Human Plasmodium knowlesi infection in Ranong province, southwestern border of Thailand

<p>Abstract</p> <p>Background</p> <p><it>Plasmodium knowlesi</it>, a simian malaria parasite, has been reported in humans in many Southeast Asian countries. In Thailand, most of the limited numbers of cases reported so far were from areas near neighbouring countries, including Myanmar.</p> <p>Methods</p> <p>Blood samples collected from 171 Thai and 248 Myanmese patients attending a malaria clinic in Ranong province, Thailand, located near the Myanmar border were investigated for <it>P. knowlesi </it>using nested PCR assays. Positive samples were also investigated by PCR for <it>Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae </it>and <it>Plasmodium ovale</it>, and were confirmed by sequencing the gene encoding the circumsporozoite protein (<it>csp</it>).</p> <p>Results</p> <p>Two samples, one obtained from a Thai and the other a Myanmese, were positive for <it>P. knowlesi </it>only. Nucleotide sequences of the <it>csp </it>gene derived from these two patients were identical and phylogenetically indistinguishable from other <it>P. knowlesi </it>sequences derived from monkeys and humans. Both patients worked in Koh Song, located in the Kawthoung district of Myanmar, which borders Thailand.</p> <p>Conclusion</p> <p>This study indicates that transmission of <it>P. knowlesi </it>is occurring in the Ranong province of Thailand or the Kawthoung district of Myanmar. Further studies are required to assess the incidence of knowlesi malaria and whether macaques in these areas are the source of the infections.</p

Parasitic infections in HIV infected individuals: Diagnostic & therapeutic challenges

After 30 years of the human immunodeficiency virus (HIV) epidemic, parasites have been one of the most common opportunistic infections (OIs) and one of the most frequent causes of morbidity and mortality associated with HIV-infected patients. Due to severe immunosuppression, enteric parasitic pathogens in general are emerging and are OIs capable of causing diarrhoeal disease associated with HIV. Of these, Cryptosporidium parvum and Isospora belli are the two most common intestinal protozoan parasites and pose a public health problem in acquired immunodeficiency syndrome (AIDS) patients. These are the only two enteric protozoan parasites that remain in the case definition of AIDS till today. Leismaniasis, strongyloidiasis and toxoplasmosis are the three main opportunistic causes of systemic involvements reported in HIV-infected patients. Of these, toxoplasmosis is the most important parasitic infection associated with the central nervous system. Due to its complexity in nature, toxoplasmosis is the only parasitic disease capable of not only causing focal but also disseminated forms and it has been included in AIDS-defining illnesses (ADI) ever since. With the introduction of highly active anti-retroviral therapy (HAART), cryptosporidiosis, leishmaniasis, schistosomiasis, strongyloidiasis, and toxoplasmosis are among parasitic diseases reported in association with immune reconstitution inflammatory syndrome (IRIS). This review addresses various aspects of parasitic infections in term of clinical, diagnostic and therapeutic challenges associated with HIV-infection

รายงานวิจัยฉบับสมบูรณ์โครงการแผนการวิจัยผลิตภัณฑ์ธรรมชาติ : การพัฒนายาต้านแบคทีเรียและยาต้านปรสิต

The Thailand Research Fun

Characterization and localization of cathepsin B proteinases expressed by adult Ancylostoma caninum hookworms

The hookworm Ancylostoma caninum induces human eosinophilic enteritis (EE), probably via allergic responses to its secretions. Cysteine and metallo-proteinases may be the components of these secretions that elicit hypersensitivity reactions. In order to characterize genes encoding cysteine proteinases (CP) secreted by A. caninum, an adult hookworm cDNA library was constructed and screened with a cloned fragment of a hookworm CP gene. This fragment was obtained using consensus oligonucleotide, CP-gene-specific primers in the polymerase chain reaction. cDNAs encoding two CPs were obtained from the library and sequenced. The first gene, AcCP-1, encoded a cathepsin B-like zymogen CP of 343 amino acids (aa), predicted to be processed in vivo into a mature CP of 255 aa. Closest nucleotide identities were to Haemonchus contortus cysteine protease (61%) and to human cathepsin B (60%). The second gene, AcCP-2, encoded a mature CP of 254 aa, that showed 86% identity to AcCP-1, and 58% and 47% identity to bovine cathepsin B and human cathepsin B, respectively. Rabbit antisera raised against recombinant AcCP-1 reacted with esophageal, amphidial and excretory glands in formalin-fixed, paraffin embedded sections of both male and female adult hookworms, and with an antigen of approx. 40 kDa in Western blot analysis of excretory/secretory products from adult hookworms. Together, these immuno-hybridization results strongly suggest that the CP encoded by the AcCP-1 gene is secreted by hookworms. These are the first reported CP genes from hookworms. Proteinases encoded by these genes may be responsible for the CP activity that we have shown previously to be secreted by adult A. caninum