Efficacy of a single-dose treatment with 300 mg diethylcarbamazine and a combination of 400 mg albendazole in reduction of Wuchereria bancrofti antigenemia and concomitant geohelminths in Myanmar migrants in Southern Thailand.

BACKGROUND: There seems to be a large magnitude of parasitic worm loads caused by nocturnally periodic Wuchereria bancrofti and geohelminths, in cross-border Myanmar migrant workers in Thailand. We are therefore considering an effective Mass Drug Administration (MDA) with Diethylcarbamazine (DEC) and Albendazole (ABZ). Due to short periods of their residency and current situation of W. bancrofti antigenemics and concomitant geohelminths, treatment effects on the containment of the infections need to be analyzed. OBJECTIVES: Analyze short-term effects on reduction of W. bancrofti antigen (WbAg) and geohelminths' egg (GhE) loads. The efficacy of a single-dose combined treatment with 300 mg DEC (for filariasis) and 400 mg ABZ (for helminthiasis) was evaluated and compared with a single-dose treatment arm with 300 mg DEC alone. MATERIAL AND METHOD: A randomized clinical trial of two treatment choices in 28 Myanmar male workers (DEC/ABZ or group I = 15, DEC or group II = 13) was conducted in Phang Nga province, Southern Thailand. Because of the withdrawal of three subjects of the DEC group, all the 10 DEC subjects were follow-up monitored at post treatment 2, 4, 8 and 12 weeks. Their mean age was 26.4 years; worm loads (mean +/- SD x 10(3)) of W. bancrofti, Ascaris and Trichuris was 103.9 +/- 44.1 antigen units (AU)/ml, 47.3 +/- 38.7 eggs per gram (EPG) and 16.6 +/- 22.2 EPG respectively. The data on the 15 DEC/ABZ subjects showed a mean age of 25.7 years; corresponding worm loads = 96.1 +/- 54.6 AU/ml, 397.0 +/- 117.3 EPG and 54.5 +/- 42.8 EPG respectively. The Antigen Reduction Rates (ARR) and Egg Reduction Rates (ERR) were presented. RESULTS: At the 12-week post treatment, WbAg loads (mean +/- SD x 10(3) AU/ml) were 61.5 +/- 58.4 for group I and 76.8 +/- 40.7 for group II. A significant WbAg reduction was noted for both groups at weeks 8 and 12 (p < 0.05). Also, the significant reduction of GhE loads was more pronounced for both groups after week 2 (p < 0.05). When comparing efficacy of the treatment choices by the treatment retention time, it was more likely to show both groups had similar adulticidal effects on either WbAg, denoted as the ARR (F = 0. 064, p = 0.806) or GhE, denoted as the ERR (F = 0.196, p = 0.669). CONCLUSION: The single-dose 300 mg DEC plus 400 mg ABZ, or 300 mg DEC alone, can be effectively used for treating infections with W. bancrofti and concomitant geohelminths commonly observed in the area. But treatment rounds are required to clear the infections. The reduction of the parasitic worm loads in the legal Myanmar migrants provide values in monitoring and evaluating an effective MDA program with the DEC/ABZ at the provincial level.

Culex quinquefasciatus in Phitsanulok as a possible vector of nocturnally periodic Wuchereria bancrofti transmission in Myanmar immigrants.

The present study was undertaken in order to study whether Culex quinquefasciatus collected in Phitsanulok Province can be an insect host for the development of Wuchereria bancrofti larvae. W. bancrofti infected blood from Myanmar workers in Mae Sot, Tak Province was fed to mosquitoes by using the artificial membrane feeding. An infection of W. bancrofti was found with the highest density of L3 in the mosquito thorax on the 14th day after feeding. The infection rate also correlated to the density of microfilaria found in the donor's blood. Our results showed that Cx. quinquefasciatus in Phitsanulok is a possible vector of nocturnally periodic W. bancrofti.

Behavioral factors and malaria infection among the migrant population, Chiang Rai province.

A cross-sectional study was conducted from January, 2001 to June, 2002 among some migrant populations, living in malaria endemic areas along the Thai-Myanmar border, in the Mae Fah Luang and Mae Sai districts, Chiang Rai Province, Northern Thailand using blood exams and face-to-face interviews as the research methods. This study focused on the knowledge and practice of primary malaria prevention, aimed at identifying the association between behavioral factors in migrant populations and malaria infection. P. vivax (51.8%) was detected more often than P. falciparum (47.7%). The proportion of malaria infections was 45.4% of the total of 421 blood examinations. The working age group (15-44 yr) and males were the majority of the study subjects. Two age groups (0-14 and 15-34 yr) and visiting or staying in the forest 14 days prior to the blood exam were significant risk factors. The ethnic group of Thai-Yai and hilltribe was a significant protective factor (p < 0. 05) compared to the Myanmar people. A poor knowledge of primary malaria prevention (63-68%), the presence of international migration, poverty, lack of malaria prevention resources, namely bednets (not using or taking them) and not using a smoky fire were factors which led to failure in primary prevention and control of malaria infections. Residence-workplace-living style in the forest need more consideration to serve the common failure of effective primary prevention.

Surveillance of imported bancroftian filariasis after two-year multiple-dose diethylcarbamazine treatment.

Myanmar migrants are at increased risk for nocturnally periodic Wuchereria bancrofti causing imported bancroftian filariasis. They have a significant influence on the effectiveness of diethylcarbamazine (DEC) mass treatment at the provincial level in the National Program to Eliminate Lymphatic Filariasis (PELF) during the fiscal years (FY) 2002-2006, in Thailand. Two oral doses of DEC 6 mg/kg are given twice a year to the eligible Myanmar migrants (> or = 2 years old). A 300 mg DEC provocation test is given once a year to all Myanmar migrants with work permits. Effectiveness evaluation parameters, such as cumulative index (CI) and the effectiveness ratio (ER), were obtained after 2 years of the multiple-dose DEC treatment program in Ranong Province, Southern Thailand. By cross-sectional night blood surveys at the end of FY 2003 in two districts of Ranong Province, the microfilarial positive rates (MPR) were 0.8% and 1.2% for Mueang Ranong and Kra Buri, respectively. The MPR in the agricultural (1.5%) and industrial (0.4%) occupations were not significantly different from each other. Our findings suggest that most untreated microfilaremics working in agriculture, with short-term residency in Thailand, may have delayed multiple-dose DEC treatment.

Short-term effects of treatment with 300 mg oral-dose diethylcarbamazine on nocturnally periodic Wuchereria bancrofti microfilaremia and antigenemia.

Seven microfilaremic Myanmar patients were treated with a single 300 mg dose of diethylcarbamazine (DEC) orally, as part of a case-finding survey in Ranong Province, Southern Thailand. This was conducted in order to evaluate the short-term effects of single-dose DEC on Wuchereria bancrofti microfilaremia and antigenemia during a 12-week course of treatment. Analysis of microfilarial periodicity on initial treatment revealed the microfilarial peak density (k) was at 52 minutes after midnight (0052). The periodicity index was then 103.26%. Single-dose DEC treatment did not affect the k values. A linear model of W. bancrofti microfilarial density reduction predicts a sharp decrease in the mean microfilarial density 2 weeks after DEC intake (Z = -2.197, p = 0.028). Over a longer period, a non-linear model predicts an increase in the mean microfilarial density to pre-treatment levels, having little or no macrofilaricidal effects. We reconfirmed the existence of nocturnally periodic W. bancrofti infection in Myanmar migrants in Ranong Province, and the short-term microfilaricidal activity of 300 mg single-dose DEC treatment used for biannual mass treatment and the DEC provocative test. Without an adequate DEC treatment dose, recrudescence can occur. A rational approach to the management of introduced nocturnally periodic W. bancrofti in Myanmar migrants, who came for short periods of stay in transmission-prone areas, is needed.

Cigarette, alcohol use and physical activity among Myanmar youth workers, Samut Sakhon Province, Thailand.

Over 1.2 million migrants from Myanmar are currently residing in Thailand. Little information is known about Myanmar youth risk behaviors. This cross-sectional study aimed to determine the prevalence and the factors associated with cigarette and alcohol use, and physical inactivity, among Myanmar youth working in a harbor town in Samut Sakhon Province, Thailand. One hundred and seventy-seven young workers aged 15-24 years, living in the study area, were interviewed by structured questionnaire. About 21.5% were current smokers, 25.4% were alcohol drinkers, and 36.7% were physically inactive. Univariate analysis indicated one variable was significantly associated with cigarette smoking: education level higher than primary school (OR=2.3, 95% CI 1.02-5.0), Three variables were significantly associated with alcohol drinking: married status (OR=2.2, 95%CI 1.02-4.5); non-seafood-processing workers, i e, street vendors, construction laborers, etc. (OR=3.4, 95% CI 1.7-7.1), and high job stress due to supervisor/boss (OR=2.1 95% CI 1.1-4.2). Two variables were significantly associated with physical inactivity: female youth (OR=3.9 95% CI 2.1-7.5), and education level higher than primary school (OR=0.4, 95% CI 0.2-0.8). The prevalence of smoking, alcohol drinking and physical inactivity among Myanmar migrant youths was quite high. Government and non-government organizations should co-operate to provide interventions to reduce youths' risk behaviors.

Evaluation of a single oral dose of diethylcarbamazine 300 mg as provocative test and simultaneous treatment in Myanmar migrant workers with Wuchereria bancrofti infection in Thailand.

We assessed the efficiency of oral diethylcarbamazine (DEC) 300 mg as a provocative test on blood examination 30 minutes after administration, while gauging the overall infection rate in Myanmar migrant workers with Wuchereria bancrofti infection who enrolled for work permits in Thailand in 2002, using circulating filarial antigens (CFA) assays, the NOW ICT Filariasis card test and the Og4C3 ELISA as reference. Overall infection rates of 0.3% (95% CI=0-0.7%), 4.2% (95% CI=1.8-6.5%) and 5.9% (95% CI=3.2-8.7%) by three diagnostic tests, respectively, were observed. Among three different location groups of Myanmar population sample tested, there were no statistically significant differences in the overall infection detection rates. When either the ICT card test or the Og4C3 ELISA was used as a reference, the specificity and positive predictive value of the DEC-provocative day test was the same, 100%. The sensitivities were 25.0% (95% CI = 0.5-49.5%) and 17.6% (95% CI = 0-35.8%) on the ICT and ELISA tests, respectively. The negative predictive values were 96.8% (95% CI = 94.8-98.9%) and 95.1% (95% CI = 92.6-97.6%), respectively. In three microfilaremic persons followed-up monitored at 8-weeks DEC post-provocation, there were 6 x 10(-1) and 7 x 10(-1) decreases in microfilaremia and antigenemia. These findings suggested that, unlike the CFA assays, the DEC-provocative day test is unsuitable for the diagnosis of active W. bancrofti infection in the population tested, and for gauging current infection prevalence. The treatment would likely be beneficial to reduce microfilaremia and antigenemia.

Comparative assessment of an Og4C3 ELISA and an ICT filariasis test: a study of Myanmar migrants in Thailand.

Detection of circulating filarial antigen has now emerged as an alternative method for the diagnosis of bancroftian filariasis. We compared two antigen detection assays, an Og4C3 ELISA and an ICT (immunochromatography) Filariasis test, for the diagnosis of Wuchereria bancrofti infections in migrant Myanmar workers in Tak province, Western Thailand. A total of 337 Myanmars participated in this study. The microfilarial rate was 3.3%. The Og4C3 ELISA could detect 19.1% of bancroftian filariasis while the ICT test detected 12.7%. Both antigen assays could detect all microfilaremics. The Og4C3 ELISA detected 14.8% of amicrofilaremics while the ICT test identified 8.1%. Those who were positive for the ICT test were also positive by the Og4C3 ELISA. Those Og4C3 positive cases, that were ICT negative (ICT-ve/Og4C3+ve) had statistically significant (p < 0.05, unpaired t-test) lower Og4C3 antigen levels (409.5 units, range 117-2,389) than those that were ICT positive (ICT+ve/Og4C3+ve) (5,252.0 units, range 130-28,062). Our results emphasize the problem of bancroftian filariasis in Myanmar migrants working in Thailand. Close monitoring and control of this disease in Myanmar migrants are of public health importance. Antigen detection systems are promising tools for the surveillance of bancroftian filariasis.

Wuchereria bancrofti antigenemia clearance among Myanmar migrants after biannual mass treatments with diethylcarbamazine, 300 mg oral-dose FILADEC tablet, in Southern Thailand.

Using qualitative ICT Filariasis and quantitative Og4C3 ELISA, we assessed a long-term macrofilaricidal effect of two-year biannual mass treatments with a 300 mg oral-dose FILADEC tablet, a reformulation of 6 mg/kg diethylcarbamazine (DEC), on clearance of the Wuchereria bancrofti adult worm circulating filarial antigens (CFA) in Myanmar migrants, at risk of emergence of imported bancroftian filariasis in Southern Thailand. Of the 34 antigenemic Myanmar index cases of varying initial CFA levels, who were initially screened out with the ICT Filariasis, 13 index cases were follow-up treated and monitored at the DEC post treatments, 6, 12, and 18 months. At the 18-month post treatment, residual antigenemias (%) in 4 of 5 index cases (group 1) with high antigen titers (99.7-181.6 x 10(3) AU/ml) were 54.44%, 33.58%, 27.43%, and 9.97%. Significant decreases of the CFA levels in only 3 out of 5 index cases were affected by the response to DEC treatments (p < 0.007). The treatment effects on clearance of the CFA in 8 index cases (group II) with low antigen titers (15.4-37.2 x 10(3) AU/ml) were shown for at least 6 months post DEC treatment and hence had 100% efficacy in the first 6 months of the first year of year round treatment. Group I, was more likely to show an increase of the DEC efficacy after the first 6 months of the second year round treatment, but there was no statistically significant difference (p = 0.063). We reemphasized that, for use in the national program to eliminate lymphatic filariasis (PELF) in Thailand, such a DEC regimen had a macrofilaricidal effect on antigenemia clearance, and confirmed its value in evaluating response to the treatment and monitoring the long-term efficacy of the DEC regimen in W. bancrofti adult worm burden reductions in Myanmar migrants on a wide scale.

A polymerase chain reaction assay for the survey of bancroftian filariasis.

A polymerase chain reaction (PCR) assay based on a highly repeated DNA sequence found in Wuchereria bancrofti (SspI repeat) has been modified for the survey of bancroftian filariasis in expatriate workers (Myamese, Karen and Mon) from Myanmar where human filariasis is endemic. The PCR was very sensitive with the ability to detect the presence of as little as 10 pg of parasite DNA. The primers used in this PCR also showed highly specific amplification of parasite DNA without the presence of non-specific and non-target PCR products such as Brugia malayi, Plasmodium falciparum and human DNA. The primers were used to investigate filariasis in four provinces in the central and western Thailand, Samut Songkram, Ratchaburi, Nakhon Pathom and Tak during 1997-2001. Among them, Tak and Ratchaburi are the only endemic areas of bancroftian filariasis. In this field study, 1,299 human blood samples (501 from Samut Songkram, 510 from Ratchaburi, 109 from Nakhon Pathom, and 179 from Tak) were collected and screened by PCR. The result showed that 1, 2, 3, and 33 patients from Samut Songkram, Ratchaburi, Nakhon Pathom, and Tak respectively were infected with W. bancrofti. These numbers were corresponded to the prevalence rate of infection of 0.2, 0.4, 2.8, and 18.5%, respectively. The PCR was able to detect the third-stage infectious larvae (L3) from Culex quinquefasciatus, mosquito vector of the W. bancrofti, that was experimentally fed to infected patient. The PCR screening of each of field mosquito pools from two endemic areas, Ratchaburi and Tak, showed that no L3 of W. bancrofti was detected.

Practical uses of acridine orange fluorescence microscopy of centrifuged blood (QBC Malaria Test) and the QBCII Hematology System in patients attending malaria clinics in Thailand.

We evaluated the detection of malaria parasites using acridine orange fluorescence microscopy of centrifuged blood (AOFM/CB or "QBC Malaria Test") at two government malaria clinics in rural Thailand. In a subgroup of the patients, a QBC Hematology System for the determination of complete blood counts was also utilized. A Giemsa-stained thick smear (GTS) reading of 100 (1,000x) microscopic fields was used as standard. The AOFM/CB sensitivities were 97% overall and 95% for P. falciparum (Pf). Sensitivity was lower for P. vivax (Pv) (76%). Pv sensitivity depended largely on ameboid form density. A threshold for AOFM/CB to consistently detect Pv ameboid forms was estimated to be 10/100 WBC (700/microliters blood). AOFM/CB was capable of detecting Pf gametocytes and schizonts more frequently than GTS. The total Pf rings per microliter blood estimated from GTS was highly correlated with the number of Pf rings per Paralens microscopic field (PMF) suggesting that AOFM/CB could be used quantitatively. From a technical standpoint, the rural tropical settings of Thailand in this study were not an obstacle to the use of QBC Hematology. The system was found to be useful in conjunction with AOFM/CB. However, in patients heavily infected with Pf gametocytes of Pv ameboid forms, their total WBC and lymphocyte counts needed to be appropriately corrected. Overall, AOFM/CB appears to be a promising tool for field diagnosis of malaria if it is affordable to developing countries.

Malaria in displaced persons along the Thai-Burmese border.

Malaria epidemiology in displaced Karen ethnic children along the Thai-Burmese (Myanmar) border was observed for 3 years. An active screening process in connection with malaria chemoprophylaxis trials showed a decrease in malaria prevalence over time in children not receiving chemoprophylaxis. The number of malaria cases detected at a primary health care clinic in the same area remained stable.