The Morges Strategy for Yaws Eradication: the First Largescale Total Community Treatment with Azithromycin Against Yaws in the Congo-Basin, using a Novel Model
Authors: Tabah Earnest Njih , Boock Alphonse Um , Djam Chefor Alain , Aloumba Gilius Axel , Bernard Boua , Tsago Nzoyem Colin , Nformi Irine Ngani , Pagning Loic Douanla , Baran-A-Bidias Elisaberth , Kouayep-Watat Christian Elvis , Afanji Smith , George Ebai , Ngassa Marielle Patty , Savadogo Bonaventure , Tchatchouang Serges , Donkeng Valerie , Barogui Yves Thierry , Eyangoh Sara , Asiedu Kingsley Bampoe 
Published: November 2024

Abstract

Context and Justification

Yaws is targeted for eradication by 2030. Total Community Treatment with azithromycin (TCT), a major component of the eradication strategy, has witnessed only three pilots since 2012. We implemented the first large-scale TCT in the Congo-Basin of Central Africa using a novel model.

Methodology

We implemented a novel 3-phase TCT model in 17 health districts of the Congo-Basin, spanning 3 countries. Two rounds were implemented in Cameroon, and one round each in Central African Republic (CAR) and the Republic of Congo; targeting 1,530,014 people (144,934(9.5%) Pygmies and 1,304,410(90.5%) Bantus). TCT was followed by post-campaign active surveillance, treatment of yaws cases and their contacts.

Results

All 17 health districts were confirmed for yaws endemicity. Overall, 1,456,691 (95.21%; 95%CI: 95.17%-95.24%) persons were treated in the first round of TCT, including 552,356/594411 (92.92%; 95%CI: 92.86%-92.99%) in Cameroon, 359,810/373,994 (96.21%; 95%CI: 96.15%-96.27%) in CAR, and 544,526/561,609 (96.96%; 95%CI: 96.91%-97.00%) in Congo. For the second round implemented only in Cameroon, 615,503/642,947 (95.73%; 95%CI: 95.68%-95.78%) were treated. There was a 3-percentage-point increase in therapeutic coverage between the first and second round (P-value<0.001), and from 89.2% to 93.1% (P-value<0.001) among the Pygmies. The prevalence of active yaws decreased from 6.5% to 0.4% (P-value<0.001) overall; and from 6.31% to 0.23% (P-value<0.001, OR=28.67, 95%CI (20.86-40.09) in Cameroon, from 2.4% to 0.8% (P-value=0.002, OR=3.19, 95% CI: 1.45-8.00) in CAR, and from 10.8% to 3.7% (P-value<0.001, OR=3.18, 95%CI: 2.09 – 5.01) in Congo.

Conclusion

A novel TCT model was successfully implemented at largescale in the Congo-Basin, achieving above recommended threshold of therapeutic coverages. The prevalence of active yaws dropped remarkably following the TCT, however complete interruption of yaws transmission was not achieved. In recommending the novel model of TCT to endemic countries, we suggest that at least three rounds, at six-monthly intervals, are implemented for complete interruption of yaws transmission.

Author summary

Yaws, a skin-NTD that affects mainly children resurfaced among the Pygmies of the Congo-Basin around 2007 after eradication in the late 1970s. Renewed efforts for eradication guided by the Morges strategy are being promoted by the WHO. In this regard, we a novel model for Total Community treatment (TCT) with azithromycin in 17 health districts of the Congo-Basin spanning three countries including Cameroon, CAR and The Republic of Congo. This was the largest scale so far, since the inception of the Morges strategy. Of a total population of 1,530,014 targeted in the first round of TCT, 1,456,691(95.21%) persons were treated including 552,356 in Cameroon, 359,810 in CAR, and 544,526 in Congo. For the second implemented only in Cameroon, 615,503 (95.73%) out of 642,947 people targeted were treated. Our novel model permitted the achievement of therapeutic coverages surpassing the 90% threshold recommended by the WHO. The TCT led to a remarkable reduction of the prevalence of active yaws in the zone, but however, did not interrupt its transmission. In recommending the novel model of TCT to yaws endemic countries, we think that at least three rounds at six-monthly intervals are necessary for complete interruption of yaws transmission.