Yaws in the Western Pacific Region: A Review of the Literature

Until the middle of the 20th century, yaws was highly endemic and considered a serious public health problem in the Western Pacific Region (WPR), leading to intensive control efforts in the 1950s–1960s. Since then, little attention has been paid to its reemergence. Its current burden is unknown. This paper presents the results of an extensive literature review, focusing on yaws in the South Pacific. Available records suggest that the region remains largely free of yaws except for Papua New Guinea, Solomon Islands, and Vanuatu. Many clinical cases reported recently were described as “attenuated”; advanced stages are rare. A single intramuscular injection of benzathine penicillin is still effective in curing yaws. In the Pacific, yaws may be amenable to elimination if adequate resources are provided and political commitment revived. A mapping of yaws prevalence in PNG, Solomon, and Vanuatu is needed before comprehensive country-tailored strategies towards yaws elimination can be developed. 1. Introduction Yaws is a nonvenereal infectious disease caused by the bacterium Treponema pallidum subspecies pertenue. It is mainly transmitted from person to person through direct contact with exudates from early skin lesions of infected people [1]. Yaws is considered a disease of poverty occurring in tropical regions throughout the world with heavy rainfall and high humidity [2]. It is more common in rural and isolated populations where access to health care is often limited [3]. Crowded environments and poor hygiene are also considered as factors facilitating transmission [4, 5]. The disease affects predominantly children younger than 15 years (the peak incidence of clinical manifestations is 2 to 10 years), who serve as the primary reservoir of the disease. The current knowledge is that transmission is by direct contact with infected lesions [2] and that flies, including nonbiting haematophagous ones, can infect skin breaches through their dejecta or regurgitation [6, 7]. Perine et al. [2] reported that a yaws-like treponema was identified in African monkeys and baboons, and more recently Robed et al. [8] mentioned that the genetic analysis of a strain collected from a Guinean baboon demonstrated a close relation to the human strains of yaws. Furthermore, yaws-like infections have been identified in nonhuman primates in Africa, in particular in the Republic of Congo where 17% of a wild gorilla population have been found with typical yaw lesions [7] leading the authors to speculate that yaws infections in gorillas and humans living in tropical rain forests might be