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Uranw, S.

Publications and source records attributed to Uranw, S..

4 recordsLinked to original sources
bioRxiv2025

Unravelling the distribution of vectors of major vector-borne diseases in Koshi Province of Nepal: A concern of expansion in diverse geo-ecological and climatic regions

BackgroundVector-borne diseases, being major public health concerns, are either slated for elimination or projected for control in Nepal. One of the major challenges in controlling these VBDs is to halt their emergence and expansion in diverse geo-ecological and climatic regions. In this study, we collected vectors of major VBDs to understand their distribution, diversity, and association with ecological variances. Methodology/Principal findingsA descriptive cross-sectional survey was conducted to collect the vectors in five districts situated at altitudes of up to 98 - 1,274 meters in Koshi Province, Eastern Nepal, representing three distinct geo-ecological and climatic regions: mountain, hills and lowlands during May and June 2023. Adult vectors were captured using CDC miniature light traps, BG sentinel traps, and manual aspirators. Association of vectors abundance in function of the geo-ecological and climatic variables was assessed in two vector species (Culex quinquefasciatus and Phlebotomus argentipes). We found the malaria vector Anopheles annularis, the lymphatic filariasis vector Cu. quinquefasciatus and visceral leishmaniasis vector Ph. argentipes from all three geo-ecological regions. The other vectors of the malaria parasite, An. pseudowillmori and An. willmori, and Japanese encephalitis vector Cu. tritaeniorhynchus were recorded from hilly districts only. Mean temperature and rainfall had positive effect on Cu. quinquefasciatus density and deleterious on Ph. argentipes. Culex quinquefasciatus and Ph. argentipes were captured in high abundance per household in hills (IRR = 1.23 and IRR = 13.00, respectively) and mountain (IRR = 1.96 and IRR = 4.00, respectively) as compared to lowland. ConclusionTwo major vectors, Cu. quinquefasciatus and Ph. argentipes were indiscriminately present in all geo-ecological regions. Climatic variables favour vectors survival, distribution and growth in diverse altitudes, including areas previously impervious to the vectors and VBDs. Our findings alert the VBD control program and suggest regular monitoring, strengthening the existing surveillance system and evidence-based planning and implementation of vector control interventions in wider geo-ecological regions to prevent the disease transmission. Authors SummaryThe Government of Nepal is committed to eliminate and control major vector-borne diseases: malaria, visceral leishmaniasis, lymphatic filariasis, Japanese encephalitis and dengue as a public health problem by 2030. These diseases, once endemic to lowlands with tropical and subtropical climates only, have been spread to a wide geography, including hills and mountains. These high-altitude areas were considered unsuitable for the existence of vectors and transmission of pathogens. Considering the impact of climate change on founding a favorable environment for the establishment of viable populations of vectors for pathogens transmission and thus threatening all the efforts of VBDs control and elimination, we conducted a cross-sectional survey to explore the diversity of vectors in varied geo-ecological regions. We collected vectors from five districts situated at different altitudes and having fairly diverse geography. Major vectors of responsible of transmission of pathogens causing VL and LF were abundantly present in all geo-ecological regions, while vectors of malarial parasites and dengue virus were sparsely present in fewer areas. This study also examined the feasibility of the integrated vector survey in favour of maximising the available resources for entomological investigations. Further, this study provides updated information on the diversity of the vectors in the areas having cases of VBDs and suggests authorities for regular monitoring, strengthening the existing surveillance system and evidence-based planning and implementation of vector control interventions to prevent the disease transmission in wider geo-ecological regions.

zoology↗
bioRxiv2022

Status of susceptibility of the visceral leishmaniasis vector, Phlebotomus argentipes (Diptera: Psychodidae: Phlebotominae), to insecticides used for vector control in Nepal

BackgroundVisceral leishmaniasis (VL) is targeted for elimination as a public health problem in Nepal by 2023. For nearly three decades, the core vector control intervention in Nepal has been indoor residual spraying (IRS) with pyrethroids. Considering the long-term use of pyrethroids and possible development of resistance of the vector Phlebotomus argentipes sand flies, we monitored susceptibility status of their field populations to the insecticides of different classes, in villages with and without IRS activities in recent years. Methodology/Principal findingsSand flies were collected from villages with and without IRS in five VL endemic districts from August 2019 to November 2020. The WHO susceptibility test procedure was adopted using filter papers impregnated at the discriminating concentrations of insecticides of the following classes: pyrethroids (alpha-cypermethrin 0.05%, deltamethrin 0.05% and lambda-cyhalothrin 0.05%), carbamates (bendiocarb 0.1%) and organophosphates (malathion 5%). Pyrethroid resistance intensity bioassays with papers impregnated with 5x of the discriminating concentrations, piperonyl butoxide (PBO) synergist-pyrethroid bioassays and DDT cross resistance bioassays were also performed. In the IRS villages, the vector sand flies were resistant (mortality rate <90%) to alpha-cypermethrin and possibly resistant (mortality rate 90-97%) to deltamethrin and lambda-cyhalothrin, while susceptibility to these insecticides was variable in the non-IRS villages. The vector was fully susceptible to bendiocarb and malathion in all villages. A delayed knockdown time (KDT50) with pyrethroids was observed in all villages. The pyrethroid resistance intensity was low, and the susceptibility improved at 5x of the discriminating concentrations. Enhanced pyrethroid susceptibility after pre-exposure to PBO and the DDT-pyrethroid cross-resistance were evident. Conclusions/SignificanceOur investigation showed that P. argentipes sand flies have emerged with pyrethroid resistance, suggesting the need to switch to alternative classes of insecticides such as organophosphates for IRS. We strongly recommend for the regular and systematic monitoring of insecticide resistance in sand flies to optimize the efficiency of vector control interventions to sustain VL elimination efforts in Nepal. Author summaryVisceral leishmaniasis (VL), transmitted by P. argentipes sand flies, is endemic in South-East Asian countries such as Bangladesh, India and Nepal, and is on the verge of elimination as a public health problem in Nepal by 2023. As part of the WHO Global Vector Control Response, entomological surveillance including insecticide resistance monitoring is one of the four main pillars of this strategy. In the early 1990s, the historical use of DDT for sand fly vector control was replaced with deltamethrin or alpha-cypermethrin, which have now been in use for almost three decades in Nepal. Suspecting that this long-term use of pyrethroids might have selected resistance in sand fly populations which would jeopardize control efforts, we conducted the first comprehensive survey to generate contemporary evidence of insecticide resistance in Nepal. For this, we performed WHO susceptibility tests in five VL endemic districts and found strong evidence of pyrethroid resistance in vector populations from the areas receiving IRS. Resistance mechanisms involved would probably be kdr mutations and monooxygenase. This study also endorses regular insecticide resistance monitoring to inform evidence-based decisions on insecticide use for vector control and to maintain the effectiveness of vector control measures as a core intervention in the fight against VL.

zoology↗
bioRxiv2019

\"Risk Factors for Visceral Leishmaniasis in Selected High Endemic Areas of Morang District, Nepal\": A case control Study

Visceral leishmaniasis is a major public health concern in Nepal. During the last few years, several KA outbreaks have been reported from Tarai region including Morang district. A case control study was conducted to assess the risk factors associated with VL in 5 endemic VDC of Morang district with 62 cases already treated from BPKIHS and Koshi zonal hospital and 248 controls selected randomly from the same village. Data collected using semi structured questionnaire from September to November 2013. This study revealed that people living in thatched house, sleeping in ground floor, ownership of animal, history of migration to India (Bihar and Jharkhand) and proximity to other KA cases within 50 m distance of household were strong risk factors for VL. Education remains protective (OR 0.39,95 % CI 0.19-0.79). The association with socioeconomic status showed clear dose - response effect. The odds for VL consistently decreased as the level of socioeconomic status increased (OR 4.26, 3.81). Strengthening surveillance system for early diagnosis and treatment, awareness programme and further extensive study is needed on risk factor, vector and control measures. Author SummaryThis study aims to explore the risk factors for visceral leishmaniasis. Based on findings there is a need to educate people in high-transmission areas how to realize, reduce or avoid environmental factors that favor the survival of the vector in the community. Similarly introduction of more exact surveillance tools in order to improve morbidity and mortality surveillance by health sector. People living in mud thatched houses need to be aware about cracks and crevices in the mud walls, their function as breeding places and how they can be controlled, for example by plastering with lime and mud.. However, a primary condition is that people need to understand the purpose of all these efforts in order to be motivated to put them into practice.

epidemiology↗