New Treatment Schemes for Yaws: The Path Toward Eradication

Abstract

Yaws—an infectious disease caused by Treponemapallidum subsp. pertenue—is a paradigmatic example ofthe neglected tropical disease and is reemerging as apublic health concern in many countries, causing suf-fering particularly in children aged 500000 people,mostly children in poor rural areas, were affected bythe disease [4]. Some of the most important endemicfoci today are located in Africa (Ghana, Congo, Cam-eroon) [5], Southeast Asia (Indonesia, Timor-Leste),and the Pacific islands (Papua New Guinea, SolomonIslands, Vanuatu) [6], but figures for the number ofpeople infected are imprecise due to patchy surveying,especially in isolated districts and islands [7].STANDARD ANTIBIOTIC TREATMENTThe WHO yaws treatment guidelines date to the1950s, and since then, no alternatives to penicillin forfirst-line treatment have been introduced. Penicillinwas proven to be highly effective against yaws andother treponemal diseases in 1948, and it revolution-ized the therapy of these infections. Tests on experi-mentally infected animals and infected patientsshowed that benzylpenicillin levels >0.03 units/mL ofserum maintained for at least 7 days were treponemi-cidal [8]. These levels can be achieved either by givingrepeated doses of short-acting benzylpenicillin prepa-rations (ie, aqueous benzylpenicillin) or a single intra-muscular injection of slowly absorbed, repositorybenzylpenicillin preparations such as benzathine ben-zylpenicillin or penicillin aluminium monostearate [9].Intramuscular benzathine benzylpenicillin was chosenas the preferred treatment for yaws because of itsconvenient pharmacokinetics and manufacturingadvantages. The WHO guidelines still recommend 1intramuscular injection of long-acting benzathine ben-zylpenicillin at a dose of 1.2 MU for adults and 0.6MU for children [7].