Mosquito Density Research Articles

Quantifying malaria acquired during travel and its role in malaria elimination on Bioko Island

BackgroundMalaria elimination is the goal for Bioko Island, Equatorial Guinea. Intensive interventions implemented since 2004 have reduced prevalence, but progress has stalled in recent years. A challenge for elimination has been malaria infections in residents acquired during travel to mainland Equatorial Guinea. The present article quantifies how off-island contributes to remaining malaria prevalence on Bioko Island, and investigates the potential role of a pre-erythrocytic vaccine in making further progress towards elimination.MethodsMalaria transmission on Bioko Island was simulated using a model calibrated based on data from the Malaria Indicator Surveys (MIS) from 2015 to 2018, including detailed travel histories and malaria positivity by rapid-diagnostic tests (RDTs), as well as geospatial estimates of malaria prevalence. Mosquito population density was adjusted to fit local transmission, conditional on importation rates under current levels of control and within-island mobility. The simulations were then used to evaluate the impact of two pre-erythrocytic vaccine distribution strategies: mass treat and vaccinate, and prophylactic vaccination for off-island travellers. Lastly, a sensitivity analysis was performed through an ensemble of simulations fit to the Bayesian joint posterior probability distribution of the geospatial prevalence estimates.ResultsThe simulations suggest that in Malabo, an urban city containing 80% of the population, there are some pockets of residual transmission, but a large proportion of infections are acquired off-island by travellers to the mainland. Outside of Malabo, prevalence was mainly attributable to local transmission. The uncertainty in the local transmission vs. importation is lowest within Malabo and highest outside. Using a pre-erythrocytic vaccine to protect travellers would have larger benefits than using the vaccine to protect residents of Bioko Island from local transmission. In simulations, mass treatment and vaccination had short-lived benefits, as malaria prevalence returned to current levels as the vaccine’s efficacy waned. Prophylactic vaccination of travellers resulted in longer-lasting reductions in prevalence. These projections were robust to underlying uncertainty in prevalence estimates.ConclusionsThe modelled outcomes suggest that the volume of malaria cases imported from the mainland is a partial driver of continued endemic malaria on Bioko Island, and that continued elimination efforts on must account for human travel activity.

Efficacy Bacillus thuringiensis var. israelensis serotype H-14 (Bti H-14) for control Aedes spp. density in Denpasar, Bali

Background: A liquid bioinsecticide formulation containing Bacillus thuringiensis var. israelensis Serotype H-14 (Bti H-14) was tested in the field in household containers. The aim was to determine the effectiveness of Bti H-14 biolarvicide in controlling the density of Aedes spp. Larvae.Methods: This study was conducted in two phases of testing. First, to test the effective dose with 5 doses, namely (50 ul, 40 ul, 30 ul, 20 ul, and 10 ul) in 2.5 liters of water. Furthermore, the number of deaths was calculated after 24 hours of treatment and control by doing four repetitions. In the second phase, by conducting tests on containers in the household as many as 3171 containers were continuously observed every month, given Bti H-14 for 6 months. Observations were made before and after the application of Bti H-14 on larva density, mosquito density, and dengue cases. Data analysis was performed using paired t-test. Bti H-14 formulation to kill 50% of mosquito larvae (LC50) within 6 hours requires a concentration of 4 µl per liter.Results: Bti H-14 liquid formulation with delta-endotoxin and spores content of 600 ITU per ml or 1.2x109 CFU is effective in reducing larva density in household containers if done regularly.Conclusions: Bti H-14 liquid formulation is proven to be effective and easy to use for the control of Aedes larvae.

Autochthonous dengue outbreak in Italy 2020: clinical, virological and entomological findings.

BackgroundIn August 2020, in the context of COVID-19 pandemics, an autochthonous dengue outbreak was identified for the first time in Italy.MethodsFollowing the reporting of the index case of autochthonous dengue, epidemiological investigation, vector control and substances of human origin safety measures were immediately activated, according to the national arbovirus surveillance plan. Dengue cases were followed-up with weekly visits and laboratory tests until recovery and clearance of viral RNA from blood.ResultsThe primary dengue case was identified in a young woman, who developed fever after returning from Indonesia to northern Italy, on 27 July 2020. She spent the mandatory quarantine for COVID-19 at home with relatives, six of whom developed dengue within two weeks. Epidemiological investigation identified further five autochthonous dengue cases among people who lived or stayed near the residence of the primary case. The last case of the outbreak developed fever on 29 September 2020. Dengue cases had a mild febrile illness, except one with persistent asthenia and myalgia. DENV-1 RNA was detected in blood and/or urine in all autochthonous cases, up to 35 days after fever onset. All cases developed IgM and IgG antibodies which cross-reacted with West Nile virus (WNV) and other flaviviruses. Sequencing of the full viral genome from blood samples showed over 99% nucleotide identity with DENV-1 strains isolated in China in 2014–2015; phylogenetic analysis classified the virus within Genotype I. Entomological site inspection identified a high density of Aedes albopictus mosquitoes, which conceivably sustained local DENV-1 transmission. Aedes koreicus mosquitoes were also collected in the site.ConclusionsAreas in Europe with high density of Aedes mosquitoes should be considered at risk for dengue transmission. The presence of endemic flaviviruses, such as WNV, might pose problems in the laboratory diagnosis.

Distribusi Spasial Habitat Larva, Kepadatan Anopheles sp dan Kasus malaria di Kampung Kiren Distrik Bonggo Kabupaten Sarmi

Geographic Information Systems (GIS) can be used to describe health problems, one of the problem can be described is malaria. Malaria is still a major health problem for people in Papua. Papua Annual Parasite Incidence (API) is the highest in Indonesia (Kemenkes RI, 2017). This study aims to describe the spatial distribution of larval habitat, adult mosquito density, and the distribution of malaria patients in January-April 2019 in Kiren Village, Bonggo District. The results showed that there were 29 positive habitats of Anopheles sp larvae, consisting of puddles (69.0%), sago marsh (3.4%), artificial ponds (13.8%), and gutters (13, 8%), the habitat is spread almost evenly throughout the Kiren Village area. Larvae species caught were: An.punctulatus (17.2%), An.maculatus (31.0%), An.farauti (6.9%), An.telatelatus (3.4%), and An.longirostris (31.0%) and not identified 10.3%. The highest density of adult mosquitoes is 7 mosquito/person/ night, the lowest is 1.5 mosquito/person/night, with an average of 3.6 mosquito/ person/night. Adult mosquito species caught : An.maculatus (37.9%), An.karwari (10.3%), An.punctulatus (31.0%), An.farauti (13.8%), and An.longoristris (6.9%). Malaria patients highest based on age group is in the 20-44 years (39.3%), and by sex in the female group (62.5%). The conclusions of this study are as follows: the highest larval habitat is puddles, the most caught larvae species are An.maculatus and An.longirostris, high mosquito density/ high MBR, adult mosquito species are mostly caught is An.punctulatus, the highest malaria patients based on age group is in the 20-44 years old and based on sex from female group

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.

Development of Machine Learning Models and the Discovery of a New Antiviral Compound against Yellow Fever Virus.

Yellow fever (YF) is an acute viral hemorrhagic disease transmitted by infected mosquitoes. Large epidemics of YF occur when the virus is introduced into heavily populated areas with high mosquito density and low vaccination coverage. The lack of a specific small molecule drug treatment against YF as well as for homologous infections, such as zika and dengue, highlights the importance of these flaviviruses as a public health concern. With the advancement in computer hardware and bioactivity data availability, new tools based on machine learning methods have been introduced into drug discovery, as a means to utilize the growing high throughput screening (HTS) data generated to reduce costs and increase the speed of drug development. The use of predictive machine learning models using previously published data from HTS campaigns or data available in public databases, can enable the selection of compounds with desirable bioactivity and absorption, distribution, metabolism, and excretion profiles. In this study, we have collated cell-based assay data for yellow fever virus from the literature and public databases. The data were used to build predictive models with several machine learning methods that could prioritize compounds for in vitro testing. Five molecules were prioritized and tested in vitro from which we have identified a new pyrazolesulfonamide derivative with EC50 3.2 μM and CC50 24 μM, which represents a new scaffold suitable for hit-to-lead optimization that can expand the available drug discovery candidates for YF.

Optimization of the feeding rate of Anopheles farauti s.s. colony mosquitoes in direct membrane feeding assays

BackgroundDirect membrane feeding assays (DMFA) are an important tool to study parasite transmission to mosquitoes. Mosquito feeding rates in these artificial systems require optimization, as there are a number of factors that potentially influence the feeding rates and there are no standardized methods that apply to all anopheline species.MethodsA range of parameters prior to and during direct membrane feeding (DMF) were evaluated for their impact on Anopheles farauti sensu stricto feeding rates, including the starving conditions and duration of starving prior to feeding, membrane type, DMF exposure time, mosquito age, feeding in the light versus the dark, blood volume, mosquito density and temperature of water bath.ResultsThe average successful DMFA feeding rate for An. farauti s.s. colony mosquitoes increased from 50 to 85% when assay parameters were varied. Overnight starvation and Baudruche membrane yielded the highest feeding rates but rates were also affected by blood volume in the feeder and the mosquito density in the feeding cups. Availability of water during the pre-feed starvation period did not significantly impact feeding rates, nor did the exposure duration to blood in membrane feeders, the age of mosquitoes (3, 5 and 7 days post-emergence), feeding in the light versus the dark, or the temperature (34 °C, 38 °C, 42 °C and 46 °C) of the water bath.ConclusionOptimal feeding conditions in An. farauti s.s. DMFA were to offer 50 female mosquitoes in a cup (with a total surface area of ~ 340 cm2 with 1 mosquito/6.8 cm2) that were starved overnight 350–500 µL of blood (collected in heparin-coated Vacutainer tubes) per feeder in feeders with a surface area ~ 5 cm2 (with a maximum capacity of 1.5 mL of blood) via a Baudruche membrane, for at least 10–20 min.Graphical

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

BackgroundWith the goal for malaria elimination in Thailand set for 2024, increased coverage and utilization of bed net, especially insecticide-treated net (ITN) or long-lasting insecticidal net (LLIN) is a key strategy. This study aims to provide the necessary information about bed net ownership and utilization among the population at risk of malaria living along the Thai-Myanmar border in Tak province.MethodsA cross-sectional study was conducted using a mixed-method approach in 331 households from 5 hamlets in the villages of the Thai-Myanmar border. The research tools included a questionnaire, bed net inspection, and semi-structured interviews. Logistic regression was used to explore the sociodemographic factors associated with bed net utilization. The qualitative analysis employed a thematic analysis approach.ResultsThis survey found that 98.5% of households had at least one bed net per household, and 74.3% had at least one ITN/LLIN. However, only 30.8% of households reached the standard policy set by the Minister of Public Health of one ITN/LLINs per two persons. Most residents used bed net (92.1% used in the previous night and 80.9% used every day). For those using bed nets, however, 61.9% used ITNs or LLINs the night before and 53.1% used them every day. Nonetheless, the usage rates of bed nets (any type) in the previous night among children and pregnant women were high, reaching 95.3% and 90.0%, respectively. Seven explanatory variables showed statistically significant associations with bed net use every day, including: “not staying overnight in the forest or the field”, “sleeping pattern based on gender”, “sufficient numbers of bed nets to cover all sleeping spaces”, “preference for free bed nets”, “age”, “gender”, and “SES score” showed statistically significant association with bed net use every day. The major reasons for the regular use of bed nets in both household and the forest were to prevent mosquito biting. The reasons for not using bednets in the household were discomfort feelings from heat, perception of unnecessity due to low mosquito density, whereas the reason for not using bed nets in the forest was inconvenience.ConclusionDespite that overall coverage and usage of bed nets was high, only one third reached the standard level specified by the policy. Overnight in the forest, the dissatisfaction with the quality of free bed nets, insufficient number of bed nets, sleeping alone, male gender, age more than 10 years, low socioeconomic status, discomfort from heat, perception of no benefits of bed nets due to low mosquito density, and inconvenience were factors influencing bed net use. Maintaining high coverage and utility rate of bed nets should be a priority for the malaria high-risk population.

Filariasis

Introduction: Expatriate workers usually contribute to the origination of some infectious diseases in the countries they reside. The aim of this study was to identify and analyze available information on filariasis imported into Najran, Saudi Arabia, by expatriate workers. Methodology: Serum (n = 497) were acquired from expatriate workers of both genders from different nationalities and various ages and also from randomly chosen parts and at different time periods of Najran. The serum samples were stored in a deep freezer at a temperature of − 65°C until utilized for the serological diagnosis of filariasis by using filariasis immunoglobulin G/immunoglobulin M (IgG/IgM) combo rapid test and human filariasis antibody (IgG4) enzyme-linked immunosorbent assay (ELISA). Results: Based on IgG/IgM rapid test, the prevalence of filariasis IgG was 3.8% (19 out of 497), whereas IgG4 ELISA showed that the prevalence of filariasis was 10.9% (10 out of 92). The highest prevalence of filariasis occurred in Indian workers, in adulthood (30–49 years), and in male workers. There was no significant agreement in results between IgG/IgM rapid test and ELISA. The percentage specificity of IgG/IgM rapid test, relative to filariasis IgG4 ELISA was 80.5%. Conclusions: The possibility of health hazard due to imported filariasis and preeminently the initiation of a novel carrier focal point of the disease are likely to relied upon the abundance of carriers of microfilaria and the density of vector mosquitoes who feed on the carriers. Furthermore, the results of this study underscore the need for screening and therapeutic strategies that guarantee the control and prevention of parasitic infectious diseases.

Kepadatan Nyamuk Mansonia dan Anopheles dengan Prevalensi Penyakit Filariasis di Kecamatan Taniwel Kabupaten Seram Bagian Barat

Filariasis is an infectious disease caused by filarial worms and transmitted by Mansonia and Anopheles mosquitoes. The prevalence of filariasis is influenced by the density of Mansonia and Anopheles mosquitoes. The purpose of this study was to determine the density of Mansonia, Anopheles mosquitoes, and zoonotic animals, and their relationship to the prevalence of filariasis in Taniwel District, West Seram Regency. This type of research is survey research and case control. The population in this study was the density of Mansonia and Anopheles mosquitoes, and cases of filariasis. While the research sample is people who suffer from filariasis, larval density, Mansonia and Anopheles mosquitoes. Data on the density of larvae/mosquitoes of Mansonia and Anopheles were analyzed descriptively, and analysis of the relationship between density of community habits and prevalence of filariasis was carried out by using the chi square test with SPSS version 20.0 program. The results showed that people used mosquito repellent lotion or brought mosquito rackets before doing activities at night. The density of Mansonia mosquitoes in Sohuwe Village is 4.00-5.85; Lumahlatal Village 5.00-6.60; and Maloang Village 4.00-6.20. Meanwhile, the density of Anopheles mosquitoes in Sohuwe Village is 7.00-9.85; Lumahlatal Village 5.89-6.82; and Maloang Village 5.00-6.50. The prevalence rate of filariasis in Sohuwe Village is 0.66; Lumahlatal Village 0.88; and Maloang Village 1.54; and there is a significant relationship between people's habits and the incidence of filariasis.

Analisis Faktor Cuaca dengan Kejadian Demam Berdarah Dengue (DBD) di Kabupaten Wonogiri Tahun 2014-2018

Background:
 Wonogiri Regency is one of the dengue endemic areas in Central Java with a fluctuating number of cases during 2014-2018. The number of dengue cases drastically increased nearly 4 times amounting 52 cases in 2016 to 207 cases in 2017. Weather factors such as rainfall, humidity, temperature, and wind velocity can affect the reproduction and spread of DHF vectors.
 Objectives:
 This study was aimed to analyze the association between weather factors (rainfall, humidity, temperature and wind velocity) with the incidence of dengue fever in Wonogiri Regency in 2014-2018.
 Research Metodes: 
 This research was an analytic observational study using cross sectional approach. The type of data used was secondary data about the weather (rainfall, humidity, temperature and wind velocity) in Wonogiri Regency which was obtained from the Wonogiri Meteorological Station and data on the number of dengue incidents in Wonogiri Regency which were obtained from the Health Office of Central Java Province. The data were used each month for 5 years, from January 2014 to December 2018. Data were analyzed by using univariate and bivariate analysis (Rank Spearman correlation test), because only the humidity variable is normally distributed.
 Results: 
 The highest number of dengue cases during 2014-2018 as many as 30 cases in November 2018 with an average of 6 cases, the highest rainfall was 887 mm with an average 191.05 mm, the highest humidity was 91.55% with an average of 86.77%, the highest temperature was 28.75oC with an average of 27.50oC and the highest wind velocity was 7.86 knots with an average of 0.89 knots. The results of the Spearman Rank correlation statistical test showed that there was a significant association with moderate strength and a positive direction between rainfall and the incidence of DHF (p = 0.001 and r = 0.420), which means that the increasing of rainfall, the more the number of DHF incidents. There was no significant association between humidity and the incidence of dengue fever (p = 0.925 and r = 0.012). There is a significant association with moderate strength and a negative direction between temperature and the incident of DHF (p = 0.001 and r = -0.415), which means that the increasing the temperature, the number of dengue cases decreases. There is no significant association between wind velocity and the incident of dengue (p = 0.577 and r = -0.073).
 Conclusion: 
 Rainfall causes the breeding place of Aedes mosquitoes to increase, as a result it has an effect on the increase of the mosquito population. Temperature affects the number of eggs produced by Aedes mosquitoes, so that the density of adult mosquitoes increases. 
 
 Keywords: DHF; rainfall; humidity; temperature; wind velocity

Assessment Of Mosquito Larvae Density In Eziobodo Community, Owerri-West L.G.A, Imo State

Larval control is of paramount importance in the reduction of malaria vector abundance and subsequent disease transmission reduction. This study is aimed at assessing mosquito larvae density and profile in Eziobodo community, Owerri West L.G.A. Imo State. Standard dipping techniques was used to determine larval density, morphological characteristic was used to determine the larvae genera, aquatic quality condition and habitat preferences were observed at the oviposition sites. A plastic dipper of 50mls was used to collect water samples from ground puddles, plastic containers, earthen pots, gutters, tin cans and old car tires. The result showed the presence of Anopheline larvae 63 (42.0%), and Culicine larvae 88(58.0%). Anopheles larvae were found mostly in surface and shallow water with semi shaded light whereas Culicine larvae were found in equal density in both shallow and deep water preferably with semi shaded and shaded light. Residents used sanitation measures mainly for mosquito control closely followed by Insecticide treated bed nets (ITNs). Some (30%) reported the use of a combination of sanitation, ITNs, insecticide sprays/coils. Understanding larval habitat and its ecology in different environments can give an insight for control of mosquito borne diseases. Community participation to improve their sanitation will help to close ground puddles, clean gutters, removal of old car tires that can serve as breeding sites of mosquitoes.

Analisis Faktor Cuaca dengan Kejadian Demam Berdarah Dengue (DBD) di Kabupaten Wonogiri Tahun 2014-2018

Background:
 Wonogiri Regency is one of the dengue endemic areas in Central Java with a fluctuating number of cases during 2014-2018. The number of dengue cases drastically increased nearly 4 times amounting 52 cases in 2016 to 207 cases in 2017. Weather factors such as rainfall, humidity, temperature, and wind velocity can affect the reproduction and spread of DHF vectors.
 Objectives:
 This study was aimed to analyze the association between weather factors (rainfall, humidity, temperature and wind velocity) with the incidence of dengue fever in Wonogiri Regency in 2014-2018.
 Research Metodes: 
 This research was an analytic observational study using cross sectional approach. The type of data used was secondary data about the weather (rainfall, humidity, temperature and wind velocity) in Wonogiri Regency which was obtained from the Wonogiri Meteorological Station and data on the number of dengue incidents in Wonogiri Regency which were obtained from the Health Office of Central Java Province. The data were used each month for 5 years, from January 2014 to December 2018. Data were analyzed by using univariate and bivariate analysis (Rank Spearman correlation test), because only the humidity variable is normally distributed.
 Results: 
 The highest number of dengue cases during 2014-2018 as many as 30 cases in November 2018 with an average of 6 cases, the highest rainfall was 887 mm with an average 191.05 mm, the highest humidity was 91.55% with an average of 86.77%, the highest temperature was 28.75oC with an average of 27.50oC and the highest wind velocity was 7.86 knots with an average of 0.89 knots. The results of the Spearman Rank correlation statistical test showed that there was a significant association with moderate strength and a positive direction between rainfall and the incidence of DHF (p = 0.001 and r = 0.420), which means that the increasing of rainfall, the more the number of DHF incidents. There was no significant association between humidity and the incidence of dengue fever (p = 0.925 and r = 0.012). There is a significant association with moderate strength and a negative direction between temperature and the incident of DHF (p = 0.001 and r = -0.415), which means that the increasing the temperature, the number of dengue cases decreases. There is no significant association between wind velocity and the incident of dengue (p = 0.577 and r = -0.073).
 Conclusion: 
 Rainfall causes the breeding place of Aedes mosquitoes to increase, as a result it has an effect on the increase of the mosquito population. Temperature affects the number of eggs produced by Aedes mosquitoes, so that the density of adult mosquitoes increases.

Detection of Vector Mosquito of Filariasis in the Endemic Areas of Bangladesh

Background: Lymphatic Filariasis (LF), a mosquito born tropical parasitic disease, caused by Wuchereria bancrofti is not only a health but also a socio-economic problem in Bangladesh. Culex quinquefasciatus is the confirmed filarial vector in Bangladesh, so by controlling of this vector population, we can prevent this disease. To control this vector and decrease incidence of filariasis, we need to know studied mosquito’s sample in endemic areas.
 Aim and objectives: Aim of this study was to see mosquito population in search of vector species in the endemic zones of malaria and filarial. Then we confirmed presence of vector species at molecular level by species specific DNA fingerprinting.
 Methods: This cross-sectional entomological study was carried out in Hobiganj (Shatchori tea garden) and Moulvibazar district (Patrokhola and Madonmohonpur tea gardens). Mosquito was collected by paper cup with net, aspirator and torch light and vector mosquitoes were identified with stereoscopic microscope. After identification of the mosquitoes, these were stored in laboratory for analysis of the density of the vector mosquitoes in the endemic areas. Then the vector mosquitoes were identified through molecular method named Polymerase Chain Reaction (PCR).
 Result: 1427 female mosquitoes belonging to 28 species under 5 genera were collected from three tea gardens. Culex quinquefasciatus which is the confirmed filarial vector in Bangladesh was found high in number (20.74%) out of the total collected mosquitoes. Other mosquito’s species were found in various ratios. Then Culex quinquefasciatus vector was identified by PCR.
 Conclusion: As vector mosquitoes of LF are available in these tea gardens, the study concludes that these areas are highly LF endemic areas of Bangladesh. Through molecular method, the vector of LF can be identified certainly. As we identify the vector mosquito, thus we can prevent this LF disease at very early stage. So, these findings will be very beneficial and cost effective for a developing country like Bangladesh.

Keep your natural enemies close – native predators can maintain low mosquito densities in temporary ponds in a malaria expansion area in Northern Tanzania

Mosquitoes and the diseases they transmit are a global public health threat that affects most human populations. Mosquito abundances are strongly linked to the number of suitable larval habitats available. However, it is still not well understood how different land uses impact larval habitat quality in different parts of the world. We investigated links between land use practices and abundance of mosquito larvae in temporary ponds located in different land uses in a malaria expansion zone in Tanzania. Temporary ponds are often cited as important sources of mosquitoes but are also of substantial conservation concern being home to a unique fauna and flora. Often, they also have high socio-economic importance. Overall, encountered mosquito larval abundances were very low, both for the collected Anopheles gambiae s.l. and Culex quinquefasciatus. Although temporary ponds are important mosquito larval habitats in other parts of Africa, currently they are unlikely to be an important factor affecting the prevalence of mosquito borne diseases in the Manyara study region. Larval abundances in temporary ponds were higher in agricultural areas where more eutrophic conditions were found and minimal in residential areas. Overall, even though temporary ponds are often modified as rice paddies in the rainy season, they were in a good ecological condition and hosted a diverse assemblage of aquatic predators that likely prevented larval mosquitoes from reaching high densities. Maintaining this good condition by preventing pesticide and nutrient input as much as possible, can be important to prevent pond degradation that is likely to make these habitats more suitable for mosquitoes in the future.

Field efficacy of ethnomedicinal plant smoke repellency against Anopheles arabiensis and Aedes aegypti

The repellency effect of smoke from burning Azadirachta indica, Eucalyptus camaldulensis and Ocimum forskolin plants to reduce human-mosquito biting activity. Ground mixed powders of the plant leaves produced smoke by direct burning and thermal expulsion on the traditional stoves in experimental huts against An. arabiensis and Ae. aegypti. A four-by-four Latin-square design was used to assign treatment and control experimental huts over different nights. In the treatment huts, the percent repellency of the smoke produced by burning powdered plant mixtures of the plants were determined by reduction mosquito density. There was a reduction on An. arabiensis (93.75%, P < 0.001) and Ae. aegypti (92%, P < 0.001) respectively, for huts with burning powder versus no treatment. Overall, plant mixed powders tested by both methods of application offered significant protection (>90%) against both mosquito species tested and has the potential to be used as an alternative mosquito control method.

A planetary health model for reducing exposure to faecal contamination in urban informal settlements: Baseline findings from Makassar, Indonesia

BackgroundThe intense interactions between people, animals and environmental systems in urban informal settlements compromise human and environmental health. Inadequate water and sanitation services, compounded by exposure to flooding and climate change risks, expose inhabitants to environmental contamination causing poor health and wellbeing and degrading ecosystems. However, the exact nature and full scope of risks and exposure pathways between human health and the environment in informal settlements are uncertain. Existing models are limited to microbiological linkages related to faecal-oral exposures at the individual level, and do not account for a broader range of human-environmental variables and interactions that affect population health and wellbeing. MethodsWe undertook a 12-month health and environmental assessment in 12 flood-prone informal settlements in Makassar, Indonesia. We obtained caregiver-reported health data, anthropometric measurements, stool and blood samples from children < 5 years, and health and wellbeing data for children 5–14 years and adult respondents. We collected environmental data including temperature, mosquito and rat species abundance, and water and sediment samples. Demographic, built environment and household asset data were also collected. We combined our data with existing literature to generate a novel planetary health model of health and environment in informal settlements. ResultsAcross the 12 settlements, 593 households and 2764 participants were enrolled. Two-thirds (64·1%) of all houses (26·3–82·7% per settlement) had formal land tenure documentation. Cough, fever and diarrhoea in the week prior to the survey were reported among an average of 34.3%, 26.9% and 9.7% of children aged < 5 years, respectively; although proportions varied over time, prevalence among these youngest children was consistently higher than among children 5–14 years or adult respondents. Among children < 5 years, 44·3% experienced stunting, 41·1% underweight, 12.4% wasting, and 26.5% were anaemic. There was self- or carer-reported poor mental health among 16.6% of children aged 5–14 years and 13.9% of adult respondents. Rates of potential risky exposures from swimming in waterways, eating uncooked produce, and eating soil or dirt were high, as were exposures to flooding and livestock. Just over one third of households (35.3%) had access to municipal water, and contamination of well water with E. coli and nitrogen species was common. Most (79·5%) houses had an in-house toilet, but no houses were connected to a piped sewer network or safe, properly constructed septic tank. Median monthly settlement outdoor temperatures ranged from 26·2 °C to 29.3 °C, and were on average, 1·1 °C warmer inside houses than outside. Mosquito density varied over time, with Culex quinquefasciatus accounting for 94·7% of species. Framed by a planetary health lens, our model includes four thematic domains: (1) the physical/built environment; (2) the ecological environment; (3) human health; and (4) socio-economic wellbeing, and is structured at individual, household, settlement, and city/beyond spatial scales. ConclusionsOur planetary health model includes key risk factors and faecal-oral exposure pathways but extends beyond conventional microbiological faecal-oral enteropathogen exposure pathways to comprehensively account for a wider range of variables affecting health in urban informal settlements. It includes broader ecological interconnections and planetary health-related variables at the household, settlement and city levels. It proposes a composite framework of markers to assess water and sanitation challenges and flood risks in urban informal settlements for optimal design and monitoring of interventions.

Assessment of Mosquito Collection Methods for Dengue Surveillance.

Several methods exist to collect and assess the abundance of dengue vector mosquitoes, i.e., morning adult collection, pupal collection, ovitraps, human landing, and larval collection. Several of these methods are officially implemented to monitor mosquito density and make decisions on treatments for dengue control. This monitoring is also constrained by the need to conduct this assessment on a “one point/one day” process, meaning that once the threshold of 100 households is reached, the assessment is made, and the collectors teams move to another place, thus preventing the use of long-term sampling methods. This diversity of methods might be a source of variability and lack of statistical significance. There is also a lack of published data regarding the efficacy of these methods. Furthermore, the Stegomyia indices are shown to be not reliable for assessing the risk of dengue outbreaks. A mosquito survey was, thus, conducted in 39 locations corresponding to 15 dengue endemic provinces in Indonesia by using the different adult and larval collection methods recommended nationwide. A total of 44,675 mosquitoes were collected. The single larva method was the most efficient. Out of a total of 89 dengue-positive pools, the most frequently encountered virus was DENV2, which made up half of the positive samples, followed by DENV3 and DENV1, respectively. Factor analysis of mixed data showed that no correlation could be found between any methods and the presence of dengue virus in mosquitoes. Moreover, no correlation could be found between any methods and the incidence of dengue. There was no consistency in the efficacy of a given method from one site to another. There was no correlation between any of the parameters considered, i.e., method, incidence of dengue, location, and the presence of dengue virus in mosquitoes.

Evaluation of the effect of alcoholic extract of some plants on Culicinae mosquito larvae and survey of mosquito species and their natural enemies

The study was conducted at the University of Baghdad (Aljadiria) by taking samples from three sites (water environments) per week, which are the stagnant water environment (Site A), the water table (Site B) and the water basin (Site C) for the purpose of studying the population density of mosquitoes and their accompanying predators. The results showed that the population density of mosquito larvae was the highest in the stagnant water environment (Site A), followed by the water table (Site B), and then the water basin (Site C). As for predators, the results indicated that small water bugs were more present in site A and in large numbers, followed by small tremors, then Gambusia fish, while large tremors and large water bugs were relatively few. It was found that using clove extract (Syzygium aromaticum) reduced mosquito larvae by 100%, at highest concentrations 10 and15% , the mortality was 100% after 2 hours. Plus, it was found that apple of sodom extract (Calotrpis procera) affected the second and fourth instars less than cloves extract. The lantana extract (Lantana camara) was the least effective extract against mosquito larvae.

Effect of cage size on Aedes albopictus wing length, survival and egg production

BackgroundAedes albopictus is currently the most widespread invasive mosquito species in the world. It has paramount medical importance since females are efficient vectors of important viruses affecting humans. The development of alternative control strategies to complement control measures has become an imperative and involves the Sterile Insect Technique (SIT). Research to improve the productivity of mass-rearing, as well as the quality of mass-reared males is of essential importance for the success of SIT. MethodsThis study compared the influence of three differently sized cages for Ae. albopictus mass-rearing on wing length, adult survival and egg production during 20 generations of colonization. Plexiglas cages of 40x40x40 cm (C1), 100 × 20 × 100 cm (C2) and 100 × 65 × 100 cm (C3) were loaded with equal adult density, and sex ratio of 1:1. An open source image processing and analysis programme (ImageJ) was used for the wing measurement and egg counting. ResultsIn all tested cages, we identified two periods separated by the generation showing the minimum value of each considered parameter (wing length, adult survival and egg production). The wing length and adult survival passed through the phases of initial decrease to about intermediate colonization time, and increased afterwards. Fecundity was steady during the first period and increased in the second one. Cage C1 demonstrated not only the best values for all parameters but also the smallest decrease in the initial phase. Recovering of the caged mosquitoes in the second half of the study was higher in cages C1 and C2, than in C3. ConclusionsC1 provided the least negative selection pressure on wing length, adult survival and egg production for reared Ae. albopictus. Anyhow, since maximising mosquito density by exploiting the minimum space is a priority in mosquito mass-rearing, C2 might be a better choice for better fitting the space of mass-rearing rooms.