Epidemiology of Post-Kala-azar Dermal Leishmaniasis

Abstract

Post-kala-azar dermal leishmaniasis (PKDL) is a cutaneous sequel of visceral leishmaniasis (VL) or kala-azar and has become an entity of epidemiological significance by virtue of its ability to maintain the disease in circulation during inter-epidemic periods. PKDL has been identified as one of the epidemiological marker of “kala-azar elimination programme.” Data obtained in 2018 showed PKDL distribution primarily concentrated in 6 countries, which includes India, Sudan, south Sudan, Bangladesh, Ethiopia, and Nepal in decreasing order of case-burden. In India, PKDL cases are mainly found in 54 districts, of which 33 are in Bihar, 11 in West Bengal, 4 in Jharkhand, and 6 in Uttar Pradesh. In West Bengal the districts reporting cases of PKDL cases include Darjeeling, Uttar Dinajpur, Dakshin Dinajpur, Malda, and Murshidabad. The vulnerability on the young age is documented in various studies. The studies also highlights a male predominance of the disease but recent active surveillance suggested that macular form of PKDL shows female-predominance. It is recommended that along with passive case detection, active survey helps in early identification of cases, thus reducing disease transmission in the community. The Accelerated plan for Kala-azar elimination in 2017 introduced by Government of India with the goal to eliminate Kala-azar as a public health problem, targets to reduceing annual incidence <1/10,000. Leishmania donovani is the established causative agent, but others like L. tropica or L. infantum may occasionally lead to the disease, especially with HIV-co-infection. Dermal tropism of the parasite has been attributed to overexpression of parasite surface receptors (like gp 63, gp46). Various host factors are also identified to contribute to the development of the disease, including high pretreatment IL 10 and parasite level, inadequate dose and duration of treatment, malnutrition, immuno-suppression, decreased interferon-gamma receptor 1 gene, etc. PKDL is mostly concentrated in the plains below an altitude of 600 mts which is attributed to the environment conducive for the vector sand fly ( Phlebotumus ). Risk factors are also linked to the habitat of the sand fly. Keeping these things in mind “Integrated vector control” is adopted under National vector borne disease control programme as one of the strategies to bring down the disease burden.

IgG3 and IL10 are effective biomarkers for monitoring therapeutic effectiveness in Post Kala-Azar Dermal Leishmaniasis

“…This study was an extension of a randomized sampling mode study where suspected cases of PKDL reported at a medical camp, and after confirmation of diagnosis were randomly allocated Miltefosine or LAmB depending on drug availability [ 13 ]. In 2010, the prevalence of PKDL was reported to range from 4.4 to 7.8 per 10,000 endemic population, and later declined to 1.1 per 10,000 population in a 2017 study [ 56 and references therein]. Accordingly, taking a real world, pragmatic approach, sample size calculation was not attempted.…”

The leishmaniases in Kenya: A scoping review

“…The clinical diagnoses and treatment of VL, CL, MCL, and PKDL are complicated by non-specific presentations early in the course of each disease [ 9 ]. Co-infection with HIV presents an important manifestation of leishmaniasis infection as its clinical presentation is often atypical and, therefore, further obscures accurate diagnosis in communities with high HIV prevalence [ 10 ].…”

“…MCL and PKDL data is scarcer than VL and CL data in Kenya. It is estimated that PKDL occurs in less than 5% of VL cases in Kenya, although research on PKDL is not as common [ 9 ]. It is within this context that leishmaniasis research has been conducted in Kenya for the last 90 years.…”

Transmission dynamics of visceral leishmaniasis with PKDL and periodic delays

“…Dewan et al [31] explored the spatial and temporal patterns of VL by studying hospital-onset VL cases in prevalent regions of Bangladesh. In diverse areas of India, Ghosh et al [32] researched the epidemiology of post-kala-azar cutaneous leishmaniasis and found that PKDL is mostly concentrated in the plains below 600 m above sea level, which is associated with sandfly habitat. There are also scholars who consider the fractional order of biological systems [33][34][35].…”