scholarly journals Risk factors for malaria infection prevalence and household vector density between mass distribution campaigns of long-lasting insecticidal nets in North-western Tanzania

2020 ◽  
Author(s):  
Jacklin Franklin Mosha ◽  
Eliud Lukole ◽  
J Derek Charlwood ◽  
Alexandra Wright ◽  
Mark Rowland ◽  
...  
Keyword(s):  
Risk Factors ◽  
Anopheles Gambiae ◽  
Mass Distribution ◽  
Malaria Infection ◽  
Pyrethroid Resistance ◽  
Good Condition ◽  
Infection Prevalence ◽  
Vector Density ◽  
Factors Associated ◽  
Long Lasting Insecticidal Nets

Abstract Background Long-lasting insecticidal nets (LLINs) are the most widely deployed vector control intervention in sub-Saharan Africa to prevent malaria. Recent reports indicate selection of pyrethroid insecticide resistance is widespread in mosquito vectors. This paper explores risk factors associated with malaria infection prevalence and vector density between mass distribution campaigns, changes in net coverage, and loss of protection in an area of high pyrethroid resistance in Northwest Tanzania. Methods A cross sectional malaria survey of 3,456 children was undertaken in 2014 in Muleba district, Kagera region west of Lake Victoria. Vector density was assessed using indoor light traps and outdoor tent traps. Anophelines were identified to species using PCR and tested for Plasmodium falciparum circumsporozoite protein. Logistic regression was used to identify household and environmental factors associated with malaria infection and regression binomial negative for vector density. Results LLIN use was 27.7%. Only 16.9% of households had sufficient nets to cover all sleeping places. Malaria infection was independently associated with access to LLINs (OR: 0.57; 95%CI 0.34 – 0.98). LLINs less than 2 years old were slightly more protective than older LLINs (53% vs 65% prevalence of infection); however, there was no evidence that LLINs in good condition (hole index <65) were more protective than LLINs which were more holed. Other risk factors for malaria infection were age, group, altitude and house construction quality. Independent risk factors for vector density were consistent with malaria outcomes and included altitude, wind, livestock, house quality, open eaves and LLIN usage. Indoor collections comprised 4.6% Anopheles funestus and 95.4% Anopheles gambiae of which 4.5% were Anopheles arabiensis and 93.5% were Anopheles gambiae sensu stricto. Conclusion Three years after the mass distribution campaign and despite top-ups, LLIN usage had declined considerably. While children living in households with access to LLINs were at lower risk of malaria, infection prevalence remained high even among users of LLINs in good condition. While effort should be made to maintain high coverage between campaigns, distribution of standard pyrethroid-only LLINs appears insufficient to prevent malaria transmission in this area of intense pyrethroid resistance.

scholarly journals Risk factors for malaria infection prevalence and household vector density between mass distribution campaigns of long-lasting insecticidal nets in Northern Tanzania

2020 ◽  
Author(s):  
Jacklin Franklin Mosha ◽  
Eliud Lukole ◽  
J Derek Charlwood ◽  
Alexandra Wright ◽  
Olivia Bullock ◽  
...  
Keyword(s):  
Risk Factors ◽  
Mass Distribution ◽  
Malaria Infection ◽  
Pyrethroid Resistance ◽  
Good Condition ◽  
Sub Saharan Africa ◽  
Infection Prevalence ◽  
Vector Density ◽  
Factors Associated ◽  
Long Lasting Insecticidal Nets

Abstract Background Long Lasting Insecticidal nets (LLINs) are the most widely deployed vector control intervention in Sub-Saharan Africa to prevent malaria. Recent reports indicate selection of pyrethroid insecticide resistance is widespread in mosquito vectors. This paper explores net coverage indicators and other risk factors associated with malaria infection prevalence and vector density three years after a mass distribution campaigns of LLINs in Northwest Tanzania. Methods A cross sectional malaria survey of 3,456 children was undertaken in 2014 in Muleba district in the Lake Zone. Vector density was assessed using indoor light traps and outdoor tent traps. Anophelines were identified to species using PCR and tested for falciparum circumsporozoite protein. Logistic regression was used to identify household and environmental factors associated with malaria infection and vector density. Results LLINs use was 27.7%. Only 16.9% of households had sufficient nets to cover all sleeping places. Malaria infection was independently associated with access to LLINs (OR: 0.57; 95%CI 0.34 – 0.98). LLINs less than 2 years old were more protective than older LLINs (53% vs 65% prevalence of infection); however, there was no evidence that LLINs in good condition (hole index <65) were more protective than LLINs which were more holed. Other risk factors for malaria infection were age group, altitude and house construction quality. Independent risk factors for vector density were consistent with malaria outcomes and included altitude, wind, livestock, house quality, open eaves and LLINs usage. Indoor collections comprised 4.6% Anopheles funestus and 95.4% An. gambiae of which 4.5% were An. arabiensis and 93.5% were An. gambiae s.s.Conclusion Three years after the mass distribution campaign and despite top-ups, LLINs usage had declined considerably. While children living in households with access to LLINs were at lower risk of malaria, infection prevalence remained high even among users of LLINs in good condition. While effort should be made to maintain high coverage between campaigns, distribution of standard pyrethroid-only LLINs appears insufficient to prevent malaria transmission in this area of intense pyrethroid resistance.

scholarly journals Risk Factors for Malaria Infection Prevalence and Household Vector Density between Mass Distribution Campaigns of Long-Lasting Insecticidal Nets in Northern Tanzania

2020 ◽  
Author(s):  
Jacklin Franklin Mosha ◽  
Eliud Lukole ◽  
J Derek Charlwood ◽  
Alexandra Wright ◽  
Olivia Bullock ◽  
...  
Keyword(s):  
Risk Factors ◽  
Mass Distribution ◽  
Malaria Infection ◽  
Pyrethroid Resistance ◽  
Good Condition ◽  
Sub Saharan Africa ◽  
Infection Prevalence ◽  
Vector Density ◽  
Factors Associated ◽  
Northern Tanzania

Abstract Background Long lasting insecticide nets (LLIN) are the intervention most widely deployed in Sub-Saharan Africa to prevent malaria. Recent reports indicate selection of pyrethroid insecticide resistance is widespread in mosquito vectors. This paper explores the risk factors associated with malaria infection prevalence and vector density between mass distribution campaigns of LLIN in Northern Tanzania. Methods A cross sectional malaria survey of 3,456 children was undertaken in 2014. Vector density was assessed using indoor light traps and outdoor tent traps. Anophelines were identified to species using PCR and tested for falciparum circumsporozoite protein. Logistic regression was used to identify household and environmental factors associated with malaria infection and vector density. Results LLIN use was 27.7%. Only 16.9% of households had sufficient nets to cover all sleeping places. Malaria infection was independently associated with access to LLIN (OR: 0.57; 95%CI 0.34 – 0.98), age group, altitude and house construction quality. LLIN less than 2 years old were more protective than older LLIN (53% vs 65% prevalence of infection); however, there was no evidence that LLIN in good condition (hole index <65) were more protective than LLIN which were more holed. Independent risk factors for vector density were consistent with malaria outcomes and included altitude, wind, livestock, house quality, open eaves and LLIN access. Indoor collections comprised 4.6% Anopheles funestus and 95.4% An. gambiae of which 4.5% were An. arabiensis and 93.5% were An. gambiae s.s . Conclusion Three years after the mass distribution campaign and despite top-ups, LLIN usage had fallen considerably. While children living in households with access to LLIN were at lower risk of malaria, infection prevalence remained high even among users of LLIN in good condition. While effort should be made to maintain high coverage between campaigns, distribution of just standard pyrethroid LLIN appears insufficient to prevent malaria transmission in this area of intense pyrethroid resistance.

scholarly journals SARS-CoV-2 screening among people living in homeless shelters in Brussels, Belgium

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0252886
Author(s):  
Michel Roland ◽  
Louisa Ben Abdelhafidh ◽  
Victoria Déom ◽  
Frank Vanbiervliet ◽  
Yves Coppieters ◽  
...  
Keyword(s):  
Risk Factors ◽  
General Population ◽  
Social Workers ◽  
Homeless People ◽  
Homeless Shelters ◽  
Infection Prevalence ◽  
High Population Density ◽  
Prevention Measures ◽  
Factors Associated ◽  
The World

Background Subgroups of precarious populations such as homeless people are more exposed to infection and at higher risk of developing severe forms of COVID-19 compared to the general population. Many of the recommended prevention measures, such as social distancing and self-isolation, are not feasible for a population living in shelters characterised by physical proximity and a high population density. The objective of the study was to describe SARS-CoV-2 infection prevalence in homeless shelters in Brussels (Belgium), and to identify risk factors and infection control practices associated with SARS-CoV-2 positivity rates. Methods A total of 1994 adults were tested by quantitative PCR tests in 52 shelters in Brussels (Belgium) between April and June, 2020, in collaboration with Doctors of the World. SARS-CoV-2 prevalence is here described site by site, and we identify risk factors associated with SARS-CoV-2 positivity rates. We also investigate associations between seropositivity and reported symptoms. Results We found an overall prevalence of 4.6% for the period, and a cluster of high rates of SARS-CoV-2 positivity (20–30% in two shelters). Among homeless people, being under 40 years of age (OR (CI95%) 2.3 (1.2–4.4), p = 0.02), having access to urgent medical care (AMU) (OR(CI95%): 2.4 (1.4–4.4)], p = 0.02), and sharing a room with someone who tested positive (OR(CI95%): 5.3 (2.9–9.9), p<0.0001) were factors associated with SARS-CoV-2 positivity rates. 93% of those who tested positive were asymptomatic. Conclusion This study shows high rates of SARS-COV-2 infection positive tests in some shelters, with a high proportion of asymptomatic cases. The survey reveals how important testing and isolation measures are, together with actions taken by medical and social workers during the outbreak.

scholarly journals Risk Factors Associated with Malaria Infection Identified through Reactive Case Detection in Zanzibar, 2012-2019

2021 ◽  
Author(s):  
Humphrey Raphael Mkali ◽  
Erik J. Reaves ◽  
Shabbir M. Lalji ◽  
Abdul-wahid Al-mafazy ◽  
Joseph J. Joseph ◽  
...  
Keyword(s):  
Risk Factors ◽  
Malaria Infection ◽  
Universal Access ◽  
Indoor Residual Spraying ◽  
P Value ◽  
Case Detection ◽  
Reactive Case Detection ◽  
Factors Associated ◽  
Llin Use ◽  
History Of

Abstract BackgroundOver the past two decades, Zanzibar substantially reduced malaria burden. As malaria decreases, sustainable improvements in prevention and control interventions may increasingly depend on accurate knowledge of malaria risk factors to further target interventions. This study aimed to investigate the risk factors associated with malaria infection in Zanzibar. MethodsWe analyzed surveillance data from Zanzibar’s Malaria Case Notification system collected between August 2012 and December 2019. This system collects data from all malaria cases passively detected and reported by public and private health facilities, from household-based follow-up and reactive case detection activities linked to those primary cases. All members of households of the passively detected malaria cases were screened for malaria using a malaria rapid diagnostic test (mRDT); individuals with a positive mRDT result were treated with artemisinin-based combination therapy. Univariate and multivariate logistic regression analyses were done to investigate the association between mRDT positivity among the household members and explanatory factors (i.e., age, sex, history of fever, history of travel, rainfall, long-lasting insecticidal net [LLIN] density, LLIN use, household indoor residual spraying [IRS], and household location) with adjustment for seasonality ResultsThe findings show that younger age (p-value for trend<0.001), history of fever in the last two weeks (odds ratio [OR]=32.0; 95% CI: 29.1-35.3), history of travel outside Zanzibar in the last 30 days (OR=2.3; 95% CI: 2.1-2.6) and living in Unguja (OR=1.2; 95% CI: 1.1-1.3) were independently associated with increased odds of mRDT positivity. In contrast, male sex (OR=0.8; 95% CI: 0.7-0.9), having higher household LLIN density (p-value for trend<0.001), sleeping under an LLIN the previous night (OR=0.8; 95% CI: 0.7-0.9), and living in a household that received IRS in the last 12 months (OR=0.9; 95% CI: 0.8-0.9) were independently associated with reduced odds of mRDT positivity. A significant effect modification of combining IRS and LLIN was also noted (OR=0.7; 95% CI:0.6-0.8).ConclusionsThe findings suggest that vector control remains an important malaria prevention intervention: they underscore the need to maintain universal access to LLINs, the persistent promotion of LLIN use, and application of IRS. Additionally, enhanced behavioral change and preventive strategies targeting children aged 5-14 years and travelers are needed.

scholarly journals Risk factors associated with malaria infection identified through reactive case detection in Zanzibar, 2012–2019

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Humphrey R. Mkali ◽  
Erik J. Reaves ◽  
Shabbir M. Lalji ◽  
Abdul-Wahid Al-mafazy ◽  
Joseph J. Joseph ◽  
...  
Keyword(s):  
Risk Factors ◽  
Malaria Infection ◽  
Universal Access ◽  
Behavioural Change ◽  
P Value ◽  
Case Detection ◽  
Reactive Case Detection ◽  
Factors Associated ◽  
Household Members ◽  
Index Cases

Abstract Background Over the past two decades, Zanzibar substantially reduced malaria burden. As malaria decreases, sustainable improvements in control interventions may increasingly depend on accurate knowledge of malaria risk factors to further target interventions. This study aimed to investigate the risk factors associated with malaria infection in Zanzibar. Methods Surveillance data from Zanzibar’s Malaria Case Notification system from August 2012 and December 2019 were analyzed. This system collects data on malaria cases passively detected and reported by all health facilities (index cases), and household-based reactive case detection (RCD) activities linked to those primary cases. All members of households of the index cases were screened for malaria using a malaria rapid diagnostic test (RDT). Individuals with a positive RDT were treated with artemisinin-based combination therapy. Univariate and multivariate logistic regression analyses were done to investigate the association between RDT positivity among the household members and explanatory factors with adjustment for seasonality and clustering at Shehia level. Results A total of 30,647 cases were reported of whom household RCD was completed for 21,443 (63%) index case households and 85,318 household members tested for malaria. The findings show that younger age (p-value for trend [Ptrend] < 0.001), history of fever in the last 2 weeks (odds ratio [OR] = 35.7; 95% CI 32.3–39.5), travel outside Zanzibar in the last 30 days (OR = 2.5; 95% CI 2.3–2.8) and living in Unguja (OR = 1.2; 95% CI 1.0–1.5) were independently associated with increased odds of RDT positivity. In contrast, male gender (OR=0.8; 95% CI 0.7–0.9), sleeping under an LLIN the previous night (OR = 0.9; 95% CI 0.7–0.9), having higher household net access (Ptrend < 0.001), and living in a household that received IRS in the last 12 months (OR = 0.8; 95% CI 0.7–0.9) were independently associated with reduced odds of RDT positivity. A significant effect modification of combining IRS and LLIN was also noted (OR = 0.7; 95% CI 0.6–0.8). Conclusions The findings suggest that vector control remains an important malaria prevention intervention: they underscore the need to maintain universal access to LLINs, the persistent promotion of LLIN use, and application of IRS. Additionally, enhanced behavioural change and preventive strategies targeting children aged 5–14 years and travellers are needed.

scholarly journals Pyrethroid resistance in Anopheles gambiae not associated with insecticide-treated mosquito net effectiveness across sub-Saharan Africa

2020 ◽  
Author(s):  
David A. Larsen ◽  
Rachael L. Church
Keyword(s):  
Anopheles Gambiae ◽  
Malaria Vector ◽  
Malaria Infection ◽  
Pyrethroid Resistance ◽  
Sub Saharan Africa ◽  
Malaria Vector Control ◽  
Lr Test ◽  
Meta Regression ◽  
Sub Saharan ◽  
The Impact

AbstractBackgroundPyrethroid resistance is a major concern for malaria vector control programs that predominantly rely on insecticide-treated mosquito nets (ITN). Contradictory results of the impact of resistance have been observed in field studies.MethodsWe combined continent-wide estimates of pyrethroid resistance in Anopheles gambiae from 2006-2017 with continent-wide survey data to assess the effect of increasing pyrethroid resistance on the effectiveness of ITNs to prevent malaria infections in sub-Saharan Africa. We utilized both a pooled-data approach and meta-regression of survey regions to assess how pyrethroid resistance affects the association between ITN ownership and malaria outcomes in children aged 6-59 months.FindingsITN ownership reduced the risk of malaria outcomes in both pooled and meta-regression approaches. In the pooled analysis, there was no observed interaction between ITN ownership and estimated level of pyrethroid resistance (Likelihood ratio [LR] test = 1.127 for the outcome of rapid diagnostic test confirmed malaria infection, p = 0.2885; LR test = 0.161 for the outcome of microscopy confirmed malaria infection, p = 0.161; LR test = 0.646 for the outcome of moderate or severe anemia, p = 0.4215). In the meta-regression approach the level of pyrethroid resistance did not explain any of the variance in subnational estimates of ITN effectiveness for any of the outcomes.InterpretationITNs decreased risk of malaria outcomes independent of the levels of pyrethroid resistance in the malaria vector populations.FundingDAL did not receive funding and RC received a SOURCE grant from Syracuse University for this project.

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