Nongyao Sawangjaroen

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

BackgroundPlasmodium knowlesi, 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.MethodsBlood 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 P. knowlesi using nested PCR assays. Positive samples were also investigated by PCR for Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae and Plasmodium ovale, and were confirmed by sequencing the gene encoding the circumsporozoite protein (csp).ResultsTwo samples, one obtained from a Thai and the other a Myanmese, were positive for P. knowlesi only. Nucleotide sequences of the csp gene derived from these two patients were identical and phylogenetically indistinguishable from other P. knowlesi sequences derived from monkeys and humans. Both patients worked in Koh Song, located in the Kawthoung district of Myanmar, which borders Thailand.ConclusionThis study indicates that transmission of P. knowlesi 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.

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.

Toxoplasmosis-Serological Evidence and Associated Risk Factors among Pregnant Women in Southern Thailand

Toxoplasma gondii is an important parasite in pregnant women. This case-controlled study assessed the seroprevalence of toxoplasmosis in 640 pregnant women in southern Thailand and identified their associated risk factors. The overall seroprevalence of toxoplasmosis was 181 (28.3%). Of this, 138 (21.6%) were positive for only anti-Toxoplasma immunoglobulin G (IgG) antibody, 43 (6.7%) were positive for both IgG and IgM antibodies, and none were positive for IgM antibody. Multivariate analysis revealed that increasing age (adjusted odds ratio [OR] = 1.64, 95% confidence interval [CI] = 1.01-2.67), living outside Songkhla province (adjusted OR = 1.56, 95% CI = 1.08-2.24), parity (adjusted OR = 1.65, 95% CI = 1.01-2.68), contact with cats (adjusted OR = 1.70, 95% CI = 1.20-2.43), and drinking of unclean water (adjusted OR = 1.70, 95% CI = 1.08-2.68) were factors associated with Toxoplasma seroprevalence. On the basis of the results obtained, a health surveillance program should be initiated as a primary preventive measure for congenital toxoplasmosis and focus on educating women of the child-bearing age group to avoid contact with cats and to strictly practice personal hygiene.

Toxoplasma infection in pregnant women: a current status in Songklanagarind hospital, southern Thailand

BackgroundToxoplasmosis, being one of the TORCH’s infections in pregnant women, is caused by Toxoplasma gondii, an obligate intracellular protozoan parasite. This parasitic infection in pregnancy congenitally causes severe outcomes to their fetus and newborn. This study aimed to determine the seroprevalence and stages of Toxoplasma infection in pregnant women and its associated risks exposures.MethodsThe study was conducted within the pregnant women attending the antenatal clinic (ANC) at Songklanagarind hospital, Hat Yai, Songkhla province, Thailand. The sera of a total of 760 consecutive pregnant women were screened using standard commercial ELISA kits for detection of anti-Toxoplasma IgG and IgM antibodies. IgG avidity in the seropositive for both anti-Toxoplasma IgG and IgM antibodies were also assessed. The pregnant women’s socio-demographic, obstetrics and risk factors associated with Toxoplasma seropositivity data were analyzed using univariate and multivariate analyses.ResultsFrom the total 760 pregnant women, 190 (25%, 95% CI = 22.05-28.20) were positive for anti-Toxoplasma antibodies. Of these, 167 (22.0%, 95% CI = 19.0-25.0) were positive for only anti-Toxoplasma IgG antibody and 23 (3.0%, 95% CI = 2.0-4.0) were positive for both anti-Toxoplasma IgG and IgM antibodies. All these samples were high avidity, indicated the infection occured prior to four to five months. By applying statistical univariate analysis, age group, occupation and sources of drinking water showed a significant association with Toxoplasma seropositivity (p < 0.05). Multivariate logistic regression analysis further indicated that the significant factors associated with Toxoplasma seropositivity are age ≥26 (OR = 1.65, 95% CI = 1.11-2.44), working as laborer (OR = 1.57, 95% CI = 1.13-2.18) and drinking unclean (piped/tap/rain) water (OR = 1.75, 95% CI = 1.08-2.84).ConclusionThe pregnant women in the active age group, working as laborers and exposure to unclean drinking water from various sources were at higher risk of Toxoplasma infection. Therefore, health education and the awareness of risk exposures regarding this parasitic disease are required to minimize the effects of this parasitic infection in pregnant women as well as in the general population.

Waterborne parasites: a current status from the Philippines

BackgroundDespite the amount of awareness created, waterborne disease still poses threat, especially in developing countries. Due to the scarcity of reported data on waterborne parasites, the consumption of unsafe water prolongs. Thus, the occurrences of waterborne parasites from various samples were investigated from one of the Southeast Asian country, the Philippines.MethodsA total of thirty three samples, each consisting of twelve liters, were collected and processed to obtain the sediment. Ten liters of sample each was processed to detect Cryptosporidium spp. and Giardia spp. using an immunomagnetic separation method prior to enumeration via fluorescence microscope. Meanwhile, the remaining two liters were cultured to detect Acanthamoeba and Naegleria through microscopy examination and polymerase chain reaction (PCR) analysis.ResultsTwelve samples (36.4%) from river (5), swimming pool (1), pond (3), rain tank (1), and natural lake (2) were positive for Cryptosporidium spp., 17 (45.5%) samples from river (9), pond (2), swimming pool (1), rain tank (1), and natural lake (4) were positive for Giardia spp. while, 13 (33.3%) samples from river (3), swimming pool (2), pond (2), dispenser (1), well (1), tap (2) and natural lake (2) were positive for Acanthamoeba spp. and 5 (18.2%) samples from river (1), natural lake (1), tap (1), dispenser (1) and mineral (1) were Naegleria spp. positive. Physical parameters such as temperature, conductivity, total dissolved solid (TDS), salinity, dissolved oxygen (DO), pH, and turbidity and chemical parameters such as ammonia, chlorine, fluoride, nitrate and nitrite were also measured. The highest chemical contamination was observed at pond 2. A good correlation was observed between Giardia and nitrite (r = 0.736, p < 0.01) and Giardia and nitrate (r = 0.502, p < 0.01).ConclusionThis study was aimed to create greater awareness of parasitic contamination in the water environment in the Philippines and also to act as a platform of the current scenario for policymakers as water pollution is a key health issue in this region.

Comparative Study on Waterborne Parasites between Malaysia and Thailand: A New Insight

This study investigated the distribution of parasites as main contaminants in water environments of peninsular Malaysia (October 2011-December 2011) and the southeastern coast of Thailand (June 2012). Sixty-four water samples, 33 from Malaysia and 31 from Thailand, of various water types were examined according to U.S. Environmental Protection Agency guidelines. Drinking or household water types from both countries were free from parasitic contamination. The recreational/environmental (except a swimming pool in Malaysia) and effluent water types from these two countries were contaminated with waterborne parasites: Giardia (0.04-4 cysts/L), Cryptosporidium (0.06-2.33 oocysts/L), hookworm (6.67-350 ova/L), Ascaris (0.33-33.33 ova/L), and Schistosoma (9.25-13.33 ova/L). The most contaminated sites were recreational lake garden 3 in Malaysia and river 2 in Thailand. Higher concentrations of Giardia, Cryptosporidium, and hookworm were found in samples from Malaysia than in samples from Thailand. The presence of Giardia cysts showed a significant association with the presence of Cryptosporidium oocysts (P < 0.005).

New dioxazole derivatives: synthesis and effects on the growth of Entamoeba histolytica and Giardia intestinalis.

Cyclization of oxime with different aldehydes and ketones under basic condition led to the formation of new dioxazole derivatives and the structure was elucidated by spectral data. The effects of diaoxazoles on the inhibition of growth of Entamoeba histolytica and Giardia intestinalis in vitro have been determined, and selected compounds further investigated for their toxicity. SAR showed that the compounds with 5-nitrothiophene group at the 3-postion of the diaoxazole ring were more active than those with the p-toluene group at the same position. It is interesting to note that the compounds found active against E. histolytica were not found active against G. intestinalis. Toxicity studies showed that the compound 8 and 9 were non-toxic against Vero cell line ATCC CCL-81.

Pathogenic waterborne free-living amoebae: An update from selected Southeast Asian countries

Data on the distribution of free-living amoebae is still lacking especially in Southeast Asian region. The aquatic environment revealed a high occurrence of free-living amoebae (FLA) due to its suitable condition and availability of food source, which subsequently causes infection to humans. A total of 94 water samples consisted of both treated and untreated from Laos (31), Myanmar (42), and Singapore (21) were investigated for the presence of pathogenic FLA. Each water sample was filtered and cultured onto non-nutrient agar seeded with live suspension of Escherichia coli and incubated at room temperature. Morphological identification was conducted for both trophozoites and cysts via microscopic stains (Giemsa and immunofluorescence). The presence of Naegleria-like structures was the most frequently encountered in both treated and untreated water samples, followed by Acanthamoeba-like and Vermamoeba-like features. To identify the pathogenic isolates, species-specific primer sets were applied for molecular identification of Acanthamoeba, Naegleria, and Vermamoeba. The pathogenic species of Acanthamoeba lenticulata and A. triangularis were detected from untreated water samples, while Vermamoeba vermiformis was found in both treated and untreated water samples. Our results suggested that poor water quality as well as inadequate maintenance and treatment might be the cause of this alarming problem since chlorine disinfection is ineffective in eradicating these amoebas in treated water samples. Regular monitoring and examination of water qualities are necessary in order to control the growth, hence, further preventing the widespread of FLA infections among the public.

Comparative study on Toxoplasma infection between Malaysian and Myanmar pregnant women

BackgroundToxoplasma gondii, an obligate intracellular protozoan parasite, causes a disease called toxoplasmosis which can sometimes be acquired congenitally by a newborn from an infected mother. This study aimed to determine the seroprevalence of Toxoplasma infection and its associated risks among 219 and 215 pregnant women from Malaysia and Myanmar, respectively.MethodsAnti-Toxoplasma IgG and IgM antibodies were screened by using standard commercial ELISA kits. The socio-demographic, obstetrics and risk factors associated with Toxoplasma infection data were compared between the two countries.ResultsThe overall prevalence of Toxoplasma infection in Malaysian pregnant women (42.47%; 95% CI = 36.11-49.09) was significantly higher (p < 0.05) than Myanmar pregnant women (30.70%; 95% CI = 27.92-37.16). By univariate analysis, this study identified that age group, education, parity, awareness on toxoplasmosis and consumption of undercooked meat were significantly associated (p < 0.05) with Toxoplasma seropositive Malaysian pregnant women but none of these factors associated with Toxoplasma seropositive Myanmar pregnant women. In comparison using univariate analysis between the two countries, it was found that Toxoplasma seropositive Malaysian pregnant women was associated with aged 30 years and above, secondary or lower-secondary level of education, the third trimester of pregnancy, having one child or more, lacking awareness of toxoplasmosis, absence of bad obstetrics history, having no history of close contact with cats or soil, living on a farm and also consumption of undercooked meat, unpasterized milk or untreated water. Avidity measurement was used to confirm the stages of Toxoplasma infection in pregnant women who were positive for both IgG and IgM antibodies and found all were infected in the past.ConclusionFrom our study, Toxoplasma screening and its risk measurement in pregnant women is firmly recommended for monitoring purposes and assisting proper management, including diagnosis and treatment during antenatal period. Also, it is necessary to initiate preventive measures for Toxoplasma infection among reproductive-age women in general and seronegative pregnant women in particular. Avidity measurement should be incorporated in Toxoplasma routine screening, especially with the availability of a single serum sample to assist in the diagnosis.

Toxoplasma gondii infection: What is the real situation?

The prevalence of chronic Toxoplasma infections reported in the literature varies enormously. We hypothesize that one factor could be due to the different methods used in the evaluation of infections. Serological evidence of Toxoplasma infections in 450 pregnant women (PW) and 300 HIV-infected patients (HIV) were investigated by the Sabin-Feldman dye test and two other commercial ELISA kits (kit1 and kit2). Anti-Toxoplasma IgG antibodies obtained from the Sabin-Feldman dye test, ELISA kit1 and ELISA kit2 in the PW subjects were 14.7%, 29.6% and 38.7%, and in the HIV subjects were 13%, 34.7% and 36.3%, respectively. So there were significant differences in the seroprevalences when different diagnostic tests were used (P<0.05). Regarding Sabin-Feldman dye test as the gold standard for anti-Toxoplasma antibodies detection, we found that the sensitivity and specificity of the ELISA kit1 and kit2 was in the range of their specification. However as the two ELISA kits used in our study identified a much higher prevalence of Toxoplasma infections which indicated that false positive cases were being reported. Based on results obtained, it is therefore highly recommended that research workers should be aware that the reports of serological studies in terms of high positive results should be treated with some skepticism until additional precise diagnostic tools are developed.