Rajshahi district, 43.0% linguiform, 21.1% smooth and 35.8% knobbed vulvar morphs were identified. In Noagon district, 23.8% linguiform, 19.6% smooth and 56.5% knobbed vulvar morphs were observed. Linguiform type vulvar morphs were predominant in Rajshahi whereas knobbed type in Noagon district. Statistically significant (P<0.001) fluctuation was observed among three major vulvar flap morph types in the study areas. Sub-linguiform B (LB) was most common (96.6%) compared to Sub-linguiform A (LA); 3.4% type vulvar flap. There were no Sub-linguiform C (LC) and Sub-linguiform D (LD) types vulvar flap of Haemonchus spp detected in the study area. Conclusions: The study showed polymorphism in vulvar morphology of female Haemonchus spp of goats in selected area of Bangladesh. The morphological characters of female Haemonchus spp can help in the identification of type of species that occurs in study area.

DETECTION OF INTESTINAL PARASITES IN PUBLIC TRANSPORT BUSES IN BELÉM, PARÁ STATE, NORTHERN BRAZIL

The purpose of this study was to investigate the frequency of intestinal parasites in public transport buses in the city of Belém, Pará, Brazil, as well as to compare the frequency of these enteroparasites according to the bus lines, collection sites within the vehicles, and presence of pathogenic and nonpathogenic parasites in the samples. This is a cross-sectional analytical study carried out between February and April 2019, in which 320 samples were analyzed, from 5 bus lines, 8 buses each, collected from 8 different surfaces inside the vehicles, according to Graham’s method. Subsequently, the statistical test was performed to evaluate the differencesbetween the variables, considering p ≤ 0.05. The results indicated that 7.8% of the samples were parasitized and the right handrail presented the highest prevalence of parasites, namely 2.2%. The pathogenic parasites corresponded to 26.7% and the non-pathogenic 73.3%. The non-pathogenic parasite most commonly found was Entamoeba coli totaling 50%, whereas the only pathogenic parasite was Giardia intestinalis in 26.7%. Thus, the presence of pathogenic and non-pathogenic parasites reflects the precarious hygiene of users of this type of transport, presenting a public health issue which needs to be addressed. KEY WORDS: Intestinal Diseases, Fomites, Transmission, Pathogenic parasites, Enteroparasite