What is yaws?

Yaws is a common chronic infectious disease that occurs mainly in warm humid regions such as the tropical areas of Africa, Asia, South and Central Americas, plus the Pacific Islands. The disease has many names (for example, pian, parangi, paru, frambesia tropica)

What are symptoms of yaws?

Yaws usually features lesions that appear as bumps on the skin of the face, hands, feet, and genital area. The disease most often starts as a single lesion that becomes slightly elevated, develops a crust that is shed, leaving a base that resembles the texture of a raspberry or strawberry. This primary lesion is termed the mother yaw (also termed buba, buba madre, or primary frambesioma). Secondary lesions, termed daughter yaws, develop in about six to 16 weeks after the primary lesion. Almost all cases of yaws begin in children under 15 years of age, with the peak incidence in 6-10-year-old children. The incidence is about the same in males and females.

What causes yaws?
Yaws is caused by a particular bacterium called a spirochete (a spiral-shaped type of bacteria). The bacterium is scientifically referred to as Treponema pertenue. This organism is considered by some investigators to be a subspecies of T. pallidum, the organism that causes syphilis (a systemic sexually-transmitted disease). Other investigators consider it to be a closely related but separate species of Treponema. T. carateum, the cause of pinta (a skin infection with bluish-black spots), is also closely related to T. pertenue. The history of yaws is unclear; the first possible mention of the disease is considered to be in the Old Testament. D. Bruce and D. Nabarro discovered the spirochete causing yaws (T. pertenue) in 1905.

What are developmental stages in the course of yaws?
Yaws has four stages: primary, secondary, latent, and tertiary. The primary stage is the appearance of the mother yaw. Patients with yaws develop recurring ("secondary") lesions and more swollen lymph nodes. This represents the secondary stage. These secondary lesions may be painless like the mother yaw or they may be filled with pus, burst, and ulcerate. The affected child often experiences malaise (feels poorly) and anorexia (loss of appetite). The latent stage occurs when the disease symptoms abate, although an occasional lesion may occur. In the tertiary stage, yaws can destroy areas of the skin, bones, and joints and deform them. The palms of the hands and soles of the feet tend to become thickened and painful (crab yaws).

How is yaws diagnosed?
Yaws is suspected in any child who has the characteristic clinical features and lives in an area where the disease is common. With increasing travel, a child once in the tropics may carry the disease to a more temperate area of the world.

Laboratory confirmation of the diagnosis is by blood serum tests (for example, RPR or rapid plasma reagent test, VDRL test or venereal disease research laboratory test, TPHA or Treponema pallidum hemagglutination test, FTA-ABS or fluorescent treponema antibody absorption), but most frequently the diagnosis is made on clinical findings. The reason that T. pallidum serum tests are used is that the spirochetes are so closely related, they have similar antigens on their surfaces so that T. pallidum and T. pertenue are cross-reactive (detected by the same serological tests). Special (dark-field) examination under the microscope in which technicians can actually see the spirochete bacterium is also used to help diagnose yaws. The lesions (both the mother yaw and the secondary lesions) usually have many T. pertenue organisms that can be visualized with dark-field examination of lesion scrapings. On a typical Gram stain (a procedure for identifying bacteria when viewed microscopically), the organisms are considered to be Gram-negative but stain so poorly and are so small and thin, the Gram stain often does not reveal the organisms; hence the use of the dark-field examination. Other tests that detect spirochetes such as a silver stain or electron microscopy are used mainly by research scientists.

How is yaws treated?
Treatment of yaws is simple and highly effective. Penicillin G benzathine given IM (intramuscularly) can cure the disease in the primary, secondary, and usually in the latent phase. Penicillin V can be given orally for about seven to 10 days, but this route is less reliable than direct injection. Anyone allergic to penicillin can be treated with another antibiotic, usually erythromycin, doxycycline, or tetracycline. Tertiary yaws, which occurs in about 10% of untreated patients five to 10 years after initially getting the disease, is not contagious. The tertiary yaws patient is treated for the symptoms of the chronic conditions (altered or destroyed areas in bones, joints, cartilage, and soft tissues) that develop as a result of the infection. There is no vaccine for yaws.

Select Language English Russian French German Italian Japanese Korean Portuguese Spanish Greek Dutch Hindi