Veeranoot Nissapatorn

Specific, Sensitive, and Rapid Diagnosis of Active Toxoplasmosis by a Loop-Mediated Isothermal Amplification Method Using Blood Samples from Patients

ABSTRACT Loop-mediated isothermal amplification (LAMP), a rapid nucleic acid amplification method, was developed for the clinical diagnosis of toxoplasmosis. Three LAMP assays based on the SAG1, SAG2, and B1 genes of Toxoplasma gondii were developed. The sensitivities and specificities of the LAMP assays were evaluated by comparison with the results of conventional nested PCR. The LAMP assays were highly sensitive and had a detection limit of 0.1 tachyzoite, and no cross-reactivity with the DNA of other parasites was observed. Blood was collected from 105 individuals to test the LAMP assays: 40 patients with active toxoplasmosis, 40 negative controls, and 25 patients with other parasitic infections. The SAG2-based LAMP (SAG2-LAMP) had a greater sensitivity (87.5%) than the SAG1-LAMP (80%), B1-LAMP (80%), and nested PCR (62.5%). All the LAMP assays and nested PCR were 100% specific. This is the first report of a study which applied the LAMP method to diagnose toxoplasmosis from human blood samples. Due to its simplicity, sensitivity, and specificity, LAMP is suggested as an appropriate method for routine diagnosis of active toxoplasmosis in humans.

Toxoplasmosis: prevalence and risk factors

A total of 200 pregnant women were recruited in this cross-sectional study. The overall seroprevalence of toxoplasmosis in pregnant women was found to be 49%, in which 39%, 4% and 6% for anti-Toxoplasma IgG, IgM and both anti-Toxoplasma IgG and IgM antibodies, respectively. We found the differences in Toxoplasma seroprevalence rates among the races were significant: the highest rate was in the Malays (55.7%), followed by the Indian (55.3%) and the Chinese (19.4%) (P < 0.05) populations. An increase in Toxoplasma seroprevalence with increasing parity was detected (P < 0.05). Women with no children had a prevalence of 39.7%, while women with one or more than two children had a prevalence of 44.2% and 62.9%, respectively. In this study, there was no significant association between Toxoplasma seroprevalence and various possible risk factors in pregnant women (P > 0.05). When multivariate analysis was performed, no significant association between Toxoplasma seroprevalence and history of contact with cats, consumption of undercooked meat and blood transfusion was found (P > 0.05). We did not find any newly diagnosed cases of acute acquired toxoplasmosis in pregnancy during the study period.

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.

Increased detection of Plasmodium knowlesi in Sandakan division, Sabah as revealed by PlasmoNex™

BackgroundPlasmodium knowlesi is a simian malaria parasite that is widespread in humans in Malaysian Borneo. However, little is known about the incidence and distribution of this parasite in the Sandakan division, Malaysian Borneo. Therefore, the aim of the present epidemiological study was to investigate the incidence and distribution of P. knowlesi as well as other Plasmodium species in this division based on a most recent developed hexaplex PCR system (PlasmoNex™).MethodsA total of 189 whole blood samples were collected from Telupid Health Clinic, Sabah, Malaysia, from 2008 to 2011. All patients who participated in the study were microscopically malaria positive before recruitment. Complete demographic details and haematological profiles were obtained from 85 patients (13 females and 72 males). Identification of Plasmodium species was conducted using PlasmoNex™ targeting the 18S ssu rRNA gene.ResultsA total of 178 samples were positive for Plasmodium species by using PlasmoNex™. Plasmodium falciparum was identified in 68 samples (38.2%) followed by 64 cases (36.0%) of Plasmodium vivax, 42 (23.6%) cases of P. knowlesi, two (1.1%) cases of Plasmodium malariae and two (1.1%) mixed-species infections (i e, P. vivax/P. falciparum). Thirty-five PlasmoNex™ positive P. knowlesi samples were misdiagnosed as P. malariae by microscopy. Plasmodium knowlesi was detected in all four districts of Sandakan division with the highest incidence in the Kinabatangan district. Thrombocytopaenia and anaemia showed to be the most frequent malaria-associated haematological complications in this study.ConclusionsThe discovery of P. knowlesi in Sandakan division showed that prospective studies on the epidemiological risk factors and transmission dynamics of P. knowlesi in these areas are crucial in order to develop strategies for effective malaria control. The availability of advanced diagnostic tool PlasmoNex™ enhanced the accuracy and accelerated the speed in the diagnosis of malaria.

Detection of Naegleria Species in Environmental Samples from Peninsular Malaysia

Background In Malaysia, researchers and medical practitioners are unfamiliar with Naegleria infections. Thus little is known about the existence of pathogenic Naegleria fowleri, and the resultant primary amoebic meningoencephalitis (PAM) is seldom included in the differential diagnosis of central nervous system infections. This study was conducted to detect the presence of Naegleria species in various environmental samples. Methods/Findings A total of 41 Naegleria-like isolates were isolated from water and dust samples. All these isolates were subjected to PCR using two primer sets designed from the ITS1-ITS2 regions. The N. fowleri species-specific primer set failed to produce the expected amplicon. The Naegleria genus-specific primers produced amplicons of 408 bp (35), 450 bp (2), 457 bp (2) or 381 bp (2) from all 41 isolates isolated from aquatic (33) and dust (8) samples. Analysis of the sequences from 10 representative isolates revealed that amplicons with fragments 408, 450 and 457 bp showed homology with non-pathogenic Naegleria species, and 381 bp showed homology with Vahlkampfia species. These results concurred with the morphological observation that all 39 isolates which exhibited flagella were Naegleria, while 2 isolates (AC7, JN034055 and AC8, JN034056) that did not exhibit flagella were Vahlkampfia species. Conclusion To date, pathogenic species of N. fowleri have not been isolated from Malaysia. All 39 isolates that produced amplicons (408, 450 and 457 bp) from the genus-specific primers were identified as being similar to nonpathogenic Naegleria. Amplicon 408 bp from 5 representative isolates showed 100% and 99.7% identity to Naegleria philippinensis isolate RJTM (AM167890) and is thus believed to be the most common species in our environment. Amplicons 450 bp and 457 bp were respectively believed to be from 2 new species of Naegleria, since representative isolates showed lower homology and had a longer base pair length when compared to the reference species in the Genbank, Naegleria schusteri (AJ566626) and Naegleria laresi (AJ566630), respectively.

Seroprevalence and Sources of Toxoplasmosis among Orang Asli (Indigenous) Communities in Peninsular Malaysia

This study aims to evaluate the current seroprevalence of toxoplasmosis among indigenous communities in Peninsular Malaysia and relate its association with epidemiological data. Overall seroprevalence of Toxoplasma gondii was 37.0% with 31.0% immunoglobulin (Ig) G, 1.8% IgM, and 4.2% seropositivity for both anti-Toxoplasma antibodies. Multivariate analysis showed that age above 12 years (odds ratio [OR] = 2.70, 95% confidence interval [CI] = 1.75-4.04, P < 0.001), using untreated river and mountain water supplies (OR = 1.50, 95% CI = 1.01-2.40, P = 0.050), and close proximity with cats (OR = 1.40, 95% CI = 1.10-1.76, P = 0.010) were factors associated with toxoplasmosis. Given the high seroprevalence of toxoplasmosis among these communities who live in poor socioeconomic conditions, a comprehensive health surveillance program and screening should be initiated among women of childbearing age and pregnant women during the antenatal period for early diagnosis and treatment. The role of domestic cats and environmental contamination with oocyst in soil and water has to be highlighted and addressed in future prevention strategies for these communities.

AIDS-defining illnesses: a comparison between before and after commencement of highly active antiretroviral therapy (HAART)

Attempts to address the significant impact of HAART on medical variables on the Malaysian HIV/AIDS population have yet to be evaluated. This study aims to analyze the proportions of AIDS-defining illnesses (ADIs) before and after HAART. A retrospective study was carried out on 128 new cases of HIV infected patients who first commenced HAART in 2004 at the national HIV reference center. Before commencement of HAART, 76 clinical episodes of ADIs were recorded in 52 patients. Most common being pulmonary Mycobacterium tuberculosis (28.9%), PCP (27.6%) and disseminated and extrapulmonary Mycobacterium tuberculosis (11.8%). During HAART, 8 clinical episodes of ADIs were documented in 7 patients with a median time of onset of 10 weeks after initiation of HAART (range, 4-36 weeks). The median CD4 count at the time of the commencement of HAART for these patients was 11 cells/mm(3). ADIs reported include PCP (2 episodes), disseminated and extrapulmonary Mycobacterium tuberculosis (2 episodes), extrapulmonary cryptococcosis (1 episode), esophageal candidiasis (1 episode), recurrent pneumonia (1 episode) and disseminated or extrapulmonary histoplasmosis (1 episode). Three (37.5%) of these occurred despite a reduction of viral load by at least 2 log(10) and an increased in the CD4 cell count. In conclusion, ADIs can still present after the initiation of successful HAART especially in those with CD4 counts below 100 cells/mm(3). In Malaysia, ADIs are the major causes of HIV/AIDS associated morbidity and mortality, thus increased awareness on the management of these illnesses is warranted especially in the months following HAART.

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.