Spatio-temporal distribution of malaria and its association with climatic factors and vector-control interventions in two high-risk districts of Nepal - PubMed (original) (raw)
Spatio-temporal distribution of malaria and its association with climatic factors and vector-control interventions in two high-risk districts of Nepal
Meghnath Dhimal et al. Malar J. 2014.
Abstract
Background: Over the last decade, the incidence of confirmed malaria has declined significantly in Nepal. The aim of this paper is to assess the spatio-temporal distribution of malaria and its association with climatic factors and vector control interventions in two high-risk districts of Nepal.
Methods: Hotspot analysis was used to visualize the spatio-temporal variation of malaria incidence over the years at village level and generalized additive mixed models were fitted to assess the association of malaria incidence with climatic variables and vector control interventions.
Results: Opposing trends of malaria incidence were observed in two high-risk malaria districts of eastern and far-western Nepal after the introduction of long-lasting insecticidal nets (LLINs). The confirmed malaria incidence was reduced from 2.24 per 10,000 in 2007 to 0.31 per 10,000 population in 2011 in Morang district but increased from 3.38 to 8.29 per 10,000 population in Kailali district. Malaria hotspots persisted mostly in the same villages of Kailali district, whereas in Morang district malaria hotspots shifted to new villages after the introduction of LLINs. A 1° C increase in minimum and mean temperatures increased malaria incidence by 27% (RR =1.27, 95% CI =1.12-1.45) and 25% (RR =1.25, 95% CI =1.11-1.43), respectively. The reduction in malaria incidence was 25% per one unit increase of LLINs (RR =0.75, 95% CI =0.62-0.92). The incidence of malaria was 82% lower in Morang than in Kailali district (RR =0.18, 95% CI =0.11-0.33).
Conclusions: The study findings suggest that LLIN coverage should be scaled up to entire districts rather than high-incidence foci only. Climatic factors should be considered for malaria micro-stratification, mosquito repellents should be prescribed for those living in forests, forest fringe and foothills and have regular visits to forests, and imported cases should be controlled by establishing fever check posts at border crossings.
Figures
Figure 1
Classification of malaria risk districts in Nepal and study areas. This figure is updated from Dhimal et al. 2014 [1].
Figure 2
Confirmed malaria hotspots in Morang district (2007–2011).
Figure 3
Imported malaria hotspots in Morang district (2007–2011).
Figure 4
Confirmed malaria hotspots in Kailali district (2007–2011).
Figure 5
Imported malaria hotspots in Kailali district (2007–2011).
Figure 6
Monthly malaria cases of Morang district with temperature, relative humidity and rainfall from 2004 to 2012.
Figure 7
Monthly malaria cases of Kailali district with temperature, relative humidity and rainfall from 2004 to 2012.
Figure 8
Effects of climatic factors and month on malaria incidence in Morang and Kailali districts (2004 to 2012). The solid line is the estimated effect, grey polygon is the 95% confidence region. The y-axis of each plot represents risk ratio of malaria incidence in log scale.
Figure 9
Confirmed malaria cases and vector-control interventions in Morang and Kailali districts (2007–2011). Panel A shows confirmed malaria cases, LLINs and average IRS coverage of Morang district. Panel B shows confirmed malaria cases, LLINs and average IRS coverage of Kailali district.
Figure 10
Effects of vector-control interventions and year on malaria incidence in Mornag and Kailali district (2007–2011). The y-axis of each plot represents risk ratio of malaria incidence in log scale.
References
- DOHS . Annual Report 2069/70 (2012/2013) Kathmandu: Department of Health Services, Ministry of Health and Population, Goverment of Nepal; 2014.
- EDCD: Nepal Malaria Report 2010–2012. Kathmandu: Nepal Epidemiology and Disease Control Division (EDCD), Department of Health Services, Ministry of Health and Population, Goverment of Nepal; 2013.
- WHO/SEARO . Nepal Malaria Programme Review (7–16 June, 2010) New Delhi: World Health Organization Regional Office for South - East Asia; 2011.
- EDCD: Nepal Malaria Strategic Plan 2011–2016 (Revised Version- December 2011). Kathmandu: Epidemiology and Diseases Control Division, Department of Health Services, Ministry of Health and Population, Government of Nepal; 2011.
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