Impact of vector control interventions on malaria transmission intensity, outdoor vector biting rates and Anopheles mosquito species composition in Tororo, Uganda

Musiime, Alex K.; Smith, David L.; Kilama, Maxwell; Rek, John; Arinaitwe, Emmanuel; Nankabirwa, Joaniter I.; Kamya, Moses R.; Conrad, Melissa D.; Dorsey, Grant; Akol, Anne M.; Staedke, Sarah G.; Lindsay, Steve W.; Egonyu, James P.

doi:10.1186/s12936-019-3076-4

Cited by 85 publications

(124 citation statements)

References 51 publications

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“…Many barriers to LLIN use have been described, including many household members [36,37], lack of space to hang LLINs [38], lower socioeconomic status, and time since the last LLINs distribution [39]. In this study setting, where malaria transmission dropped substantially, individuals may have felt that it was no longer necessary to use their LLINs [5,28]. During travel, a possible barrier to LLIN adherence is limited availability of LLINs to use away from home.…”

Section: Discussionmentioning

confidence: 96%

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Association Between Recent Overnight Travel And Use Of Long-Lasting Insecticidal Nets In Rural Uganda: A Prospective Cohort Study In Tororo

Arinaitwe

Nankabirwa

Krezanoski

et al. 2020

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Background: The burden of malaria in Uganda remains high, but has become increasingly heterogenous following intensified malaria control. Travel within Uganda is recognised as a risk factor for malaria, but behaviours associated with travel are not well-understood. To address this knowledge gap, malaria-relevant behaviours of cohort participants were assessed during travel and at home in Uganda.Methods: Residents from 80 randomly selected households in Nagongera sub-county, Tororo district were enrolled into a cohort to study malaria in rural Uganda. All participants were given long-lasting insecticidal nets (LLINs) at enrolment and were evaluated every 4 weeks at the study clinic. Participants were asked if they had travelled overnight from their home, and if so, a questionnaire was administered to capture information on travel details and behaviours. Behaviour while at home was assessed using a similar questionnaire during two-weekly home visits. Behaviours while travelling vs at home were compared using generalized estimating equations adjusting for repeated measures in the same individual. Results: Between October 2017 and October 2019, 527 participants were enrolled and assessed for travel. Of these, 123 (23.2%) reported taking 211 overnight trips; 149 (70.6%) trips were within Tororo. Participants were less likely to use LLINs when travelling than when at home (41.0% vs. 56.2%, relative risk [RR] 0.73, 95% CI: 0.60-0.89, p=0.002); this difference was noted for women (38.8% vs 59.2%, RR 0.66, 95% CI 0.52-0.83, p=0.001) but not men (48.3% vs 46.6%, RR 0.96, 95% CI 0.67-1.40, p=0.85). In an adjusted analysis, factors associated with LLIN use when travelling included destination (travelling to districts not receiving indoor residual spraying [IRS] 65.8% vs Tororo district 32.2%, RR 1.80, 95% CI 1.31-2.46, p<0.001) and duration of travel (>7 nights 60.3% vs one night 24.4%, RR 1.97, 95% CI 1.07-3.64, p=0.03).Conclusions: Travellers, particularly women, were less likely to use LLINs when travelling than when at home. LLIN adherence was higher among those who travelled to non-IRS districts and for more than one week, suggesting that perceived malaria risk influences LLIN use. Strategies are needed to raise awareness of the importance of using LLINs while travelling.

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Section: Discussionmentioning

confidence: 96%

“…In addition to IRS, LLINs were distributed to all households in Tororo through national campaigns in 2013 and 2017. The interventions have been associated with a drastic reduction in key malaria indicators, including malaria incidence, parasite prevalence and EIR which was <1% in 2018 [5,27,28].…”

Section: Study Sitementioning

confidence: 99%

Association Between Recent Overnight Travel And Use Of Long-Lasting Insecticidal Nets In Rural Uganda: A Prospective Cohort Study In Tororo

Arinaitwe

Nankabirwa

Krezanoski

et al. 2020

Preprint

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“…Nagongera sub-county is located in Tororo district (00°46′ 10.6″, N 34°01′ 34.1″ E). At the time the study was initiated, Tororo was an area of intense malaria transmission [20], although transmission has been greatly reduced following the implementation of IRS starting in December 2014 [8,21,22]. Tororo is situated at an elevation of 1,185 m above sea level, and houses are constructed on lowlying hills.…”

Section: Study Sitesmentioning

confidence: 99%

Identification and characterization of immature Anopheles and culicines (Diptera: Culicidae) at three sites of varying malaria transmission intensities in Uganda.

Musiime

Smith

Kilama

et al. 2020

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Background: Over the last two decades, there has been remarkable progress in malaria control in sub-Saharan Africa, due mainly to the massive deployment of long-lasting insecticidal nets and indoor residual spraying. Despite these gains, it is clear that in many situations, additional interventions are needed to further reduce malaria transmission. Larval source management (LSM) is a potential supplementary measure that could be used to control malaria. However, prior to its roll-out, knowledge on ecology of larval aquatic habitats is required. Methods: Aquatic habitats colonized by Anopheles vectors were characterised at three sites of low, medium and high malaria transmission in Uganda from October 2011 to June 2016. Larval surveys were conducted along transects in each site and aquatic habitats described according to type and size. Anopheles mosquito larvae and pupae from the described habitats were sampled using standard dipping methods to determine larval densities. Larvae were identified as anopheline or culicine and counted. Pupae were not identified further. Binary logistic regression analysis was used to identify factors associated with the presence of Anopheles larvae in each site. Results: A total of 1,205 larval aquatic habitats were surveyed and yielded a total of 17,028 anopheline larvae, 26,958 culicine larvae and 1,189 pupae. Peaks in larval abundance occurred in all sites in March-May and August-October coinciding with the rainy seasons. Anopheles larvae were found in 52.4 % (n = 251) of aquatic habitats in Tororo, a site of high transmission, 41.9 % (n = 536) of habitats in Kanungu, a site with moderate malaria transmission, and 15.8 % (n=418) in Jinja, a site with low malaria transmission. The odds of finding Anopheles larvae was highest in rice fields compared to pools in both Tororo (odds ratio, OR = 4.21, 95% CI 1.22-14.56, p = 0.02) and Kanungu (OR= 2.14, 95% CI 1.12-4.07, p =0.02). In Kanungu, Anopheles larvae were less likely to be found in open drains compared to pools (OR = 0.15, 95% CI 0.03-0.72, p = 0.02) and river fringe (OR = 0.19, 95% CI 0.07-0.52, p = 0.001). Conclusions: These findings show that Anopheles larvae were common in areas of high and moderate transmission but were rare in areas of low transmission. Although Anopheles larvae were found in all types of water bodies, they were most common in rice fields and less common in open drains and on river fringes. Methods are needed to reduce the aquatic stages of anopheline mosquitoes in human-made habitats, particularly rice fields.

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“…Despite major public health efforts to eliminate malaria worldwide, the incidence of malaria illnesses is still high in many areas, particularly in sub-Saharan African (1). Although prompt recognition and treatment of malaria illnesses with artemisinin combination therapies is increasing, and measures to reduce the transmission of malaria parasites (e.g., indoor residual spraying and long-lasting insecticide treated bed nets) are being widely used in many malaria-endemic areas (2,3), there is growing evidence that low-density Plasmodium falciparum infections remain widespread (4)(5)(6)(7)(8). These low-density P. falciparum infections act as transmission reservoir of malaria (9)(10)(11), however, their contribution to symptomatic malaria is not well understood.…”

Section: Introductionmentioning

confidence: 99%

Submicroscopic malaria infection is not associated with fever in cross-sectional studies in Malawi

Vareta

Buchwald

Barrall

et al. 2020

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Abstract Background: Submicroscopic Plasmodium falciparum infections are widespread in many areas. However, the contribution of these infections to symptomatic malaria is not well understood. In this study we evaluated whether participants with submicroscopic P. falciparum infections have higher prevalence of fever than uninfected participants in southern Malawi.Methods: We enrolled a total of 16,650 children and adults in the course of six cross-sectional surveys during the dry season (October - November) and after the rainy season (April - May) between 2012 - 2014 in three districts in southern Malawi. Demographic and socioeconomic data were collected in conjunction with data on clinical histories, use of malaria preventive measures, and antimalarial medication taken within two weeks of the survey. Axillary temperatures were measured, and blood samples were collected for P. falciparum detection by microscopy and PCR. Participants without malaria parasites detected on microscopy but with a positive PCR for P. falciparum were defined as having submicroscopic infection. Fever was defined as having any one of: reported fever in the past two weeks, reported fever in the past 48 hours, or a temperature of ≥37.5 °C measured at the time of interview.Results: Submicroscopic P. falciparum infections and fever were both detected in 9% of the study population. In the final analysis adjusted for clustering within household and enumeration area, having submicroscopic P. falciparum infection was associated with reduced odds of fever in the dry season (odds ratio = 0.52; 95% CI: 0.33 – 0.82); the association in the rainy season did not achieve statistical significance (odds ratio = 1.20; 95% CI: 0.91 – 1.59). The association between submicroscopic infection and fever was consistent across all age groups. When we limited the definition of fever to temperature of ≥37.5 °C measured at the time of interview, the association was not statistically significant in either the rainy or dry season.Conclusions: In this series of cross-sectional studies in southern Malawi, submicroscopic P. falciparum infection was not associated with increased risk of fever. Submicroscopic detection of the malaria parasite is important in efforts to decrease transmission but is not essential for the clinical recognition of malaria disease.

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Impact of vector control interventions on malaria transmission intensity, outdoor vector biting rates and Anopheles mosquito species composition in Tororo, Uganda

Cited by 85 publications

References 51 publications

Association Between Recent Overnight Travel And Use Of Long-Lasting Insecticidal Nets In Rural Uganda: A Prospective Cohort Study In Tororo

Association Between Recent Overnight Travel And Use Of Long-Lasting Insecticidal Nets In Rural Uganda: A Prospective Cohort Study In Tororo

Identification and characterization of immature Anopheles and culicines (Diptera: Culicidae) at three sites of varying malaria transmission intensities in Uganda.

Submicroscopic malaria infection is not associated with fever in cross-sectional studies in Malawi

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