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

Abstract

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.

Keywords: administration en masse de médicaments; bioimpedance spectroscopy; chimiothérapie préventive; extrémités inférieurs; filariose lymphatique; global programme to eliminate lymphatic filariasis; indurometry; indurométrie; lower extremity; lymphatic filariasis; lymphedema; lymphoedème; mass drug administration; preventive chemotherapy; programme mondial d’élimination de la filariose lymphatique; spectroscopie de bio-impédance.

Figure 1

Timeline of data collection activities.

Figure 2

Map of Amarapura Township area (coloured) showing the village tracts (shaded) where study participants were resident at the time of recruitment into the cross‐sectional study. Mandalay city centre is also identified (star).

Figure 3

Flow chart of participants through the study. [Colour figure can be viewed at http://wileyonlinelibrary.com]

Figure 4

(a) Whole cohort mean indurometer scores for each measurement site at all three time points. Higher values = higher tissue compressibility. **P < 0.000, *P < 0.05 Oct 14 vs. Jun 15. (b) Whole cohort mean BIS scores for each leg at all three time points. Higher values = less extracellular free fluid. **P < 0.000, *P < 0.05 Oct 14 vs. Jun 15.

Figure 5

(a) Unadjusted comparison of indurometer scores between‐infection groups at baseline (Oct 14) and second follow‐up (Jun 15). (b) Unadjusted comparison of BIS scores between‐infection groups at baseline (Oct 14) and second follow‐up (Jun 15).

Figure 6

(a) Box and whisper plots showing the marginal change in indurometer scores. Higher scores indicate increased tissue compressibility. (b) Box and whisper plots showing the marginal change in BIS scores. Higher scores indicate reduced free fluid.