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Other Treponema Species
Yaws
Yaws ( Treponema pallidum subsp. Pertenue infection) is an infectious disease of childhood. It is seen in warm, humid tropical regions in rural, often inaccessible areas and is associated with poverty, overcrowding, poor hygiene, and lack of access to health services. “Yaws begins where the road ends.” Endemic areas include Africa, Southeast Asia, the Western Pacific, and South and Central America. Yaws is also known as framboesia, pian, parangi, paru, bouba, and buba.
Mass treatment campaigns of approximately 50 million people in the 1950s and 1960s eradicated yaws from many areas. However, a resurgence of the disease occurred in the 1980s, particularly in parts of West and Central Africa and Southeast Asia. , The successful yaws eradication campaign in India renewed energy and efforts to eliminate yaws worldwide. In 2012 the World Health Organization (WHO) devised the Morges Strategy to eradicate yaws by 2020 ; however, this ambitious target has not been reached. This plan included treating entire communities with 1 dose of azithromycin with close follow-up for 3 years with serosurveys and retreatment if necessary. Although a successful mass treatment campaign in Papua New Guinea used this strategy, follow-up data showed the re-emergence of yaws, making it clear that multiple cycles of community treatment may be required to interrupt transmission. Also, recent diagnoses of yaws in the Philippines, where cases have not been reported since the 1970s, indicates the need for increased surveillance and testing, even in countries previously considered eradicated of yaws. WHO has described the need to verify and certify interruption of yaws transmission and eventual eradication of disease.
Clinical Manifestations
Yaws is passed from child to child through nonsexual contact with primary or secondary skin lesions. The primary lesion, the mother yaw, generally occurs on the lower half of the body at sites of minor trauma. The lesion begins as a painless, erythematous papule that enlarges, ulcerates, and becomes covered by a honey-colored crust 9–90 days after inoculation. Painless, regional lymphadenopathy occurs. The primary lesion heals after several weeks to months.
Organisms disseminated during the primary stage form the basis of secondary disease. This stage manifests as multiple cutaneous lesions (daughter yaws), which resemble the mother yaw both clinically and histologically but are smaller, as well as painful periostitis involving bones of the extremities, especially the hands and feet. Secondary lesions heal spontaneously and without scarring.
The pathologic features of primary and secondary lesions resemble those seen in sexually acquired syphilis. Latent yaws is characterized by intermittent relapses of skin lesions at intervals for up to 5 years, but congenital infection is not seen. Experimental infections of guinea pigs have confirmed the lack of congenital infection in yaws.
Tertiary yaws, which develops in approximately 10% of untreated patients after several years, consists of destructive lesions of bone, cartilage, soft tissue, and skin. Characteristic findings are as follows: palmar-plantar hyperkeratosis; goundou, a rare lesion in which symmetric involvement of the nasal processes of the maxilla leads to excessive bone formation and obstruction of the airway; gangosa (destructive ulcerative rhinopharyngitis); and chronic osteitis leading to saber tibia.
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