The role of parasite persistence in pathogenesis of Chagas heart disease

Chagas disease (CD) is caused by the infection with the protozoan haemoflagellate Trypanosoma cruzi . This disease is still a great menace to public health, and is largely neglected as it affects mostly the poorest populations of Latin America. Nonetheless, there are neither effective diagnostic markers nor therapeutic options to accurately detect and efficiently cure this chronic infection. In spite of the great advances in the knowledge of the biology of natural transmission, as well as the immunobiology of the host–parasite interaction, the understanding of the pathogenesis of CD remains largely elusive. In the recent decades, a controversy in the research community has developed about the relevance of parasite persistence or autoimmune phenomena in the development of chronic cardiac pathology. One of the most notable aspects of chronic CD is the progressive deterioration of cardiac function, derived mostly from structural derangement, as a consequence of the intense inflammatory process. Here we review the evidence supporting the multifactorial nature of Chagas heart disease comprising pathogen persistence and altered host immunoregulatory mechanisms.     

Endoparasites of red fox (Vulpes vulpes) in the Slovak Republic with the emphasis on zoonotic species Echinococcus multilocularis and Trichinella spp.

Summary  Due to specific geographical localization, climatic and geomorphologic conditions, several serious parasitic diseases circulate in the territory of the Slovak Republic that makes this area an ideal model territory of the central European red fox system. The red fox is an important reservoir host of parasites, which can be spread to another animals and humans. Our study was aimed at determining the current prevalence of certain parasites in red foxes from the entire territory of the Slovak Republic and identifies some ecological factors influencing their epidemiology. Within the first systematic investigation of red foxes carried out between the years 2000 and 2006 in total 4026 foxes were examined for Echinococcus multilocularis (prevalence 31.1 %) and 4699 foxes were investigated for the presence of Trichinella spp. larvae (10.4 % infected). The results of the next separate study revealed that 83.3 % of 1198 red foxes in the Slovak Republic had coccidian oocysts and helminth eggs in their faeces. Fifteen helminth species including two trematode, four cestode and nine nematode species were detected by coprological examination. Nine of these parasite taxa have zoonotic potential: Capillaria spp. (prevalence 22.4 %), Ancylostoma caninum (18.1 %), Toxocara canis (12.5 %), Taenia spp. (12.2 %), Mesocestoides spp. (5.8 %), Strongyloides stercoralis (1.6 %), Hymenolepis diminuta (0.6 %), Dipylidium caninum (0.4 %) and Opisthorchis felineus (0.3 %). Toxascaris leonina was the most common helminth species found in this survey (42.9 %).     

武鸣县人体肠道寄生虫病监测结果分析

目的了解武鸣县肠道寄生虫感染现状,为今后的防治工作提供可靠依据。方法收集本单位历年人群粪便检查等疫情资料进行汇总分类和分析。粪便检查方法采用改良加藤法和醚醛法。结果 1990-1995年查出肠道寄生虫13种,感染率为61.93%,其中线虫感染率为42.37%,吸虫感染率为28.38%。1996-2000年线虫感染率下降至20.32%,吸虫感染率上升至32.12%。2001-2008年查出7种虫种,线虫感染率降至4.81%,吸虫感染率上升至44.00%。结论肠道寄生虫感染虫种大幅下降,部分线虫、原虫感染率已控制在较低水平,肝吸虫感染率逐年上升,已成为主要感染虫种,应加强防控工作。     

Parasite density and serum cytokine levels in Plasmodium vivax malaria in Turkey

We aimed to investigate the relationship between quantitative Plasmodium vivax parasitaemia and serum cytokine levels in a highly endemic region of Turkey, where such a relation has not been investigated before. Active screening was done in a total of 1316 people residing in 33 villages of Sanliurfa province, Turkey. The study population consisted of 79 consecutive patients with P. vivax malaria, and a control group included 89 healthy subjects. Thick blood smears were examined for malaria parasite and parasite count. Serum samples were analysed for IL-1beta, IL-2, IL-4, IL-6, IL-8, IL-10 and IL-12 by the ELISA method. Compared to controls, levels of pro-inflammatory cytokines, i.e. IL-1beta, IL-6 and IL-12, were significantly higher in patients with parasitaemia. There was a significant positive correlation between serum IL-10 and IL-12 levels and the parasite burden (r = 0.264, P = 0.024 and r = 0.264, P = 0.024, respectively). Serum IL-8 levels showed a significant negative correlation with parasite burden (r =-0.356, P = 0.002). There was a positive correlation between IL-8 levels and age, while the opposite was observed for IL-12. High fever was correlated with IL-6 and IL-10 levels. Compared to controls, patients with a parasite count greater than 5000/microL had a significantly higher IL-1beta and IL-10 levels (P < 0.05), while the difference was not significant for patients with a parasite count less than 1000/microL. Thus, we can conclude that pro-inflammatory response against P. vivax gains more importance during periods of increased parasite burden.     

A new standard for the assessment of disease progression in murine cutaneous leishmaniasis

Infection of mice with Leishmania major has been used both as a model for the cutaneous disease in humans and as a model for the more general control and function of helper T cells in immunity. In both cases, disease patterns and disease progression have been assessed by two complementary methods, lesion size and parasite burden in the draining lymph nodes. We propose a much improved method for the graphical representation of lesion development which conveys more information with better accuracy. We also describe a polymerase chain reaction method for determining parasite burden, which is faster and allows the analysis of larger numbers of experimental animals than the current limiting dilution analysis. Moreover, these methods are equally applicable to other infectious diseases, an obvious one being schistosomiasis.     

Parasitic rachiopagus conjoined twins with herniation of the autosite spinal cord into the parasite: case report

A female newborn was found to have a rachiopagus parasite consisting of hypoplastic lower limbs attached to the dorsal thoracolumbar region; at surgery, when the infant was 30 days old, the autosite spinal cord was found to have herniated through a spina bifida into the parasite.     

The evolution of immune-related genes from disease carrying mosquitoes: diversity in a peptidoglycan- and a thioester-recognizing protein

Adaptive polymorphism may be common in immune system genes as co-evolutionary interactions foster diversity; either through ongoing positive selection (arms races), or balancing selection. DNA sequence diversity in two putative immune system genes was examined in species of the genus Anopheles and from Aedes aegypti. For one gene, encoding the peptidoglycan recognizing protein PGRPLB, there was evidence of purifying selection, suggesting that selection acts to eliminate sequence variation. For another gene, encoding the thioester-containing protein TEP3, higher levels of amino acid replacement were found than would be expected under neutral models of evolution - an indication that this gene has been subject to repeated bouts of positive selection.     

微山县人体肠道寄生虫病流行现状调查

目的了解微山县农村人群人体肠道寄生虫感染现状. 方法 2002年采用分层整体随机抽样方法抽取3个村,对抽取到的人群进行人体肠道寄生虫感染调查. 结果共调查1 570人,查出7种肠道寄生虫,感染率6.34%,感染者以10～14岁年龄组最高. 结论感染率较1989年第1次调查结果有大幅度下降.卫生条件差,卫生习惯不良是存在的主要问题.应加强农村卫生知识普及、粪便无害化处理和重点人群药物驱虫.     

Identification and biochemical characterisation of a protein phosphatase 5 homologue from Plasmodium falciparum

We report the identification of a new serine/threonine phosphatase from Plasmodium falciparum at the DNA and protein levels. A 1.8 kb cDNA fragment encoding the protein phosphatase was identified via PCR amplification. The sequence has a coding capacity of 594 amino acids. Immunoblot analysis of P. falciparum extracts showed that antibodies generated against the His₆-fusion protein recognise a protein of approximately 80 kDa. The deduced amino acid sequence shares 55% identity with a mouse protein, identified as Protein Phosphatase 5 (PP5). We show that the P. falciparum PP5 homologue (PfPP5) has all structural and functional characteristics of this class of enzymes. It contains three tetratricopeptide repeats (TPR) and a nuclear targeting sequence at its N-terminus and a highly conserved C-terminal catalytic domain. Southern blot results are compatible with the existence of PfPP5 as a single copy gene. Purified recombinant protein, like the native protein enriched from P. falciparum extracts exhibited phosphatase activity that can be enhanced by both arachidonic and oleic acids, but not by myristic or stearic acid. In addition, the activity is inhibited by okadaic acid (OA) with an IC₅₀ of 4 nM. Immunofluorescence microscopy has localised PfPP5 preferentially to the nucleus. The function of PfPP5 is presently unclear, but like other PP5s of many eukaryotic organisms, it may have important regulatory functions in the parasite cell cycle.