Risk factors for lymphatic filariasis and mass drug administration non-participation in Mandalay Region, Myanmar.

BACKGROUND: Myanmar commenced a lymphatic filariasis (LF) elimination programme in 2000. Whilst the country has made considerable progress since then, a number of districts have demonstrated persistent transmission after many rounds of mass drug administration (MDA). The causes of unsuccessful MDA have been examined elsewhere; however, there remains little information on the factors that contribute in Myanmar. METHODS: We conducted an analysis of factors associated with persistent infection, LF-related hydrocoele and MDA participation in an area with ongoing transmission in 2015. A cross-sectional household survey was undertaken in 24 villages across four townships of Mandalay Region. Participants were screened for circulating filarial antigen (CFA) using immunochromatographic tests and, if positive, for microfilaria by night-time thick blood slide. Individuals 15 year and older were assessed for filariasis morbidity (lymphoedema and, if male, hydrocoele) by ultrasound-assisted clinical examination. A pre-coded questionnaire was used to assess risk factors for LF and for non-participation (never taking MDA). Significant variables identified in univariate analyses were included in separate step-wise multivariate logistic regressions for each outcome. RESULTS: After adjustment for covariates and survey design, being CFA positive was significantly associated with age [odds ratio (OR) 1.03, 95% CI 1.01-1.06), per year], male gender (OR 3.14, 1.27-7.76), elevation (OR 0.96, 0.94-0.99, per metre) and the density of people per household room (OR 1.59, 1.31-1.92). LF-related hydrocoele was associated with age (OR 1.06, 1.03-1.09, per year) and residing in Amarapura Township (OR 8.93, 1.37-58.32). Never taking MDA was associated with male gender [OR 6.89 (2.13-22.28)] and age, particularly in females, with a significant interaction term. Overall, compared to those aged 30-44 years, the proportion never taking MDA was higher in all age groups (OR highest in those < 5 years and > 60 years, ranging from 3.37 to 12.82). Never taking MDA was also associated with residing in Amarapura township (OR 2.48, 1.15-5.31), moving to one's current village from another (OR 2.62, 1.12-6.11) and ever having declined medication (OR 11.82, 4.25-32.91). Decreased likelihood of never taking MDA was associated with a higher proportion of household members being present during the last MDA round (OR 0.16, 0.03-0.74) and the number visits by the MDA programme (OR 0.69, 0.48-1.00). CONCLUSIONS: These results contribute to the understanding of LF and MDA participation-related risk factors and will assist Myanmar to improve its elimination and morbidity management programmes.

Preventive chemotherapy reverses covert, lymphatic-associated tissue change in young people with lymphatic filariasis in Myanmar.

OBJECTIVES: This longitudinal comparative study investigated the effect of preventive chemotherapy (PC) on covert tissue changes associated with lymphatic filariasis (LF) among young people living in an LF-endemic area in Myanmar. METHODS: Tissue compressibility and extracellular free fluid in the lower limbs of people aged 10-21 years were measured using indurometry and bioimpedance spectroscopy (BIS). Baseline measures were taken in October 2014, annual mass drug administration (MDA) of PC was delivered in December, and in March 2015 further PC was offered to LF-positive cases who had missed MDA. Follow-up measures were taken in February and June 2015. RESULTS: A total of 50 antigen-positive cases and 46 antigen-negative controls were included. Self-reported PC consumption was 60.1% during 2014 MDA and 66.2% overall. At second follow-up, 24 of 34 cases and 27 of 43 controls had consumed PC. Significant and clinically relevant between-group differences at baseline were not found post-PC. Bayesian linear mixed models showed a significant change in indurometer scores at both calves for antigen-positive cases who consumed any PC (dominant calf: -0.30 [95% CI -0.52, -0.07], P < 0.05 and non-dominant calf: -0.35 [95% CI -0.58, -0.12], P < 0.01). Changes in antigen-negative participants or those not consuming PC were not significant. CONCLUSION: This study is the first attempt to use simple field-friendly tools to track fluid and tissue changes after treatment of asymptomatic people infected with LF. Results suggested that PC alone is sufficient to reverse covert lymphatic disturbance. Longer follow-up of larger cohorts is required to confirm these improvements and whether they persist over time. These findings should prompt increased efforts to overcome low PC coverage, which misses many infected young people, particularly males, who are unaware of their infection status, unmotivated to take PC and at risk of developing lymphoedema. Indurometry and BIS should be considered in assessment of lymphatic filariasis-related lymphedema.

OBJECTIFS: Cette étude comparative longitudinale a investigué l'effet de la chimiothérapie préventive (CP) sur les modifications tissulaires cachées associées à la filariose lymphatique (FL) chez les jeunes vivant dans une zone d'endémie pour la FL au Myanmar. MÉTHODES: La compressibilité des tissus et le liquide libre extracellulaire dans les membres inférieurs des personnes âgées de 10 à 21 ans ont été mesurés par indurométrie et spectroscopie de bioimpédance (BIS). Les mesures de base ont été prises en octobre 2014, la distribution en masse de médicament (DMM) annuelle a été administrée en décembre et en mars 2015, et une CP additionnelle a été offerte aux cas positifs pour la FL qui avaient manqué la DMM. Des mesures de suivi ont été prises en février et juin 2015. RÉSULTATS: 50 cas positifs pour l'antigène et 46 témoins négatifs ont été inclus. L'administration de CP auto-déclarée était de 60,1% durant la DMM de 2014 et de 66,2% au total. Au deuxième suivi, 24 des 34 cas et 27 des 43 témoins avaient pris la CP. Des différences significatives et cliniquement pertinentes entre les groupes au départ n'ont pas été trouvées après la CP. Les modèles mixtes linéaires bayésiens ont montré un changement significatif des scores d'indurometrie aux deux mollets pour les cas positifs pour l'antigène qui prenaient une CP (mollet dominant: -0,30 [IC95%: -0,52, -0,07], p <0,05, mollet non dominant: - 0,35 [IC95%: -0,58, -0,12], p <0,01). Les changements chez les participants négatifs pour l'antigène ou ceux qui ne prenaient pas de CP n'étaient pas significatifs. CONCLUSION: Cette étude est la première tentative d'utilisation d'outils simples, conviviaux sur le terrain, pour suivre les modifications du tissu conjonctif après le traitement de personnes asymptomatiques infectées par la FL. Les résultats suggèrent que la CP seule est suffisante pour inverser les modifications lymphatiques cachées. Un suivi plus long de plus grandes cohortes est nécessaire pour confirmer ces améliorations et déterminer si elles persistent ou non. Ces résultats devraient inciter à redoubler d'efforts pour surmonter la faible couverture en CP, qui rate beaucoup de jeunes infectés, en particulier les hommes, qui ne sont pas au courant de leur statut d'infection, qui ne sont pas motivés pour prendre une CP et risquent de développer un lymphœdème. L'indurométrie et la BIS devraient être considérées dans l'évaluation du lymphoedème associé à la filariose lymphatique.

The prevalence of lymphatic filariasis infection and disease following six rounds of mass drug administration in Mandalay Region, Myanmar.

Lymphatic filariasis is widely endemic in Myanmar. Despite the establishment of an elimination program in 2000, knowledge of the remaining burden of disease relies predominantly on programmatic information. To assist the program, we conducted an independent cross-sectional household cluster survey to determine the prevalence of filariasis infection, morbidity and mass-drug administration coverage in four townships of the Mandalay Region: Amarapura, Patheingyi, Tada-U and Wundwin. The survey included 1014 individuals from 430 randomly selected households in 24 villages. Household members one year and older were assessed for antigenaemia using immunochromatographic test cards and if positive, microfilaraemia by night-time thick blood smear. Participants 15 years and older were assessed for filariasis morbidity by ultrasound-assisted clinical examination. The overall prevalence of infection was 2.63% by antigenaemia (95% confidence interval (CI) 1.71-4.04%) and 1.03% by microfilaraemia (95%CI 0.59-1.47%). The prevalence of hydrocoele in adult males was 2.78% (95%CI 1.23-6.15%) and of lymphoedema in both genders was 0% (95%CI 0-0.45%). These results indicate the persistence of filarial infection and transmission despite six rounds of annual mass drug administration and highlight the need for further rounds as well as the implementation of morbidity management programs in the country.

Mapping and modelling the impact of mass drug adminstration on filariasis prevalence in Myanmar.

BACKGROUND: Lymphatic filariasis (LF) is endemic in Myanmar and targeted for elimination. To highlight the National Programme to Eliminate Lymphatic Filariasis (NPELF) progress between 2000 and 2014, this paper describes the geographical distribution of LF, the scale-up and impact of mass drug administration (MDA) implementation, and the first evidence of the decline in transmission in five districts. METHODS: The LF distribution was determined by mapping historical and baseline prevalence data collected by NPELF. Data on the MDA implementation, reported coverage rates and sentinel site surveillance were summarized. A statistical model was developed from the available prevalence data to predict prevalence at township level by year of measurement. Transmission assessment survey (TAS) methods, measuring antigenemia (Ag) prevalence in children, were used to determine whether prevalence was below a level where recrudescence is unlikely to occur. RESULTS: The highest baseline LF prevalence was found in the Central Valley region. The MDA implementation activities scaled up to cover 45 districts, representing the majority of the endemic population, with drug coverage rates ranging from 60.0% to 98.5%. Challenges related to drug supply and local conflict were reported, and interrupted MDA in some districts. Overall, significant reductions in LF prevalence were found, especially after the first 2 to 3 rounds of MDA, which was supported by the corresponding model. The TAS activities in five districts found only two Ag positive children, resulting in all districts passing the critical threshold. CONCLUSION: Overall, the Myanmar NPELF has made positive steps forward in the elimination of LF despite several challenges, however, it needs to maintain momentum, drawing on international stakeholder support, to aim towards the national and global goals of elimination.

Socioeconomic and behavioural determinants of malaria among the migrants in gold mining, rubber and oil palm plantation areas in Myanmar.

BACKGROUND: Malaria is a major public health problem in Myanmar. Migrant populations are at high risk of contracting malaria and its control is more difficult than for settled population. Studies on malaria and migration are rare in Myanmar. This study was undertaken with the main objective of identifying socioeconomic and behavioural determinants of malaria among the migrant workers involved in gold mining, rubber and oil palm plantations. METHODS: A cross-sectional analytic study was conducted using pretested interview-administered questionnaires among internal migrants (n = 406) in the malaria endemic townships of Shwegyin, Bago Region, Thanbyuzayat, Mon State and Kawthaung, Taninthayi Region from August to November, 2015. Data were collected by well-trained Basic Health Staff members in study areas, and then analysed by SPSS version 16.0 using Chi-square tests with significant level at 0.05. RESULTS: Majority of participants were male, Bahmar nationals, married and with primary basic education level and below. The mean duration of migratory work was 4.51 years. 43.1% of them gave definite previous history of malaria within last two years during migration. 92.9% (377/406) of them always used bed nets. Malaria determinants found were male gender (OR = 1.84, 95% CI: 1.22-2.77; P = 0.0040), habit of going out at dawn (OR = 2.36, 95% CI: 1.58-3.52; P < 0.001), usual sleeping indoors (OR = 2.14, 95% CI: 1.04-4.42; P = 0.036), torn bed net or net with large hole(s) (OR = 2.0, 95% CI: 1.21-3.3; P = 0.006), habit of not always sleeping under a bed net at night (OR = 2.02, 95% CI: 1.15-3.52; P = 0.014), alcohol drinking (OR = 2.71, 95% CI: 1.73-4.26; P < 0.001) and failure to attend malaria health talk (OR = 1.78, 95% CI: 1.2-2.65; P = 0.004). CONCLUSIONS: The present study highlighted that it is warranted to launch an effective health education programme for malaria, and to encourage the proper use of insecticide-treated bed nets, blankets and/or mufflers and mosquito repellents to reduce the occurrence of malaria among the migrants.

Lymphatic Filariasis Increases Tissue Compressibility and Extracellular Fluid in Lower Limbs of Asymptomatic Young People in Central Myanmar.

When normal lymphatic function is hampered, imperceptible subcutaneous edema can develop and progress to overt lymphedema. Low-cost reliable devices for objective assessment of lymphedema are well accepted in clinical practice and research on breast-cancer related lymphedema but are untested in populations with lymphatic filariasis (LF). This is a cross-sectional analysis of baseline data in a longitudinal study on asymptomatic, LF antigen-positive and -negative young people in Myanmar. Rapid field screening was used to identify antigen-positive cases and a group of antigen-negative controls of similar age and gender were invited to continue in the study. Tissue compressibility was assessed with three tissue tonometers, and free fluids were assessed using bio-impedance spectroscopy (BIS). Infection status was confirmed by Og4C3 antigen assay. At baseline (n = 98), antigen-positive cases had clinically relevant increases in tissue compressibility at the calf using a digital Indurometer (11.1%, p = 0.021), and in whole-leg free fluid using BIS (9.2%, p = 0.053). Regression analysis for moderating factors (age, gender, hydration) reinforced the between-infection group differences. Results demonstrate that sub-clinical changes associated with infection can be detected in asymptomatic cases. Further exploration of these low-cost devices in clinical and research settings on filariasis-related lymphedema are warranted.