text: These findings corroborate those of Linn et al. who recently conducted a qualitative survey on barriers to MDA participation in Myanmar (unpublished) [34]. They interviewed members of the community and National Program to Eliminate LF (NPELF) in three townships with persistent transmission in Mandalay and the adjacent Magway and Sagaing Regions. They found community members were often unaware of previous rounds, suggesting they may have been missed. Of those who were aware of the previous rounds, a number stated they had not received medication because they were away. Meanwhile, drug distributors reported that financial, human resource and time limitations prevented them from fulfilling their duties and mopping-up recipients who were initially missed. The NPELF should therefore ensure that future rounds reach all households, are sufficiently resourced and are conducted at a time when household members are likely to be present. A strong emphasis should also be made to track down eligible recipients who were missed during the initial round.
  In addition to programmatic reach, never taking MDA was also at least partly related to individual compliance in the study area. A notable proportion of the participants (8% of 935) reported that they had refused MDA at least once in the past. Of those, 52% had never taken MDA compared to only 11% among participants who had never actively refused medication. Thus, ever declining medication was strongly associated with never taking MDA. The most common reasons for declining MDA reported in both our study and that of Linn et al. were fear of side effects and a perception that co-morbidities were a contraindication [34]. Although adverse events are rare, community concern has hampered MDA in many countries and resulted in the postponement of the 2006 MDA round in the Mandalay Region [3].
  Education initiatives regarding LF, the MDA programme and common misconceptions have been effective in improving MDA compliance [35,36,37]. These studies reported that greater LF knowledge reduced the likelihood of declining medication and non-participation, suggesting that these interventions would likely also be effective in Myanmar. The NPELF should consider efforts to improve community education and dispel myths to improve MDA participation.
  Amarapura had significantly more individuals who had never taken MDA compared to the other townships in the study. Douglass et al. similarly found low participation in young people surveyed there in 2013 and 2014 [10]. This lower participation could not be accounted for by the programmatic reach and compliance factors assessed. Of the four townships, Amarapura is the most urban and had the highest average household income. Studies elsewhere have found that MDA participation can be more difficult to achieve in urban areas because of a lack of urban strategy, fewer peripheral health workers, poor health care infrastructure, the presence of unorganised settlements and large numbers of migrants [11]. Compared to other townships, Amarapura had the highest proportion of individuals who had moved from another village but a similar ratio of household members present during the last round and the highest number of NPELF visits. Within urban areas, studies have also found that higher income individuals can be harder to reach in surveys and are more likely to decline to participate in MDA programmes [11]. Amarapura had the lowest proportion of individuals who reported declining MDA medication. When income was assessed in a subgroup analysis of the township, however, there was a trend toward lower participation with higher income but it did not reach significance (cOR = 1.07; p = 0.642; aOR = 1.41; p = 0.080). The lower participation levels in Amarapura, therefore, may relate to its urban location, more mobile population and higher incomes, but this requires further analysis.
  In addition to exploring potential causes for persistent infection and never taking MDA, this study also assessed risk factors for LF-related hydrocoele. The positive association found between age and hydrocoele has been well documented [15]. This is thought to be due to the progressive onset of lymphatic dysfunction with chronic filarial infection [38]. Hydrocoele was not found to be associated with CFA positivity following adjustment for survey design. Men with hydrocoele are often CFA negative, reflecting the fact that the active infection has often ceased by the time hydrocoeles develop. The higher risk of hydrocoele in Amarapura probably relates to the historically high infection prevalence there. These findings underscore the importance of reducing infection to prevent the development of LF-related hydrocoele.
  The study results reported should be interpreted in light of some limitations. First, more females than males participated in the study. Whilst gender was adjusted for, it led to wider odds ratio confidence intervals. Second, data were missing from a number of risk factor variables (see total column in Tables 1, 3 and 5) leading to fewer numbers of participants in the final models for infection and never taking MDA. In addition to widening confidence intervals, it is possible this may have biased the results. Third, other potential environmental factors such as rainfall, temperature and population density were not included, which may have provided a more complete explanation of risk. Lastly, local health workers and members of the NPELF assisted with data collection. It is therefore possible that participants’ responses regarding MDA participation could have been biased towards ‘acceptable’ replies. The low levels of reported MDA participation, however, suggest this was unlikely.
  The results of this study will assist Myanmar’s NPELF and contribute to the global understanding of LF risk factors. Knowledge of the factors associated with persistent infection and never taking MDA will help the National Programme to better allocate its resources in elimination efforts. Maximising MDA participation is critical as Myanmar transitions from the two-drug to three-drug MDA (ivermectin, diethylcarbamazine and albendazole, IDA) starting in 2020, since models predict that fewer rounds of IDA are needed to stop transmission [39]. To do this, our results suggest that emphasis should be placed on both improving reach, with particular attention to mopping-up missed participants, and compliance through educational initiatives. Since the findings reflect many common global reasons for poor MDA uptake and those of Linn et al., it is reasonable to infer that they could be generalisable to other regions of Myanmar. The identified infection risk factors may also apply to other countries where Culex is the vector. Finally, the identification of hydrocoele risk factors contributes to the understanding of LF morbidity and will help Myanmar to better target alleviation programmes.
  This population-representative study assessed risk factors for LF infection, disease and never taking MDA in an area of persistent LF transmission in Myanmar. It found that persistent LF infection was linked to both individual and household factors. In turn, never taking MDA was related to both programme reach and individual compliance factors. It also highlighted that hydrocoele risk was higher in those who were older and residing in the historically high prevalence township of Amarapura. These results will assist the NPELF to improve its MDA rounds and to better target its morbidity management programmes.
  Win KM, Tripathy JP, Maung TM, Oo T, Thi A, Lon KN, et al. Rapid progress towards elimination of lymphatic filariasis in endemic regions of Myanmar as a result of 16 years of anti-filarial activities (2001–2016). Trop Med Health. 2018;46(1):14.