Evolution and assembly of Anopheles aquasalis's immune genes: primary malaria vector of coastal Central and South America and the Caribbean Islands.

Anophelines are vectors of malaria, the deadliest disease worldwide transmitted by mosquitoes. The availability of genomic data from various Anopheles species allowed evolutionary comparisons of the immune response genes in search of alternative vector control of the malarial parasites. Now, with the Anopheles aquasalis genome, it was possible to obtain more information about the evolution of the immune response genes. Anopheles aquasalis has 278 immune genes in 24 families or groups. Comparatively, the American anophelines possess fewer genes than Anopheles gambiae s. s., the most dangerous African vector. The most remarkable differences were found in the pathogen recognition and modulation families like FREPs, CLIP and C-type lectins. Even so, genes related to the modulation of the expression of effectors in response to pathogens and gene families that control the production of reactive oxygen species were more conserved. Overall, the results show a variable pattern of evolution in the immune response genes in the anopheline species. Environmental factors, such as exposure to different pathogens and differences in the microbiota composition, could shape the expression of this group of genes. The results presented here will contribute to a better knowledge of the Neotropical vector and open opportunities for malaria control in the endemic-affected areas of the New World.

Characterization of the anopheline vector breeding habitats: Implications for elimination of malaria in tribal inhabited Car Nicobar Island.

Background & objectives: Malaria is an important public health problem in Andaman & Nicobar archipelago. Among the three districts, Nicobar is the most endemic district where API is >2. In this district, the malaria incidence in Car Nicobar Tehsil has declined steadily over the past 10 years. A renewed initiative to consolidate this gain is being made with the ultimate objective of achieving zero indigenous transmission of malaria in Car Nicobar. So, the present study undertook a close environmental monitoring of water bodies for assessing changes in the risk potential of mosquito vector breeding habitats which can augment the elimination programme. Methods: The breeding habitats of anopheline mosquitoes were sampled in 16 areas of Car Nicobar Island for eight time periods during 2017-2020. Along with anophelines, various associated water parameters (n=60) were estimated, viz. physicochemical (n=13), and biological, which included culicine mosquito immatures, insect predators (n=5), phytoplanktons (n=31) and zooplanktons (n=10). Results: In the 16 study sites, overall 1126 surface water stagnating bodies constituting 21 different habitat types were surveyed. Of these, 17 were positive for anopheline breeding. Water bodies from three villages were consistently found to be positive for anopheline breeding. However, early instars of anopheline larvae were more abundant compared to the late instars. Four anopheline species were recorded, including Anopheles sundaicus, A. barbirostris, A. insulaeflorum and A. subpictus, in which 48 per cent were A. sundaicus. Multivariable analysis indicated that anopheline density was significantly higher in permanent water bodies than in temporary habitats (P<0.05) (high risk of anophelines). The highest pH (≥8.2), dissolved solids (≥0.39) levels showed significantly (P<0.05) decreased larval densities (lower risk of breeding), adjusted with breeding sites and season. Nitrite levels increased (P=0.022) larval densities. Interpretation & conclusions: The present study facilitated estimating the productive period of a larval habitat enabling target larval sources to reduce adult populations. Implementing larviciding strategy before monsoon season is presumably the most cost-effective strategy. The output can be utilized for environmental monitoring of mosquito breeding risk in other malaria endemic areas, particularly where medium/large water bodies are the predominant breeding sites for malaria vectors.

Impact of cattle on the abundance of indoor and outdoor resting malaria vectors in southern Malawi.

BACKGROUND: Understanding the blood feeding preferences and resting habits of malaria vectors is important for assessing and designing effective malaria vector control tools. The presence of livestock, such as cattle, which are used as blood meal hosts by some malaria vectors, may impact malaria parasite transmission dynamics. The presence of livestock may provide sufficient blood meals for the vectors, thereby reducing the frequency of vectors biting humans. Alternatively, the presence of cattle may enhance the availability of blood meals such that infectious mosquitoes may survive longer, thereby increasing the risk of malaria transmission. This study assessed the effect of household-level cattle presence and distribution on the abundance of indoor and outdoor resting malaria vectors. METHODS: Houses with and without cattle were selected in Chikwawa district, southern Malawi for sampling resting malaria vectors. Prokopack aspirators and clay pots were used for indoor and outdoor sampling, respectively. Each house was sampled over two consecutive days. For houses with cattle nearby, the number of cattle and the distances from the house to where the cattle were corralled the previous night were recorded. All data were analysed using generalized linear models fitted with Poisson distribution. RESULTS: The malaria vectors caught resting indoors were Anopheles gambiae sensu stricto (s.s.), Anopheles arabiensis and Anopheles funestus s.s. Outdoor collections consisted primarily of An. arabiensis. The catch sizes of indoor resting An. gambiae sensu lato (s.l.) were not different in houses with and without cattle (P = 0.34). The presence of cattle near a house was associated with a reduction in the abundance of indoor resting An. funestus s.l. (P = 0.04). This effect was strongest when cattle were kept overnight ≤ 15 m away from the houses (P = 0.03). The blood meal hosts varied across the species. CONCLUSION: These results highlight differences between malaria vector species and their interactions with potential blood meal hosts, which may have implications for malaria risk. Whereas An. arabiensis remained unaffected, the reduction of An. funestus s.s. in houses near cattle suggests a potential protective effect of cattle. However, the low abundance of mosquitoes reduced the power of some analyses and limited the generalizability of the results to other settings. Therefore, further studies incorporating the vectors' host-seeking behaviour/human biting rates are recommended to fully support the primary finding.

Mobile app based pictorial identification key for Indian anophelines.

BACKGROUND & OBJECTIVES: Malaria control strategies for a particular area largely depends on the correct identification of the mosquito species prevalent in that area. This study aimed to develop an android mobile app named 'Pictorial Indian anophelines key', which can be used to identify the 58 species of Indian female adult anophelines based on morphological characteristics. METHODS: The pre-requisite to use this app requires a minimum basic knowledge of mosquito morphological characteristics and features. The user needs to view the collected mosquito under a dissecting binocular microscope and has to select the observations on the app presented in the form of labelled picture format. The app uses a divide and conquer algorithm which narrows the selection from genus level to final identification of species. RESULTS: The app is user-friendly, quick and it accurately identifies the mosquito species in a maximum of six consecutive clicks. The result displays a complete image of identified mosquito along with its quick identification features. It can be used for both subgenus Cellia and Anopheles. INTERPRETATION & CONCLUSION: This pictorial key-based mobile app could be helpful for entomologists, malariologists, researchers, public health workers as well as students in the quick and correct identification of anopheline mosquitoes prevalent in India which in turn could be helpful in devising appropriate approaches towards malaria control and prevention. The app can be modified as per future requirements.

Establecimiento de una línea de base entomológica de malaria en la parroquia San Isidro del municipio Sifontes del estado Bolívar, Venezuela / Establishment of an entomological malaria baseline in the San Isidro parish of the Sifontes municipality of Bolívar state, Venezuela

La malaria en Venezuela es altamente heterogénea y focalizada. En 2016 se reportaron más de 242 mil casos nuevos en el país, de los cuales 73% provenían del estado Bolívar, 42% del municipio Sifontes y 29% de la parroquia San Isidro. Entre octubre 2016 y mayo 2017 se realizó en la parroquia San Isidro un estudio exploratorio, con el fin de establecer una línea basal entomológica en malaria que permitiera la evaluación posterior de Rociamientos Intradomiciliarios de Insecticida y Mosquiteros Tratados con insecticida de Larga Duracion.Las capturas de mosquitos adultos con Trampas Mosquito Magnet Independence™, atrayente humano y en reposo pre-hematofágico, permitieron determinar que en esta parroquia, hay por lo menos tres especies de anofelinos con actividad hematofágica antropofílica, An. darlingi, An. albitarsis s.l. y An. nuneztovari s.l., cuyos hábitos de reposo y actividad de picada fueron descritos. Asimismo, el muestreo de hábitats larvales permitió determinar que las lagunas residuales de la actividad minera son los más importantes y que An. albitarsis s.l. y An. triannulatus s.l. son las especies de mayor prevalencia en estos hábitats. Estos hallazgos permiten actualizar la data entomológica de este foco caliente de malaria y sientan las bases para la evaluación y seguimiento de las medidas de control de vectores implementadas(AU)

Malaria in Venezuela is highly heterogeneous and focused. In 2016, more than 242,000 malaria cases were reported in the country, from which 73% came from Bolivar state, 42% from Sifontes municipality and 29% from the San Isidro parish. Between October 2016 and May 2017, an exploratory study was carried out in order to establishing an entomologic baseline that would allow posterior evaluations of indoors insecticide spraying and long lasting insecticidal nets. Adults captures with Mosquito Magnet Independence™ traps, human landing, and pre-feedingresting habits allowed to determine that in San Isidro there are at least three anopheline species with significant anthropophilic activity: An darlingi, An. albitarsis s.l. and An. nuneztovari s.l. Resting habits and biting activities were described for the three species. Likewise, larval sampling were carried out which allowed to identify that abandoned gold mine dugouts are the most important habitatsfor these species. Particularly, An. albitarsis s.l. and An. triannulatus s.l. were the most prevalent anophelines colonizing these breeding sites. Our results update entomologic data of this malaria hot spot area and establish the baseline for further evaluations ofthe vector control measures implemented(AU)

Influence of house characteristics on mosquito distribution and malaria transmission in the city of Yaoundé, Cameroon.

BACKGROUND: Improving house structure is known to limit contact between humans and mosquitoes and reduce malaria transmission risk. In the present study, the influence of house characteristics on mosquito distribution and malaria transmission risk was assessed in the city of Yaoundé. METHODS: The study was conducted from March 2017 to June 2018 in 32 districts of the city of Yaoundé. Mosquito collections were performed indoor in 10 to 15 houses per district using CDC light traps. A total of 467 houses, selected randomly were used. A pretested questionnaire was submitted to participants of the study to collect information on the household: the number of people per house, education level, type of walls, presence of ceilings and eaves, number of windows, usage of long-lasting insecticidal nets (LLINs), number of bedroom and number of window. Mosquitoes collected were identified morphologically. Anophelines were tested by ELISA to detect infection by Plasmodium parasites. General Estimating Equations adjusting for repeated measures in the same house fitting negative binomial analysis were used to assess the influence of house characteristics on mosquito distribution. RESULTS: A total of 168,039 mosquitoes were collected; Culex spp emerged as the predominant species (96.48%), followed by Anopheles gambiae sensu lato (s.l.) (2.49%). Out of the 1033 An. gambiae s.l. identified by PCR, 90.03% were Anopheles coluzzii and the remaining were An. gambiae sensu stricto (s.s.) (9.97%). The high number of people per household, the presence of screens on window and the possession of LLINs were all associated with fewer mosquitoes collected indoors, whilst opened eaves, the high number of windows, the presence of holes in walls and living close to breeding sites were associated with high densities of mosquitoes indoor. Out of 3557 Anophelines tested using ELISA CSP, 80 were found infected by Plasmodium falciparum parasites. The proportion of mosquitoes infected did not vary significantly according to house characteristics. CONCLUSION: The study indicated that several house characteristics such as, the presence of holes on walls, opened eaves, unscreened window and living close to breeding sites, favored mosquito presence in houses. Promoting frequent use of LLINs and house improvement measures, such as the use of screen on windows, closing eaves, cleaning the nearby environment, should be integrated in strategies to improve malaria control in the city of Yaoundé.

Biting patterns of malaria vectors of the lower Shire valley, southern Malawi.

Assessing the biting behaviour of malaria vectors plays an integral role in understanding the dynamics of malaria transmission in a region. Biting times and preference for biting indoors or outdoors varies among mosquito species and across regions. These behaviours may also change over time in response to vector control measures such as long-lasting insecticidal nets (LLINs). Data on these parameters can provide the sites and times at which different interventions would be effective for vector control. This study assessed the biting patterns of malaria vectors in Chikwawa district, southern Malawi. The study was conducted during the dry and wet seasons in 2016 and 2017, respectively. In each season, mosquitoes were collected indoors and outdoors for 24 nights in six houses per night using the human landing catch. Volunteers were organized into six teams of two individuals, whereby three teams collected mosquitoes indoors and the other three collected mosquitoes outdoors each night, and the teams were rotated among twelve houses. All data were analyzed using Poisson log-linear models. The most abundant species were Anopheles gambiae sensu lato (primarily An. arabiensis) and An. funestus s.l. (exclusively An. funestus s.s.). During the dry season, the biting activity of An. gambiaes.l. was constant outdoors across the categorized hours (18:00 h to 08:45 h), but highest in the late evening hours (21:00 h to 23:45 h) during the wet season. The biting activity of An. funestus s.l. was highest in the late evening hours (21:00 h to 23:45 h) during the dry season and in the late night hours (03:00 h to 05:45 h) during the wet season. Whereas the number of An. funestuss.l. biting was constant (P = 0.662) in both seasons, that of An. gambiaes.l. was higher during the wet season than in the dry season (P = 0.001). Anopheles gambiae s.l. was more likely to bite outdoors than indoors in both seasons. During the wet season, An. funestus s.l. was more likely to bite indoors than outdoors but during the dry season, the bites were similar both indoors and outdoors. The biting activity that occurred in the early and late evening hours, both indoors and outdoors coincides with the times at which individuals may still be awake and physically active, and therefore unprotected by LLINs. Additionally, a substantial number of anopheline bites occurred outdoors. These findings imply that LLINs would only provide partial protection from malaria vectors, which would affect malaria transmission in this area. Therefore, protection against bites by malaria mosquitoes in the early and late evening hours is essential and can be achieved by designing interventions that reduce vector-host contacts during this period.

Assessment of the Suna trap for sampling mosquitoes indoors and outdoors.

BACKGROUND: Entomological monitoring is important for public health because it provides data on the distribution, abundance and host-seeking behaviour of disease vectors. Various methods for sampling mosquitoes exist, most of which are biased towards, or specifically target, certain portions of a mosquito population. This study assessed the Suna trap, an odour-baited trap for sampling host-seeking mosquitoes both indoors and outdoors. METHODS: Two separate field experiments were conducted in villages in southern Malawi. The efficiency of the Suna trap in sampling mosquitoes was compared to that of the human landing catch (HLC) indoors and outdoors and the Centers for Disease, Control and Prevention Light Trap (CDC-LT) indoors. Potential competition between two Suna traps during simultaneous use of the traps indoors and outdoors was assessed by comparing mosquito catch sizes across three treatments: one trap indoors only; one trap outdoors only; and one trap indoors and one trap outdoors used simultaneously at the same house. RESULTS: The efficiency of the Suna trap in sampling female anophelines was similar to that of HLC indoors (P = 0.271) and HLC outdoors (P = 0.125), but lower than that of CDC-LT indoors (P = 0.001). Anopheline catch sizes in the Suna trap used alone indoors were similar to indoor Suna trap catch sizes when another Suna trap was simultaneously present outdoors (P = 0.891). Similarly, catch sizes of female anophelines with the Suna trap outdoors were similar to those that were caught outdoors when another Suna trap was simultaneously present indoors (P = 0.731). CONCLUSIONS: The efficiency of the Suna trap in sampling mosquitoes was equivalent to that of the HLC. Whereas the CDC-LT was more efficient in collecting female anophelines indoors, the use of this trap outdoors is limited given the requirement of setting it next to an occupied bed net. As demonstrated in this research, outdoor collections are also essential because they provide data on the relative contribution of outdoor biting to malaria transmission. Therefore, the Suna trap could serve as an alternative to the HLC and the CDC-LT, because it does not require the use of humans as natural baits, allows standardised sampling conditions across sampling points, and can be used outdoors. Furthermore, using two Suna traps simultaneously indoors and outdoors does not interfere with the sampling efficiency of either trap, which would save a considerable amount of time, energy, and resources compared to setting the traps indoors and then outdoors in two consecutive nights.

Anopheline salivary protein genes and gene families: an evolutionary overview after the whole genome sequence of sixteen Anopheles species.

BACKGROUND: Mosquito saliva is a complex cocktail whose pharmacological properties play an essential role in blood feeding by counteracting host physiological response to tissue injury. Moreover, vector borne pathogens are transmitted to vertebrates and exposed to their immune system in the context of mosquito saliva which, in virtue of its immunomodulatory properties, can modify the local environment at the feeding site and eventually affect pathogen transmission. In addition, the host antibody response to salivary proteins may be used to assess human exposure to mosquito vectors. Even though the role of quite a few mosquito salivary proteins has been clarified in the last decade, we still completely ignore the physiological role of many of them as well as the extent of their involvement in the complex interactions taking place between the mosquito vectors, the pathogens they transmit and the vertebrate host. The recent release of the genomes of 16 Anopheles species offered the opportunity to get insights into function and evolution of salivary protein families in anopheline mosquitoes. RESULTS: Orthologues of fifty three Anopheles gambiae salivary proteins were retrieved and annotated from 18 additional anopheline species belonging to the three subgenera Cellia, Anopheles, and Nyssorhynchus. Our analysis included 824 full-length salivary proteins from 24 different families and allowed the identification of 79 novel salivary genes and re-annotation of 379 wrong predictions. The comparative, structural and phylogenetic analyses yielded an unprecedented view of the anopheline salivary repertoires and of their evolution over 100 million years of anopheline radiation shedding light on mechanisms and evolutionary forces that contributed shaping the anopheline sialomes. CONCLUSIONS: We provide here a comprehensive description, classification and evolutionary overview of the main anopheline salivary protein families and identify two novel candidate markers of human exposure to malaria vectors worldwide. This anopheline sialome catalogue, which is easily accessible as hyperlinked spreadsheet, is expected to be useful to the vector biology community and to improve the capacity to gain a deeper understanding of mosquito salivary proteins facilitating their possible exploitation for epidemiological and/or pathogen-vector-host interaction studies.

The influence of the area of the Serra da Mesa Hydroelectric Plant, State of Goiás, on the frequency and diversity of anophelines (Diptera: Culicidae): a study on the effect of a reservoir

INTRODUCTION: Bioecological aspects of anophelines (Diptera: Culicidae) near areas under the direct influence of the hydroelectric plant reservoir of Serra da Mesa in Goiás, Brazil, were analyzed. METHODS: Samples were collected at the surrounding dam area during the phases before and after reservoir impoundment. The influence of climatic and environmental factors on the occurrence of Anopheles darlingi, Anopheles albitarsis, Anopheles triannulatus, Anopheles oswaldoi and Anopheles evansae was assessed using Pearson's correlations with indicators for richness and diversity as well as the index of species abundance (ISA) and the standardized index of species abundance (SISA). RESULTS: The highest anopheline density occurred during the phase after filling the tank; however, no direct correlation with the climatic factors was observed during this stage. The reservoir formation determined the incidence of the anopheline species. An. darlingi was the predominant species (SISA = 1.00). CONCLUSIONS: The significant difference (p < 0.05) observed between the species incidence during the different reservoir phases demonstrates the environmental effect of the reservoir on anophelines. .

Structure of Anopheles (Diptera: Culicidae) population in areas with different degrees of human settlement: Cantá - Roraima - Brazil / Estrutura da população de Anopheles (Diptera: Culicidae) em áreas com diferentes graus de colonização humana: Cantá - Roraima - Brasil

Malaria has still been one of the most important endemic diseases in the Amazonian region. This study presents the impact of human settlements on the structure of Anopheles population. Diversity, abundance, richness and distribution of the genus Anopheles were observed in two areas with different levels of human settlement in the Cantá city, Roraima State, Northern Brazil. The influence of the dry and rainy seasons on mosquito populations was also observed. Mosquito captures were performed between 6:00 and 10:00 pm during the dry (February and November) and rainy (May and August) seasons at four different sites of each area. Among the 11 species of Anopheles identified through the adults' characteristics, An. albitarsis s.l. (45.5 percent) and An. darlingi (19.2 percent) were the most abundant in the more intensively anthropized area while An. triannulatus (19.2 percent) was more common in the less modified area. Other species found were An. nuneztovari (10.9 percent), An. oswaldoi (2.0 percent), An. evansae (1.7 percent), An. brasiliensis (0.6 percent), An. intermedius (0.3 percent), An. mediopunctatus (0.5 percent), An. periassui (0.08 percent) and An. argyritarsis (0.04 percent). The highest mosquitoes' population density was observed in May and the lowest one was observed in February and November. These results demonstrate the existence of a high diversity of anophelines in the study areas, showing that anthropic changes in the environment and climate variability affect both the population density and relative abundance of these vectors.

Malária continua sendo uma das mais importantes doenças endêmicas da região Amazônica. Esse estudo mostra o impacto da colonização humana sobre a estrutura populacional de Anopheles. Diversidade, abundância, riqueza e distribuição do gênero Anopheles foi observado em duas áreas com diferentes graus de antropização no município do Cantá, Estado de Roraima, Norte do Brasil. A influência das estações seca e chuvosa sobre a população dos mosquitos também foram investigadas. A captura dos mosquitos foi realizada entre 6:00 e 10:00 pm na estação seca (Fevereiro e Novembro) e estação chuvosa (Maio e Agosto) em quatro locais diferentes. Entre as 11 espécies de Anopheles identificadas através das características dos adultos, An. albitarsis s.l. (45.5 por cento) e An. darlingi (19.2 por cento) foram as mais abundantes nas áreas mais intensamente antropizadas, enquanto An. triannulatus (19.2 por cento) foi a espécie mais comum na área menos modificada. As outras espécies encontradas foram An. nuneztovari (10.9 por cento), An. oswaldoi (2.0 por cento), An. evansae (1.7 por cento), An. brasiliensis (0.6 por cento), An. intermedius (0.3 por cento), An. mediopunctatus (0.5 por cento), An. periassui (0.08 por cento) e An. argyritarsis (0.04 por cento). A mais alta densidade populacional de mosquitos foi observada em Maio e as mais baixas em Fevereiro e Novembro. Esses resultados demonstram a existência de uma alta diversidade de anofelinos na área estudada e que mudanças antrópicas no ambiente e variabilidade climática afetam a densidade populacional desses vetores.

Affinity and diversity indices for anopheline immature forms

As for the entire Amazon Region, malaria continues to be a major health public problem in Roraima that presented an Annual Parasitic Index of 85.4 in 2005, the highest in Brazil. Information on anopheline breeding sites is an essential component in malaria control strategies. Aiming to contribute to the limited knowledge on anopheline immature forms in Roraima, collections and breeding site observations were performed in 10 breeding sites around the capital city Boa Vista. Collections were carried out in the rainy and dry season periods between April 2004 and January 2005. Breeding sites comprised natural and artificial water reservoirs. A total of 623 immature forms were collected belonging to Anopheles albitarsis s.l., An.triannulatus s.l., An. nuneztovari/dunhami, An. braziliensis, An. evansae, An. oswaldoi s.l., An. strodei and An. darlingi. An. albitarsis and An. braziliensis were the most frequently found species. Eight larvae of An. darlingi were found in only one breeding site located in the forest. An. triannulatus/An. nuneztovari and An. albitarsis/An. braziliensis were the pairs of species that mostly occurred together. Both pair of species displayed the highest affinity index what might indicate a high compatibility for the same breeding conditions and/or a synergistic co-occurrence. Species diversity index was higher for the dry season.

Como para toda a Amazônia, a malária representa um importante problema de saúde pública em Roraima. Roraima apresentou um índice parasitário anual de 85,4 em 2005, o maior do Brasil. O conhecimento dos criadouros de anofelinos constitui-se num componente primordial nas estratégias de controle da malária. No intuito de contribuir para o limitado conhecimento dos criadouros de anofelinos em Roraima, coleções de imaturos e observações dos criadouros foram realizadas no entorno da capital Boa Vista. As coletas foram feitas nas estações seca e chuvosa entre abril de 2004 e janeiro de 2005. Os criadouros observados foram reservatórios de água naturais e artificiais. Um total de 623 formas imaturas foram coletadas pertencentes às espécies An. albitarsis s.l., An.triannulatus s.l., An. nuneztovari/dunhami, An. braziliensis, An. evansae, An. oswaldoi s.l., An. strodei e An. darlingi. An. braziliensis e An. albitarsis foram as espécies mais freqüentemente encontradas. Oito larvas de An. darlingi foram encontradas em apenas um criadouro na floresta. An. triannulatus/An. nuneztovari e An. albitarsis/An. braziliensis foram os pares de espécies de maior co-ocorrência. Ambos pares de espécies apresentaram o maior índice de afinidade o que pode indicar compatibilidade para as mesmas condições prevalentes nos criadouros e/ou sinergismo. O índice de diversidade de espécies foi maior para a estação seca.