24 research outputs found
Characterisation of human exposure to nocturnal biting by malaria and arbovirus vectors in a rural community in ChĂłkwĂš district, southern Mozambique
BACKGROUND : Understanding the magnitude of human exposure to mosquito biting is fundamental to reduce pathogen transmission. Here we report on a study quantifying the levels of mosquitoes attacking humans throughout the night in a rural area of Southern Mozambique.
METHODS : Surveys were carried out in Massavasse village, southern Mozambique. The abundance and composition of host-seeking mosquito communities at night were assessed by human-landing catches (HLC) at one-hour intervals. Periods when people were located predominantly outdoors or indoors were used to estimate the amount of residentsâ exposure to mosquito bites in either location, to explore the potential impact a bed net could have had in reducing biting by each vector species.
RESULTS : A total of 69,758 host-seeking female mosquitoes comprising 23 species in four genera were collected. The exposure to biting by virtually all vector species was consistently high outdoors, typically at early evening and morning, with exception of An. gambiae s.l which was likely of biting a person with nearly same intensity indoors and outdoors throughout the night. Bed nets use could have reduced biting by An. gambiae s.l (dominated by An. arabiensis), Ma. africana, Ma. uniformis, Cx. pipiens, Cx. antennatus, and Cx. poicilipes by 53%, 47%, 46%, 38%, 31%, and 28% respectively, compared to non-users. Conversely, a bed net user would have had little protection against An. pharoensis, An. ziemanni, An. tenebrosus, and Cx. tritaeniorhynchus biting exposures.
CONCLUSIONS : This study showed that Massavasse residents were exposed to high levels of outdoor biting by malaria and arbovirus vectors that abound in the village. The findings help to identify entomological drivers of persistent malaria transmission in Mozambique and identify a wide range of arbovirus vectors nocturnally active in rural areas, many with outbreak potential. The study highlights the need for a surveillance system for monitoring arboviral diseases vectors in Mozambique.Wellcome [098562] under the fellowship in Tropical Medicine and Public Health.https://wellcomeopenresearch.orgZoology and Entomolog
2,2âČ,5,5âČ-TetraÂmethyl-1,1âČ-(hexane-1,6-diÂyl)di-1H-pyrrole
The molÂecule of the title compound, C18H28N2, composed of two 2,5-dimethylÂpyrrole groups linked by a hexane chain, lies across a crystallographic inversion centre. The mean plane of the pyrrole ring is almost perpendicular to the mean plane of the central chain, making a dihedral angle of 89.09â
(8)°. The crystal structure is stabilized by interÂmolecular CâHâŻÏ interÂactions
Long-lasting insecticidal nets no longer effectively kill the highly resistant Anopheles funestus of southern Mozambique
BACKGROUND: Chemical insecticides are crucial to malaria control
and elimination programmes. The frontline vector control
interventions depend mainly on pyrethroids; all long-lasting
insecticidal nets (LLINs) and more than 80% of indoor residual
spraying (IRS) campaigns use chemicals from this class. This
extensive use of pyrethroids imposes a strong selection pressure
for resistance in mosquito populations, and so continuous
resistance monitoring and evaluation are important. As
pyrethroids have also been used for many years in the Manhica
District, an area in southern Mozambique with perennial malaria
transmission, an assessment of their efficacy against the local
malaria vectors was conducted. METHODS: Female offspring of
wild-caught Anopheles funestus s.s. females were exposed to
deltamethrin, lambda-cyhalothrin and permethrin using the World
Health Organization (WHO) insecticide-resistance monitoring
protocols. The 3-min WHO cone bioassay was used to evaluate the
effectiveness of the bed nets distributed or available for
purchase in the area (Olyset, permethrin LLIN; PermaNet 2.0,
deltamethrin LLIN) against An. funestus. Mosquitoes were also
exposed to PermaNet 2.0 for up to 8 h in time-exposure assays.
RESULTS: Resistance to pyrethroids in An. funestus s.s. was
extremely high, much higher than reported in 2002 and 2009. No
exposure killed more than 25.8% of the mosquitoes tested
(average mortality, deltamethrin: 6.4%; lambda-cyhalothrin:
5.1%; permethrin: 19.1%). There was no significant difference in
the mortality generated by 3-min exposure to any net (Olyset:
9.3% mortality, PermaNet 2.0: 6.0%, untreated: 2.0%; p = 0.2).
Six hours of exposure were required to kill 50% of the An.
funestus s.s. on PermaNet 2.0. CONCLUSIONS: Anopheles funestus
s.s. in Manhica is extremely resistant to pyrethroids, and this
area is clearly a pyrethroid-resistance hotspot. This could
severely undermine vector control in this district if no
appropriate countermeasures are undertaken. The National Malaria
Control Programme (NMCP) of Mozambique is currently improving
its resistance monitoring programme, to design and scale up new
management strategies. These actions are urgently needed, as the
goal of the NMCP and its partners is to reach elimination in
southern Mozambique by 2020
High Prevalence of Malaria in Zambezia, Mozambique: The Protective Effect of IRS versus Increased Risks Due to Pig-Keeping and House Construction
BACKGROUND: African countries are scaling up malaria interventions, especially insecticide treated nets (ITN) and indoor residual spraying (IRS), for which ambitious coverage targets have been set. In spite of these efforts infection prevalence remains high in many parts of the continent. This study investigated risk factors for malaria infection in children using three malaria indicator surveys from Zambezia province, Mozambique. The impact of IRS and ITNs, the effects of keeping farm animals and of the construction material of roofs of houses and other potential risk factors associated with malaria infection in children were assessed. METHODS: Cross-sectional community-based surveys were conducted in October of 2006, 2007 and 2008. A total of 8338 children (ages 1-15 years) from 2748 households were included in the study. All children were screened for malaria by rapid diagnostic tests. Caregiver interviews were used to assess household demographic and wealth characteristics and ITN and IRS coverage. Associations between malaria infection, vector control interventions and potential risk factors were assessed. RESULTS: Overall, the prevalence of malaria infection was 47.8% (95%CI: 38.7%-57.1%) in children 1-15 years of age, less than a quarter of children (23.1%, 95%CI: 19.1%-27.6%) were sleeping under ITN and almost two thirds were living in IRS treated houses (coverage 65.4%, 95%CI: 51.5%-77.0%). Protective factors that were independently associated with malaria infection were: sleeping in an IRS house without sleeping under ITN (Odds Ratio (OR)=â0.6; 95%CI: 0.4-0.9); additional protection due to sleeping under ITN in an IRS treated house (ORâ=â0.5; 95%CI: 0.3-0.7) versus sleeping in an unsprayed house without a ITN; and parental education (primary/secondary: ORâ=â0.6; 95%CI: 0.5-0.7) versus parents with no education. Increased risk of infection was associated with: current fever (ORâ=â1.2; 95%CI: 1.0-1.5) versus no fever; pig keeping (ORâ=â3.2; 95%CI: 2.1-4.9) versus not keeping pigs; living in houses with a grass roof (ORâ=â1.7; 95%CI: 1.3-2.4) versus other roofing materials and bigger household size (8-15 people: ORâ=â1.6; 95%CI: 1.3-2.1) versus small households (1-4 persons). CONCLUSION: Malaria infection among children under 15 years of age in Zambezia remained high but conventional malaria vector control methods, in particular IRS, provided effective means of protection. Household ownership of farm animals, particularly pigs, and living in houses with a grass roof were independently associated with increased risk of infection, even after allowing for household wealth. To reduce the burden of malaria, national control programs need to ensure high coverage of effective IRS and promote the use of ITNs, particularly in households with elevated risks of infection, such as those keeping farm animals, and those with grass roofs
Comparison of seven prognostic tools to identify low-risk pulmonary embolism in patients aged <50 years
publishersversionPeer reviewe
Association Between Preexisting Versus Newly Identified Atrial Fibrillation and Outcomes of Patients With Acute Pulmonary Embolism
Background Atrial fibrillation (AF) may exist before or occur early in the course of pulmonary embolism (PE). We determined the PE outcomes based on the presence and timing of AF. Methods and Results Using the data from a multicenter PE registry, we identified 3 groups: (1) those with preexisting AF, (2) patients with new AF within 2 days from acute PE (incident AF), and (3) patients without AF. We assessed the 90-day and 1-year risk of mortality and stroke in patients with AF, compared with those without AF (reference group). Among 16 497 patients with PE, 792 had preexisting AF. These patients had increased odds of 90-day all-cause (odds ratio [OR], 2.81; 95% CI, 2.33-3.38) and PE-related mortality (OR, 2.38; 95% CI, 1.37-4.14) and increased 1-year hazard for ischemic stroke (hazard ratio, 5.48; 95% CI, 3.10-9.69) compared with those without AF. After multivariable adjustment, preexisting AF was associated with significantly increased odds of all-cause mortality (OR, 1.91; 95% CI, 1.57-2.32) but not PE-related mortality (OR, 1.50; 95% CI, 0.85-2.66). Among 16 497 patients with PE, 445 developed new incident AF within 2 days of acute PE. Incident AF was associated with increased odds of 90-day all-cause (OR, 2.28; 95% CI, 1.75-2.97) and PE-related (OR, 3.64; 95% CI, 2.01-6.59) mortality but not stroke. Findings were similar in multivariable analyses. Conclusions In patients with acute symptomatic PE, both preexisting AF and incident AF predict adverse clinical outcomes. The type of adverse outcomes may differ depending on the timing of AF onset.info:eu-repo/semantics/publishedVersio
Design and methods for a quasi-experimental pilot study to evaluate the impact of dual active ingredient insecticide-treated nets on malaria burden in five regions in sub-Saharan Africa
Background:Vector control tools have contributed significantly to a reduction in malaria burden since 2000, primarâily through insecticidalâtreated bed nets (ITNs) and indoor residual spraying. In the face of increasing insecticide resistâance in key malaria vector species, global progress in malaria control has stalled. Innovative tools, such as dual active ingredient (dualâAI) ITNs that are effective at killing insecticideâresistant mosquitoes have recently been introduced. However, largeâscale uptake has been slow for several reasons, including higher costs and limited evidence on their incremental effectiveness and costâeffectiveness. The present report describes the design of several observational studies aimed to determine the effectiveness and costâeffectiveness of dualâAI ITNs, compared to standard pyreâthroidâonly ITNs, at reducing malaria transmission across a variety of transmission settings.Methods:Observational pilot studies are ongoing in Burkina Faso, Mozambique, Nigeria, and Rwanda, leveraging dualâAI ITN rollouts nested within the 2019 and 2020 mass distribution campaigns in each country. Enhanced surveilâlance occurring in select study districts include annual crossâsectional surveys during peak transmission seasons, monthly entomological surveillance, passive case detection using routine health facility surveillance systems, and studies on human behaviour and ITN use patterns. Data will compare changes in malaria transmission and disease burden in districts receiving dualâAI ITNs to similar districts receiving standard pyrethroidâonly ITNs over three years. The costs of net distribution will be calculated using the provider perspective including financial and economic costs, and a costâeffectiveness analysis will assess incremental costâeffectiveness ratios for InterceptorÂź G2, Royal GuardÂź, and piperonyl butoxide ITNs in comparison to standard pyrethroidâonly ITNs, based on incidence rate ratios calcuâlated from routine data.Conclusions:Evidence of the effectiveness and costâeffectiveness of the dualâAI ITNs from these pilot studies will complement evidence from two contemporary cluster randomized control trials, one in Benin and one in Tanzania, to provide key information to malaria control programmes, policymakers, and donors to help guide decisionâmaking and planning for local malaria control and elimination strategies. Understanding the breadth of contexts where these dualâAI ITNs are most effective and collecting robust information on factors influencing comparative effectiveness could improve uptake and availability and help maximize their impact
Characterisation of human exposure to nocturnal biting by malaria and arbovirus vectors in a rural community in ChĂłkwĂš district, southern Mozambique.
The magnitude of exposure to mosquito biting determines transmission risks and intensity. This study quantified the levels of human exposure to mosquito vectors biting throughout the night in a rural area of Southern Mozambique
Map of Mozambique showing Zambezia province, the study site.
<p>Map of Mozambique showing Zambezia province, the study site.</p
Multivariable logistical regression model of risk factors for malaria infection in Zambezia province.
<p>OR* adjusted for age, year of survey and wealth index. Estimates of OR* for covariates not related with farm animals were done with pig variable in the model.</p><p>*P-value derived from Wald test adjusted for the combine effect of categories in the variable.</p