Entomological Investigations on Malaria Vectors in Some War-Torn Areas in the Trincomalee District of Sri Lanka after Settlement of 30-Year Civil Disturbance

Background. Malaria was an endemic problem in Trincomalee District, Eastern Province of Sri Lanka. Very few recent data concerning Anopheles are available which transmit malaria. Therefore, the aim of this study is to identify various Anopheles species and the dynamics of anophelines including malaria vectors in Trincomalee District for effective vector control under the current malaria elimination program embarked in the country. Method. Entomological surveys were conducted on a monthly basis, using five entomological techniques, namely, indoor hand collection (HC), window trap collection (WTC), cattle-baited net collection (CBNC), and cattle-baited hut collection (CBHC) from June 2010 to June 2012 in 32 study areas under five entomological sentinel sites. Results. Seventeen anopheline species were encountered, of which Anopheles subpictus was the predominant species in all sampling methods. It is noted that A. culicifacies and A. subpictus have adapted to breed in polluted water in urban settings which may cause serious implications on the epidemiology of malaria in the country. Conclusions. It is important to determine the abundance, biology, distribution, and relationship with climatic factors of main and secondary malaria vectors in Sri Lanka in order to initiate evidence based controlling programs under the current malaria elimination program in Sri Lanka.

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Species Composition and Diversity of Malaria Vector Breeding Habitats in Trincomalee District of Sri Lanka

BioMed Research International ◽

10.1155/2015/823810 ◽

2015 ◽

Vol 2015 ◽

pp. 1-10 ◽

Cited By ~ 8

Author(s):

Nayana Gunathilaka ◽

Wimaladharma Abeyewickreme ◽

Menaka Hapugoda ◽

Rajitha Wickremasinghe

Keyword(s):

Sri Lanka ◽

Larval Habitat ◽

Malaria Vectors ◽

Entomological Surveillance ◽

Anopheles Subpictus ◽

Control Programs ◽

Breeding Habitats ◽

Elimination Programme ◽

Total Dissolved Solid ◽

The Relationship

Introduction. Mosquito larval ecology is important in determining larval densities and species assemblage. This in turn influences malaria transmission in an area. Therefore, understanding larval habitat ecology is important in designing malaria control programs.Method. Larval surveys were conducted in 20 localities under five sentinel sites (Padavisiripura, Gomarankadawala, Thoppur, Mollipothana, and Ichchallampaththu) in Trincomalee District, Eastern Province of Sri Lanka, between June 2010 and July 2013. The relationship between seven abiotic variables (temperature, pH, conductivity, Total Dissolved Solid (TDS), turbidity, Dissolved Oxygen (DO), and salinity) was measured.Results. A total of 21,347 anophelines were recorded representing 15 species.Anopheles subpictus24.72% (5,278/21,347) was the predominant species, followed by 24.67% (5,267/21,347) ofAn. nigerrimusand 14.56% (3,109/21,347) ofAn. peditaeniatus. A total of 9,430 breeding habitats under twenty-one categories were identified.An. culcicifacieswas noted to be highest from built wells (20.5%) with high salinity (1102.3 ± 81.8 mg/L), followed by waste water collections (20.2%) having low DO levels (2.85 ± 0.03 mg/L) and high TDS (1,654 ± 140 mg/L).Conclusion. This study opens an avenue to explore new breeding habitats of malaria vectors in the country and reemphasizes the requirement of conducting entomological surveillance to detect potential transmission of malaria in Sri Lanka under the current malaria elimination programme.

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Genetic evidence for malaria vectors of the Anopheles sundaicus complex in Sri Lanka with morphological characteristics attributed to Anopheles subpictus species B

Malaria Journal ◽

10.1186/1475-2875-9-343 ◽

2010 ◽

Vol 9 (1) ◽

Cited By ~ 24

Author(s):

Sinnathamby N Surendran ◽

Om P Singh ◽

Pavillupillai J Jude ◽

Ranjan Ramasamy

Keyword(s):

Sri Lanka ◽

Morphological Characteristics ◽

Genetic Evidence ◽

Malaria Vectors ◽

Anopheles Subpictus

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Impact of Climatic Factors on Dengue Incidences in Eastern Province, Sri Lanka

International Journal of TROPICAL DISEASE & Health ◽

10.9734/ijtdh/2019/v40i330228 ◽

2020 ◽

pp. 1-19

Author(s):

K. A. N. K. Karunarathna ◽

J. Sriranganesan

Keyword(s):

Sri Lanka ◽

Climatic Factors ◽

Human Life ◽

Climatic Factor ◽

Climatic Variables ◽

Health Practices ◽

Eastern Province ◽

Dengue Disease ◽

The Impact ◽

Rainy Days

Introduction: Health sector is one of the most important sectors of any country. Many aspects such as diseases, health practices, and institutions are associated with health. Among different infectious diseases, dengue has become a major health issue for human in most tropical and subtropical regions. It is a viral disease originated and spread from mosquito and it is in several forms. Since, this seriously affects human life, taking necessary measures, including policies, rules, regulation and best practices to bring this menace into a minimum level, is essential. Such actions require proper background about the disease including factors that this disease depends on. Several factors may be associated with dengue fever and climatic variables take a greater place. Effect of these variables may vary from area to area. Aims: This study aimed to investigate the impact of climatic variables for progression of dengue disease in the Eastern Province of Sri Lanka, which is consisted of three districts: Batticaloa; Trincomalee and Ampara. Study Design: Number of dengue incidences and climatic variables such as rainfall, temperature, number of rainy days, day time humidity, night-time humidity, number of sunny days, and UV Index were obtained for each month in the period from 2009 to 2017 from Meteorology Department and statistical abstracts of Sri Lanka. Analysis was carried out by using the statistical techniques: correlation analysis; regression analysis; principle component analysis and a graphical technique, contour maps. Results: Only a few climatic factors affect dengue incidences in these three districts. However, no any regular pattern could be observed. Impact of each climatic factor varies from district to district. In Batticaloa district, a number of rainy days and day time humidity affect dengue incidences negatively and positively respectively meanwhile wind speed positively affects dengue incidences in Ampara district. No any climatic variables in Trincomalee district show a relationship with dengue incidences in the district. In general, moderate humidity creates a favourable situation for the spread of dengue disease irrespective of districts. Heavy rainfall does not show a relation with dengue incidences as people believe. Conclusion: It is difficult to investigate the impact of each climatic factor alone on dengue incidences because there are inter correlated. Number of dengue incidences may depend on many other variables such as population density, geographical location, health practices, personal health status, knowledge, policies of different institutes and organizations. It is essential to incorporate these sorts of variables also to have a proper understanding of the dengue disease and its spread.

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Variations in salinity tolerance of malaria vectors of the Anopheles subpictus complex in Sri Lanka and the implications for malaria transmission

Parasites & Vectors ◽

10.1186/1756-3305-4-117 ◽

2011 ◽

Vol 4 (1) ◽

Cited By ~ 13

Author(s):

Sinnathamby N Surendran ◽

Pavillupillai J Jude ◽

Ranjan Ramasamy

Keyword(s):

Sri Lanka ◽

Malaria Transmission ◽

Salinity Tolerance ◽

Malaria Vectors ◽

Anopheles Subpictus

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Spatiotemporal distributed lag modelling of multiple Plasmodium species in a malaria elimination setting

Statistical Methods in Medical Research ◽

10.1177/0962280220938977 ◽

2021 ◽

Vol 30 (1) ◽

pp. 22-34

Author(s):

Chawarat Rotejanaprasert ◽

Duncan Lee ◽

Nattwut Ekapirat ◽

Prayuth Sudathip ◽

Richard J Maude

Keyword(s):

Data Streams ◽

Malaria Elimination ◽

Parasite Species ◽

Climatic Factors ◽

Plasmodium Species ◽

Clinical Malaria ◽

Spatiotemporal Patterns ◽

Distributed Lag ◽

Multiple Data

In much of the Greater Mekong Sub-region, malaria is now confined to patches and small foci of transmission. Malaria transmission is seasonal with the spatiotemporal patterns being associated with variation in environmental and climatic factors. However, the possible effect at different lag periods between meteorological variables and clinical malaria has not been well studied in the region. Thus, in this study we developed distributed lagged modelling accounting for spatiotemporal excessive zero cases in a malaria elimination setting. A multivariate framework was also extended to incorporate multiple data streams and investigate the spatiotemporal patterns from multiple parasite species via their lagged association with climatic variables. A simulation study was conducted to examine robustness of the methodology and a case study is provided of weekly data of clinical malaria cases at sub-district level in Thailand.

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A Comprehensive Analysis on Abundance, Distribution, and Bionomics of Potential Malaria Vectors in Mannar District of Sri Lanka

Malaria Research and Treatment ◽

10.1155/2019/1650180 ◽

2019 ◽

Vol 2019 ◽

pp. 1-13

Author(s):

Nayana Gunathilaka ◽

Menaka Hapugoda ◽

Rajitha Wickremasinghe ◽

Wimaladharma Abeyewickreme

Keyword(s):

Waste Water ◽

Sri Lanka ◽

Current Knowledge ◽

Breeding Habitat ◽

Control Measures ◽

Malaria Vectors ◽

Detailed Knowledge ◽

Lagoon Water ◽

Breeding Habitats ◽

The Mean

Background. A detailed knowledge of the distribution of the malaria vectors in Mannar district of Sri Lanka has not been studied after 1927. Past records indicated the presence of only seven species of anophelines, namely, An. culicifacies, An. subpictus, An. barbirostris, An. peditaeniatus, An. nigerrimus, An. Jamesii, and An. maculatus. There have been many changes in terms of distribution of Anopheles in the district over time. Methods. Entomological surveillance was conducted on a monthly basis, comprising indoor hand collection, window trap collection, cattle-baited net collection, cattle-baited hut collection, and larval survey from June 2010 to June 2012 in 12 study areas under three entomological sentinel sites. The relationship between seven abiotic variables of the breeding habitats was measured. Pearson’s correlation coefficients were used to determine the associations between climatic variables and anopheline densities. Results. A total of 74,181 mosquitoes belonging to 14 Anopheles species were recorded. An. subpictus was the most predominant species from all techniques representing 92% (n=68,268) of the total anopheline collection. However, Anopheles culicifacies was not recorded from any site during the study period. Larval surveys identified 12 breeding habitat categories including waste water collections, lagoon water collections, and drains which were not recorded as breeding habitats by previous studies. The mean dissolved oxygen level of waste water collections was 3.45±0.15 mg/l. The mean salinity and conductivity of lagoon water collections were 21105±1344 mg/l and 34734±1974 μs/cm, respectively. Conclusion. The present study provides the updated knowledge on anopheline distribution and vector bionomics. Therefore, documentation of the current knowledge would be useful for learners and health authorities to design appropriate vector control measures in the prevention of reintroduction of malaria.

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