Pinta, also called puru-puru or carate, is a relatively benign (mild and non-progressive) skin disease, caused by bacteria called Treponema carateum. Other species of Treponema are responsible for yaws and syphilis in humans, but unlike these conditions, pinta only affects the skin. Pinta is only found in scattered rural areas of Central and South America. It was first described in the 16th century in Aztec and Caribbean Amerindians. The prevalence of pinta is decreasing; in the 1950s about 1 million cases of pinta were reported, currently only a few hundred cases are reported per year.
Pinta primarily affects children and young adults. Although the exact mode of transmission is unknown, pinta is probably transmitted by direct skin or mucous membrane contact. Insect bites have been implicated in transmission, since they break the skin.
Clinical features of pinta
Pinta is classified into three stages.
Primary or early pinta occurs fter an incubation period of 2 to 3 weeks. It presents as one or more papules (small raised bumps) that slowly enlarge to become itchy, red, scaly plaques (large, flat lesiosn). The areas most commonly affected are exposed skin on the top of the feet, legs, back of the hands, and the forearms. Lymph nodes near affected skin may become enlarged, but the patient does not develop any systemic symptoms.
During the second phase, a more widespread skin eruption may appear. These are small papules and larger plaques called “pintids”, which occur after 6 months to 3 years, with abnormal pigmentation and scaling. Lesions may appear red, white, blue, violet, or brown.
Tertiary pinta refers to late lesions, where the skin becomes achromic (with complete loss of pigment/colour) and atrophic (thin).
- The diagnosis is commonly made based upon the appearance of the lesions.
- T carateum cannot be distinguished from other Treponema species that cause yaws and syphilis with commercially available laboratory tests.
- Dark field microscopy of swabs taken from early lesions may reveal treponemes.
- Serological blood tests will be positive for syphilis.
- Biopsy of the lesions may reveal characteristic microscopic changes. In early lesions, treponemes may be demonstrated using silver stain.
Pinta is treated with benzathine penicillin. Other useful antibiotics include tetracycline or erythromycin. Skin lesions become non-infectious within 24 hours of treatment. Early lesions heal within 6 to 12 months, but pigmentary changes persist in late lesions.