Yaws in Haiti

In the Dubois book I reviewed in a prior blog, Haiti - the Aftershocks of History, I learned that Duvalier, the infamous Papa Doc, graduated and worked as a medical doctor before he became a much-reviled tyrant and dictator. As a medical doctor, he worked on a Yaws eradication program in Haiti. Go figure.

"Yaws," I thought when I read the book. "What do I know about Yaws?" "Not much" was the answer, and since this disease is still present in Haiti, some reading was in order. 

According to a May 2012 World Health Organization (WHO) report, Yaws is "widely prevalent" in Haiti. Almost 75% of people affected with yaws are children under 15 years, and the peak incidence occurs in children aged 6–10.

  

Yaws is a chronic bacterial infection due to Treponema pallidumpertenue, a slender spirochete that is serologically indistinguishable from the bacteria that causes syphillis. The germ is transmitted primarily through skin contact with an infected person.

After an incubation period of about three weeks  (9-90 days), the primary lesion, or the mother yaw, develops where the germ enters the skin in a scratch, bite, or abrasion, most commonly on the legs, feet, or buttocks. The initial lesion is a red, non-tender, papule or nodule.

The mother yaw ulcer develops a honey-brown crust and enlarges up to 1 to 5 cm in diameter, sometimes coalescing with satellite lesions. The crust frequently sloughs and reveals a raspberry-like base. The exudate of the raspberry-like ulcer is teeming with treponemes and these lesions are highly infectious. After the mother yaw heals, an atrophic scar with central hypopigmentation remains.

Following about 6 to 16 weeks of latency, disseminated skin lesions, bone lesions, and constitutional symptoms develop. The cutaneous lesions, or the daughter yaws, resemble the mother yaw but are smaller and only up to 2 cm and are frequently located adjacent to body orifices, particularly the mouth and the nose. The daughter yaws expand, ulcerate, and exude a fibrinous fluid teeming with treponemes, which dries into a crust. The exudate attracts flies, which are bothersome to the person who is affected.

Secondary "daughter yaws." Photo courtesy WHO.

Lesions on the sole of the foot can form thick, hyper-keratotic plaques that become fissured or eroded. These lesions are painful and cause a deliberate crab-like gait (crab yaws).

Relapses develop over a lifetime, and can occur at intervals of up to 5 years.

The diagnosis of yaws is made by identification of the typical spirochete lesions in serum obtained by squeezing the base of a lesion and examination of the liquid by dark-field microscopy.

Treatment of yaws got much easier after a January 2012 study was published in The Lancet. A study in Papua New Guinea revealed that a single dose of oral azithromycin is as effective as a single injection of benzathine penicillin. At 6 months of follow-up, 96% of patients in the azithromycin group were cured, compared with 93% in the benzathine benzylpenicillin group.

A thorough physical exam is always part of my assessment. Now that I know what to look for, perhaps I will see and help cure this chronic infection in a few children.