High insecticide resistances levels in Anopheles gambiaes s.l. in northern Uganda and its relevance for future malaria control

Echodu, Richard; Iga, Julius; Oyet, William Samuel; Mireji, Paul O.; Anena, Juliet; Onanyang, David; Iwiru, Tereza; Lutwama, Julius J.; Opiyo, Elizabeth A.

doi:10.1186/s13104-020-05193-0

Cited by 10 publications

(17 citation statements)

References 27 publications

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“…gambiae s.s and An. funestus [57,[60][61][62][63][64][65][66] that are the major malaria vector in Uganda and now An. arabiensis in this current study in Karamoja region, this is a major threat to LLINs and IRS use in malaria vector control programmes in the country and the whole of the neighbouring countries.…”

Section: Discussionmentioning

confidence: 99%

High level of resistance in Anopheles arabiensis mosquito to pyrethroid insecticides from low malaria transmission zone of Moroto district, Karamoja region, Uganda: Implication for malaria vector control

Echodu¹,

Anena²,

Iwiru³

et al. 2020

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Background: Karamoja region of Uganda previously classified as low malaria transmission zone is currently experiencing significant upsurge of malaria incidences. Long lasting insecticidal nets (LLINs) impregnated with pyrethroids constitute a major tool for malaria control in this region. Efficacy of this tool can be hampered by resistance to the pyrethroids in the Anopheles mosquito vectors. Resistance status of these mosquitoes in this region is poorly understood, effectively hampering better understanding of the impact of LLINs in the malaria control initiative. Here, we assessed susceptibility of the Anopheles arabiensis from the region to deltamethrin, permethrin (pyrethroids) and pirirmiphos-methyl (organophosphate) insecticides.Method: We collected anopheline mosquito larvae from their natural habitats and reared them to adult emergence in situ field insectary in Karamoja region. We then identified them morphological to species level and exposed 513 emerge adult female An gambiae s.l., mosquitoes to diagnostic dosages of deltamethrin (0.05%), permethrin (0.75%) and pirimiphos-methyl (0.25%) pyrethroids exposure using the standard WHO insecticide susceptibility test assay. Synergic assays using piperonyl butoxide (PBO) were done to check for the involvement of detoxification enzymes in pyrethroid resistant populations. We then screened for knockdown resistance (KDR) and mosquito species diversity using Polymerase Chain Reaction (PCR).Results: Majority (96%) of the mosquitoes we sampled were identified as An. arabiensis and 4% as An. gambiae sensu stricto. We observed cross-resistance to both deltamethrin (11.9%) and permethrin (47%) but susceptibility (100% mortality) to pirimiphos-methyl in An. arabiensis. The pre-exposure to PBO ameliorated the resistance to both pyrethroids. We detected homozygous KDR -eastern variant in 1.8 and 50% of the An. arabiensis and An. gambiae s.s. respectively.Conclusion: Anopheles arabiensis and An. gambiae s.s. are the malaria vector in Karamoja region with An. arabiensis predominating. Both species are susceptible to pirimiphos-methyl but resistant to both deltamethrin and permethrin, through a metabolic process (phenotype). Mosquotoes with genetic (kdr) mutations for resistance were minimal and hence have minimal contribution to the pyrethroid resistance profile. An. arabiensis can thus be controled in Karamoja region using deltamethrin and/or permethrin impregnated mosquito nets integrated with PBO and/or through indoor residual spraying of sprayable human dwellings with pirimiphos-methyl.

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Section: Discussionmentioning

confidence: 99%

High level of resistance in Anopheles arabiensis mosquito to pyrethroid insecticides from low malaria transmission zone of Moroto district, Karamoja region, Uganda: Implication for malaria vector control

Echodu¹,

Anena²,

Iwiru³

et al. 2020

Preprint

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“…This is evident by results that show high incidence of malaria strongly related to lack of bed nets or use thereof and also linked directly to the number of individuals in a house. Recent studies by Echodu et al [12], in the same study area show high mosquito insecticides resistance. We also think that the high malaria burden in the study area could be attributed to communities in northern Uganda who always spend a lot of time outdoors in the evenings when preparing family meals, drinking, during cultural marriages, cultural festivities and burial ceremonies that pre-exposes them to outdoor mosquito bites.…”

Section: Discussionmentioning

confidence: 69%

“…In 2015, there was cessation of IRS activities in the region [42]. This cessation of IRS activities led to the worst epidemic of malaria affecting ten districts of Lamwo, Gulu, Kitgum, Oyam, Agago, Apc, Amuru, Kole, Nowya and Pader with an average of 5000 cases per district and 40,000 cases per week [42,43] Since then, IRS activities have continued to be implemented in the study area using Acetellic 300CS (an organophosphate insecticide) [44] much as there is insecticide resistance currently seen in the region [12].…”

Section: Discussionmentioning

confidence: 99%

“…Despite these many control strategies deployed in Uganda, malaria cases and deaths remain high in the country mainly due to delayed health seeking, clinical judgment without laboratory con rmation, widespread insecticide resistance in mosquito populations [5,[9][10][11][12]. Understanding changes in malaria transmission and household predictor factors could shade light on the success of these control strategies.…”

Section: World Health Organization Recommends Intermediate Interventimentioning

confidence: 99%

“…In northern Uganda, malaria season picks up with transmission between May to November to as high as 1,500 infective bites per person per year, the highest in the whole world [14]. The current primary malaria vector control interventions in the region rely on universal distribution of LLINs and IRS with pyrethroids and non-pyrethroids insecticides [11,12]. However, household and individual level of protection using LLINs and IRS is largely derived from community level coverage [15,16].…”

Section: World Health Organization Recommends Intermediate Interventimentioning

confidence: 99%

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Household Predictors of Incidence of Malaria in Northern Uganda: Its Implication for Future Malaria Control

Echodu

Oyet

Iwiru

et al. 2020

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Background: Use of indoor residual spraying (IRS), long-lasting insecticidal nets (LLINS) and treatment with artemisinin-based combination therapy (ACT) have been greatly promoted in northern Uganda but the region still records highest number of malaria cases with prevalence up to 63%. This study assesses household predicators of malaria in the region and its impact on incidence of malaria at household levels.Methods: A cross-sectional study was conducted in four districts of Gulu, Oyam, Kitgum and Agago covering sixteen known hyper-endemics villages with high malaria burden in northern Uganda. In total, 193 households were surveyed. Data was collected through pre-tested structured questionnaires and systematically coded and analyzed using R software.Results:Women headed 58% of the 193 households surveyed. Six hundred and five (605) individuals were declared to have spent a night in the 193 households surveyed. Nighttime is when mosquitoes mostly gain access to victims in the study area. On average, there were two bed nets per household and out of the 605 individuals declared, 502 502 (86%) spent the night prior to interview under a bed net. Despite this effort, these households still reported malaria incidences in the last three months. Overall, children were prone to malaria more than adults by a ratio of 3:2, and in general, malaria incidences were strongly related to lack of bed nets or use thereof, and also linked directly to the number of individuals in a house. Households without bed nets controlled malaria by means of IRS in combination with closing doors (with the hope of keeping mosquitos at bay), draining stagnant water pool where mosquitos lay their eggs, trimming mosquito covers (grass) around homestead and/or receiving treatment after malaria incidences. When given a choice between insecticides (IRS) and treated bed nets, 1 in 3 households preferred treated bed nets. At the same time, bed nets were perceived unnecessary once IRS was applied. If true, the driving force to spraying insecticides indoor then becomes lack of a bed net. Conclusions:Household predicators of incidence of malaria in northern Uganda includes bed nets, use of treated bed nets, and indoor residual spraying with households not practicing any of these bearing the heaviest burden of malaria. Hierarchical clustering on principal components (HCPC) clusters households into four types in northern Uganda, 1) household that use bed nets and sleep in houses sprayed with insecticides; 2) households that use bed nets but no indoor residual spraying with insecticides; 3) households that have no bed nets and no indoor residual spraying; and 4) test bed nets before use. An opportunity therefore arises for tailoring malaria messages to fit each cluster of households given that clustering here appears not to be random. Malaria incidence was higher in children as compared to the adults that necessities having guidelines for management of interventions in local community setting.

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The impact of stopping and starting indoor residual spraying on malaria burden in Uganda

et al. 2021

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The scale-up of malaria control efforts has led to marked reductions in malaria burden over the past twenty years, but progress has slowed. Implementation of indoor residual spraying (IRS) of insecticide, a proven vector control intervention, has been limited and difficult to sustain partly because questions remain on its added impact over widely accepted interventions such as bed nets. Using data from 14 enhanced surveillance health facilities in Uganda, a country with high bed net coverage yet high malaria burden, we estimate the impact of starting and stopping IRS on changes in malaria incidence. We show that stopping IRS was associated with a 5-fold increase in malaria incidence within 10 months, but reinstating IRS was associated with an over 5-fold decrease within 8 months. In areas where IRS was initiated and sustained, malaria incidence dropped by 85% after year 4. IRS could play a critical role in achieving global malaria targets, particularly in areas where progress has stalled.

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High insecticide resistances levels in Anopheles gambiaes s.l. in northern Uganda and its relevance for future malaria control

Cited by 10 publications

References 27 publications

High level of resistance in Anopheles arabiensis mosquito to pyrethroid insecticides from low malaria transmission zone of Moroto district, Karamoja region, Uganda: Implication for malaria vector control

High level of resistance in Anopheles arabiensis mosquito to pyrethroid insecticides from low malaria transmission zone of Moroto district, Karamoja region, Uganda: Implication for malaria vector control

Household Predictors of Incidence of Malaria in Northern Uganda: Its Implication for Future Malaria Control

The impact of stopping and starting indoor residual spraying on malaria burden in Uganda

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