Description, Causes and Risk Factors:
An infectious tropical disease caused by Treponema pertenue and characterized by the development of crusted granulomatous ulcers on the extremities; may involve bone, but, unlike syphilis, does not produce central nervous system or cardiovascular pathology
Yaws is a long-term (chronic) infection that mainly affects the skin, bones, and joints. Yaws is an infection caused by the spiral-shaped bacteria, Treponema pallidum (a bacterial species that causes syphilis in humans; this organism can be experimentally transmitted to anthropoid apes and to rabbits; it is the type species of the genus Treponema), subspecies pertenue. It is closely related to the bacteria that cause syphilis, but this disease is not sexually transmitted. Yaws mainly affects children in rural, warm, tropical areas, such as the Caribbean Islands, Latin America, West Africa, India, and Southeast Asia.
Yaws begins when T. pertenue penetrates the skin at a site where skin was scraped, cut, or otherwise compromised. In most cases, T. pertenue is transmitted from person to person. At the entrance site, a painless bump lesion, or bump, arises within two to eight weeks and grows. The initial lesion is referred to as the mother yaw. The lymph nodes in the area of the mother yaw are often swollen (regional lymphadenopathy). When the mother yaw heals, a light-colored scar remains.
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).
Since 1990, formal reporting of yaws to WHO stopped due to the discontinuation of yaws programmes in many countries. The last estimate by WHO in 1995 recorded a global prevalence of 2.5 million cases of endemic treponematoses (mostly yaws), including 460 000 infectious cases.
The global prevalence today is unknown. Only a few countries have kept yaws as part of their health programme but possibly some of the 46 previously endemic countries may still harbour the disease.
About 2 - 4 weeks after infection, the person develops a sore called a "mother yaw" where bacteria entered the skin. The sore is a growth that looks like a raspberry. It is usually painless. These sores may last for months. More sores may appear shortly before or after the mother yaw heals.
Other symptoms include:
Scarring of the skin.
Swelling of the bones and fingers.
In the final stage, sores on the skin and bones can lead to severe disfigurement and disability. This occurs in up to 1 in 5 people who do not get antibiotic treatment.
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 (rapid plasma reagent) test, VDRL (venereal disease research laboratory) test, TPHA (Treponema pallidum hemagglutination) test, FTA-ABS (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.
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.
NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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