YAWS: A Neglected Tropical Disease

YAWS is a chronic bacterial infection caused by Treponema pallidum subspecies pertenue which mainly affects the skin and bones and is a disfiguring, disabling and non-venereal infection.

Incubation Period: After the bacterium has penetrated into the skin within a period of 3 to 4 weeks with range from 10 to 90 days, early lesion appears on near the infection .Early second lesion appears usually after an interval of 6-16 weeks (or even up to 2 years) of the primary lesion .By the end of five years, destructive and often deforming lesions of the skin, bone and periosteum appear.

Location: The disease occurs mainly in poor communities in warm, humid, tropical areas of Africa, Asia and Latin America.
In India:
As per the reports YAWS perpetuated in remote, inaccessible, hilly and forest tribal areas of Andhra Pradesh, Assam, Gujarat, Jharkhand, Chhattisgarh, Madhya Pradesh, Maharashtra, Orissa, Tamil Nadu, and Uttar Pradesh.

Places where YAWS eradication program was implemented.

Untitled-1Prevalence in India:
Past Prevalence:
Year wise reported number of cases of YAWS from 1996-2006(August).

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Present Prevalence: Prevalence today is not known.

Signs & Symptoms:

There are two basic stages of yaws disease – early (infectious) and late (non-infectious):
1.In early yaws, an initial papule develops at the site of entry of the causative organism. This papule is full of the organisms and may persist for 3-6 months followed by natural healing. Without treatment, this is followed by disseminated skin lesions over the body. Bone pain and bone lesions may also occur.
2.Late yaws appears after five years of the initial infection and is characterized by disabling consequences of the nose, bones and palmar/plantar hyperkeratosis.
In the field, diagnosis is primarily based on clinical and epidemiological findings.
A person (75% are children below 15 years) who lives in an endemic area and presents with one or more of the following signs:

1.painless ulcer with scab
2.papilloma’s
3.Palmar/plantar hyperkeratosis (thickening).

Classification and nomenclature of YAWS Lesions :

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Differential Diagnosis:

The greatest challenge remains the syphilis .Bone lesions of YAWS can be identical to those of venereal syphilis, endemic syphilis,tuberculosis.Nasopharengyeal lesions can mimic mucocutaneous leishmaniasis, rhinosporidiosis, rhinoscleroma, leprosy. Diseases which are confused with YAWS are Impetigo, Tinea versicolor, scabies, lichen planus, tropical ulcer, plantar warts, tungisis.Recent reports have shown that ulcers caused by Haemophilus ducreyi co-exists in YAWS endemic areas and are possible confounder of YAWS.

Diagnosis:
Clinical:
In the field, diagnosis is primarily based on clinical and epidemiological findings. There are two basic stages of yaws: early (infectious) and late (non-infectious).

1.Papilloma: This is a single or multiple yellow bumps on the skin. For children who live in endemic villages, this may be the early presentation of yaws.

im12.Ulcers: Single or multiple wounds, often round in shape.

im_23.Squamous macules: Scaly, thickened, or discolored skin patches.

im_34.Bone swelling: This is a painful swelling of bones or joints without any external lesion.

im_45.Palmar and Plantar: These can be holes, cracks or discoloration of the soles of the feet or palms of the hand.

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Serology:

Serological tests such as Treponema pallidum particle agglutination (TPPA) and rapid plasma reagin (RPR) are widely used to diagnose Treponemal infections (e.g. syphilis and yaws). These cannot distinguish yaws from syphilis however, and the interpretation of results from these tests on adults who live in yaws endemic areas need careful clinical assessment.

Rapid point-of-care tests:
Rapid tests allow the point-of-care diagnosis and treatment of patients. There are 2 types of rapid tests:
Rapid Treponemal tests are widely used in diagnosis of syphilis, however these tests cannot distinguish between present active yaws and past infections. Therefore its use alone could lead to overtreatment of patients and over reporting of cases.
The new Chembio DPP Syphilis Screen & Confirm Assay is a single-use immune chromatographic rapid screening test for the simultaneous detection of antibodies against non-Treponemal and Treponema pallidum antigens in finger stick whole blood, venous whole blood, serum, and plasma. This test is able to detect both present and past infections to guide treatment.
Polymerase chain reaction:
Genomic analysis using polymerase chain reaction (PCR) can be used to definitively confirm yaws. The PCR technique can also be used to determine azithromycin resistance from swabs taken from yaws lesions.

Treatment & Dosage:

Two antibiotics may be used to treat yaws:
1.Azithromycin (single oral dose) at 30 mg/kg (maximum 2 gm.)
2.Benzathine penicillin (single intramuscular dose) at 1.2 million units (adults) and 600 000 units (children).Azithromycin given orally is preferred to benzathine penicillin. The recommended dosage is 30 mg/kg body weight (maximum, 2 g) as a single dose by mouth. For children aged less than 6 years, Syrup is preferable; if this formulation is not available, a tablet should be crushed and mixed with water.

Benzathine penicillin (single intramuscular dose) at 1.2 million units (adults) and 600 000 units (children).Azithromycin given orally is preferred to benzathine penicillin. The recommended dosage is 30 mg/kg body weight (maximum, 2 g) as a single dose by mouth. For children aged less than 6 years, Syrup is preferable; if this formulation is not available, a tablet should be crushed and mixed with water.

Recommended dosages of azithromycin by age:
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