Anopheline and human drivers of malaria risk in northern coastal, Ecuador: a pilot study

Abstract Background Understanding local anopheline vector species and their bionomic traits, as well as related human factors, can help combat gaps in protection. Methods In San José de Chamanga, Esmeraldas, at the Ecuadorian Pacific coast, anopheline mosquitoes were sampled by both human landing collections (HLCs) and indoor-resting aspirations (IAs) and identified using both morphological and molecular methods. Human behaviour observations (HBOs) (including temporal location and bed net use) were documented during HLCs as well as through community surveys to determine exposure to mosquito bites. A cross-sectional evaluation of Plasmodium falciparum and Plasmodium vivax infections was conducted alongside a malaria questionnaire. Results Among 222 anopheline specimens captured, based on molecular analysis, 218 were Nyssorhynchus albimanus, 3 Anopheles calderoni (n = 3), and one remains unidentified. Anopheline mean human-biting rate (HBR) outdoors was (13.69), and indoors (3.38) (p = 0.006). No anophelines were documented resting on walls during IAs. HBO-adjusted human landing rates suggested that the highest risk of being bitten was outdoors between 18.00 and 20.00 h. Human behaviour-adjusted biting rates suggest that overall, long-lasting insecticidal bed nets (LLINs) only protected against 13.2% of exposure to bites, with 86.8% of exposure during the night spent outside of bed net protection. The malaria survey found 2/398 individuals positive for asymptomatic P. falciparum infections. The questionnaire reported high (73.4%) bed net use, with low knowledge of malaria. Conclusion The exophagic feeding of anopheline vectors in San Jose de Chamanga, when analysed in conjunction with human behaviour, indicates a clear gap in protection even with high LLIN coverage. The lack of indoor-resting anophelines suggests that indoor residual spraying (IRS) may have limited effect. The presence of asymptomatic infections implies the presence of a human reservoir that may maintain transmission.

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Knowledge, Attitudes, and Practices about Malaria and Its Control in Rural Northwest Tanzania

Malaria Research and Treatment ◽

10.4061/2010/794261 ◽

2010 ◽

Vol 2010 ◽

pp. 1-9 ◽

Cited By ~ 23

Author(s):

Humphrey D. Mazigo ◽

Emmanuel Obasy ◽

Wilhellmus Mauka ◽

Paulina Manyiri ◽

Maria Zinga ◽

...

Keyword(s):

Indoor Residual Spraying ◽

Education Level ◽

Bed Nets ◽

Bed Net ◽

Cross Sectional Survey ◽

Cross Sectional ◽

Attitudes And Practices ◽

Significant Difference ◽

Household Heads ◽

Knowledge Attitudes And Practices

Background. We assessed community knowledge, attitudes, and practices on malaria as well as acceptability to indoor residual spraying. Material and Methods. A cross-sectional survey was done in a community in Geita district (northwest Tanzania). Household heads (n=366) were interviewed Results. Knowledge on malaria transmission, prevention, and treatment was reasonable; 56% of respondents associated the disease with mosquito bites, with a significant difference between education level and knowledge on transmission (P<.001). Knowledge of mosquito breeding areas was also associated with education (illiterate: 22%; literate: 59% (P<.001). Bed nets were used by 236 (64.5%), and usage was significantly associated with education level (P<.01). The level of bed net ownership was 77.3%. Most respondents (86.3%) agreed with indoor residual spraying of insecticides. Health facilities were the first option for malaria treatment by 47.3%. Artemether-lumefantrine was the most common antimalarial therapy used. Conclusions. Despite reasonable knowledge on malaria and its preventive measures, there is a need to improve availability of information through proper community channels. Special attention should be given to illiterate community members. High acceptance of indoor residual spraying and high level of bed net ownership should be taken as an advantage to improve malaria control.

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Ownership, utilization, and motivations for use or non-use of bed nets among community members at risk of malaria along the Thai-Myanmar border

10.21203/rs.3.rs-418488/v1 ◽

2021 ◽

Author(s):

Kasama Pooseesod ◽

Daniel M. Parker ◽

Natthani Meemon ◽

Saranath Lawpoolsri ◽

Pratap Singhasivanon ◽

...

Keyword(s):

At Risk ◽

Bed Nets ◽

High Risk Population ◽

Bed Net ◽

Mosquito Density ◽

Previous Night ◽

High Coverage ◽

Cross Sectional ◽

Net Use ◽

Heat Perception

Abstract Background With the goal for malaria elimination in Thailand set for 2024, increased coverage and utilization of bed net, especially insecticide-treated net (ITN) or long-lasting insecticidal net (LLIN) is a key strategy. This study aims to provide the necessary information about bed net ownership and utilization among the population at risk of malaria living along the Thai-Myanmar border in Tak province. Methods A cross-sectional study was conducted using a mixed-method approach in 331 households from 5 hamlets in the villages of the Thai-Myanmar border. The research tools included a questionnaire, bed net inspection, and semi-structured interviews. Log-binomial regression was used to explore the sociodemographic factors associated with bed net utilization. The qualitative analysis employed a thematic analysis approach. Results This survey found that 98.5% of households had at least one bed net per household, and 74.3% had at least one ITN/LLIN. However, only 30.8% of households reached the standard policy set by the Minister of Public Health of one ITN/LLINs per two persons. Most residents used bed net (92.1% used in the previous night and 80.9% used every day). For those using bed nets, however, 61.9% used ITNs or LLINs the night before and 53.1% used them every day. Nonetheless, the usage rates of bed nets (any type) in the previous night among children and pregnant women were high, reaching 95.3% and 90.0%, respectively. Three explanatory variables including “not stay overnight in the forest”, “preference of free bed nets”, and “sufficient numbers of bed nets to cover all sleeping spaces”, showed statistically significant association with bed net use every day. The major reasons for the regular use of bed nets in both household and the forest were to prevent mosquito biting. The reasons for not using bednets in the household were discomfort feelings from heat, perception of unnecessity due to low mosquito density, whereas the reason for not using bednets in the forest was inconvenience. Conclusion Despite that overall coverage and usage of bed nets was high, only one third reached the standard level specified by the policy. Overnight in the forest, the dissatisfaction with the quality of free bed nets, insufficient number of bed nets, discomfort from heat, perception of no benefits of bed nets due to low mosquito density, and inconvenience were factors influencing bed net use. Maintaining high coverage and utility rate of bed nets should be a priority for the malaria high-risk population.

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

10.21203/rs.3.rs-74137/v1 ◽

2020 ◽

Author(s):

Richard Echodu ◽

William Sam Oyet ◽

Tereza Iwiru ◽

Felister Apili ◽

Julius Julian Lutwama ◽

...

Keyword(s):

Local Community ◽

Malaria Incidence ◽

Indoor Residual Spraying ◽

Community Setting ◽

Cross Sectional Study ◽

Bed Nets ◽

Northern Uganda ◽

Bed Net ◽

Test Bed ◽

Cross Sectional

Abstract 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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Modeling the Impact of Bed-Net Use and Treatment on Malaria Transmission Dynamics

International Scholarly Research Notices ◽

10.1155/2017/6182492 ◽

2017 ◽

Vol 2017 ◽

pp. 1-16 ◽

Cited By ~ 3

Author(s):

Bello Gimba ◽

Saminu Iliyasu Bala

Keyword(s):

Sensitivity Analysis ◽

Malaria Transmission ◽

Intervention Strategy ◽

Transmission Dynamics ◽

Necessary Condition ◽

Bed Nets ◽

Bed Net ◽

Net Use ◽

Biting Rate ◽

The Impact

We modeled the impact of bed-net use and insecticide treated nets (ITNs), temperature, and treatment on malaria transmission dynamics using ordinary differential equations. To achieve this we formulated a simple model of mosquito biting rate that depends on temperature and usage of insecticides treated bed nets. We conducted global uncertainty and sensitivity analysis using Latin Hypercube Sampling (LHC) and Partial Rank Correlation Coefficient (PRCC) in order to find the most effective parameters that affect malaria transmission dynamics. We established the existence of the region where the model is epidemiologically feasible. We conducted the stability analysis of the disease-free equilibrium by the threshold parameter. We found the condition for the existence of the endemic equilibrium and provided necessary condition for its stability. Our results show that the peak of mosquitoes biting rate occurs at a range of temperature values not on a single value as previously reported in literature. The results also show that the combination of treatment and ITNs usage is the most effective intervention strategy towards control and eradication of malaria transmissions. Sensitivity analysis results indicate that the biting rate and the mosquitoes death rates are the most important parameters in the dynamics of malaria transmission.

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Analysis of Immunity to Febrile Malaria in Children That Distinguishes Immunity from Lack of Exposure

Infection and Immunity ◽

10.1128/iai.01358-08 ◽

2009 ◽

Vol 77 (5) ◽

pp. 1917-1923 ◽

Cited By ~ 76

Author(s):

Philip Bejon ◽

George Warimwe ◽

Claire L. Mackintosh ◽

Margaret J. Mackinnon ◽

Sam M. Kinyanjui ◽

...

Keyword(s):

Cell Surface ◽

Antibody Response ◽

Observational Studies ◽

Asymptomatic Infection ◽

Bed Nets ◽

Bed Net ◽

Red Cell ◽

Vaccine Trials ◽

Net Use ◽

Malaria Episodes

ABSTRACT In studies of immunity to malaria, the absence of febrile malaria is commonly considered evidence of “protection.” However, apparent “protection” may be due to a lack of exposure to infective mosquito bites or due to immunity. We studied a cohort that was given curative antimalarials before monitoring began and documented newly acquired asymptomatic parasitemia and febrile malaria episodes during 3 months of surveillance. With increasing age, there was a shift away from febrile malaria to acquiring asymptomatic parasitemia, with no change in the overall incidence of infection. Antibodies to the infected red cell surface were associated with acquiring asymptomatic infection rather than febrile malaria or remaining uninfected. Bed net use was associated with remaining uninfected rather than acquiring asymptomatic infection or febrile malaria. These observations suggest that most uninfected children were unexposed rather than “immune.” Had they been immune, we would have expected the proportion of uninfected children to rise with age and that the uninfected children would have been distinguished from children with febrile malaria by the protective antibody response. We show that removing the less exposed children from conventional analyses clarifies the effects of immunity, transmission intensity, bed nets, and age. Observational studies and vaccine trials will have increased power if they differentiate between unexposed and immune children.

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Cross-Study of Malaria Prevalence in History, Bed Net Utilization, and Knowledge about the Disease among Tanzanian College Students

Malaria Research and Treatment ◽

10.1155/2018/8137051 ◽

2018 ◽

Vol 2018 ◽

pp. 1-5

Author(s):

Yakobo Nyahoga ◽

Zanda Bochkaeva

Keyword(s):

Malaria Prevention ◽

Cross Sectional Study ◽

Malaria Prevalence ◽

Bed Nets ◽

Bed Net ◽

Prevention Measures ◽

Cross Sectional ◽

University Campuses ◽

High Prevalence ◽

Two Factors

University campuses are potential reservoirs of infectious diseases, but they are not in the research focus. It is obvious that the use of malaria preventive tools is extremely necessary in campus conditions in endemic countries. This study is the first malaria survey, conducted in a student campus in Tanzania. This cross-sectional study uncovered a surprisingly high prevalence of malaria history among students: 89,4% of 246 random respondents assume that they had malaria in history, among whom 145 (58,9%) suffered from the disease during the last year. And although students are relatively confident about the vector, parasite, and prevention measures of the disease, only 44,7% of the students use bed nets and 4,5% use a body spray or ointment daily. The others seldom use spray or ointment or do not care about the problem at all. This situation was found to be associated with two factors, financial and educational. Current results show that students are relatively educated on malaria, but they do not follow the malaria prevention guidance. It has become clear that at least proper informational propaganda of bed net use is required in Tanzanian university campuses.

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Use of Bed Nets and Factors That Influence Bed Net Use among Jinuo Ethnic Minority in Southern China

PLoS ONE ◽

10.1371/journal.pone.0103780 ◽

2014 ◽

Vol 9 (7) ◽

pp. e103780 ◽

Cited By ~ 18

Author(s):

Jian-wei Xu ◽

Yuan-mei Liao ◽

Hui Liu ◽

Ren-hua Nie ◽

Joshua Havumaki

Keyword(s):

Ethnic Minority ◽

Southern China ◽

Bed Nets ◽

Bed Net ◽

Net Use

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

10.21203/rs.3.rs-918628/v1 ◽

2021 ◽

Author(s):

Richard Echodu ◽

William Sam Oyet ◽

Tereza Iwiru ◽

Felister Apili ◽

Julius Julian Lutwama ◽

...

Keyword(s):

Malaria Incidence ◽

Indoor Residual Spraying ◽

Malaria Episode ◽

Bed Nets ◽

Northern Uganda ◽

Bed Net ◽

Test Bed ◽

Time Data ◽

Previous Night ◽

Malaria Episodes

Abstract Background: Uses of indoor residual spraying (IRS), long-lasting insecticidal nets (LLINS) and treatment with artemisinin-based combination therapy (ACT) are greatly promoted in northern part of Uganda as mitigating strategies for malaria episodes. Unfortunately, the region still records the highest malaria prevalence of 63%. This study assesses household predicators of malaria in the region and their impact on malaria episodes at the household levels.Methods: A cross-sectional study was conducted in four districts of Gulu, Oyam, Kitgum and Agago covering sixteen villages in northern Uganda. In total, 193 households were surveyed. Data was collected through pre-tested structured questionnaire and systematically coded for analysis using R software.Results:Women headed 58% of the 193 households surveyed. Six hundred and five (605) individuals were declared to have spent the previous night in these households. On average, there were two bed nets per household and 502 (86%) spent the night prior to interview under a bed net. Overall, malaria episodes were strongly related to lack of bed nets or lack of use thereof, and directly linked to the number of individuals in a household. Children were prone to malaria more than adults by a ratio of 2:1. When given a choice between insecticides (IRS) and treated bed nets, 1 in 3 households preferred treated bed nets. At the same time, data suggests that 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. Malaria incidence was higher in children as compared to the adults.

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Asymptomatic and Submicroscopic Plasmodium Infections in an Area Before and During Integrated Vector Control in Homa Bay, Western Kenya

10.21203/rs.3.rs-1201971/v1 ◽

2022 ◽

Author(s):

Collince Jared Omondi ◽

Otambo O Wilfred ◽

David Odongo ◽

Kevin O. Ochwedo ◽

Antony Otieno ◽

...

Keyword(s):

Vector Control ◽

Blood Smear ◽

Geometric Mean ◽

Indoor Residual Spraying ◽

Infection Prevalence ◽

Cross Sectional ◽

Western Kenya ◽

Primary Vector ◽

Asymptomatic Infections ◽

The Impact

Abstract Background Long lasting insecticidal bednets (LLINs) have been the primary vector control strategy until indoor residual spraying (IRS) was added in Homa Bay and Migori Counties in western Kenya. The objective of this study was to evaluate the impact of LLINs integrated with organophosphate-based (Actellic 300 CS) IRS on the prevalence of asymptomatic and submicroscopic Plasmodium species infections in Homa Bay County. Methods Four consecutive community cross-sectional surveys for Plasmodium species infection were conducted in residents of Homa Bay County, Kenya commencing immediately before and 2 years after introduction of annual IRS. Finger-prick blood samples were obtained to prepare thick and thin smears for microscopic determination and qPCR diagnosis of Plasmodium genus, P. falciparum, P. malariae and P. ovale infection. Results Plasmodium spp. infection prevalence by microscopy was 18.5% before IRS and 14.2%, 3.3% and 1.3% after two annual rounds of IRS (χ²= 186.9, df = 3, p < 0.0001). Submicroscopic (blood smear negative, qPCR positive) parasitemia was 50.4% before IRS and 43.2%, 68.0% and 80.7% after IRS (χ²= 31.98, df = 3, p < 0.0001). Geometric mean density of P. falciparum parasitemia decreased over the 2-year study period (ANOVA, F = 28.95, df = 3, 243, p < 0.0001). The proportion of blood smear positive asymptomatic infections that included P. falciparum did not significantly change over the study period. In contrast, the proportion of asymptomatic submicroscopic P. falciparum infections trended upward following introduction of IRS (pre-IRS 48.2% versus post-IRS 41.6%, 61.3% and 75.4%; (χ²= 24.00, df = 3, p = 0.0002). Conclusions These data suggest that two annual rounds of IRS integrated with LLIN significantly reduced the prevalence of Plasmodium parasitemia, whereas the proportion of submicroscopic infections that included P. falciparum parasite increases. Strategies that aim at reducing the number of asymptomatic submicroscopic infections should be considered to diminish cryptic P. falciparum transmission and enhance malaria control.

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Exploring the Mechanisms of Multiple Insecticide Resistance in a Highly Plasmodium-Infected Malaria Vector Anopheles funestus Sensu Stricto from Sahel of Northern Nigeria

Genes ◽

10.3390/genes11040454 ◽

2020 ◽

Vol 11 (4) ◽

pp. 454

Author(s):

Sulaiman S. Ibrahim ◽

Muhammad M. Mukhtar ◽

Helen Irving ◽

Jacob M. Riveron ◽

Amen N. Fadel ◽

...

Keyword(s):

Insecticide Resistance ◽

Malaria Vector ◽

Anopheles Funestus ◽

Indoor Residual Spraying ◽

Sensu Stricto ◽

Bed Nets ◽

Metabolic Resistance ◽

Biting Rate ◽

Insecticide Treated Bed Nets ◽

Sahel Region

The Nigerian Government is scaling up the distribution of insecticide-treated bed nets for malaria control, but the lack of surveillance data, especially in the Sudan/Sahel region of the country, may hinder targeting priority populations. Here, the vectorial role and insecticide resistance profile of a population of a major malaria vector Anopheles funestus sensu stricto from Sahel of Nigeria was characterised. An. funestus s.s. was the only vector found, with a high human blood index (100%) and a biting rate of 5.3/person/night. High Plasmodium falciparum infection was discovered (sporozoite rate = 54.55%). The population is resistant to permethrin (mortality = 48.30%, LT50 = 65.76 min), deltamethrin, DDT (dichlorodiphenyltrichloroethane) and bendiocarb, with mortalities of 29.44%, 56.34% and 54.05%, respectively. Cone-bioassays established loss of efficacy of the pyrethroid-only long-lasting insecticidal nets (LLINs); but 100% recovery of susceptibility was obtained for piperonylbutoxide (PBO)-containing PermaNet®3.0. Synergist bioassays with PBO and diethyl maleate recovered susceptibility, implicating CYP450s (permethrin mortality = 78.73%, χ2 = 22.33, P < 0.0001) and GSTs (DDT mortality = 81.44%, χ2 = 19.12, P < 0.0001). A high frequency of 119F GSTe2 mutation (0.84) was observed (OR = 16, χ2 = 3.40, P = 0.05), suggesting the preeminent role of metabolic resistance. These findings highlight challenges associated with deployment of LLINs and indoor residual spraying (IRS) in Nigeria.

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