Mosquito Breeding Sites Research Articles

Seasonal variation of mosquito breeding sites in the industrial areas of the city of Abidjan, south-eastern Cote d'Ivoire

The expanding of industrial activities in Côte d'Ivoire, particularly in the city of Abidjan (73% of the national industrial sector), has led to significant environmental imbalances. These have created favourable conditions for the reproduction and maintenance of many disease vectors such as mosquitoes. Controlling these insect vectors requires the understanding of their ecology, including genus diversity and their breeding sites types. It is in this context that a study was conducted on the seasonal variation of mosquito breeding sites in the industrial areas of Abidjan. Larval surveys were conducted from February to March 2019 (dry season) and from June to July 2019 (rainy season) in the industrial zones of the communes of Koumassi, Port-Bouët and Yopougon. This study led to the identification of 2,015 and 1,977 potential breeding sites in the rainy and dry seasons respectively. The breeding sites were grouped into four types : abandoned tyres, discarded containers, natural breeding sites, other breeding sites. Of these sites, 740 (36.72%) and 288 (14.57%) were positive in the rainy and dry seasons respectively. Abandoned tyres were abundant with 1,685 (85.23%) observed in the dry season and 1,593 (79.06%) in the wet season in the study sites. The presence of vegetation and sunshine negatively influenced the presence of larvae in the Vridi industrial zone (Port-Bouët). In addition, Aedes breeding sites were most frequently observed with 218 (75.69%) in the dry season and 495 (66.89%) in the rainy season. The results obtained in this study could be used to develop an effective method to fight against mosquitoes in the industrial zones of Abidjan.

Assessment of physico-chemical characteristics of mosquito breeding sites in Northwest Nigeria

Assessment of physico-chemical characteristics of mosquito breeding sites in Northwest Nigeria

A case study from Guyana of adapting engaged research design to promote ‘fairness in knowing’

In this paper, we have combined ideas drawn from philosophy (epistemic injustice), critical theory (epistemicide) and practical approaches (engaged research design) with Indigenous knowledge to promote ‘fairness in knowing’ in a project called DETECT (Integrated Space Technology Vector Control for Enhancing community health and resilience against escalating climatic disruptions), an early warning system to support communities in identifying mosquito breeding sites using satellite, drone and ground-sensing technologies. DETECT used engaged research design to inform pre-award planning. We document how the project team, comprising Indigenous and other researchers, re-imagined the plans in the light of the COVID-19 pandemic to allow project participants to meet safely and equitably, and reflect on some of the key challenges in engaging across borders and cultures in the context of rapidly changing conditions characterised by vulnerability, risk, complexity and uncertainty.

Larvicidal Activity of Solvent Extracts of Nicotiana tabacum L, and Datura metel L, (Solanales: Solanaceae) Against Larvae of Three Mosquito Species

Mosquitoes are insects that vector many of the life threatening diseases. Control of these insects is one of the major problems of the world today. Leaves and seed kernel extracts of Tobacco; Nicotiana tabacum (L.) and Thorn-Apple; Datura metel (L.) were assayed for larvicidal activity against three mosquito species of Aedes, Anopheles and Culex respectively. Samples of the three species were collected from mosquito breeding sites and reared in the laboratory for continued source of larvae following standard procedures. The plants parts used were extracted with hexane, chloroform and methanol in increasing order of polarity. Each extract was formulated into 0.9, 1.6, 2.4, 3.5 and 4.0mg/mL concentrations, and tested for larvicidal activity against 25 larvae of each genus in three replicates, alongside the controls over 12 to 72 hrs periods. The extracts that exhibited highest larvicidal activity were subjected to phytochemical screenings for searching active ingredients. Data were analyzed using Analysis of Variance, treatment means separated through DNMRT and lethal concentrations of the extracts were determined. Among the extracts tested, hexane extract of D. metel and methanol extract of N. tabacum caused highest larvicidal activity with more than 70% mortality on Aedes and Anopheles larvae when 4.0mg/mL was applied after 72 hrs (LC50 2.94±0.1 and LC502.58±0.1 mg/mL respectively). Culex larvae were less susceptible to all concentrations of the extracts. Though, larvicidal activity was observed to be directly proportional to concentrations and larval exposure periods, significant differences (p< 0.05) in the means of larval death were observed. The active extracts were found to contain alkaloids, saponins steroids, flavonoids and glycosides from moderate to high quantity which could be responsible for larvicidal activity. Future formulation studies, toxicity profile and possible mechanism of action may lead to the development of potential insecticidal products.

Endemicity of Dengue with Density Figure and Maya Index in Bengkulu City, Indonesia

BACKGROUND: One of the factors contributing to dengue’s endemicity is the density of the dengue vector, namely, Aedes aegypti as the primary vector and Aedes albopictus as the secondary vector. Bentiring and Kandang Limun villages are high endemic areas of dengue. AIM: This study aimed to determine the relationship between dengue endemicity and density figure (DF) and Maya index (MI) in Bentiring and Kandang Limun villages, Bengkulu city. METHODS: This study used a cross-sectional design. The sampling technique used proportionate stratified sampling. The sampling refers to the guidelines for dengue entomology surveys according to the WHO 1999 criteria. A total of 400 ovitraps were installed, 200 ovitraps inside the house and 200 ovitraps outside the house. RESULTS: The results showed that Bentiring and Kandang Limun villages had a high risk of dengue transmission based on entomological parameters, namely, ovitrap index (OI) 56% and 55% (DF 6), house index (HI) 45% and 44% (DF 6), container index (CI) 23% and 23% (DF 6), and BI 96% and 120% (DF 7 and 8). The areas have a high risk of dengue transmission based on the MI 71% and 76%, respectively. There is a relationship between dengue endemicity and entomological index in Bentiring and Kandang Limun villages, Bengkulu city, with a significance value (p = 0.000) and a powerful correlation (r = 1.000). CONCLUSION: There is a relationship between dengue endemicity and the MI in Bentiring village and Kandang Limun village, Bengkulu city, with a significance value (p = 0.014 and 0.058) and a powerful correlation (r = 0.920 and r = 1.000), respectively. The entomological index and DF are predictors for dengue prevention and control environment to minimize mosquito breeding sites and reduce disease transmission.

Low Malaria Transmission in Rosso, an Irrigated Rice-Growing Area in Mauritania

The construction of dams along the Senegal River resulted in an increase in irrigated land areas and changes in the epidemiology and transmission of water-related diseases. The objective of this study was to update epidemiological data on malaria in Rosso, one of the major Mauritanian cities along the Senegal River. Febrile patients (n = 318) were screened for malaria using a rapid diagnostic test (RDT) for malaria and microscopic examination of blood smears. Diagnosis was later confirmed by polymerase chain reaction (PCR). The mean age of 318 febrile patients was 25.1 (range 1–80 years). Only 7 (2.2%) and 2 (0.6%) had a positive RDT and thick smear, respectively. PCR confirmed the diagnosis in two Plasmodium vivax-infected patients. Most participants (198/318, 62.3%) had no recent travel history outside Rosso. The majority of the febrile patients (90%, 284/311) owned at least one insecticide-treated net (ITN). The frequency of the use of ITNs was not significantly associated with season (rainy vs. dry seasons; p = 0.9) or with the number of ITNs per household (rs = 0.07; n = 285; p = 0.19). Of 285 individuals with ITNs, only two (0.7%) with no travel history were PCR-positive for malaria. Despite the presence of mosquito breeding sites related to rice irrigation, malaria transmission in Rosso remained very low, possibly due to the high coverage and frequent use of bed nets. Regular entomological surveillance for possible changes in the prevalence of Anopheles mosquito species and their behavioural aspects should be implemented.

Towards Integrated Management of Dengue in Mumbai.

With increasing urbanisation, the dengue disease burden is on the rise in India, especially in large cities such as Mumbai. Current dengue surveillance in Mumbai includes municipal corporation carrying out specific activities to reduce mosquito breeding sites and the use of insecticides to suppress the adult mosquito populations. Clinical cases remain either underreported or misreported due to the restriction to government clinics, missing the large private health care sector. There is a need for an integrated approach to manage dengue outbreaks in Mumbai. There are various novel strategies available for use that can be utilised to improve disease detection, mosquito surveillance, and control of mosquito-borne diseases. These novel technologies are discussed in this manuscript. Given the complex ecosystem of mosquito-borne diseases in Mumbai, integrating data obtained from these technologies would support the ongoing mosquito control measures in Mumbai.

ABUNDANCE AND DISTRIBUTION OF ANOPHELES MOSQUITO IN RELATION TO PHYSICOCHEMICAL PROPERTIES IN DELTA STATE, NIGERIA

In this study, the effect of physicochemical parameters as determinants for the abundance and distribution of Anopheles mosquitoes was examined. Physicochemical variables such as pH, temperature, DO, TDS, flow velocity, salinity and electrical conductivity were determined using standard procedures. Three communities in Ukwani LGA, Delta State were mapped out and sampled. Immature stages of Anopheles mosquitoes were collected from potential breeding sites using 350 ml dip ladles and scooping spoon. The physicochemical parameters showed that air, and water temperature, pH, and dissolved oxygen were higher in Umutu compared to the other sampled communities (Obiaruku and Umukwata). Salinity, conductivity, total dissolved solids and flow velocity were higher in Obiaruku and Umukwata compared to Umutu. Various levels of significance (p <0.05) were recorded within sampled months and communities. The density of Anopheles mosquitoes were higher in ponds and puddles (42.1 and 32.6%) in Obiaruku compared to other locations irrespective of the sampled months. Highest density was also recorded in the month of September (42.3%) compared to other sampled months. Temperature, pH, DO, TDS and conductivity were in acceptable limits for mosquito survival. All parameters were positively correlated with the density of Anopheles mosquitoes. Thus, in practical terms for vector control, this study has demonstrated the importance of considering these physicochemical parameters when manipulating mosquito breeding sites for mosquito control programs, discourage their proliferation and decline the malaria burdens

Integrated mosquito management in rice field in China

Rice cultivation is important in China with over 29.33 million hm2 of rice fields, producing 28.9% of rice yields worldwide. Rice fields are mass breeding sites for mosquitoes with approximately 40 mosquito species found breeding amongst them. Anopheles sinensis, Anopheles lesteri, and Culex tritaeniorhynchus are the three main species that are found breeding in rice fields. An. sinensis and An. lesteri are important vectors of malaria in flat areas of China, and Cx. tritaeniorhynchus is a main vector of Japanese B encephalitis. This review provides the principles of mosquito control used to target the species of mosquitoes breeding in rice fields, as well as some main approaches that have been tested and implemented for mosquito control in the past 70 years. The irrigation management of rice fields is included, such as intermittent irrigation, wet irrigation, controlled irrigation, and rotation of rice fields and dry fields. Biocontrol measures and agents, including rice-fish coculture, Azolla, Bacillus thuringiensis israelensis (Bti), and Bacillus sphaericus, for mosquito control are discussed. These control methods benefit the prevention and control of mosquito-borne disease, especially malaria elimination in China.

Mapping Of Mosquito Distribution And Influencing Factors From Salem District, Tamilnadu Using Geographical Information System (Gis)

In India, Mosquito borne diseases constitute a major public health problem in the list of communicable diseases. The most important are malaria, dengue fever, chikungunya fever. Some environmental factors greatly influence the vector prevalence. One of the important components of vector-borne disease control programme is to impart awareness about mosquito bite prevention in the general community. Therefore, the urgent need a technology to give awareness to public about present situation of mosquito-borne disease epidemic prevalence in the country. Geographic information system (GIS) is a powerful tool to analyse the distribution of mosquitoes and their relationship to different environmental factors, and can substantially improve our ability to quantify the impacts of demographic, climatic and ecological changes in vector distribution. The influence factor of vector prevalence was collected from particular departments and direct inspection of field survey. The collected data was interpreted using ArcGIS (version 10.0) for thematic map preparation. Result of the study obtained the environmental factors such as human population, percentage of education greatly influence the mosquito breeding sites. The output is laymen friendly model and reaches the public with more interest. This study also stresses the importance of mosquito control measures.

Monthly biological larviciding associated with a tenfold decrease in larval density in fish farming ponds and reduced community-wide malaria incidence in northwestern Brazil

BackgroundLarvicides are typically applied to fixed and findable mosquito breeding sites, such as fish farming ponds used in commercial aquaculture, to kill immature forms and thereby reduce the size of adult malaria vector populations. However, there is little evidence suggesting that larviciding may suppress community-wide malaria transmission outside Africa. Here, we tested whether the biological larvicide VectoMax FG applied at monthly intervals to fish farming ponds can reduce malaria incidence in Amazonian Brazil.MethodsThis study was carried out in Vila Assis Brasil (VAB; population 1700), a peri-urban malaria hotspot in northwestern Brazil with a baseline annual parasite incidence of 553 malaria cases per 1000 inhabitants. The intervention consisted of monthly treatments with 20 kg/ha of VectoMax FG of all water-filled fish ponds in VAB (n ranging between 167 and 170) with a surface area between 20 and 8000 m2, using knapsack power mistblowers. We used single-group interrupted time-series analysis to compare monthly larval density measurements in fish ponds during a 14-month pre-intervention period (September 2017–October 2018), with measurements made during November 2018–October 2019 and shortly after the 12-month intervention (November 2019). We used interrupted time-series analysis with a comparison group to contrast the malaria incidence trends in VAB and nearby nonintervention localities before and during the intervention.ResultsAverage larval densities decreased tenfold in treated fish farming ponds, from 0.467 (95% confidence interval [CI], 0.444–0.490) anopheline larvae per dip pre-intervention (September 2017–October 2018) to 0.046 (95% CI, 0.041–0.051) larvae per dip during (November 2018–October 2019) and shortly after the intervention (November 2019). Average malaria incidence rates decreased by 0.08 (95% CI, 0.04–0.11) cases per 100 person-months (P < 0.0001) during the intervention in VAB and remained nearly unchanged in comparison localities. We estimate that the intervention averted 24.5 (95% CI, 6.2–42.8) malaria cases in VAB between January and December 2019.ConclusionsRegular larviciding is associated with a dramatic decrease in larval density and a modest but significant decrease in community-wide malaria incidence. Larviciding may provide a valuable complementary vector control strategy in commercial aquaculture settings across the Amazon.Graphical abstract

Risk Factors Analysis of Malaria Transmission at Cross-Boundaries Area in Menoreh Hills, Java, Indonesia.

Background:Risk factors of Malaria transmission at cross-boundaries area is important to be identified. This study aimed to identify the risk factors of Malaria transmission at cross-boundaries area in Menoreh Hills, Java, Indonesia.Methods:The design of the study was an observational study with a case-control design. Data on malaria cases and controls were obtained from the Primary Health Care in Menoreh. All malaria positive patients with clinical and laboratory examinations recorded in health services during 1 Jan 2015–31 Dec 2015. Overall, 138 cases and 138 controls were included. Several variables were collected such as altitude, night out behavior, the use of mosquito nets, nighttime bed, travel history, mosquito bite prevention activities, cattle ownership, distance to mosquito breeding site, etc. Data were obtained by structured questionnaires and observation. Data were analyzed by univariate, bivariate and multivariateResults:The altitude of house >500 m above sea level proved to be influential as a risk factor for Malaria (OR 3.62, 95% CI 1.61–8.16, P=0.002). Several variables were identified as a risk factor of Malaria such as the wall of the house from bamboo/wood, no insecticide and distance of house <100 m from mosquito breeding site.Conclusion:An awareness for the local health sector particularly to provide a recommendation for house construction to protect a community from Malaria transmission.

59Outbreak investigation of dengue fever in union council (UC) Bharakahu, Islamabad, Pakistan, 2019

Abstract Background During third week of September 2019, lady health workers reported twelve suspected cases of dengue fever from UC Bharakahu, Islamabad (population 70,000) to health department. Outbreak investigation conducted with objectives to determine risk factors and recommend control measures. Methods Investigation conducted from 20th September to 04th November 2019. Case was defined as any resident of UC Bharakahu with fever and two or more of following signs/symptoms; headache, retro-orbital pain, arthralgia, myalgia, petechial rash with NS1 (Nonstructural Protein 1) positive during 12th August to 18th November 2019. Age and sex matched healthy controls recruited from same neighborhood. Blood samples from seven suspected cases sent for laboratory confirmation. Results Total 993 houses surveyed and 113 cases identified. Mean age was 34.2 years (range 13-90 years). Most affected age group was 35-44 years (Attack Rate 0.78%), Overall attack rate was 0.15%. Males were predominantly involved n = 70 (62%). Out of total cases, 34 (70%) had stagnant water inside and around houses (OR 2.0, CI 1.06-3.75, p &amp;lt; 0.005), 40 (35%) used repellent lotions (OR 0.55, CI 0.32-0.95, p &amp;lt; 0.05), 34 (30%) used insecticide spray (OR 0.35, CI 0.20-0.61, p &amp;lt; 0.05), 97 (86%) used full protective clothing (OR 0.22, CI 0.07-0.68, p &amp;lt; 0.05). All seven blood samples tested positive for NS-1 Ag. Conclusion Presence of stagnant rain water inside and around houses acted as breeding grounds for aedes aegypti mosquitoes and was most probable cause of outbreak. Following our recommendations, health department initiated mosquito breeding sites control activities through insecticide residual spray and advocacy on use of protective measures against mosquito bites. Key words Outbreak, dengue, stagnant water, Bhara Kahu, Islamabad, 2019

Automatic detection of potential mosquito breeding sites from aerial images acquired by unmanned aerial vehicles

The World Health Organization (WHO) has stated that effective vector control measures are critical to achieving and sustaining reduction of vector-borne infectious disease incidence. Unmanned aerial vehicles (UAVs), popularly known as drones, can be an important technological tool for health surveillance teams to locate and eliminate mosquito breeding sites in areas where vector-borne diseases such as dengue, zika, chikungunya or malaria are endemic, since they allow the acquisition of aerial images with high spatial and temporal resolution. Currently, though, such images are often analyzed through manual processes that are excessively time-consuming when implementing vector control interventions. In this work we propose computational approaches for the automatic identification of objects and scenarios suspected of being potential mosquito breeding sites from aerial images acquired by drones. These approaches were developed using convolutional neural networks (CNN) and Bag of Visual Words combined with the Support Vector Machine classifier (BoVW + SVM), and their performances were evaluated in terms of mean Average Precision - mAP-50. In the detection of objects using a CNN YOLOv3 model the rate of 0.9651 was obtained for the mAP-50. In the detection of scenarios, in which the performances of BoVW+SVM and a CNN YOLOv3 were compared, the respective rates of 0.6453 and 0.9028 were obtained. These findings indicate that the proposed CNN-based approaches can be used to identify potential mosquito breeding sites from images acquired by UAVs, providing substantial improvements in vector control programs aiming the reduction of mosquito-breeding sources in the environment.

Evaluation of different deployment strategies for larviciding to control malaria: a simulation study

BackgroundLarviciding against malaria vectors in Africa has been limited compared to indoor residual spraying and insecticide treated nets but is increasingly being considered by some countries as a complementary strategy. However, despite progress towards improved larvicides and new tools for mapping or treating mosquito-breeding sites, little is known about the optimal deployment strategies for larviciding in different transmission and seasonality settings.MethodsA malaria transmission model, OpenMalaria, was used to simulate varying larviciding strategies and their impact on host-seeking mosquito densities, entomological inoculation rate (EIR) and malaria prevalence. Variations in coverage, duration, frequency, and timing of larviciding were simulated for three transmission intensities and four transmission seasonality profiles. Malaria transmission was assumed to follow rainfall with a lag of one month. Theoretical sub-Saharan African settings with Anopheles gambiae as the dominant vector were chosen to explore impact. Relative reduction compared to no larviciding was predicted for each indicator during the simulated larviciding period.ResultsLarviciding immediately reduced the predicted host-seeking mosquito densities and EIRs to a maximum that approached or exceeded the simulated coverage. Reduction in prevalence was delayed by approximately one month. The relative reduction in prevalence was up to four times higher at low than high transmission. Reducing larviciding frequency (i.e., from every 5 to 10 days) resulted in substantial loss in effectiveness (54, 45 and 53% loss of impact for host-seeking mosquito densities, EIR and prevalence, respectively). In seasonal settings the most effective timing of larviciding was during or at the beginning of the rainy season and least impactful during the dry season, assuming larviciding deployment for four months.ConclusionThe results highlight the critical role of deployment strategies on the impact of larviciding. Overall, larviciding would be more effective in settings with low and seasonal transmission, and at the beginning and during the peak densities of the target species populations. For maximum impact, implementers should consider the practical ranges of coverage, duration, frequency, and timing of larviciding in their respective contexts. More operational data and improved calibration would enable models to become a practical tool to support malaria control programmes in developing larviciding strategies that account for the diversity of contexts.

Short communication: New report of Aedes albopictus in Souk Ahras, Northeast Algeria

Abstract. Hamaidia K, Soltani N. 2021. Short communication: New report of Aedes albopictus in Souk Ahras, Northeast Algeria. Biodiversitas 22: 2901-2906. The present paper reports the occurrence of Aedes albopictus (Skuse), an aggressive Asian tiger mosquito in the city of Souk-Ahras (Northeast of Algeria). A “26 April” estate’ inhabitants (Souk-Ahras province) have reported unusual daytime bites by a striped mosquito. On early September 2020, an intensive field inspection was carried out for potential mosquito breeding sites in the locations around the city. A total of 105 specimens (8 larvae, 24 pupae and 73 adults) of Ae. albopictus were collected in a pile of old tyres in a residential garden. After previous records of this species in Algeria, this is the first evidence of its presence in Souk-Ahras province, and the findings enhance combined public participation with professional validation in surveillance of vector borne-diseases programs with emphasis on the need for sensitising citizens about controlling this important vector.

Development of a chimeric odour blend for attracting gravid malaria vectors

BackgroundOdour-based tools targeting gravid malaria vectors may complement existing intervention strategies. Anopheles arabiensis are attracted to, and stimulated to oviposit by, natural and synthetic odours of wild and domesticated grasses associated with mosquito breeding sites. While such synthetic odour lures may be used for vector control, these may have limited efficacy when placed in direct competition with the natural source. In this study, workflows developed for plant-feeding pests was used to design and evaluate a chimeric odour blend based on shared attractive compounds found in domesticated grass odours.MethodsVariants of a synthetic odour blend, composed of shared bioactive compounds previously identified in domesticated grasses, was evaluated sequentially in a two-choice olfactometer to identify a ratio-optimized attractive blend for malaria vectors. During this process, blends with ratios that were significantly more attractive than the previously identified synthetic rice blend were compared to determine which was most attractive in the two-choice olfactometer. To determine whether all volatile components of the most attractive blend were necessary for maximal attraction, subtractive assays were then conducted, in which individual components were removed for the most attractive blend, to define the final composition of the chimeric blend. Binary logistic regression models were used to determine significance in all two-choice assays. The chimeric blend was then assessed under field conditions in malaria endemic villages in Ethiopia, to assess the effect of dose, trap type, and placement relative to ground level. Field data were analyzed both descriptively and using a Welch-corrected t-test.ResultsA ratio-optimized chimeric blend was identified that significantly attracted gravid An. arabiensis under laboratory conditions. In the field, trap captures of An. arabiensis and Anopheles pharoensis were dependent on the presence of the lure, trap type (CDC, BG Sentinel and Suna traps), placement relevant to ground level, with low release rates generally luring more mosquitoes.ConclusionsThe workflow designed for the development of chimeric lures provides an innovative strategy to target odour-mediated behaviours. The chimeric lure identified here can be used in existing trapping systems, and be customized to increase sustainability, in line with goals of the Global Vector Control Response Group.

Older children are at increased risk of Plasmodium vivax in south-central Ethiopia: a cohort study

BackgroundBetter understanding of the distribution of Plasmodium vivax and its risk factors could be used to prevent and control malaria infection. Therefore, the aim of this study was to characterize the distribution and risk factors of P. vivax, and to compare them with Plasmodium falciparum occurrence in south-central Ethiopia.MethodsA cohort of 34,548 individuals were followed for 121 weeks between 2014 and 2016 as part of larger cluster randomized controlled trial to evaluate the effect of long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) on malaria prevention in Ethiopia. Weekly home visit (active search) and patient self- report to health post (passive search) between the weekly home visits were used to register malaria cases. A blood sample was collected by finger prick and malaria was diagnosed using rapid diagnostic test (RDT). Generalized estimating equation (GEE) Poisson model that accounts for repeated measure of malaria episodes was applied to assess the risk factors of P. vivax episode.ResultsThe overall incidence rate of P. vivax was 7.4 episodes per 1000 person-years of observation. The study showed households closer to the lake Zeway and Bulbula river (potential mosquito breeding sites) were more at risk of P. vivax infection (incidence rate ratio (IRR): 1.33; 95% CI = 1.23–1.45). Furthermore, the age group under 5 years (IRR: 1.40, 95% CI = 1.10–1.79), the age group 5–14 years (IRR: 1.27, 95% CI = 1.03–1.57), households with less educated household head (IRR: 1.63, 95% CI = 1.10–2.44) and house roof made of thatch/leaf (IRR: 1.35, 95% CI = 1.11–1.65) were at higher risk for P. vivax. Similar explanatory variables such as distance from the breeding sites, age group (under 5 years but not 5–14 years old), educational status and type of housing were also found to be the predictors of P. falciparum incidence.ConclusionHouseholds living closer to a mosquito breeding site, age group under 15 years, less educated household heads and thatch/leaf roof housing were the risk factor for P. vivax. The result of this study can be used for tailored interventions for malaria control and prevention by prioritizing those living close to potential mosquito breeding site, enhancing bed net use of children less than 15 years of age, and improving housing.

Analysis of Control Interventions against Malaria in communities with Limited Resources

Abstract The aim of this paper is to analyse the potential impact of multiple current interventions in communities with limited resources in order to obtain optimal control strategies and provide a basis for future predictions of the most effective control measures against the spread of malaria. We developed a population-based model of malaria transmission dynamics to investigate the effectiveness of five different interventions. The model captured both the human and the mosquito compartments. The control interventions considered were: educational campaigns to mobilise people for diagnostic test and treatment and to sleep under bed nets; treatment through mass drug administration; indoor residual spraying(IRS) with insecticide to reduce malaria transmission; insecticide treated net (ITN) to reduce morbidity; and regular destruction of mosquito breeding sites to reduce the number of new mosquito and bites/contact at dusks and dawn. Analysis of the potential impact of the multiple control interventions were carried out and the optimal control strategies that minimized the number of infected human and mosquito and the cost of applying the various control interventions were determined.

Prevalence of Plasmodium falciparum isolates lacking the histidine rich protein 2 gene among symptomatic malaria patients in Kwilu Province of the Democratic Republic of Congo

BackgroundMalaria rapid diagnostic tests have become a primary and critical tool for malaria diagnosis in malaria-endemic countries where Plasmodium falciparum Histidine Rich Protein 2-based rapid diagnostic tests (PfHRP2-based RDTs) are widely used. However, in the last decade, the accuracy of PfHRP2-based RDTs has been challenged by the emergence of P. falciparum strains harbouring deletions of the P. falciparum histidine rich protein 2 (pfhrp2) gene, resulting in false-negative results. In the Democratic Republic of Congo (D.R. Congo), little is known about the prevalence of the pfhrp2 gene deletion among P. falciparum isolates infecting symptomatic patients, especially in low to moderate transmission areas where pfhrp2 deletion parasites are assumed to emerge and spread. Here we determine the local prevalence and factors associated with pfhrp2 gene deletions among symptomatic malaria patients in the Kwilu Province of the D.R. Congo.MethodsWe used secondary data from a prospective health facility-based cross-sectional study conducted in 2018. Blood was collected for microscopy, PfHRP2-RDT, and spotted onto Whatman filter paper for downstream genetic analysis. Genomic DNA was extracted and used to perform PCR assays for the detection and confirmation of pfhrp2 gene deletions. Fischer’s exact and the Kruskal–Wallis tests were applied to look for associations between potential explanatory variables and the pfhrp2 gene deletion with a level of statistical significance set at P < 0.05.ResultsOf the 684 enrolled symptomatic patients, 391 (57.7%) were female. The majority (87.7%) reported the presence of mosquito breeding sites within the household’s compound, and fever was the most reported symptom (81.6%). The overall prevalence of the pfhrp2 gene deletion was 9.2% (95% CI: 6.7%–12.1%). The deletion of the pfhrp2 gene was associated with health zone of origin (P = 0.012) and age (P = 0.019). Among false-negative PfHRP2-RDT results, only 9.9% were due to pfhrp2 gene deletion.ConclusionsP. falciparum isolates with pfhrp2 gene deletions are relatively common among symptomatic patients in Kwilu province. Further investigations are needed to provide enough evidence for policy change. Meanwhile, the use of RDTs targeting PfHRP2 and parasite lactate dehydrogenase (pLDH) antigens could limit the spread of deleted isolates.Graphic