Simple techniques for a complex problem: Sampling malaria vectors in Africa.

Disease surveillance, including entomological surveillance, serves as the basis for all vector control program activities. How to do this in the most ecologically sensible way, so that the most suitable, naturalistic method, of control for that population can be identified, should be a priority. Here we describe a set of techniques, whose only energy requirement is a torch (flashlight), that can be used to collect both endo and exophagic and endo and exophilic malaria vectors. The data obtained over a number of years from an individual sentinel house in a village in Mozambique and from a village in Cambodia using these kinds of collection techniques, is presented.

A protocol for evaluating the entomological impact of larval source reduction on mosquito vectors at hotel compounds in Zanzibar.

There is an increasing awareness of the association between tourism activity and risks of emerging mosquito-borne diseases (MBDs) worldwide. In previous studies we showed that hotels in Zanzibar may play an important role in maintaining residual foci of mosquito vectors populations of public health concern. These findings indicated larval sources removal (LSR) interventions may have a significant negative impact on vector communities. However, a thorough analysis of the response vector species to potential LSM strategies must be evaluated prior to implementation of a large-scale area-wide control campaign. Here we propose a protocol for evaluation of the impact of LSR against mosquito vectors at hotel settings in Zanzibar. This protocol is set to determine the efficacy of LSR in a randomized control partial cross-over experimental design with four hotel compounds representing the unit of randomization for allocation of interventions. However, the protocol can be applied to evaluate the impact of LRS in more than four sites. Proposed interventions are active removal of disposed containers, and installation of water dispenser to replace single use discarded plastic water bottles, which were identified as the most important source of mosquitoes studied hotels. The ideal time for allocating intervention to the intervention arms the dry season, when the mosquito abundance is predictably lower. The possible impact of interventions on mosquito occurrence and abundance risks is then evaluated throughout subsequent rainy and dry seasons. If an appreciable reduction in mosquito abundance and occurrence risks is observed during the trial period, intervention could be extended to the control arm to determine whether any potential reduction of mosquito density is reproducible. A rigorous evaluation of the proposed LRS interventions will inspire large scale trials and provide support for evidence-based mosquito management at hotel facilities in Zanzibar and similar settings.

Characterisation of human exposure to nocturnal biting by malaria and arbovirus vectors in a rural community in Chókwè district, southern Mozambique.

Background: Understanding the magnitude of human exposure to mosquito biting is fundamental to reduce pathogen transmission. Here we report on a study quantifying the levels of mosquitoes attacking humans throughout the night in a rural area of Southern Mozambique. Methods: Surveys were carried out in Massavasse village, southern Mozambique. The abundance and composition of host-seeking mosquito communities at night were assessed by human-landing catches (HLC) at one-hour intervals. Periods when people were located predominantly outdoors or indoors were used to estimate the amount of residents' exposure to mosquito bites in either location, to explore the potential impact a bed net could have had in reducing biting by each vector species. Results: A total of 69,758 host-seeking female mosquitoes comprising 23 species in four genera were collected. The exposure to biting by virtually all vector species was consistently high outdoors, typically at early evening and morning, with exception of An. gambiae s.l which was likely of biting a person with nearly same intensity indoors and outdoors throughout the night. Bed nets use could have reduced biting by An. gambiae s.l (dominated by An. arabiensis), Ma. africana, Ma. uniformis, Cx. pipiens, Cx. antennatus, and Cx. poicilipes by 53%, 47%, 46%, 38%, 31%, and 28% respectively, compared to non-users. Conversely, a bed net user would have had little protection against An. pharoensis, An. ziemanni, An. tenebrosus, and Cx. tritaeniorhynchus biting exposures. Conclusions: This study showed that Massavasse residents were exposed to high levels of outdoor biting by malaria and arbovirus vectors that abound in the village. The findings help to identify entomological drivers of persistent malaria transmission in Mozambique and identify a wide range of arbovirus vectors nocturnally active in rural areas, many with outbreak potential. The study highlights the need for a surveillance system for monitoring arboviral diseases vectors in Mozambique.

Time series analysis of survival and oviposition cycle duration of Anopheles funestus (Giles) in Mozambique.

Background: Survival and gonotrophic cycle duration are important determinants of the vectorial capacity of malaria vectors but there are a limited number of approaches to estimate these quantities from field data. Time-series of observations of mosquitoes at different stages in the life-cycle are under-used. Methods: Anopheles funestus mosquitoes were caught using various methods over a 7.6-year period in Furvela, Mozambique. Survival and oviposition cycle duration were estimated using (i) an existing time-series approach for analysing dissections of mosquitoes caught in light-traps, extended to allow for variability in the duration of the cycle; (ii) an established approach for estimating cycle duration from resting collection data; (iii) a novel time-series approach fitted to numbers and categories of mosquitoes caught in exit-traps. Results: Data were available from 7,396, 6,041 and 1,527 trap-nights for exit-traps, light-traps and resting collections respectively. Estimates of cycle duration varied considerably between the different methods. The estimated proportion of female mosquitoes surviving each day of 0.740 (95% credible interval [0.650-0.815]) derived from light-trap data was much lower than the estimated daily survival of male mosquitoes from the model fitted to exit-trap data (0.881, 95% credible interval [0.747-0.987]). There was no tendency for the oviposition cycle to become shorter at higher temperature while the odds of survival of females through the cycle was estimated to be multiplied by 1.021 for every degree of mean weekly temperature increase (95% credible interval [0.991-1.051]). There was negligible temperature dependence and little inter-annual variation in male survival. Discussion: The time-series approach fitted to the exit-traps suggests that male An. funestus have higher survival than do females, and that male survival was temperature independent and unaffected by the introduction of long-lasting insecticidal nets (LLINs). The patterns of temperature dependence in females are at variance with results of laboratory studies. Time series approaches have the advantage for estimating survival that they do not depend on representative sampling of mosquitoes over the whole year. However, the estimates of oviposition cycle duration were associated with considerable uncertainty, which appears to be due to variability between insects in the duration of the resting period, and the estimates based on exit-trap data are sensitive to assumptions about relative trapping efficiencies.

The Shockwè trap: a human-baited exposure-free device for surveillance and behaviour studies of anthropophilic vectors.

Background: The human biting rate (MBR) and entomological inoculation rate (EIR) are common parameters routinely used to measure the risk of malaria transmission. Both parameters can be estimated using human landing catches (HLC). Although it is considered the gold-standard, HLC puts collectors at higher risk of infection with mosquito-transmitted pathogens. Methods: A novel exposure-free host-seeking mosquito electrocution trap, the Shockwè trap (SHK), was developed and its efficiency for monitoring mosquito community composition and abundance was compared with human landing catches (HLC) as the gold-standard. Field experiments were performed in Massavasse village, southern Mozambique. Simultaneous indoor and outdoor collections of nocturnal host-seeking mosquitoes were carried out using the SHK and HLC methods. The relative sampling efficiency of SHK was estimated as the ratio of the numbers of mosquitoes caught in SHK compared HLC. Proportionality and density-dependence between SHK and HLC catches were estimated by mean of Bayesian regression approaches. Results: A total of 69,758 and 27,359 host-seeking mosquitoes comprising nineteen species and four genera, were collected by HLC and SHK respectively. In general, SHK and HLC sampled similar numbers of mosquito species, with the exceptions of the least common species Aedes sudanensis, Ae. subargenteus, and Coquillettidia versicolor that were caught only by HLC. The relative sampling efficiency and proportionality between SHK and matched HLC catches varied greatly between species and collection site. However, all mosquitoes collected by SHK were unfed, confirming the Shockwè trap design's performance and reliability as a successful mosquito exposure free sampling approach. Conclusions: Results demonstrate that SHK is a safe and reliable human-exposure free device for monitoring the occurrence of a wide range of mosquito, including major malaria and arboviruses vector species. However, improvements are needed to increase its sampling efficiency for less abundant mosquito species.

High DDT resistance without apparent association to kdr and Glutathione-S-transferase (GST) gene mutations in Aedes aegypti population at hotel compounds in Zanzibar.

Global efforts to control Aedes mosquito-transmitted pathogens still rely heavily on insecticides. However, available information on vector resistance is mainly restricted to mosquito populations located in residential and public areas, whereas commercial settings, such as hotels are overlooked. This may obscure the real magnitude of the insecticide resistance problem and lead to ineffective vector control and resistance management. We investigated the profile of insecticide susceptibility of Aedes aegypti mosquitoes occurring at selected hotel compounds on Zanzibar Island. At least 100 adults Ae. aegypti females from larvae collected at four hotel compounds were exposed to papers impregnated with discriminant concentrations of DDT (4%), permethrin (0.75%), 0.05 deltamethrin (0.05%), propoxur (0.1%) and bendiocarb (0.1%) to determine their susceptibility profile. Allele-specific qPCR and sequencing analysis were applied to determine the possible association between observed resistance and presence of single nucleotide polymorphisms (SNPs) in the voltage-gated sodium channel gene (VGSC) linked to DDT/pyrethroid cross-resistance. Additionally, we explored the possible involvement of Glutathione-S-Transferase gene (GSTe2) mutations for the observed resistance profile. In vivo resistance bioassay indicated that Ae. aegypti at studied sites were highly resistant to DDT, mortality rate ranged from 26.3% to 55.3% and, moderately resistant to deltamethrin with a mortality rate between 79% to and 100%. However, genotyping of kdr mutations affecting the voltage-gated sodium channel only showed a low frequency of the V1016G mutation (n = 5; 0.97%). Moreover, for GSTe2, seven non-synonymous SNPs were detected (L111S, C115F, P117S, E132A, I150V, E178A and A198E) across two distinct haplotypes, but none of these were significantly associated with the observed resistance to DDT. Our findings suggest that cross-resistance to DDT/deltamethrin at hotel compounds in Zanzibar is not primarily mediated by mutations in VGSC. Moreover, the role of identified GSTe2 mutations in the resistance against DDT remains inconclusive. We encourage further studies to investigate the role of other potential insecticide resistance markers.

Risk factors for occurrence and abundance of Aedes aegypti and Aedes bromeliae at hotel compounds in Zanzibar.

BACKGROUND: A field survey was performed to investigate local environmental factors promoting occurrence and abundance of Aedes aegypti and Ae. bromeliae mosquitoes at hotel compounds in the south-east coastal region of Zanzibar Island. METHODS: The potential risk factors were determined using generalized linear mixed models. Aedes (Stegomyia) spp. indices such as container index (CI) and pupae per container (PPC) index were also estimated. RESULTS: Aedes aegypti and Ae. bromeliae were the most abundant vector species, accounting for 70.8% of all Aedes mosquitoes collected. The highest CI was observed for plastic containers irrespective of the season, whereas the highest PPC was observed for coconut shells and aluminium containers in the rainy and dry seasons, respectively. The risk of Aedes mosquito occurrence and abundance were significantly associated with presence of plastic containers, coconut shells, used tyres and steel containers. These were discarded in shaded places, in the open and gardens, or found in plant nurseries. CONCLUSION: This study shows that Aedes species of global health significance occur at hotel compounds on this part of Zanzibar Island. The occurrence and abundance are sustained by the presence of abundant and poorly managed solid wastes and containers used for gardening tasks. This highlights an urgent need for the adoption of area-wide environmentally sustainable Aedes mosquito management interventions that also integrate solid waste management and ornamental plant production practices for reducing the risk of arboviral disease epidemics.

Knockdown times in a simple assay determination of insecticide resistance in malaria vectors.

BACKGROUND: Determining the insecticide resistance status of malaria vectors, particularly to insecticides used on mosquito nets, is important but is limited to a relatively small number of locations. We describe a simple assay that enables this information to be obtained over a much wider area. METHODS: The time to knockdown of mosquitoes in an insecticide-treated netting-covered metal frame cage were recorded. The shape of the curve of the proportion of knocked down mosquitoes provides information on resistance status. RESULTS: Resistant Anopheles funestus took significantly longer for knockdown than did susceptible Anopheles arabiensis. CONCLUSIONS: This simple technique will enable a wide range of locations to be sampled, enhancing our understanding of the spread of resistance to pyrethroids.

Utilization of a local 'Malaria Post' indicates that carers from a village in Mozambique respond appropriately to malaria attacks

As malaria elimination becomes a possibility the focus of interventions changes from vector control to disease control. It is important that treatment occurs early during an infection in order for it to be efficacious, especially at the population level. The time between the onset of symptoms and treatment seeking is, therefore, crucial. Following a census and an oral autopsy survey of the inhabitants of Furvela, a village in southern Mozambique, a malaria post (MP) where malaria was diagnosed and treated was established in 2001. The time between the onset of symptoms and attendance at the MP was determined and compared to the severity of disease. A cross-sectional survey was also conducted, in 2007, to determine prevalence amongst 235 children aged between 6 months and 15 years of age. Malaria was hyperendemic in the village and was responsible for most deaths reported from the two years prior to the start of the project. In the prevalence survey 74% of two-to-four-year-old children had malaria parasites. The likelihood of being parasite positive was significantly higher in children living in houses with roofs made of traditional materials compared to those living in houses with tin roofs. At the start of the project only 12% of residents owned or used a mosquito net, most of which were not treated with insecticide. However, even before any formal intervention, malaria declined in the village between 2001 and 2007, but there was a rebound in later years. Nevertheless, the relative proportion of patients who had to be referred to the hospital declined significantly in the latter years of the project, and the incidence of both Plasmodium ovale and P. malariae also decreased significantly. Overall 16698 patients, the majority of which were under one year of age, attended the MP between 2001 and 2010. The proportion of patients with a positive slide for P. falciparum remained relatively constant throughout the study (mean 0.66 std. dev. 0.3) Most of the patients came from the village of Furvela, or its environs, but some came from the nearby town, ostensibly because of the good treatment they received. Infection rates increased up to the first three years of life to a peak incidence of 92% at 31 months. Children with fever had higher parasite densities than those without fever. Mothers generally bought their children to the MP on the second day of symptoms but on the first day if they had fever. Older patients, with lower density infections, delayed in coming for treatment. These patients may harbour sub-microscopic gametocytes which would help maintain transmission in the village. Mothers acted appropriately in their treatment seeking behaviour. The establishment of village-based MPs are an effective way of providing adequate diagnosis and treatment in villages such as Furvela.

Novel sampling methods for monitoring Anopheles arabiensis from Eritrea.

BACKGROUND: Studies comparing novel collection methods for host seeking and resting mosquitoes A. arabiensis were undertaken in a village in Eritrea. Techniques included an odor baited trap, a novel tent-trap, human landing collection and three methods of resting collection. A technique for the collection of mosquitoes exiting vegetation is also described. Pre-gravid rates were determined by dissection of host seeking insects and post-prandial egg development among insects collected resting. RESULTS: Overall 5,382 host-seeking, 2,296 resting and 357 A. arabiensis exiting vegetation were collected. The Furvela tent-trap was the most efficient, risk-free method for the collection of outdoor host-seeking insects, whilst the Suna trap was the least effective method. Mechanical aspirators (the CDC backpack or the Prokopack aspirator) were superior to manual aspiration in a dark shelter but there was no advantage over manual aspiration in a well-lit one. An estimated two-thirds of newly-emerged mosquitoes went through a pre-gravid phase, feeding twice before producing eggs. Mosquitoes completed gonotrophic development in a dark shelter but left a well-lit shelter soon after feeding. One blood-fed female marked in the village was recaptured 2 days after release exiting vegetation close to the oviposition site and another, shortly after oviposition, attempting to feed on a human host 3 days after release. Exit rates of males from vegetation peaked 3 min after the initial male had left. Unfed and gravid females exited approximately 6 min after the first males. CONCLUSIONS: Furvela tent-traps are suitable for the collection of outdoor biting A. arabiensis in Eritrea whilst the Prokopack sampler is the method of choice for the collection of resting insects. Constructing well-lit, rather than dark, animal shelters, may encourage otherwise endophilic mosquitoes to leave and so reduce their survival and hence their vectorial capacity.

Utilization of a local 'Malaria Post' indicates that carers from a village in Mozambique respond appropriately to malaria attacks.

As malaria elimination becomes a possibility the focus of interventions changes from vector control to disease control. It is important that treatment occurs early during an infection in order for it to be efficacious, especially at the population level. The time between the onset of symptoms and treatment seeking is, therefore, crucial. Following a census and an oral autopsy survey of the inhabitants of Furvela, a village in southern Mozambique, a malaria post (MP) where malaria was diagnosed and treated was established in 2001. The time between the onset of symptoms and attendance at the MP was determined and compared to the severity of disease. A cross-sectional survey was also conducted, in 2007, to determine prevalence amongst 235 children aged between 6 months and 15 years of age. Malaria was hyperendemic in the village and was responsible for most deaths reported from the two years prior to the start of the project. In the prevalence survey 74% of two-to-four-year-old children had malaria parasites. The likelihood of being parasite positive was significantly higher in children living in houses with roofs made of traditional materials compared to those living in houses with tin roofs. At the start of the project only 12% of residents owned or used a mosquito net, most of which were not treated with insecticide. However, even before any formal intervention, malaria declined in the village between 2001 and 2007, but there was a rebound in later years. Nevertheless, the relative proportion of patients who had to be referred to the hospital declined significantly in the latter years of the project, and the incidence of both Plasmodium ovale and P. malariae also decreased significantly. Overall 16698 patients, the majority of which were under one year of age, attended the MP between 2001 and 2010. The proportion of patients with a positive slide for P. falciparum remained relatively constant throughout the study (mean 0.66 std. dev. 0.3) Most of the patients came from the village of Furvela, or its environs, but some came from the nearby town, ostensibly because of the good treatment they received. Infection rates increased up to the first three years of life to a peak incidence of 92% at 31 months. Children with fever had higher parasite densities than those without fever. Mothers generally bought their children to the MP on the second day of symptoms but on the first day if they had fever. Older patients, with lower density infections, delayed in coming for treatment. These patients may harbour sub-microscopic gametocytes which would help maintain transmission in the village. Mothers acted appropriately in their treatment seeking behaviour. The establishment of village-based MPs are an effective way of providing adequate diagnosis and treatment in villages such as Furvela.

Epidemic risk of arboviral diseases: Determining the habitats, spatial-temporal distribution, and abundance of immature Aedes aegypti in the Urban and Rural areas of Zanzibar, Tanzania.

BACKGROUND: In Zanzibar, little is known about the arboviral disease vector Aedes aegypti in terms of abundance, spatio-temporal distribution of its larval habitats or factors associated with its proliferation. Effective control of the vector requires knowledge on ecology and habitat characteristics and is currently the only available option for reducing the risk of arboviral epidemics in the island nation of Zanzibar. METHODOLOGY: We conducted entomological surveys in households and surrounding compounds from February to May 2018 in the urban (Mwembemakumbi and Chumbuni) and rural (Chuini and Kama) Shehias (lowest government administrative unit) situated in the Urban-West region of Unguja island, Zanzibar. Larvae and pupae were collected, transported to the insectary, reared to adult, and identified to species level. Characteristics and types of water containers were also recorded on site. Generalized linear mixed models with binomial and negative binomial distributions were applied to determine factors associated with presence of Ae. aegypti immatures (i.e. both larvae and pupae) or pupae, alone and significant predictors of the abundance of immature Ae. aegypti or pupae, respectively. RESULTS: The survey provided evidence of widespread presence and abundance of Ae. aegypti mosquitoes in both urban and rural settings of Unguja Island. Interestingly, rural setting had higher numbers of infested containers, all immatures, and pupae than urban setting. Likewise, higher House and Breteau indices were recorded in rural compared to the urban setting. There was no statistically significant difference in Stegomyia indices between seasons across settings. Plastics, metal containers and car tires were identified as the most productive habitats which collectively produced over 90% of all Ae. aegypti pupae. Water storage, sun exposure, vegetation, and organic matter were significant predictors of the abundance of immature Ae. aegypti. CONCLUSIONS: Widespread presence and abundance of Ae. aegypti were found in rural and urban areas of Unguja, the main island of Zanzibar. Information on productive habitats and predictors of colonization of water containers are important for the development of a routine Aedes surveillance system and targeted control interventions in Zanzibar and similar settings.

First confirmed occurrence of the yellow fever virus and dengue virus vector Aedes (Stegomyia) luteocephalus (Newstead, 1907) in Mozambique.

BACKGROUND: Mozambique, same as many other tropical countries, is at high risk of arthropod-borne virus (arbovirus) diseases and recently two dengue virus (DENV) outbreaks occurred in the northern part of the country. The occurrence of some important vector species, such as Aedes (Stegomyia) aegypti (Linnaeus) and Ae. (Stg.) albopictus (Skuse), besides several other sylvatic vectors, have been reported in the country, which may indicate that the transmission of some arboviruses of public health importance may involve multiple-vector systems. Therefore, knowing the occurrence and distribution of existing and the new important vectors species, is crucial for devising systematic transmission surveillance and vector control approaches. The aim of this study was to map the occurrence and distribution of mosquito species with potential for transmitting arboviruses of human and veterinary relevance in Niassa Province, Northern Mozambique. METHODS: Field entomological surveys were undertaken in April 2016 in Lago District, Niassa Province, northern Mozambique. Breeding sites of mosquitoes were inspected and immature stages were collected and reared into adult. Mosquitoes in the adult stages were morphologically identified using taxonomic keys. Morphological identification of Aedes (Stegomyia) luteocephalus (Newstead) were later confirmed using dissected male genitalia and molecular based on the phylogenetic analyses of the sequenced barcode (cox1 mtDNA) gene. RESULTS: A total of 92 mosquito larvae collected developed into adults. Of these, 16 (17.39%) were morphologically identified as Ae. luteocephalus. The remaining specimens belonged to Ae. (Stg.) aegypti (n = 4, 4.35%), Ae. (Aedimorphus) vittatus (n = 24, 26.09%), Anopheles garnhami (n = 1, 1.09%), Culex (Culiciomyia) nebulosus (n = 28, 30.43%), Eretmapodites subsimplicipes (n = 18, 19.57%) and Toxorhynchites brevipalpis (n = 1, 1.09%), taxa already known to the country. Male genitalia and phylogenetic analyses confirmed the identity of Ae. luteocephalus specimens collected in this study. CONCLUSIONS: To our knowledge, this is the first detection of Ae. luteocephalus in Mozambican territory, a vector species of yellow fever virus (YFV), Zika virus (ZIKV) and dengue virus (DENV) in Africa. Further studies are encouraged to investigate the role of Ae. luteocephalus in the transmission of arboviral diseases in Mozambique.

A survey of RNA viruses in mosquitoes from Mozambique reveals novel genetic lineages of flaviviruses and phenuiviruses, as well as frequent flavivirus-like viral DNA forms in Mansonia.

BACKGROUND: Mosquito-borne diseases involving arboviruses represent expanding threats to sub-Saharan Africa imposing as considerable burden to human and veterinary public health. In Mozambique over one hundred species of potential arbovirus mosquito vectors have been identified, although their precise role in maintaining such viruses in circulation in the country remains to be elucidated. The aim of this study was to screen for the presence of flaviviruses, alphaviruses and bunyaviruses in mosquitoes from different regions of Mozambique. RESULTS: Our survey analyzed 14,519 mosquitoes, and the results obtained revealed genetically distinct insect-specific flaviviruses, detected in multiple species of mosquitoes from different genera. In addition, smaller flavivirus-like NS5 sequences, frequently detected in Mansonia seemed to correspond to defective viral sequences, present as viral DNA forms. Furthermore, three lineages of putative members of the Phenuiviridae family were also detected, two of which apparently corresponding to novel viral genetic lineages. CONCLUSION: This study reports for the first-time novel insect-specific flaviviruses and novel phenuiviruses, as well as frequent flavivirus-like viral DNA forms in several widely known vector species. This unique work represents recent investigation of virus screening conducted in mosquitoes from Mozambique and an important contribution to inform the establishment of a vector control program for arbovirus in the country and in the region.

Distribution and breeding sites of Aedes aegypti and Aedes albopictus in 32 urban/peri-urban districts of Mozambique: implication for assessing the risk of arbovirus outbreaks.

BACKGROUND: Aedes-borne arboviruses have emerged as an important public health problem worldwide and, in Mozambique, the number of cases and its geographical spread have been growing. However, information on the occurrence, distribution and ecology of Aedes aegypti and Ae. albopictus mosquitoes remain poorly known in the country. METHODS: Between March and April 2016, a cross-sectional study was conducted in 32 districts in Mozambique to determine the distribution and breeding sites of Ae. aegypti and Ae. albopictus. Larvae and pupae were collected from a total of 2,807 water-holding containers using pipette, dipper, funnel and sweeping procedures, depending on the container type and location. Both outdoor and indoor water-holding containers were inspected. The immature forms were reared to adults and the identifications of the mosquito species was carried out with a stereomicroscope using a taxonomic key. RESULTS: Aedes aegypti was found in every district sampled, while Ae. albopictus was only found in Moatize district, situated in Tete Province in the central part of the country. Six hundred and twenty-eight of 2,807 (22.4%) containers were positive for Ae. aegypti but only one (0.03%) was positive for Ae. albopictus. The Container Index (CI) of Aedes was highest in densely populated suburban areas of the central region (260/604; 43.0%), followed by suburban areas in northern areas (228/617; 36.9%) whilst the lowest proportion was found in urbanized southern areas (140/1586; 8.8%). The highest CI of Aedes was found in used tires (448/1268; 35.3%), cement tanks (20/62; 32.3%) and drums (21/95; 22.1%). CONCLUSION: Data from our study showed that Ae. aegypti is present nation-wide, since it occurred in every sampled district, whilst Ae. albopictus had a limited distribution. Therefore, the risk of transmission of dengue and chikungunya is likely to have been underestimated in Mozambique. This study highlights the need for the establishment of a national entomological surveillance program for Aedes spp. in Mozambique in order to gain a better understanding about vector bionomics and to support the development of informed effective vector control strategies.

The Asian tiger hunts in Maputo city--the first confirmed report of Aedes (Stegomyia) albopictus (Skuse, 1895) in Mozambique.

BACKGROUND: Increasing evidence suggests that dengue fever is endemic in Mozambique. Larvae of both the Afrotropical vector Aedes aegypti and its subspecies, Ae. aegypti formosus, have been reported from three provinces in Mozambique, two of which recently experienced dengue outbreaks. Despite reports of the invasive Oriental vector Ae. albopictus on the islands in the Mozambique Channel and nearby Indian Ocean, the species has not yet been reported in Mozambique. FINDINGS: Four host-seeking female mosquitoes, collected biting the authors in an urban neighbourhood of Maputo City in the late afternoon of 6 December, 2015, are herein morphologically confirmed as Ae. albopictus. CONCLUSION: This is the first report confirming the occurrence in Mozambique of Ae. albopictus, an invasive species and an important vector of human arboviruses. In view of its potential role as a vector of dengue, Chikungunya and Zika viruses, studies are urgently needed to assess the geographical expansion and relative abundance of these important vectors to better understand the potential transmission impact of arboviruses that are efficiently transmitted and globally spread by these vectors.

Bio-efficacy of new long-lasting insecticide-treated bed nets against Anopheles funestus and Anopheles gambiae from central and northern Mozambique.

BACKGROUND: Long-lasting insecticide-treated nets (LLINs) are one of the main methods used for controlling malaria transmission in Mozambique. The proliferation of several types of LLINs and the re-emergence of insecticide resistance in the local vector populations poses challenges to the local malaria control programme on selecting suitable insecticide-based vector control products. Therefore, this study evaluated the insecticide susceptibility and bio-efficacy of selected new LLINs against wild populations of Anopheles funestus sensu lato and A. gambiae s.l. from Northern and Central Mozambique. The study also investigated whether the insecticide contents on the LINNs fabrics were within the WHOPES recommended target range. METHODS: The susceptibility of 2-5 day old wild female A. funestus and A. gambiae sensu stricto against the major classes of insecticides used for vector control, viz: deltamethrin (0.05 %), permethrin (0.75 %), propoxur (0.1 %), bendiocarb (0.1 %) and DDT (4 %), was determined using WHO cylinder susceptibility tests. WHO cone bioassays were conducted to determine the bio-efficacy of both pyrethroid-only LLINs (Olyset(®), Permanet 2.0(®), NetProtect(®) and Interceptor(®)) and, Permanet 3.0(®) a combination LLIN against A. funestus s.s, from Balama, Mocuba and Milange districts, respectively. The bio-efficacy of LLINs against the insectary-susceptible A. arabiensis (Durban strain) was assessed, as well. Untreated bed net swatches were used as negative controls. Chemical analyses, by high performance liquid chromatography, were undertaken to assess whether the insecticide contents on the LLINs fabrics fell within recommended target dose ranges. The frequency of kdr gene mutations was determined from a random sample of A. gambiae s.s. from both WHO susceptibility and cone bioassay experiments. RESULTS: Anopheles funestus from Balama district showed resistance to deltamethrin and possible resistance to permethrin, propoxur and bendiocarb, whilst A. gambiae from Mocuba district was susceptible to deltamethrin, bendiocarb and propoxur. There were no kdr mutants found in the sample of 256 A. gambiae tested. Overall, 186 LLIN swatches were tested. Mosquitoes exposed to Olyset(®) had the lowest knockdown (±standard error) and mortality rate (±standard error) in all studied sites regardless of vectors species tested. Permanet 3.0 showed the highest bio-efficacy independent of vector species tested and level of insecticide resistance detected. All types of LLINs effectively killed susceptible A. arabiensis Durban strain. The insecticide content of Olyset(®) and Permanet 2.0(®) was higher than the target dose but NetProtect(®) had a lower insecticide content than the target dose. CONCLUSION: The study shows evidence of considerable heterogeneity in both insecticide susceptibility and the level of bio-efficacy of commonly available types of LLINs against wild A. funestus and A. gambiae from Balama, Mocuba and Milange districts, located in north and centre of Mozambique. The findings suggest that vector control approaches combining different types of insecticides might help to tackle the apparent problem of pyrethroid resistance in the vector populations from these three sites. Results from bioassays on laboratory-susceptible A. arabiensis strongly suggest that LLINs can offer some protection against susceptible malaria vectors.

Netting barriers to prevent mosquito entry into houses in southern Mozambique: a pilot study.

BACKGROUND: One of the best ways to control the transmission of malaria is by breaking the vector-human link, either by reducing the effective population size of mosquitoes or avoiding infective bites. Reducing house entry rates in endophagic vectors by obstructing openings is one simple way of achieving this. Mosquito netting has previously been shown to have this effect. More recently different materials that could also be used have come onto the market. Therefore, a pilot study was conducted to investigate the protective effect of three types of material against Anopheles funestus and Anopheles gambiae s.l entry into village houses in Mozambique when applied over the large opening at the gables and both gables and eaves. METHODS: A two-step intervention was implemented in which the gable ends of houses (the largest opening) were covered with one of three materials (four year old mosquito bed nets; locally purchased untreated shade cloth or deltamethrin-impregnated shade cloth) followed by covering both gable ends and eaves with material. Four experimental rounds (each of three weeks duration), from four houses randomly assigned to be a control or to receive one of the three intervention materials, were undertaken from March to August 2010 in the village of Furvela in southern Mozambique. Mosquito entry rates were assessed by light-trap collection and the efficacy of the different materials was determined in terms of incidence rate ratio (IRR), obtained through a Generalized Estimating Equations (GEE), of mosquito entry in a treated house compared to the untreated (control) house. RESULTS: Altogether 9,692 An. funestus and 1,670 An. gambiae s.l. were collected. Houses treated with mosquito netting or the untreated shade cloth had 61.3% [IRR = 0.39 (0.32-0.46); P <0.0001] and 70% [IRR = 0.30 (0.25 - 0.37); P <0.001] fewer An. funestus in relation to untreated houses, but there was no difference in An. funestus in houses treated with the deltamethrin-impregnated shade cloth [IRR = 0.92 (0.76 -1.12); P = 0.4] compared to untreated houses. Houses treated with mosquito netting reduced entry rates of An. gambiae s.l, by 84% [IRR = 0.16 (0.10 - 0.25); P <0.001], whilst untreated shade cloth reduced entry rates by 69% [IRR = 0.31 (0.19 -0.53); P <0.001] and entry rates were reduced by 76% [IRR = 0.24 (0.15 0.38); P <0.001] in houses fitted with deltamethrin-impregnated shade cloth.

A novel experimental hut for the study of entrance and exit behaviour of endophilic malaria vectors.

Experimental huts have played a long and illustrious role in the study of mosquito vectors of disease. Here we present a design of a novel, cheap, 12 sided, experimental hut based on the African roundhouse. The panels covering each side can open and act as a door and above each panel there is a shutter that can also open. This allows for a great combination of possible openings for the study of entry and exit behaviour of mosquitoes. Preliminary results describing the exit behaviour of Anopheles funestus when four of the panels were open are described.