A fine scale eco-epidemiological study on endemic visceral leishmaniasis in north ethiopian villages

Kirstein, Oscar D.; Skrip, Laura; Aliyu, Ibrahim; Iungman, Tamara; Horwitz, Ben Zion; Gebresilassie, Araya; Spitzová, Tatiana; Waitz, Yoni; Gebre-Michael, Teshome; Volf, Petr; Hailu, Asrat; Warburg, Alon

doi:10.1016/j.actatropica.2018.04.005

Cited by 11 publications

(15 citation statements)

References 41 publications

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“…The collective studies in Sudan and NW Ethiopia lead to the consensus that P . orientalis has a low propensity to enter household buildings [ 17 , 21 , 25 , 26 , 27 , 28 , 53 , 54 ], which is corroborated by the current data showing that comparatively few P . orientalis were captured inside sleeping huts as measured by chemical knockdown (KD) methods.…”

Section: Discussionsupporting

confidence: 89%

“…In East Africa, the prominent VL vector is Phlebotomus orientalis , which thrives in remote woodlands, villages, and peridomestic habitats, characterized by the presence of black cotton soil and Acacia seyal and Balanites aegyptiaca trees [ 13 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. The vector is highly exophilic and exophagic, rarely captured inside household buildings [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ] with villagers being exposed outdoors in the household compound and in the peridomestic surroundings. Phlebotomus orientalis is a highly seasonal species.…”

Section: Introductionmentioning

confidence: 99%

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Outdoor Residual Insecticide Spraying (ODRS), a New Approach for the Control of the Exophilic Vectors of Human Visceral Leishmaniasis: Phlebotomus orientalis in East Africa

et al. 2020

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Visceral Leishmaniasis (VL) due to Leishmania donovani is a neglected protozoan parasitic disease in humans, which is usually fatal if untreated. Phlebotomus orientalis , the predominant VL vector in East Africa, is a highly exophilic/exophagic species that poses a major challenge to current Integrated Vector Management (IVM). Here we report results of pilot studies conducted in rural villages in Gedarif state, Sudan, to evaluate outdoor residual spraying of 20mg active ingredient (a.i.) /m 2 deltamethrin insecticide applied to the characteristic household compound boundary reed fence and to the outside of household buildings (Outdoor Residual Insecticide Spraying, ODRS), and as an alternative, spraying restricted to the boundary fence only (Restricted Outdoor Residual Insecticide Spraying, RODRS). Four to six clusters of 20 households were assigned to insecticide treatments or control in three experiments. Changes in sand fly numbers were monitored over 2,033 trap-nights over 43–76 days follow-up in four sentinel houses per cluster relative to unsprayed control clusters. Sand fly numbers were monitored by sticky traps placed on the ground on the inside (“outdoor”) and the outside (“peridomestic”) of the boundary fence, and by CDC light traps suspended outdoors in the household compound. The effects of ODRS on sand fly numbers inside sleeping huts were monitored by insecticide knockdown. After a single application, ODRS reduced P . orientalis abundance by 83%-99% in outdoor and peridomestic trap locations. ODRS also reduced numbers of P . orientalis found resting inside sleeping huts. RODRS reduced outdoor and peridomestic P . orientalis by 60%-88%. By direct comparison, RODRS was 58%-100% as effective as ODRS depending on the trapping method. These impacts were immediate on intervention and persisted during follow-up, representing a large fraction of the P . orientalis activity season. Relative costs of ODRS and RODRS delivery were $5.76 and $3.48 per household, respectively. The study demonstrates the feasibility and high entomological efficacy of ODRS and RODRS, and the expected low costs relative to current IVM practises. These methods represent novel sand fly vector control tools against predominantly exophilic/exophagic sand fly vectors, aimed to lower VL burdens in Sudan, with potential application in other endemic regions in East Africa.

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Section: Discussionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Outdoor Residual Insecticide Spraying (ODRS), a New Approach for the Control of the Exophilic Vectors of Human Visceral Leishmaniasis: Phlebotomus orientalis in East Africa

et al. 2020

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“…In northern Ethiopia (Fig. 1), we used rbcL PCR to identify plants consumed by wild-caught Phlebotomus orientalis, the local vector of visceral leishmaniasis (VL) (20). We extracted DNA from 804 sand flies, achieved rbcL amplification in 65 of them, and sequenced the rbcL amplicons from 36 ( Table 1 and SI Appendix, Fig.…”

Section: Resultsmentioning

confidence: 99%

Plant-feeding phlebotomine sand flies, vectors of leishmaniasis, prefer Cannabis sativa

Abbasi

Queiroz

Kirstein

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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Blood-sucking phlebotomine sand flies (Diptera: Psychodidae) transmit leishmaniasis as well as arboviral diseases and bartonellosis. Sand fly females become infected with Leishmania parasites and transmit them while imbibing vertebrates’ blood, required as a source of protein for maturation of eggs. In addition, both females and males consume plant-derived sugar meals as a source of energy. Plant meals may comprise sugary solutions such as nectar or honeydew (secreted by plant-sucking homopteran insects), as well as phloem sap that sand flies obtain by piercing leaves and stems with their needle-like mouthparts. Hence, the structure of plant communities can influence the distribution and epidemiology of leishmaniasis. We designed a next-generation sequencing (NGS)–based assay for determining the source of sand fly plant meals, based upon the chloroplast DNA gene ribulose bisphosphate carboxylase large chain (rbcL). Here, we report on the predilection of several sand fly species, vectors of leishmaniasis in different parts of the world, for feeding on Cannabis sativa. We infer this preference based on the substantial percentage of sand flies that had fed on C. sativa plants despite the apparent “absence” of these plants from most of the field sites. We discuss the conceivable implications of the affinity of sand flies for C. sativa on their vectorial capacity for Leishmania and the putative exploitation of their attraction to C. sativa for the control of sand fly-borne diseases.

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“…In India, the probability or seroreversion has varied between 0 and 87% by 12 months [20, 27, 28]. In Ethiopia, a recent study amongst the general population in northern Ethiopia reported that 71% of DAT-positive individuals seroreverted by 12 months [29]. High rates of LST reversion have also been observed in the South of Ethiopia [11].…”

Section: Discussionmentioning

confidence: 99%

Longitudinal evaluation of asymptomatic Leishmania infection in HIV-infected individuals in North-West Ethiopia: A pilot study

et al. 2019

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BackgroundIn endemic regions, asymptomatic Leishmania infection is common. In HIV patients, detection of asymptomatic Leishmania infection could potentially identify those at risk of visceral leishmaniasis (VL). However, data on the prevalence, incidence, and determinants of asymptomatic infection, and the risk of VL are lacking.MethodsWe conducted a cross-sectional survey at a single ART centre, followed by a prospective cohort study amongst HIV-infected adults in HIV care in a district hospital in a VL-endemic area in North-West Ethiopia (9/2015-8/2016). Asymptomatic Leishmania infection was detected using the direct agglutination test (DAT), rK39-rapid diagnostic test (RDT)), PCR on peripheral blood and the KAtex urine antigen test, and defined as positivity on any Leishmania marker. All individuals were followed longitudinally (irrespective of the Leishmania test results). Risk factors for asymptomatic Leishmania infection were determined using logistic regression.ResultsA total of 534 HIV-infected individuals enrolled in HIV care were included in the study. After excluding 13 patients with a history of VL and an 10 patients with incomplete baseline Leishmania tests, 511 were included in analysis. The median age was 38 years (interquartile range (IQR) 30–45), 62.6% were male. The median follow-up time was 12 months (IQR 9–12). No deaths were reported during the study period. Most (95.5%) were on antiretroviral treatment at enrolment, for a median of 52 months (IQR 27–79). The median CD4 count at enrolment was 377 cells/mm3 (IQR 250–518). The baseline prevalence of Leishmania infection was 12.8% in males and 4.2% in females. Overall, 7.4% tested positive for rK39, 4.3% for DAT, 0.2% for PCR and 0.2% for KAtex. Independent risk factors for a prevalent infection were male sex (odds ratio (OR) 3.2; 95% confidence intervals (CI) 14–7.0) and concurrent malaria infection (OR 6.1; 95% CI 1.9–18.9). Amongst the 49 prevalent (baseline) infections with further follow-up, the cumulative incidence of losing the Leishmania markers by one year was 40.1%. There were 36 incident infections during the course of the study, with a cumulative one-year risk of 9.5%. Only one case of VL was detected during follow-up.ConclusionsWe found a high prevalence of asymptomatic Leishmania infection, persisting in most cases. The incidence was more modest and overt VL was rare. Larger and longer studies with more complete follow-up may help to decide whether a test and treat strategy would be justified in this context.Trial registrationClinicalTrials.gov NCT02839603

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A fine scale eco-epidemiological study on endemic visceral leishmaniasis in north ethiopian villages

Cited by 11 publications

References 41 publications

Outdoor Residual Insecticide Spraying (ODRS), a New Approach for the Control of the Exophilic Vectors of Human Visceral Leishmaniasis: Phlebotomus orientalis in East Africa

Outdoor Residual Insecticide Spraying (ODRS), a New Approach for the Control of the Exophilic Vectors of Human Visceral Leishmaniasis: Phlebotomus orientalis in East Africa

Plant-feeding phlebotomine sand flies, vectors of leishmaniasis, prefer Cannabis sativa

Longitudinal evaluation of asymptomatic Leishmania infection in HIV-infected individuals in North-West Ethiopia: A pilot study

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