Since Yaws is prevalent in some parts of tribal areas only, a survey is conducted twice a year in tribal districts of Chandrapur and Gadchiroli.
- Yaws is primarily a disease of childhood and adolescence.
- Males are more affected than females.
- Yaws is mostly endemic among the tribal people in India, whose ways of living favour its transmission.
The Primary lesion or “Mother Yaw” appears at the site of inoculation after an incubation period of 3 to 5 weeks. The lesion is extra genital and is seen on exposed parts of the body such as legs, arms, buttocks or face. The local lymph glands are enlarged and the blood becomes positive for STS. Within the next 3 to 6 weeks, a generalized eruption appears consisting of large, yellow, crusted, granulomatous eruptions often resembling condylomata lata in secondary syphilis. During the next five years skin, mucous membrane, periosteal and bone lesions may develop, subside and relapse at irregular intervals. The early lesions are highly infectous.
From the end of 5 years, destructive and often deforming lesions of the skin, bone and periosteum appear. The lesions of sole and palms are called “Crab Yaws”. The destructive lesions of soft palate, hard palate, and nose are called “Gangosa”. Swelling of the side of the nose due to osteo–periositis of the superior maxillary bone is called “Goundu”.
Causative Agent of Yaws
Yaws is caused by T. pertenue which closely resembles T. pallidum culturally and morphologically. It measures 20 u in length with 8 to 12 rigid spirals. The agent occurs in the epidermis of the lesions, lymph, spleen and bone marrow. The organism rapidly dies outside the tissues. Man is the only known reservoir of Yaws.