Search PubMed⌕ Search

Biomedical subjects

Pratap Singhasivanon

Publications and source records attributed to Pratap Singhasivanon.

At least 37 records · Page 2Linked to original sources
PubMed2005

Water quality and breeding habitats of anopheline mosquito in northwestern Thailand.

Malaria transmission is dependent upon many hydrology-driven ecological factors that directly affect the vectorial competence, including the presence of suitable habitats for the development of anopheline larvae. Larval habitats were identified and characterized at three malaria endemic villages (Ban Khun Huay, Ban Pa Dae, and Ban Tham Seau) in Mae Sot district, Tak Province, in northwestern Thailand between July 2002 and June 2003. The Global Positioning System (GPS) was used to provide precise locational data for the spatial distribution of anopheline mosquito larvae and their habitats. Ten habitat categories were identified. Eighteen adult Anopheles species were identified from larvae in all the surveyed habitats. An. minimus was the most common species throughout the year. The relationship between eight abiotic variables (temperature, hardness, carbon dioxide, dissolved oxygen, nitrate, phosphate, silica and pH) and the abundance of four major species of malaria vectors (An. (Cel.) dirus, An. (Cel.) minimus, An. (Cel.) maculatus, and An. (Cel.) sawadwongporni), and six species of non-vectors (An. (Cel.) kochi, An. (Cel.) jamesii, An. (Ano.) peditaeniatus, An. (Ano.) barbirostris, An. (Ano.) campestris, and An (Cel.) vagus) larvae was investigated. The results from the multiple regression models suggest that hardness, water temperature and carbon dioxide are the best predictor variables associated with the abundance of An. minimus larvae (p < 0.001); water pH for An. dirus larvae (p < 0.001); temperature and pH for An. kochi larvae (p < 0.01); temperature and silica concentration for An. jamesii larvae (p < 0.001); dissolved oxygen and silica concentration for An. campestris larvae (p < 0.001); and pH and silica concentration for An. vagus larvae (p < 0.001). We could not identify key environmental variables for An. maculatus, An. sawadwongporni, An. peditaeniatus, and An. barbirostris.

Animals↗
PubMed2005

Chronicle of malaria epidemics in Thailand, 1980-2000.

The occurrence of malaria epidemics in Thailand was reviewed from the malaria surveillance report of the National Malaria Control Program. The literature review revealed that the four epidemic periods recorded during 1980-2000 almost always occurred in the provinces and districts located along international borders. Malaria epidemics are caused by various factors such as: extensive population movement, multi-drug resistance development, low immune status of the population, lack of knowledge and appropriate personal protection against mosquito biting, and the re-emergence of malaria transmission in low malarious areas. Such factors can lead to changes in the parasite ratio and appearance of malaria epidemics throughout the country. Evidence related to the burden of malaria epidemics was also reviewed to identify causal factors that will be helpful in future research.

Cambodia↗
PubMed2005

In vitro susceptibility and genetic variations for chloroquine and mefloquine in Plasmodium falciparum isolates from Thai-Myanmar border.

In vitro drug susceptibility to chloroquine (CQ) and mefloquine (MF) were assessed in 39 P. falciparum isolates from the Thai-Myanmar border area. To further characterize CQ- and MF-resistance profiles in this area, we also analyzed pfcrt K76T mutation that is critical for CQ resistance, and pfmdr1 polymorphism that has an association with MF resistance. Eighteen isolates were successfully examined by in vitro tests for CQ, and 17 of them had resistance to the drug. Geometric mean concentration of CQ that inhibited the growth of parasites at 50% (IC50) was 371 +/- 227 nM (105-971 nM). Sixteen isolates were successfully examined by in vitro tests for MF, and 8 of them were resistant to the drug. Geometric mean of IC50 for MF was 41 +/- 31 nM (4-125 nM). Genotypes of drug resistance, such as pfcrt and pfmdr1 mutations, were also analyzed. All the 39 isolates had the same haplotype (CVIET) for PfCRT at its 72-76th amino acids. A pfmdr1 Y86 mutation was found in 95% of isolates. A pfmdr1 D1042 mutation was also present in 7 isolates, while no pfmdr1 Y1246 mutation was observed. These results indicated a correlation between CQ resistance and the pfcrt T76 and pfmdr1 Y86 mutations.

Animals↗
PubMed2005

Causal relationship between health promoting behavior and quality of life in cervical cancer patients undergoing radiotherapy.

The purpose of this cross-sectional study was to examine the causal relationships among age, education, family income, and stage of carcinoma, perceived benefits, perceived barriers, perceived self-efficacy, health promoting behavior and quality of life in patients with cervical cancer. Pender's Health Promotion Model (1996) provided a guide for the conceptual framework of this study. Purposive sampling was employed to recruit 488 cervical cancer patients who were undergoing radiotherapy at seven public hospitals in five areas of Thailand. The instruments used in this study included a Personal Data Form, Cognitive perception Form, Health promoting behavior scale, the social support questionnaire and The Functional Assessment of Cancer Therapy General (FACT-G) form. The proposed model was tested and modified by the LISREL Program. The modified model adequately fitted with the data. The results demonstrate that health promoting behavior had a significant direct positive effect on quality of life (beta = 0.71, p < 0.01). Cognitive perceptual factors had a significant direct effect on health promoting behaviors (P = 0.69, p < 0.01). Social support had a significant direct effect on the cognitive perceptual factors (P = 0.64, p < 0.01), health promoting behavior (beta = 0.70, p < 0.01), and the quality of life (beta = 0.48, p < 0.01). Age and education did not have a significant total effect on the quality of life. Family income had a significant direct effect on cognitive perceptual factors (beta = 0.10, p < 0.05). The stage of cancer had a significant direct negative effect on cognitive perceptual factors (beta = -0.11, p < 0.05) and the quality of life (beta = -0.12, p < 0.01). The direct effect of the predictors on the quality of life indicated that cervical cancer patients with higher practice of health promoting behavior tended to have a higher quality of life. The findings indicate that Pender's Health Promotion Model is a useful guide for explaining and predicting the health promoting behavior and the quality of life of Thai cervical cancer patients who were undergoing radiotherapy. The significance of cognitive perceptual factors and social support confirm health promoting behavior as a goal directed towards the level of well being. This has implications for health care systems in planning interventions to promote health promoting behavior in a health promotion setting in cervical cancer patients for a better quality of life and healthy. A longitudinal study and experimental study are recommended for further study.

Adult↗
PubMed2005

The Asian center of international parasite control (ACIPAC): five years of achievement. I. Introduction.

ACIPAC has made an effort to promote the concept of the school-based approach to malaria and STH control, mainly through human resource development, which could be eventually extended to any other health promotion program. Implementation of SSPP resulted in the establishment of national policies on parasite control and/or school health in some partner countries. It also provides a good opportunity for the formulation of partnerships among health and education sectors and international partners, although it did cause some problems concerning the enrollment of persons of authority from partner countries, and the staff of JICA resident offices as well. As described in the Joint Evaluation Report, ACIPAC is expected to further contribute to human resource development and to strengthening human resource and information networking at regional and global levels.

Asia↗
PubMed2004

Comparison of artesunate and chloroquine activities against Plasmodium vivax gametocytes.

The gametocidal activities of chloroquine and artesunate were compared. The relative risk (RR) of having detectable gametocytes appear after treatment initiation was lower in artesunate-treated patients (n = 792) than in chloroquine-treated patients (n = 695) (RR = 0.29; 95% CI = 0.2 to 0.40; P < 0.0001). The duration and magnitude of gametocyte carriage were also lower for artesunate than chloroquine. By reducing the transmission of Plasmodium vivax to the vector, artesunate could therefore reduce the incidence of P. vivax malaria.

Adolescent↗
PubMed2004

Association of intestinal helminths with decreased liver size and sCD23 concentration during falciparum malaria.

To determine if intestinal helminths and the CD23/nitric oxide pathway had an influence on liver size, we conducted a cross-sectional study on 438 patients with confirmed P. falciparum malaria admitted at the Hospital for Tropical Diseases in Bangkok. For all patients the liver size was measured as number of centimeters below the rib cage, a stool examination was conducted, and CD23 and reactive nitrogen intermediates were measured. The median liver size was smaller in helminth-infected patients than in helminth-free patients (chi2 for trend = 9.1, p = 0.003). Liver size significantly increased with the concentration of sCD23 (p < 0.0001). The median sCD23 concentration (OD) was significantly lower in helminth-infected patients than in helminth-free patients, respectively 0.33 (quartiles 0.24-0.57) and 0.45 (quartiles 0.27-0.59), (p = 0.01). There was a negative correlation between sCD23 concentrations and RNI (Spearman's rho = -0.40, p < 0.0001). All the above results remained significant after controlling for potential confounders. These results are compatible with a CD23/NO-mediated decrease in liver size in helminth-infected patients.

Adolescent↗
PubMed2004

Gender difference in treatment seeking behaviors of tuberculosis cases in rural communities of Bangladesh.

This descriptive cross-sectional study was conducted to investigate gender differences in the epidemiological factors associated with the treatment seeking behaviors of TB cases in the rural communities of Bangladesh. The study reveals that there is significant gender difference in treatment seeking behaviors of rural TB cases and the majority of them (52%) have taken prior treatment from various traditional healers, 70% of them are females who attended health centers (UZHCs) as the other choice (adjusted OR: 4.2, 95% CI: 2.0-8.4). It was found that the mean patient delay was 63 days (range 14-210 days) where half of the females delayed more than 60 days while they were spreading their disease. The study findings reveal gender differences in treatment seeking behaviors associated with socio-cultural barriers, particularly among females in their access to TB care. Fifty-five percent of cases wanted the diagnosis of TB remain confidential to avoid being labeled as TB patients, where 82.7% were female, 85.6% of female TB patients had problems in their relationships with their spouse (61%) and family members (58%) after being diagnosed with TB. The results of the TB service factors found that 39% of females were not satisfied with their provider's behaviors, which was significantly associated with treatment seeking behavior (adjusted OR: 2.6, 95% CI: 1.0-6.6). The study findings strongly suggest that there was a significant gender difference in treatment seeking behavior in rural Bangladesh. Based on the study findings, we recommend developing an appropriate gender strategy for developing a TB control program, comprised of operational, socio-cultural and community awareness interventions aimed at treating undiscovered reservoirs of female TB cases in rural Bangladesh.

Adolescent↗
PubMed2004

Risk factors for Plasmodium vivax gametocyte carriage in Thailand.

To study the risk factors for Plasmodium vivax gametocyte carriage, the presence or absence of gametocytes was determined in 2,125 patients with P. vivax malaria participating in clinical trials at the Hospital for Tropical Diseases in Bangkok, Thailand. Stepwise logistic regression models were used to determine which variables were significantly related to gametocyte carriage. On admission, 615 patients (29%) had detectable gametocytes (before treatment). After treatment had started, an additional 245 patients (11%) developed patent gametocytemia. The variables retained by multivariate analysis were highest observed temperature (adjusted odds ratio [AOR] per degrees C increase = 0.82, 95% confidence interval [CI] = 0.71-0.94, P = 0.006), asexual parasitemia > 9,200/muL (AOR = 2.8, 95% CI = 1.9-4.2, P < 0.0001), erythrocyte counts (AOR = 0.8/million/muL increase, 95% CI = 0.67-0.95, P = 0.01), monocyte percentage (AOR = 0.93 per % increase, 95% CI = 0.89-0.96, P < 0.0001), lymphocyte percentage (AOR = 0.98 per % increase, 95% CI = 0.97-0.99, P = 0.006), albumin (AOR = 0.67 per 10 g/mL increase, 95% CI = 0.5-0.9, P = 0.007), and anion gap (AOR = 1.1 per unit increase, 95% CI = 1.02-1.14, P = 0.009). The possible significance of these observations is discussed.

Adolescent↗
PubMed2004

A survey of the Th2R and Th3R allelic variants in the circumsporozoite protein gene of P. falciparum parasites from western Thailand.

Allelic variation in the Plasmodium falciparum circumsporozoite protein (CS) gene has been determined by sequencing the immunodominant T-cell epitopes, Th2R and Th3R, from 95 isolates from two malaria-endemic areas in the west of Thailand. Comparison with a reference sequence revealed only non-synonymous point mutations in the two epitope regions. Point mutations were found outside these epitopes in a minority of samples, and all but four were also non-synonymous. A relatively high number of variants, 11 Th2R and 9 Th3R, were detected and comprised some that had not been previously observed. However, the Th2R*05 and the Th3R*01 allelic variants predominated, as they were found in more than 70% of the 101 sequences obtained.

Alleles↗
PubMed2004

Gender differences in epidemiological factors associated with treatment completion status of leprosy patients in the most hyperendemic district of Nepal.

The introduction of multidrug therapy (MDT), recommended by WHO, has been a major advance in the treatment of leprosy because of its relatively short treatment course and low rate of relapse. Although leprosy treatment is provided to both sexes equally, in most parts of the world significant differences have been found in treatment status. The main objective of the study was to investigate gender differences in epidemiological factors associated with treatment status of leprosy patients. An analytic cross-sectional study was carried out in the most hyperendemic Dhanusa District, Nepal. Stratified random sampling was applied for selection of the patients. Statistical analysis of the differences in treatment status, between males and females, and among other epidemiological factors of interest was carried out using multiple logistic regression. Chi-square/Fisher's exact test were also used to assess significant differences in values between males and females. There were 580 leprosy patients (385 male and 195 female) aged >15 years registered for MDT between April 1, 2001 to March 31, 2002 in the 16 main health centers of the district. Of the 580 patients, a total of 273 (183 male and 90 female) were included in the study, to collect data on clinical type of leprosy, patterns of physical deformity/disability, site of skin lesions, and socio-demographic information. There were 183 male (68.3% on MB-MDT) and 90 female (61.1% MB-MDT) leprosy patients. We found that 79.2% of male patients completed treatment, while 34.4% female patients did not complete within the given time frame. Significant gender differences among leprosy patients were found in the distribution of disability grades and treatment completion status. However, there was no significant gender difference in the distribution of leprosy types and skin lesion sites. The study also found significant associations between treatment completion status and gender (adjusted OR 2.05, 95% CI: 1.07-3.94), educational status (adjusted OR 2.37, 95% CI: 1.12-4.99), disability grade I (adjusted OR 3.14, 95% CI: 1.23-8.04), and disability grade 0 (adjusted OR 2.92, 95% CI: 1.14-7.47) after adjustment for all other leprosy/demographic factors.

Adolescent↗
PubMed2004

Application of real-time polymerase chain reaction (PCR) analysis for detection and discrimination of malaria parasite species in Thai patients.

A TaqMan real-time PCR system was used to detect and discriminate the 4 species of human malaria parasites in clinical blood samples. A 150-base pair (bp) region of the small subunit ribosomal RNA (SSU rRNA) gene of each malaria parasite, including species-specific sequences to be detected by TaqMan probe, was used as a target for PCR analysis. The PCR method used universal primers and species-specific TaqMan probes for Plasmodium falciparum, P. vivax, P. ovale, and P. malariae. The detection threshold for the method, as determined with serial dilution of cultured P. falciparum-infected erythrocytes, was 5 parasite-infected erythrocytes per reaction. Fifty blood samples of falciparum malaria and a second set of 50 samples of vivax malaria, diagnosed by microscopic examination at the Hospital for Tropical Diseases, Mahidol University, Thailand, were analyzed by real-time PCR. In the 50 samples of microscopically-diagnosed falciparum malaria, 40 were regarded as P. falciparum single infection, 7 were P. falciparum and P. vivax mixed infections, and 3 were P. vivax single infection by real-time PCR. In the second set of 50 samples of microscopically diagnosed vivax malaria, all were considered P. vivax single infection by PCR. Neither P. ovale nor P. malariae infection was identified in the 100 blood samples. Real-time PCR analysis was shown to be more sensitive and accurate than routine diagnostic methods. Application and extension of the PCR method reported here will provide a powerful tool for further studies of malaria.

Animals↗
PubMed2004

Gender difference in socio-epidemiological factors for leprosy in the most hyper-endemic district of Nepal.

Leprosy which has caused stigma and social ostracism for millennium is nearing elimination worldwide as a public health problem, but the leprosy burden in Nepal is still 4.4 times greater than WHO's target level of less than one case per 10,000 population. Although leprosy affects both the sexes, in most parts of the world males are affected more than females at a ratio of 2:1. The general objective of the study was to investigate the gender difference in socio-epidemiological factors for leprosy. The analytic cross-sectional study was carried out in one of the most hyper endemic district- Dhanusa district of Nepal. Stratified random sampling method was applied for the selection of the patients. Chi-square/Fisher's exact test was applied to assess statistically significant differences in values between males and females. There were 580 leprosy patients (385 male and 195 female) aged above 15 years registered for multi drug therapy between April 1, 2001 to March 31,2002 in the 16 main health centers of the district. Out of 580 patients, 273 patients (183 males and 90 females) were included in the study in order to collect the data on socio-demographics, patient's knowledge on leprosy, treatment seeking behaviour, and social problems faced by the patients. Data were collected using a structured interview schedule. The mean age of the male patients was 45.1 years (range 15-77 years) and female patients were 40.3 years (range 15-75 years). Among male patients 93.4% were married while among female patients 70.0% were married. Among male patients 51.9% were illiterate whereas 71.1% were illiterate among female patients. Most of the patients (69.6%) lived in joint family and the rest in nuclear family. Among male patients, 86.9% had good knowledge about the disease compared to 73.3% among females. This study showed that among the female patients 12.2% were facing high level of social problems, while among male patients only 4.4% were facing the same. About 15% patients had poor treatment seeking behaviors (8.2% among males and 27.8% among females). A significant gender differences among leprosy patients have been found in age distribution, educational status, marital status, caste types, family members, and overall knowledge on the general aspect of leprosy, social problems faced by the patients and treatment seeking behaviour.

Adolescent↗
PubMed2003

Molecular characterization of hereditary persistence of fetal hemoglobin in the Karen people of Thailand.

Hereditary persistence of fetal hemoglobin (HPFH) is the condition whereby a continuously active gamma-globin gene expression leads to elevated fetal hemoglobin (Hb F) levels in adult life [Stamatoyannopoulos G, Grosveld F. Hemoglobin switching. In: Stamatoyannopoulos G, Majerus PW, Perlmutter RM, Varmus H, eds. The Molecular Basis of Blood Diseases. Philadelphia: W.B. Saunders, 2001:135-182; Wood WG. Hereditary persistence of fetal hemoglobin and delta(beta) thalassemia. In: Steinberg MH, Forget BG, Higgs DR, Nagel RL, eds. Disorders of Hemoglobin: Genetics, Pathophysiology, and Clinical Management. Cambridge: Cambridge University Press, 2001:356-388; and Weatherall DJ, Clegg JB. Hereditary persistence of fetal hemoglobin. In: Weatherall DJ, Clegg JB, eds. The Thalassaemia Syndromes. Oxford: Blackwell Scientific Publishers, 1981:450-507]. The condition is caused either by mutation of the beta- and gamma-globin genes, or the gamma-gene controlled region on other chromosomes. Several families with this condition have been reported from Vietnam, Cambodia and China, and the Southeast Asian mutation (or HPFH-6), a 27 kb deletion, was demonstrated. Here we report on a mother and her daughter of the Karen ethnic group with high levels of Hb F, living in the Suan Pueng District on the border of Thailand and Myanmar. Genotyping showed a heterozygosity for the 27 kb deletion of the beta-globin gene. Their conditions have been confirmed by gap polymerase chain reaction (PCR) with three oligonucleotide primers recently developed by Xu et al. [Xu X-M, Li Z-Q, Liu Z-Y, Zhong X-L, Zhao Y-Z, Mo Q-H. Molecular characterization and PCR detection of a deletional HPFH: application to rapid prenatal diagnosis for compound heterozygotes of this defect with beta-thalassemia in a Chinese family. Am J Hematol 2000; 65:183-188.], and a DNA sequencing method. Thus far there has been no official report of the HPFH-6 anomaly from Thailand. The compound heterozygosity of beta-thalassemia (thal) and hereditary persistence of Hb F causes the phenotype of thalassemia intermedia; in contrast, homozygotes for this anomaly show only mild microcytic anemia. Hence, genetic counseling for hereditary persistence of Hb F carriers is needed for family planning.

Adult↗
PubMed2003

Trend of malaria incidence in highly endemic provinces along the Thai borders, 1991-2001.

The intercountry border areas of Thailand have high malaria receptivity and vulnerability that present numerous problems in the control of malaria transmission. This study focused on the 30 provinces of Thailand situated next to neighboring countries, which can be divided into 4 groups: the Thai-Myanmar border (10 provinces), the Thai-Cambodia border (6 provinces), the Thai-Lao border (10 provinces) and the Thai-Malaysia border (4 provinces). The purpose of the present study was to describe the pattern and trend of malaria incidence in the highly endemic provinces along the Thai borders for the 11 years from 1991 to 2001. Analysis of trends showed the distribution of malaria parasites to have shifted from a preponderance of Plasmodium falciparum to Plasmodium vivax along the western border with Myanmar, the northern border with Lao PDR and along the eastern border with Cambodia whereas the southern border with Malaysia the pattern changed from a preponderance of P. vivax to P. falciparum, since 1997. There was a significant difference in annual parasite incidence between borders and non-border districts, especially along the Thai-Myanmar and Thai-Cambodia borders. It is thus evident that all border districts should pay more attention to control of malaria transmission and the activities of the malaria surveillance system, and that monitoring and evaluation of the Thai Malaria Control Program needs to be performed consistently, including some areas where a few malaria cases were found as well as in malaria free areas.

Endemic Diseases↗
PubMed2003

Some entomological observations on temporal and spatial distribution of malaria vectors in three villages in northwestern Thailand using a geographic information system.

This spatial and temporal heterogeneity in the distribution of Anopheles mosquitos were studied during August 2001 to December 2002 in three villages Ban Khun Huay, Ban Pa Dae, and Ban Tham Seau, in northwestern Thailand in Mae Sot district, Tak Province. The three Karen villages are located about 20 km east of the city of Mae Sot near the Myanmar border. Twenty-one species were collected on human collections during 68 nights of 17 months. Anopheles minimus comprised of 86% of the specimens biting man. An. minimus was implicated as a vector based on the detection of sporozoite infections using enzyme-linked immunosorbent assays for Plasmodium falciparum and P. vivax. Seasonal comparison of vectorial capacity and entomological inoculation rate was calculated. An. dirus was rarely encountered and probably played little part in transmission in these three villages during the period of study. Information is provided on nightly biting activity, parity rate, infectivity, and adult and larval bionomics. Spatial and temporal comparisons among the collections were displayed on different satellite images including the Normalized Difference Vegetation Index data from on the National Oceanographic and Atmospheric Administration satellites (NOAA/NDVI), the LANDSAT satellite Thematic Mapper (spatial resolution 30x30 m) and the IKONOS satellite (spatial resolution 1x1 m) in a Geographical Information System (GIS).

Animals↗
PubMed2003

Use of GIS-based spatial modeling approach to characterize the spatial patterns of malaria mosquito vector breeding habitats in northwestern Thailand.

We sampled 291 bodies of water for Anopheles larvae around three malaria-endemic villages of Ban Khun Huay, Ban Pa Dae, and Ban Tham Seau, Mae Sot district, Tak Province, Thailand during August 2001-December 2002 and collected 4,387 larvae from 12 categories of breeding habitat types. We modeled surface slope and wetness indices to identify the extent and spatial pattern of potential mosquito breeding habitats by digitizing base topographical maps of the study site and overlaying them with coordinates for each larval habitat. Topographical contours and streamlines were incorporated into the Geographical Information System (GIS). We used Global Positioning System (GPS) instruments to locate accurately each field observed breeding habitat, and produced a 30-m spatial resolution Digital Elevation Model (DEM). The slope (of less than 12 degrees) and wetness (more than 8 units) derived from spatial modeling were positively associated with the abundance of major malaria vectors An. dirus, An. maculatus, An. minimus, and An. sawadwongporni. These associations permit real-time monitoring and possibly forecasting of the distributions of these four species, enabling public health agencies to institute control measures before the mosquitos emerge as adults and transmit disease.

Animals↗