Yaws is a contagious, nonvenereal, treponemal infection in humans that presents mainly in children younger than 15 years. Infection with Treponema pertenue, a subspecies of Treponema pallidum (the causative agent of syphilis), causes the disease. It occurs primarily in warm, humid, tropical areas among poor rural populations where conditions of overcrowding, poor sanitation and inadequate water supply prevail.
The major route of infection is through direct person-to-person contact. The treponemes associated with yaws are present primarily in the epidermis. The ulcerative skin lesions present early in the disease are teaming with spirochetes, which can be transmitted via direct skin-to-skin contact and via breaks in the skin from trauma, bites, or excoriations.
Yaws is classified into the following 4 stages:
* Primary stage: Initial yaws lesion develops at inoculation site
* Secondary stage: Widespread dissemination of treponemes results in multiple skin lesions similar to primary yaws lesion
* Latent stage: Usually, no symptoms are present, but skin lesions can relapse
* Tertiary stage: Bone, joint, and soft tissue deformities may occur
Another classification distinguishes early yaws from late yaws. Early yaws includes primary and secondary stages and is characterized by the presence of contagious skin lesions. Late yaws includes the tertiary stage, when lesions are not contagious.
In the majority of patients, yaws remains limited to the skin, but early bone and joint involvement can occur. Although yaws lesions disappear spontaneously, secondary bacterial infections and scarring are common complications.
After 5-10 years, 10% of untreated patients develop destructive lesions involving bone, cartilage, skin, and soft tissue, similar to those seen in tertiary syphilis. In contrast to venereal syphilis, cardiovascular and neurological abnormalities almost never occur in patients with yaws.
No sex predilection exists. Yaws predominantly affects children younger than 15 years. Peak incidence occurs in children aged 6-10 years
Long-acting Penicillin is the drug of choice for treatment of yaws cases and their contacts.
1.2 million units of Injection Penicillin G Aluminium Monostearate (PAM) to adults as single intra-muscular injection and 0.6 million units to children below 10 years cures the disease and make the patient non-infectious within 24 hours.
Penicillin is contraindicated in patients/contacts with history of drug hyper-sensitivity. No penicillin resistant strains have been reported so far.