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1.
Malar J ; 23(1): 229, 2024 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-39095782

RESUMO

BACKGROUND: Indoor residual spraying (IRS) is a cornerstone malaria control intervention in Burkina Faso. From 2018 to 2021, non-pyrethroid IRS was implemented annually in two regions of Burkina Faso with distinct malaria transmission patterns, concurrently with annual seasonal malaria chemoprevention (SMC), and a mass insecticide-treated net (ITN) distribution in 2019. METHODS: A retrospective quasi-experimental approach was used to evaluate the impact of the 2018, 2020, and 2021 IRS campaigns on routinely reported confirmed malaria case incidence at health facilities. The 2019 campaign was excluded due to lack of data reporting during a health sector strike. Controlled interrupted time series models were fit to detect changes in level and trend in malaria case incidence rates following each IRS campaign when compared to the baseline period 24-months before IRS. IRS districts Solenzo (Sudano-Sahelien climate), and Kampti (tropical climate) were compared with neighbouring control districts and the analyses were stratified by region. Modelled health facility catchment population estimates based on travel time to health facilities and weighted by non-malaria outpatient visits were used as an offset. The study period encompassed July 2016 through June 2022, excluding July 2018 to June 2019. RESULTS: District-level population and structure coverage achieved by IRS campaigns was greater than 85% in 2018, 2020, and 2021 in Solenzo and Kampti. In Solenzo a significant difference in malaria case incidence rates was detected after the 2018 campaign (IRR = 0.683; 95% CI 0.564-0.827) when compared to the control district. The effect was not detected following the 2020 or 2021 IRS campaigns. In Kampti, estimated malaria incidence rates were between 36 and 38% lower than in the control district following all three IRS campaigns compared to the baseline period. CONCLUSIONS: Implementation of IRS in Kampti, a tropical region of Burkina Faso, appeared to have a consistent significant beneficial impact on malaria case rates. An initial positive impact in Solenzo after the first IRS campaign was not sustained in the successive evaluated IRS campaigns. This study points to a differential effect of IRS in different malaria transmission settings and in combination with ITN and SMC implementation.


Assuntos
Inseticidas , Malária , Controle de Mosquitos , Burkina Faso/epidemiologia , Controle de Mosquitos/estatística & dados numéricos , Malária/prevenção & controle , Malária/epidemiologia , Estudos Retrospectivos , Humanos , Incidência , Mosquiteiros Tratados com Inseticida/estatística & dados numéricos
2.
Malar J ; 23(1): 161, 2024 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-38783348

RESUMO

BACKGROUND: Mosquitoes of the Anopheles gambiae complex are one of the major vectors of malaria in sub-Saharan Africa. Their ability to transmit this disease of major public health importance is dependent on their abundance, biting behaviour, susceptibility and their ability to survive long enough to transmit malaria parasites. A deeper understanding of this behaviour can be exploited for improving vector surveillance and malaria control. FINDINGS: Adult mosquitoes emerge from aquatic habitats at dusk. After a 24 h teneral period, in which the cuticle hardens and the adult matures, they may disperse at random and search upwind for a mate or to feed. Mating generally takes place at dusk in swarms that form over species-specific 'markers'. Well-nourished females may mate before blood-feeding, but the reverse is true for poorly-nourished insects. Females are monogamous and only mate once whilst males, that only feed on nectar, swarm nightly and can potentially mate up to four times. Females are able to locate hosts by following their carbon dioxide and odour gradients. When in close proximity to the host, visual cues, temperature and relative humidity are also used. Most blood-feeding occurs at night, indoors, with mosquitoes entering houses mainly through gaps between the roof and the walls. With the exception of the first feed, females are gonotrophically concordant and a blood meal gives rise to a complete egg batch. Egg development takes two or three days depending on temperature. Gravid females leave their resting sites at dusk. They are attracted by water gradients and volatile chemicals that provide a suitable aquatic habitat in which to lay their eggs. CONCLUSION: Whilst traditional interventions, using insecticides, target mosquitoes indoors, additional protection can be achieved using spatial repellents outdoors, attractant traps or house modifications to prevent mosquito entry. Future research on the variability of species-specific behaviour, movement of mosquitoes across the landscape, the importance of light and vision, reproductive barriers to gene flow, male mosquito behaviour and evolutionary changes in mosquito behaviour could lead to an improvement in malaria surveillance and better methods of control reducing the current over-reliance on the indoor application of insecticides.


Assuntos
Anopheles , Malária , Mosquitos Vetores , Animais , Anopheles/fisiologia , Mosquitos Vetores/fisiologia , Malária/prevenção & controle , Malária/transmissão , África Subsaariana , Controle de Mosquitos/métodos , Feminino , Comportamento Alimentar , Masculino
3.
Malar J ; 23(1): 158, 2024 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-38773512

RESUMO

BACKGROUND: This study aimed to assess the spatial distribution of Anopheles mosquito larval habitats and the environmental factors associated with them, as a prerequisite for the implementation of larviciding. METHODS: The study was conducted in December 2021, during the transition period between the end of the short rainy season (September-November) and the short dry season (December-February). Physical, biological, and land cover data were integrated with entomological observations to collect Anopheles larvae in three major towns: Mitzic, Oyem, and Bitam, using the "dipping" method during the transition from rainy to dry season. The collected larvae were then reared in a field laboratory established for the study period. After the Anopheles mosquitoes had emerged, their species were identified using appropriate morphological taxonomic keys. To determine the influence of environmental factors on the breeding of Anopheles mosquitoes, multiple-factor analysis (MFA) and a binomial generalized linear model were used. RESULTS: According to the study, only 33.1% out of the 284 larval habitats examined were found to be positive for Anopheles larvae, which were primarily identified as belonging to the Anopheles gambiae complex. The findings of the research suggested that the presence of An. gambiae complex larvae in larval habitats was associated with various significant factors such as higher urbanization, the size and type of the larval habitats (pools and puddles), co-occurrence with Culex and Aedes larvae, hot spots in ambient temperature, moderate rainfall, and land use patterns. CONCLUSIONS: The results of this research mark the initiation of a focused vector control plan that aims to eradicate or lessen the larval habitats of An. gambiae mosquitoes in Gabon's Woleu Ntem province. This approach deals with the root causes of malaria transmission through larvae and is consistent with the World Health Organization's (WHO) worldwide objective to decrease malaria prevalence in regions where it is endemic.


Assuntos
Anopheles , Ecossistema , Larva , Malária , Mosquitos Vetores , Animais , Anopheles/fisiologia , Anopheles/crescimento & desenvolvimento , Larva/crescimento & desenvolvimento , Larva/fisiologia , Gabão , Malária/transmissão , Mosquitos Vetores/fisiologia , Estações do Ano , Análise Espacial , Distribuição Animal
4.
Malar J ; 23(1): 272, 2024 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-39256754

RESUMO

BACKGROUND: Reactive case detection (RCD) aims to reduce malaria transmission stemming from asymptomatic carriers. Symptomatic individuals diagnosed with malaria at a health centre are followed to their households, where members of the index case and neighbouring households are tested and treated for malaria. An RCD programme was tested in the Ashanti region of Ghana in order to study diagnostic accuracy in the hospital and household settings, assess the prevalence of subclinical infections and possible clustering in index case households, and identify operational challenges for future RCD programmes. Currently, transmission in this region is high, but reactive interventions might become an option once transmission is reduced. METHODS: 264 febrile individuals were enrolled at the Mankranso Government Hospital and tested for malaria using rapid diagnostic tests (RDT). From the pool of RDT-positive febrile index cases, 14 successful RCD follow-ups were conducted, and 233 individuals were enrolled from the index case, neighbour, and control households. The sensitivity of diagnostic tools for clinical and subclinical cases was compared, including RDT, expert microscopy by World Health Organization-certified microscopists, field microscopy, and qPCR. RESULTS: Poor diagnosis and low receptivity to RCD-style follow-ups were major limitations to a successful and effective RCD programme. Field microscopy detected only 49% of clinical infections compared to RDT. 54% of individuals did not agree to a follow-up, and 66% of attempted follow-ups failed. The system effectiveness of RCD, calculated as the product of correctly diagnosed index cases, successful follow-ups, and proportion of asymptomatic infections detected by RDT, was very low at 4.0%. CONCLUSIONS: Due to low system effectiveness and the endemic nature of the disease setting in which asymptomatic prevalence is high and infections are not clustered around index case households, RCD is currently not a feasible option for malaria control in this region. The operational challenges identified through this study may help inform future reactive intervention programme designs once transmission is reduced.


Assuntos
Infecções Assintomáticas , Testes Diagnósticos de Rotina , Malária Falciparum , Gana/epidemiologia , Humanos , Malária Falciparum/diagnóstico , Malária Falciparum/epidemiologia , Malária Falciparum/prevenção & controle , Infecções Assintomáticas/epidemiologia , Feminino , Masculino , Pré-Escolar , Criança , Adolescente , Testes Diagnósticos de Rotina/métodos , Testes Diagnósticos de Rotina/estatística & dados numéricos , Adulto , Adulto Jovem , Lactente , Pessoa de Meia-Idade , Plasmodium falciparum/isolamento & purificação , Prevalência , Sensibilidade e Especificidade , Idoso
5.
Malar J ; 23(1): 25, 2024 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-38238781

RESUMO

This paper examines the far-reaching implications of Triple Artemisinin-Based Combination Therapy (TACT) in the global battle against malaria. Artemisinin-Based Combination Therapy (ACT) is recognized for its cost-effectiveness, lower likelihood of adverse events, and widespread acceptance by patients and healthcare providers. However, TACT introduces novel dimensions to the fight against malaria that make them a superior choice in several aspects. TACT has been demonstrated to address resistance, offer a broader spectrum of action, reduce the risk of treatment failure, and can be tailored to meet regional needs, strengthening the global effort to combat malaria. However, maximizing these benefits of TACT depends on accessibility, particularly in resource-limited regions where malaria is most prevalent. Collaborative efforts among stakeholders, sustainable pricing strategies, efficient supply chains, and public-private partnerships are essential to ensure that TACT reaches needy populations. Moreover, dispelling prevalent malaria myths through health education campaigns is critical in this endeavour. The paper underscores the significance of collaborative initiatives and partnerships among governments, international organizations, research institutions, acadaemia, pharmaceutical companies, and local communities. Together, these efforts can pave the way for the acceptance, adoption, and success of TACT, ultimately advancing the global goal of a malaria-free world.


Assuntos
Antimaláricos , Artemisininas , Malária , Humanos , Antimaláricos/uso terapêutico , Quimioterapia Combinada , Malária/tratamento farmacológico , Malária/prevenção & controle , Artemisininas/uso terapêutico
6.
Malar J ; 23(1): 277, 2024 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-39267082

RESUMO

BACKGROUND: A quasi-experimental comparative trial will be designed in Burkina Faso. The study will compare the use and preferences for two groups types of insecticide-treated nets textile: polyester-based and polyethylene-based, according to their use and preferences in selected health districts. These health districts will be selected in three eco-climate zones (Sahelian, dry savannah and wet savannah) in the country. These findings will inform decisions on future net procurements for national malaria control programme in 2025. METHODS: Quantitative surveys and qualitative data collection will be carried out to gather information on the type of net textile most commonly used and preferred by the community. They will be performed between the end of the dry season and the early rainy season. The quantitative surveys involved household interviews with households and individuals' questionnaires, while the qualitative data collection involved in-depth individual interviews and focus group discussions to explore and clarify some key evaluation criteria. A total of 9450 insecticide-treated nets were surveyed for quantitative survey purposes. For the qualitative study, 48 in-depth individual interviews and 12 focus group discussions were carried out. A mixed model approach combining the results from quantitative surveys and qualitative studies will be used for decision-making on the type of insecticide-treated net preference. CONCLUSION: This methodological approach will be used by the National Malaria Control Programme to conduct this study on determinants of net use in Burkina Faso in order to provide robust evidence across diverse settings. This mixed-methods approach for data collection and analysis could be used in other countries to provide evidence that would help to increase the uptake of insecticide-treated nets, the main vector control tool in Africa.


Assuntos
Características da Família , Mosquiteiros Tratados com Inseticida , Malária , Controle de Mosquitos , Burkina Faso , Malária/prevenção & controle , Humanos , Controle de Mosquitos/métodos , Controle de Mosquitos/estatística & dados numéricos , Mosquiteiros Tratados com Inseticida/estatística & dados numéricos , Polietileno , Poliésteres , Tomada de Decisões , Têxteis , Inquéritos e Questionários
7.
Clin Infect Dis ; 76(4): 704-712, 2023 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-35767269

RESUMO

BACKGROUND: Assessing the infectious reservoir is critical in malaria control and elimination strategies. We conducted a longitudinal epidemiological study in a high-malaria-burden region in Kenya to characterize transmission in an asymptomatic population. METHODS: 488 study participants encompassing all ages in 120 households within 30 clusters were followed for 1 year with monthly sampling. Malaria was diagnosed by microscopy and molecular methods. Transmission potential in gametocytemic participants was assessed using direct skin and/or membrane mosquito feeding assays, then treated with artemether-lumefantrine. Study variables were assessed using mixed-effects generalized linear models. RESULTS: Asexual and sexual parasite data were collected from 3792 participant visits, with 903 linked with feeding assays. Univariate analysis revealed that the 6-11-year-old age group was at higher risk of harboring asexual and sexual infections than those <6 years old (odds ratio [OR] 1.68, P < .001; and OR 1.81, P < .001), respectively. Participants with submicroscopic parasitemia were at a lower risk of gametocytemia compared with microscopic parasitemia (OR 0.04, P < .001), but they transmitted at a significantly higher rate (OR 2.00, P = .002). A large proportion of the study population who were infected at least once remained infected (despite treatment) with asexual (71.7%, 291/406) or sexual (37.4%, 152/406) parasites. 88.6% (365/412) of feeding assays conducted in individuals who failed treatment the previous month resulted in transmissions. CONCLUSIONS: Individuals with asymptomatic infection sustain the transmission cycle, with the 6-11-year age group serving as an important reservoir. The high rates of artemether-lumefantrine treatment failures suggest surveillance programs using molecular methods need to be expanded for accurate monitoring and evaluation of treatment outcomes.


Assuntos
Antimaláricos , Artemisininas , Malária Falciparum , Malária , Animais , Humanos , Criança , Antimaláricos/uso terapêutico , Malária Falciparum/epidemiologia , Artemisininas/uso terapêutico , Artemeter/uso terapêutico , Plasmodium falciparum , Quênia/epidemiologia , Parasitemia/tratamento farmacológico , Combinação Arteméter e Lumefantrina/uso terapêutico , Malária/tratamento farmacológico
8.
Malar J ; 22(1): 111, 2023 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-36991411

RESUMO

BACKGROUND: This study aimed to assess the perception and awareness of malaria vaccine policy implementation among health policy actors in Nigeria. METHODS: A descriptive study was conducted to assess the opinions and perceptions of policy actors on the implementation of a vaccination programme against malaria in Nigeria. Descriptive statistics were carried out to study the characteristics of the population and the univariate analysis of the responses to questions presented to the participants. Multinomial logistic regression was conducted to evaluate the association between demographic characteristics and the responses. RESULTS: The study revealed that malaria vaccine awareness was poor, with only 48.9% of the policy actors having previous knowledge of the malaria vaccine. The majority of participants (67.8%) declared that they were aware of the importance of vaccine policy in efforts to manage disease transmission. As the number of years of work experience of the participants increased, the odds of being more likely to be aware of the malaria vaccine increased [OR 2.491 (1.183-5.250), p value < 0.05]. CONCLUSION: It is recommended that policy-makers develop methods of educating populations, increase awareness of the acceptability of the vaccine and ensure that an affordable malaria vaccine programme is implemented in the population.


Assuntos
Vacinas Antimaláricas , Malária , Humanos , Nigéria/epidemiologia , Política de Saúde , Malária/prevenção & controle , Percepção , Conhecimentos, Atitudes e Prática em Saúde
9.
Malar J ; 22(1): 69, 2023 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-36849883

RESUMO

BACKGROUND: Malaria disproportionately affects low-income households in rural communities where poor housing is common. Despite evidence that well-constructed and mosquito-proofed houses can reduce malaria risk, housing improvement is rarely included in malaria control toolboxes. This study assessed the need, magnitude, and opportunities for housing improvement to control malaria in rural Tanzania. METHODS: A mixed-methods study was conducted in 19 villages across four district councils in southern Tanzania. A structured survey was administered to 1292 community members to assess need, perceptions, and opportunities for housing improvement for malaria control. Direct observations of 802 houses and surrounding environments were done to identify the actual needs and opportunities, and to validate the survey findings. A market survey was done to assess availability and cost of resources and services necessary for mosquito-proofing homes. Focus group discussions were conducted with key stakeholders to explore insights on the potential and challenges of housing improvement as a malaria intervention. RESULTS: Compared to other methods for malaria control, housing improvement was among the best understood and most preferred by community members. Of the 735 survey respondents who needed housing improvements, a majority needed window screening (91.1%), repairs of holes in walls (79.4%), door covers (41.6%), closing of eave spaces (31.2%) and better roofs (19.0%). Community members invested significant efforts to improve their own homes against malaria and other dangers, but these efforts were often slow and delayed due to high costs and limited household incomes. Study participants suggested several mechanisms of support to improve their homes, including government loans and subsidies. CONCLUSION: Addressing the need for housing improvement is a critical component of malaria control efforts in southern Tanzania. In this study, a majority of the community members surveyed needed modest modifications and had plans to work on those modifications. Without additional support, their efforts were however generally slow; households would take years to sufficiently mosquito-proof their houses. It is, therefore, crucial to bring together the key players across sectors to reduce barriers in malaria-proofing housing in endemic settings. These may include government subsidies or partnerships with businesses to make housing improvement more accessible and affordable to residents.


Assuntos
Culicidae , Malária , Animais , Humanos , Habitação , Tanzânia , Comércio , Malária/prevenção & controle
10.
Malar J ; 22(1): 219, 2023 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-37517990

RESUMO

BACKGROUND: In order to reignite gains and accelerate progress toward improved malaria control and elimination, policy, strategy, and operational decisions should be derived from high-quality evidence. The U.S. President's Malaria Initiative (PMI) Insights project together with the Université Cheikh Anta Diop of Dakar, Senegal, conducted a broad stakeholder consultation process to identify pressing evidence gaps in malaria control and elimination across sub-Saharan Africa (SSA), and developed a priority list of country-driven malaria operational research (OR) and programme evaluation (PE) topics to address these gaps. METHODS: Five key stakeholder groups were engaged in the process: national malaria programmes (NMPs), research institutions in SSA, World Health Organization (WHO) representatives in SSA, international funding agencies, and global technical partners who support malaria programme implementation and research. Stakeholders were engaged through individual or small group interviews and an online survey, and asked about key operational challenges faced by NMPs, pressing evidence gaps in current strategy and implementation guidance, and priority OR and PE questions to address the challenges and gaps. RESULTS: Altogether, 47 interviews were conducted with 82 individuals, and through the online survey, input was provided by 46 global technical partners. A total of 33 emergent OR and PE topics were identified through the consultation process and were subsequently evaluated and prioritized by an external evaluation committee of experts from NMPs, research institutions, and the WHO. The resulting prioritized OR and PE topics predominantly focused on generating evidence needed to close gaps in intervention coverage, address persistent challenges faced by NMPs in the implementation of core strategic interventions, and inform the effective deployment of new tools. CONCLUSION: The prioritized research list is intended to serve as a key resource for informing OR and PE investments, thereby ensuring future investments focus on generating the evidence needed to strengthen national strategies and programme implementation and facilitating a more coordinated and impactful approach to malaria operational research.


Assuntos
Malária , Pesquisa Operacional , Humanos , Senegal , Malária/prevenção & controle , Política de Saúde , África Subsaariana
11.
Malar J ; 22(1): 161, 2023 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-37208735

RESUMO

BACKGROUND: The unmet demand for effective malaria transmission-blocking agents targeting the transmissible stages of Plasmodium necessitates intensive discovery efforts. In this study, a bioactive bisbenzylisoquinoline (BBIQ), isoliensinine, from Cissampelos pariera (Menispermaceae) rhizomes was identified and characterized for its anti-malarial activity. METHODS: Malaria SYBR Green I fluorescence assay was performed to evaluate the in vitro antimalarial activity against D6, Dd2, and F32-ART5 clones, and immediate ex vivo (IEV) susceptibility for 10 freshly collected P. falciparum isolates. To determine the speed- and stage-of-action of isoliensinine, an IC50 speed assay and morphological analyses were performed using synchronized Dd2 asexuals. Gametocytocidal activity against two culture-adapted gametocyte-producing clinical isolates was determined using microscopy readouts, with possible molecular targets and their binding affinities deduced in silico. RESULTS: Isoliensinine displayed a potent in vitro gametocytocidal activity at mean IC50gam values ranging between 0.41 and 0.69 µM for Plasmodium falciparum clinical isolates. The BBIQ compound also inhibited asexual replication at mean IC50Asexual of 2.17 µM, 2.22 µM, and 2.39 µM for D6, Dd2 and F32-ART5 respectively, targeting the late-trophozoite to schizont transition. Further characterization demonstrated a considerable immediate ex vivo potency against human clinical isolates at a geometric mean IC50IEV = 1.433 µM (95% CI 0.917-2.242). In silico analyses postulated a probable anti-malarial mechanism of action by high binding affinities for four mitotic division protein kinases; Pfnek1, Pfmap2, Pfclk1, and Pfclk4. Additionally, isoliensinine was predicted to possess an optimal pharmacokinetics profile and drug-likeness properties. CONCLUSION: These findings highlight considerable grounds for further exploration of isoliensinine as an amenable scaffold for malaria transmission-blocking chemistry and target validation.


Assuntos
Antimaláricos , Cissampelos , Malária Falciparum , Malária , Humanos , Antimaláricos/química , Plasmodium falciparum , Rizoma
12.
Malar J ; 22(1): 4, 2023 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-36604693

RESUMO

BACKGROUND: Since 2013, the National Malaria Control Programme in mainland Tanzania and the Zanzibar Malaria Elimination Programme have implemented mass insecticide-treated net (ITN) distribution campaigns, routine ITN distribution to pregnant women and infants, and continuous distribution through primary schools (mainland) and community leaders (Zanzibar) to further malaria control efforts. Mass campaigns are triggered when ITN access falls below 40%. In this context, there is a need to monitor ITN access annually to assess whether it is below threshold and inform quantification of ITNs for the following year. Annual estimates of access are needed at the council level to inform programmatic decision-making. METHODS: An age-structured stock and flow model was used to predict annual net crops from council-level distribution data in Tanzania from 2012 to 2020 parameterized with a Tanzania-specific net median lifespan of 2.15 years. Annual nets-per-capita (NPC) was calculated by dividing each annual net crop by mid-year council projected population. A previously fit nonparametric conditional quantile function for the proportion of the population with access to an ITN (ITN access) as a function of NPC was used to predict ITN access at the council level based on the predicted NPC value. These estimates were compared to regional-level ITN access from large household surveys. RESULTS: For regions with the same ITN strategy for all councils, predicted council-level ITN access was consistent with regional-level survey data for 79% of councils. Regions where ITN strategy varied by council had regional estimates of ITN access that diverged from the council-specific estimates. Predicted ITN access reached 60% only when "nets issued as a percentage of the council population" (NPP) exceeded 15%, and approached 80% ITN access when NPP was at or above 20%. CONCLUSION: Modelling ITN access with country-specific net decay rates, council-level population, and ITN distribution data is a promising approach to monitor ITN coverage sub-regionally and between household surveys in Tanzania and beyond.


Assuntos
Mosquiteiros Tratados com Inseticida , Inseticidas , Malária , Pré-Escolar , Feminino , Humanos , Gravidez , Malária/prevenção & controle , Controle de Mosquitos , Tanzânia
13.
Proc Natl Acad Sci U S A ; 117(36): 22042-22050, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32843339

RESUMO

Malaria vector control may be compromised by resistance to insecticides in vector populations. Actions to mitigate against resistance rely on surveillance using standard susceptibility tests, but there are large gaps in the monitoring data across Africa. Using a published geostatistical ensemble model, we have generated maps that bridge these gaps and consider the likelihood that resistance exceeds recommended thresholds. Our results show that this model provides more accurate next-year predictions than two simpler approaches. We have used the model to generate district-level maps for the probability that pyrethroid resistance in Anopheles gambiae s.l. exceeds the World Health Organization thresholds for susceptibility and confirmed resistance. In addition, we have mapped the three criteria for the deployment of piperonyl butoxide-treated nets that mitigate against the effects of metabolic resistance to pyrethroids. This includes a critical review of the evidence for presence of cytochrome P450-mediated metabolic resistance mechanisms across Africa. The maps for pyrethroid resistance are available on the IR Mapper website, where they can be viewed alongside the latest survey data.


Assuntos
Anopheles/efeitos dos fármacos , Resistência a Inseticidas , Inseticidas/farmacologia , Malária/transmissão , Controle de Mosquitos/métodos , Mosquitos Vetores/efeitos dos fármacos , África , Animais , Anopheles/fisiologia , Humanos , Mosquiteiros Tratados com Inseticida , Mosquitos Vetores/fisiologia , Piretrinas/farmacologia
14.
Int J Mol Sci ; 24(18)2023 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-37762222

RESUMO

Malaria parasites must acquire all necessary nutrients from the vertebrate and mosquito hosts to successfully complete their life cycle. Failure to acquire these nutrients can limit or even block parasite development and presents a novel target for malaria control. One such essential nutrient is pantothenate, also known as vitamin B5, which the parasite cannot synthesize de novo and is required for the synthesis of coenzyme A (CoA) in the parasite. This review examines pantothenate and the CoA biosynthesis pathway in the human-mosquito-malaria parasite triad and explores possible approaches to leverage the CoA biosynthesis pathway to limit malaria parasite development in both human and mosquito hosts. This includes a discussion of sources for pantothenate for the mosquito, human, and parasite, examining the diverse strategies used by the parasite to acquire substrates for CoA synthesis across life stages and host resource pools and a discussion of drugs and alternative approaches being studied to disrupt CoA biosynthesis in the parasite. The latter includes antimalarial pantothenate analogs, known as pantothenamides, that have been developed to target this pathway during the human erythrocytic stages. In addition to these parasite-targeted drugs, we review studies of mosquito-targeted allosteric enzymatic regulators known as pantazines as an approach to limit pantothenate availability in the mosquito and subsequently deprive the parasite of this essential nutrient.

15.
J Theor Biol ; 555: 111281, 2022 12 21.
Artigo em Inglês | MEDLINE | ID: mdl-36154815

RESUMO

The mosquito-borne disease, malaria, continues to impose a devastating health and economic burden worldwide. In malaria-endemic areas, insecticide-treated nets (ITNs) have been useful in curtailing the burden of the disease. However, mosquito resistance to insecticides, decay in ITN efficacy, net attrition, etc., undermine the effectiveness of ITNs in combatting malaria. In this study, mathematical models that account for asymptomatic infectious humans (through a partially immune class or a separate asymptomatic infectious class), insecticide resistance, and decay in ITN efficacy are proposed and analyzed. Analytical and numerical results of the models when ITN efficacy is constant show that there are parameter regimes for which a backward bifurcation occurs. Local and global sensitivity analyses are performed to identify parameters (some of which are potential targets for disease control) with the most significant influence on the control reproduction (Rc) and disease prevalence. These influential parameters include the maximum biting rate of resistant mosquitoes, ITN coverage, initial ITN efficacy against sensitive mosquitoes, the probability that an infectious mosquito (human) infects a susceptible human (mosquito), and the rate at which adult mosquitoes develop (lose) resistance to insecticides. Simulations of the models show that accounting for asymptomatic infectious humans through a separate class, or not accounting for the decay in ITN efficacy leads to an underestimation of disease burden. In particular, if the initial efficacy of ITNs against sensitive and resistance mosquitoes is 96%, the minimum ITN coverage required to reduce Rc below one (and hence, contain malaria) is approximately 11% (27%) lower when ITN efficacy is averaged (constant) for a model with a separate asymptomatic class. For the model with a partially immune class and decaying ITN efficacy, reducing Rc below one is impossible even if the entire populace uses ITNs. The study shows that replacing ITNs before their prescribed lifespans, or designing ITNs with longer lifespans is important for malaria control. Furthermore, the study shows that piperonyl butoxide (PBO) ITNs (which inhibit or reverse insecticide resistance) outperform regular ITNs in malaria control. Hence, prospects for effectively controlling malaria are enhanced by widespread use of high quality ITNs (e.g. PBO ITNs), especially if the useful lifespans of the ITNs are long enough and the ITNs are replaced before the end of their useful lifespans.


Assuntos
Culicidae , Mosquiteiros Tratados com Inseticida , Inseticidas , Malária , Humanos , Adulto , Animais , Resistência a Inseticidas , Inseticidas/farmacologia , Controle de Mosquitos/métodos , Butóxido de Piperonila , Malária/prevenção & controle , Malária/epidemiologia
16.
Malar J ; 21(1): 347, 2022 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-36414935

RESUMO

BACKGROUND: Malaria is an infectious disease which has been globally targeted for elimination in at least 35 of 90 endemic countries by 2030. Most successful malaria elimination country programmes have engaged the private health sector in an effort to identify, document, investigate, provide effective treatment, and follow-up cases. However, there has been limited rigorous research showing evidence of adherence among healthcare providers of the formal private health sector to national malaria diagnosis and treatment guidelines in Ethiopia, starting from malaria control to elimination phases. The aims of this study were to investigate and explain the level of adherence to malaria diagnosis and treatment guidelines among healthcare providers working in formal private health facilities in north-western Ethiopia. METHODS: An explanatory sequential mixed method design was conducted in the West Gojjam Zone of Ethiopia. Quantitative data were extracted from 1650 medical records of adult uncomplicated malaria outpatients served in 11 private-for-profit health facilities. In addition, using a qualitative approach, 33 in-depth interviews (IDIs) with healthcare providers were conducted. All interviews were audio-recorded, transcribed verbatim, and analysed using eight steps. RESULTS: Of 1650 suspected malaria cases in adult outpatients, 80.6% (1330/1650) were screen tested using microscopy and the remainder 19.4% (320/1650) were tested using multispecies rapid diagnosis tests (RDTs). Hence, the results revealed that private healthcare providers universally adhered to diagnosis guidelines. In addition, after following-up and excluding other causes of fever, 4.1% (56/1376) patients were clinically diagnosed with uncomplicated malaria. Despite this, the proportion of private healthcare provider adherence with confirmed malaria case treatment guidelines was 20.9% (69/330). In addition, 1320 (95.9%) of adult outpatients with negative laboratory results were not treated. Some of the identified determinant factors for sub-optimal adherence of healthcare providers to malaria guidelines were interruptions in supply and lack of availability of recommended anti-malarial drugs, lack of availability of quality assured laboratory supplies, and poor knowledge of the recommendations of the national standards. CONCLUSIONS: Private healthcare providers adhered to universal parasitological diagnosis, providing comprehensive counseling, and linking patients with community health workers. In addition, almost all laboratory negative patients were not treated with anti-malarial drugs. However, only one-fifth of confirmed patients were treated in line with national guideline recommendations. Malaria control and elimination efforts across Ethiopia could be improved through establishing a collaborative function of a win-win public private mix partnership model. In addition, including the data of the private health sector in the health information system could show real malaria burden and use the information to improve the adherence to malaria diagnosis, treatment, and reporting standards within the targeted era of elimination. Therefore, building the capacity of private healthcare providers and ensuring the availability of all nationally recommended drugs and supplies in private health sector facilities is recommended to improve the quality of services.


Assuntos
Antimaláricos , Malária , Adulto , Humanos , Setor Privado , Antimaláricos/uso terapêutico , Administração de Caso , Etiópia , Malária/diagnóstico , Malária/tratamento farmacológico , Malária/prevenção & controle , Agentes Comunitários de Saúde
17.
Malar J ; 21(1): 231, 2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-35915503

RESUMO

BACKGROUND: Malaria was endemic in Sri Lanka for centuries and was eliminated in 2012. It is widely assumed that the costs of elimination are generally greater than that of control. The costs of malaria elimination in Sri Lanka with that of malaria control in the past using periods in which starting transmission dynamics were similar were compared. METHODS: The expenditure of the Anti-Malaria Campaign (AMC), total and by budget category, during 2002-2010 is compared with that of malaria control during the period 1980-1989, using regression analyses and the Mann Whitney U statistic. RESULTS: The expenditure on malaria control and malaria elimination was similar ranging from 21 to 45 million USD per year when adjusted for inflation. In both periods, external funding for the malaria progamme constituted around 24% of the total budget; during the control phase in the 1980s, external funds came from bilateral agencies and were disbursed in accordance with government budget guidelines. In the elimination phase in the 2000s, most of external funding was from the Global Fund and had flexibility of disbursement. In the 1980s, most funds were expended on commodities-insecticides, diagnostics and medicines and their delivery; in the elimination phase, they were spent on programme management, human resources, technical assistance and monitoring and evaluation; monitoring and evaluation was not a budget line in the 1980s. Although the cost per case of malaria was considerably higher during the elimination phase than in the control phase, expenditure was not on individual cases but on general systems strengthening. CONCLUSION: Malaria elimination in Southeast Asia may not require more funding than malaria control. But sustained funding for an agile programme with flexibility in fund utilization and improved efficiencies in programme management with stringent monitoring and evaluation appears to be critically important.


Assuntos
Antimaláricos , Inseticidas , Malária , Antimaláricos/uso terapêutico , Gastos em Saúde , Humanos , Malária/epidemiologia , Sri Lanka/epidemiologia
18.
Malar J ; 21(1): 246, 2022 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-36028866

RESUMO

BACKGROUND: Since 2013, the National Malaria Control Programme in mainland Tanzania has deployed annual distributions of insecticide-treated nets (ITNs) through primary schools to maintain ITN access and use. This School Net Programme (SNP) is slated to be used throughout mainland Tanzania by 2023. This modelling study projects ITN access under different ITN distribution strategies and quantification approaches. METHODS: A stock and flow model with a Tanzania-specific ITN decay rate was used to calculate annual net crops for four different ITN distribution strategies, varying quantification approaches within each strategy. Annual nets-per-capita (NPC) was derived from net crop and a standardized population projection. Nonparametric conditional quartile functions for the proportion of the population with access to an ITN (ITN access) as a function of NPC were used to predict ITN access and its variability. The number of ITNs required under the varying quantification approaches for the period 2022-2030 was calculated. RESULTS: Annual SNP quantified using a "population times 15%" approach maintained ITN access between 80 and 90%, when combined with reproductive and child health (RCH) ITN distribution, requiring 133.2 million ITNs. The same strategy quantified with "population times 22%" maintained ITN access at or above 90%, requiring 175.5 million ITNs. Under 5-year mass campaigns with RCH distribution for pregnant women and infants, ITN access reached 90% post-campaign and fell to 27-35% in the 4th year post-campaign, requiring 120.5 million ITNs over 8 years. 3-yearly mass campaigns with RCH reached 100% ITN access post-campaign and fell to 70% in the 3rd year post-campaign, requiring 154.4 million ITNs. CONCLUSION: Given an ITN retention time in Tanzania of 2.15 years, the model predicts that mass campaigns conducted every 3 years in mainland Tanzania will not maintain ITN access at target levels of 80%, even with strong RCH channels. Mainland Tanzania can however expect to maintain ITN access at 80% or above by quantifying SNP using "population × 15%", in addition to RCH ITN delivery. This strategy requires 14% fewer ITNs than a 3-year campaign strategy while providing more consistent ITN coverage. Meeting the targets of 80% ITN use would require maintaining 90% ITN access, achievable using a "population times 22%" quantification approach for SNP.


Assuntos
Mosquiteiros Tratados com Inseticida , Inseticidas , Malária , Criança , Feminino , Humanos , Lactente , Controle de Mosquitos , Gravidez , Instituições Acadêmicas , Tanzânia
19.
Malar J ; 21(1): 363, 2022 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-36461059

RESUMO

BACKGROUND: The use of insecticide-treated bed nets has been proven to be effective in reducing malaria transmission in highly endemic areas. Use of long-lasting insecticidal nets (LLINs) has been embraced by many malaria endemic countries. LLINs are up to 95% effective in inhibiting blood feeding, when used consistently even after 7 years. The challenge, however, is enhancing their consistent use, especially by the most vulnerable groups (children under 5 years and pregnant women). The study established factors associated with consistent use of bed nets for malaria control among children under 5 years in Soroti district. METHODS: The study employed a cross-sectional design, with multi-stage sampling of households. A total of 400 households (HH) were sampled and the HH head in each household interviewed. Key informant interviews (KIIs) were conducted with 7 key informants who were knowledgeable on the subject matter. Data analysis was done using SPSS 17.0 at Univariate, Bivariate and Multivariable levels; after entry and cleaning. Key informants' data were summarized manually; verbatim quotes and text used to reinforce quantitative data in line with objectives. RESULTS: Only 56.8% of the 690 children under 5 years used bed nets consistently. The factors affecting consistent bed net use were age of the child, their use of bed nets the previous night, occupation of caretaker, respondents' perceived susceptibility, perceived risk of getting malaria, size and shape of the bed nets. Rectangular nets were difficult to hang daily in huts according to most key informants. CONCLUSION: Consistent bed net use among under fives is still below the RBM target of 85% by 2015 and can be enhanced by providing conical bed nets and setting aside a health education programme to emphasize the effectiveness of even one mosquito in spreading malaria at night to the entire household and ability of bed nets to stop transmission better than other methods.


Assuntos
Culicidae , Mosquiteiros Tratados com Inseticida , Inseticidas , Malária , Gravidez , Criança , Animais , Humanos , Feminino , Pré-Escolar , Estudos Transversais , Uganda , Malária/prevenção & controle
20.
Malar J ; 21(1): 190, 2022 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-35710474

RESUMO

BACKGROUND: To avoid misuse of anti-malarials, correct diagnosis of fever prior to drug prescription is essential. Presumptive treatment in the private healthcare sector is a concern in Nigeria, where availability of affordable artemisinin-based combination therapy (ACT) is high following the implementation of subsidy schemes from 2010 to 2017. Similar subsidies have not, however, been implemented for malaria rapid diagnostic tests (RDTs). A market survey in 2018 predominantly designed to assess the ACT market in the private sector also collected data related to RDTs, results of which are presented herein. METHODS: A 2018 market survey consisted of (i) an outlet survey targeting private pharmacies and Proprietary and Patent Medicine Vendors (PPMVs) across different regions of Nigeria to assess supply-side market factors related to availability of RDTs (defined as having stock available for purchase at the time of the survey) and (ii) a household survey to determine demand-side factors related to knowledge of RDTs, healthcare-seeking practices and affordability. RESULTS: Availability of RDTs at the time of the survey was low in both outlet types and significantly lower in PPMVs (22.1%, 95% CI) among pharmacies versus (13.6%, 95% CI) among PPMVs (p < 0.01). Reasons for not restocking RDTs included low demand and no supply. The majority of households diagnose malaria based on experience, while one-third would visit a PPMV or pharmacy. Half of households had heard of RDTs (48.4%) and 38.6% thought they were affordable. CONCLUSIONS: Low availability of RDTs among PPMVs and pharmacies may be attributed to lack of demand, supply-side issues and cost. Increasing household knowledge of RDTs may aid increasing demand, while subsidized RDTs may address supply and price issues. Addressing the deficit in RDT provision is important for targeting of ACT medicines.


Assuntos
Antimaláricos , Malária , Antimaláricos/uso terapêutico , Estudos Transversais , Testes Diagnósticos de Rotina , Humanos , Malária/diagnóstico , Malária/tratamento farmacológico , Nigéria , Setor Privado , Inquéritos e Questionários
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