Post kala azar dermal leishmaniasis and leprosy prevalence and distribution in the Muzaffarpur health and demographic surveillance site.

Post-kala-azar dermal leishmaniasis (PKDL) is a skin manifestation that is a late clinical outcome of visceral leishmaniasis (VL). Its presentation is similar to leprosy, and the differential diagnosis is not always easy. In VL endemic rural areas of Bihar, India, both infectious diseases co-exist. This observational study aimed to determine the prevalence and distribution of both conditions in an area that had until recently been highly endemic for VL. We conducted a door-to-door survey in an area that belongs to the Health and Demographic Surveillance Site (HDSS) of Muzaffarpur, Bihar, India. Within the HDSS we selected the villages that had reported the highest numbers of VL cases in preceding years. All consenting household members were screened for skin conditions, and minor conditions were treated on the spot. Upon completion of screening activities at the level of a few villages, a dermatology clinic ("skin camp") was conducted to which suspect leprosy and PKDL patients and other patients with skin conditions requiring expert advice were referred. We studied the association between distance from an index case of leprosy and the probability of disease in the neighborhood by fitting a Poisson model. We recorded a population of 33,319, out of which 25,686 (77.1%) were clinically screened. Participation in skin camps was excellent. Most common conditions were fungal infections, eczema, and scabies. There were three PKDL patients and 44 active leprosy patients, equivalent to a prevalence rate of leprosy of 17.1 per 10,000. Two out of three PKDL patients had a history of VL. Leprosy patients were widely spread across villages, but within villages, we found strong spatial clustering, with incidence rate ratios of 6.3 (95% C.I. 1.9–21.0) for household members and 3.6 (95% C.I. 1.3–10.2) for neighbors within 25 meters, with those living at more than 100 meters as the reference category. Even in this previously highly VL endemic area, PKDL is a rare condition. Nevertheless, even a single case can trigger a new VL outbreak. Leprosy is also a rare disease, but current prevalence is over 17 times the elimination threshold proclaimed by WHO. Both diseases require continued surveillance. Active case finding for leprosy can be recommended among household members and close neighbors of leprosy patients but would not be feasible for entire populations. Periodic skin camps may be a feasible and affordable alternative. We describe a survey for post kala azar dermal leishmaniasis (PKDL) and leprosy carried out in a surveillance site in Bihar, India, that has until recently been highly endemic for visceral leishmaniasis (VL). Both leprosy and VL are subject to elimination initiatives, for both diseases the target prevalence is set at less than 1 case per 10,000 population. PKDL, a dermatological sequel of VL, is important because it can act as a reservoir for VL in inter-epidemic periods. So far very little is known about prevalence of PKDL in India and the frequency of PKDL among former VL patients. Our survey was population based, allowing us to assess PKDL prevalence not only among former VL patients but also among those not known to have suffered from VL in the past. We conducted door-to-door screening and suspect cases of leprosy and PKDL were referred to a 'skin camp', an outreach consultation for skin conditions at village level. We recorded geographic coordinates of each household screened, thus we were able to explore spatial associations. Participation in the survey and in the skin camps was very good. On a population of over 25,000 screened we found only three PKDL cases but 44 active leprosy patients. For leprosy this equates to a prevalence of 17.1 per 10,000, way above the elimination threshold. Of our three PKDL cases, two had occurred in known former VL cases, one was in a person who reported never to have suffered from VL. For leprosy we found strong spatial associations with a six-fold increase in risk for household members but also a three to four-fold increase for neighbors at less than 25 meters. The three PKDL cases were from three different villages, their numbers were too low for any meaningful spatial analysis. We conclude that leprosy is still a major problem in the area that requires more efforts. Active screening of household contacts is rational but should be extended to nearby neighbors. Though relatively efficient, this approach would miss out on the bulk of leprosy patients. PKDL is a rare condition but needs to be kept under surveillance. Skin camps can provide a feasible alternative to door-to-door screening, allowing to target both conditions simultaneously. [ABSTRACT FROM AUTHOR]