Spatiotemporal distribution of cutaneous leishmaniasis in Sri Lanka and future case burden estimates

Abstract

Background Leishmaniasis is a neglected tropical vector-borne disease, which is on the rise in Sri Lanka. Spatiotemporal and risk factor analyses are useful for understanding transmission dynamics, spatial clustering and predicting future disease distribution and trends to facilitate effective infection control. Methods The nationwide clinically confirmed cutaneous leishmaniasis and climatic data were collected from 2001 to 2019. Hierarchical clustering and spatiotemporal cross-correlation analysis were used to measure the region-wide and local (between neighboring districts) synchrony of transmission. A mixed spatiotemporal regression-autoregression model was built to study the effects of climatic, neighboring-district dispersal, and infection carryover variables on leishmaniasis dynamics and spatial distribution. Same model without climatic variables was used to predict the future distribution and trends of leishmaniasis cases in Sri Lanka. Results A total of 19,361 clinically confirmed leishmaniasis cases have been reported in Sri Lanka from 2001–2019. There were three phases identified: low-transmission phase (2001–2010), parasite population buildup phase (2011–2017), and outbreak phase (2018–2019). Spatially, the districts were divided into three groups based on similarity in temporal dynamics. The global mean correlation among district incidence dynamics was 0.30 (95% CI 0.25–0.35), and the localized mean correlation between neighboring districts was 0.58 (95% CI 0.42–0.73). Risk analysis for the seven districts with the highest incidence rates indicated that precipitation, neighboring-district effect, and infection carryover effect exhibited significant correlation with district-level incidence dynamics. Model-predicted incidence dynamics and case distribution matched well with observed results, except for the outbreak in 2018. The model-predicted 2020 case number is about 5,400 cases, with intensified transmission and expansion of high-transmission area. The predicted case number will be 9115 in 2022 and 19212 in 2025. Conclusions The drastic upsurge in leishmaniasis cases in Sri Lanka in the last few year was unprecedented and it was strongly linked to precipitation, high burden of localized infections and inter-district dispersal. Targeted interventions are urgently needed to arrest an uncontrollable disease spread.

Community Engagement in Cutaneous Leishmaniasis Research in Brazil, Ethiopia, and Sri Lanka: A Decolonial Approach for Global Health

“…In contrast to Brazil and Ethiopia, CL is an emerging public health issue in Sri Lanka and there is believed to be little awareness of the condition in newly endemic regions. The first locally acquired case was reported in 1992 ( 44 ) and there has been a major increase in new cases in the north of the island over the last decade ( 45 , 46 ) with a prediction of continued increases unless effective control measures are put in place ( 47 ). There is large variability in terms of reported cases across Sri Lanka, and even within districts suggesting that despite there being a mandatory requirement for healthcare professionals to report cases of CL, this is currently not always happening ( 48 ).…”

ELISA‐based evaluation of antibody response to Leishmania in a region endemic for cutaneous leishmaniasis

“…The study was a laboratory based evaluation conducted using archived samples from a risk factor survey that was carried out from 2018 to 2020 in 14 Regional Director of Health Services areas in Sri Lanka where CL is endemic, as described before 28 . The study area covered all nine provinces of Sri Lanka.…”

“…The study was a laboratory based evaluation conducted using archived samples from a risk factor survey that was carried out from 2018 to 2020 in 14 Regional Director of Health Services areas in Sri Lanka where CL is endemic, as described before. 28 The study area covered all nine provinces of Sri Lanka. Endemic/non-endemic status of an area was determined based on case incidence data during the past 18 years (2001-2019), with annual incidence rate of <1 case/1000 people taken as non-endemic and ≥10 cases/1000 people considered as endemic.…”

Genetic diversity of <em>Phlebotomus (Euphlebotomus) argentipes</em> species complex in Sri Lanka

“…Leishmaniasis was made a notifiable disease in 2009 in Sri Lanka. Since then, the number of cases reported was more than a thousand in Hambantota and Anuradhapura districts (Amarasinghe and Wickramasinghe, 2020; Karunaweera et al, 2021). Matara, Kurunagala, and Polonnaruwa districts were reported with more than 500 cases.…”

“…Few cases were notified in the Jaffna District as well (Galgamuwa et al, 2018). Several leishmaniasis outbreaks were reported in Matara, Anuradhapura, Hambantota, Kurunagala, Polonnaruwa and Mullaitivu districts (Semage, 2014;Karunaweera et al, 2021). According to the Epidemiology Unit of Sri Lanka, in 2018, 3271 cases were reported and 90% of them were from these districts.…”