Evaluation of an Intensive 3-round MDA Strategy Towards Yaws Eradication

In 2013 WHO piloted the yaws eradication MDA strategy in several countries, including PNG. A study carried out on Lihir Island has shown that 1-round MDA with single-dose oral AZI reduced the prevalence of yaws by 90% at 12-months. However, this did not suffice to stop transmission of infection. At baseline, the estimated prevalence of PCR-confirmed active infection was 1.8% and greatly reduced to 0.4% at 6-months, and 0.1% at 24 months; but prevalence increased again to 0.4% at 42 months after MDA. The relapse of untreated latent infections appeared to hinder elimination efforts in this community. Almost half of subjects with newly identified active yaws cases during follow up targeted treatment programs reported having not been present for MDA. T. p. pertenue may become resistant to macrolide antibiotics, as has occurred with T. p. pallidum (the causative agent of syphilis) in some developed countries, which necessitates close monitoring for the emergence of resistance. The investigators recently reported the first documented genotypic macrolide resistance in T. p. pertenue infections in PNG. A total of five clinical specimens, out of 208 samples tested during the post-MDA period of 3·5 years, demonstrated a T. p. pertenue strain carrying the A2059G point mutation. There was only local spread of the resistant clone among relatives and friends and further spread was immediately stopped through the use of alternative (benzathine penicillin) antibiotic to treat the newly identified cases and contacts.

The eligible population will be people targeted for MDA treatment living in the three LLG study areas at time of implementation. The 38 wards will be randomly assigned (1:1) to receive 1 vs 3 rounds of MDA using AZI. All villages within a ward will receive the same intervention in an effort to minimize contamination between villages. The intervention arm will receive 3 rounds (0, 6, 12 months) of MDA with AZI, each round known as total community treatment (TCT); control arm will receive 1 round (0 months) of MDA with AZI followed by total targeted treatment (TTT) (6 and 12 months). During each MDA round all study participants will receive 30 mg/Kg (maximum 2 g) of AZI orally under direct observation.

The primary outcome will be prevalence of PCR-confirmed active yaws measured in the entire population at 18 months. The investigators will estimate the evolution of latent yaws prevalence measured as the proportion of children 1-15 years who are dually positive on the DPP test at two time-points (0, 18 months).

Inclusion criteria

• all people resident or not in wards in the study region present at time of implementation or in subsequent surveys

Exclusion criteria

• Children younger than 6 months
• Known allergy to macrolide antibiotics
• Refusal at village or individual levels