Forest edge landscape context affects mosquito community composition and risk of pathogen emergence.

Forest edges, where humans, mosquitoes, and wildlife interact, may serve as a nexus for zoonotic arbovirus exchange. Although often treated as uniform interfaces, the landscape context of edge habitats can greatly impact ecological interactions. Here, we investigated how the landscape context of forest edges shapes mosquito community structure in an Amazon rainforest reserve near the city of Manaus, Brazil, using hand-nets to sample mosquitoes at three distinct forest edge types. Sampling sites were situated at edges bordering urban land cover, rural land cover, and natural treefall gaps, while sites in continuous forest served as controls. Community composition differed substantially among edge types, with rural edges supporting the highest species diversity. Rural edges also provided suitable habitat for forest specialists, including key sylvatic vectors, of which Haemagogus janthinomys was the most abundant species sampled overall. Our findings emphasize the importance of landscape context in assessing pathogen emergence risk at forest edges.

Where boundaries become bridges: Mosquito community composition, key vectors, and environmental associations at forest edges in the central Brazilian Amazon.

Risk of spillover and spillback of mosquito-borne viruses in the neotropics, including yellow fever, dengue, Zika (Flaviviridae: Flavivirus), chikungunya, and Mayaro (Togaviridae: Alphavirus) viruses, is highest at ecotones where humans, monkeys, and mosquitoes coexist. With a view to identifying potential bridge vectors, we investigated changes in mosquito community composition and environmental variables at ground level at distances of 0, 500, 1000, and 2000 m from the edge of a rainforest reserve bordering the city of Manaus in the central Brazilian Amazon. During two rainy seasons in 2019 and 2020, we sampled 9,467 mosquitoes at 244 unique sites using BG-Sentinel traps, hand-nets, and Prokopack aspirators. Species richness and diversity were generally higher at 0 m and 500 m than at 1000 m and 2000 m, while mosquito community composition changed considerably between the forest edge and 500 m before stabilizing by 1000 m. Shifts in environmental variables mainly occurred between the edge and 500 m, and the occurrence of key taxa (Aedes albopictus, Ae. scapularis, Limatus durhamii, Psorophora amazonica, Haemagogus, and Sabethes) was associated with one or more of these variables. Sites where Ae. aegypti and Ae. albopictus were detected had significantly higher surrounding mean NDBI (Normalized Difference Built-up Index) values than sites where they were not detected, while the opposite was true for Sabethes mosquitoes. Our findings suggest that major changes in mosquito communities and environmental variables occur within 500 m of the forest edge, where there is high risk for contact with both urban and sylvatic vectors. By 1000 m, conditions stabilize, species diversity decreases, and forest mosquitoes predominate. Environmental variables associated with the occurrence of key taxa may be leveraged to characterize suitable habitat and refine risk models for pathogen spillover and spillback.

Towards the Laboratory Maintenance of Haemagogus janthinomys (Dyar, 1921), the Major Neotropical Vector of Sylvatic Yellow Fever.

Haemagogus (Haemagogus) janthinomys (Dyar, 1921), the major neotropical vector of sylvatic yellow fever virus, is notoriously difficult to maintain in captivity. It has never been reared beyond an F1 generation, and almost no experimental transmission studies have been performed with this species since the 1940s. Herein we describe installment hatching, artificial blood feeding, and forced-mating techniques that enabled us to produce small numbers of F3 generation Hg. janthinomys eggs for the first time. A total of 62.8% (1562/2486) F1 generation eggs hatched during ≤10 four-day cycles of immersion in a bamboo leaf infusion followed by partial drying. Hatching decreased to 20.1% (190/944) in the F2 generation for eggs laid by mosquitoes copulated by forced mating. More than 85% (79/92) female F2 mosquitoes fed on an artificial blood feeding system. While we were unable to maintain a laboratory colony of Hg. janthinomys past the F3 generation, our methods provide a foundation for experimental transmission studies with this species in a laboratory setting, a critical capacity in a region with hyper-endemic transmission of dengue, Zika, and chikungunya viruses, all posing a risk of spillback into a sylvatic cycle.

Microclimate and the vertical stratification of potential bridge vectors of mosquito­borne viruses captured by nets and ovitraps in a central Amazonian forest bordering Manaus, Brazil.

In the Americas, some mosquito-borne viruses such as Zika, chikungunya, and dengue circulate among humans in urban transmission cycles, while others, including yellow fever and Mayaro, circulate among monkeys in sylvatic cycles. The intersection of humans and wildlife at forest edges creates risk for zoonotic virus exchange. We built a scaffold tower at the edge of a treefall gap in rainforest bordering Manaus, Brazil, to identify vectors that may bridge transmission between humans and monkeys. We vertically sampled diurnally active, anthropophilic mosquitoes using handheld nets at 0, 5, and 9 m and container-breeding mosquitoes in ovitraps at 0, 5, 10, and 15 m. Haemagogus janthinomys and Psorophora amazonica were present in high relative abundance in nets at each height sampled, while anthropophilic species were uncommon in ovitraps. Hg. janthinomys was more abundant at elevated heights than at ground level, while Ps. amazonica abundance was not significantly stratified across heights. The presence of each species increased with increasing 7-day rainfall lagged at 1 week, and at 1 and 4 weeks prior to collection, respectively. In addition, Hg. janthinomys was most frequently collected at 29.9 °C, irrespective of height. These data provide insight into the potential role of each species as bridge vectors.

The vertical stratification of potential bridge vectors of mosquito-borne viruses in a central Amazonian forest bordering Manaus, Brazil.

The emergence of Zika virus (ZIKV) in Latin America brought to the fore longstanding concerns that forests bordering urban areas may provide a gateway for arbovirus spillback from humans to wildlife. To bridge urban and sylvatic transmission cycles, mosquitoes must co-occur with both humans and potential wildlife hosts, such as monkeys, in space and time. We deployed BG-Sentinel traps at heights of 0, 5, 10, and 15 m in trees in a rainforest reserve bordering Manaus, Brazil, to characterize the vertical stratification of mosquitoes and their associations with microclimate and to identify potential bridge vectors. Haemagogus janthinomys and Sabethes chloropterus, two known flavivirus vectors, showed significant stratification, occurring most frequently above the ground. Psorophora amazonica, a poorly studied anthropophilic species of unknown vector status, showed no stratification and was the most abundant species at all heights sampled. High temperatures and low humidity are common features of forest edges and microclimate analyses revealed negative associations between minimum relative humidity, which was inversely correlated with maximum temperature, and the occurrence of Haemagogus and Sabethes mosquitoes. In this reserve, human habitations border the forest while tamarin and capuchin monkeys are also common to edge habitats, creating opportunities for the spillback of mosquito-borne viruses.

Clinical profile of confirmed scorpion stings in a referral center in Manaus, Western Brazilian Amazon.

Scorpion envenomations are a major public health problem in Brazil, and most medically important cases are attributable to the Tityus genus. The objective of this study is to describe the clinical and epidemiological aspects of a series of 151 cases of confirmed scorpion stings, which were treated at the hospitals of two cities in the Western Brazilian Amazon, between June 2014 and December 2019. This study shows that the genus Tityus was the most prevalent. Tityus (Atreus) metuendus (Pocock, 1897) was responsible for the greatest number of cases (68.2%), followed by Tityus (Archaeotityus) silvestris (Pocock, 1897) (14.6%). Most of the envenomations involved males (53.6%), and analysis showed a slight predominance in the group from 40 to 49 years (22.5%). The most affected body regions were feet (49.0%) and hands (31.8%). The time elapsed between the accident and medical care was ≤6 h in 92.1% of cases. Regarding clinical severity, classes I (80.8%) and II (15.9%) predominated. However, there were five (3.3%) class III cases; four for T. metuendus and one for T. silvestris. The most frequent local and systemic manifestations were, respectively, pain (84.1%), paresthesia (34.4%) and mild edema (25.8%), and nausea (9.3%) and myoclonia (8.6%). The clinical manifestations were similar among the patients stung by the different species of scorpions. There were no differences between the manifestations of envenomation caused by T. metuendus, T. silvestris and T. raquelae. For victims of T. apiacas, a higher frequency of piloerection and myoclonia was observed, and was described by the affected patients as a 'sensation of receiving an electric shock' throughout the body. No deaths were registered. The species of greatest epidemiological importance in Manaus is T. metuendus, a species that leads to clinical pictures that do not differ substantially from those observed in other Brazilian regions. T. apiacas causes neurological manifestations that differed from other Tityus species. Our findings suggest that the available antivenoms have little effectiveness when used in the treatment of envenomations by some Amazonian scorpions.

Into the woods: Changes in mosquito community composition and presence of key vectors at increasing distances from the urban edge in urban forest parks in Manaus, Brazil.

Mosquito-borne Zika virus (ZIKV) was recently introduced into the Americas and now has the potential to spill back into a sylvatic cycle in the region, likely involving non-human primates and Aedes, Haemagogus, and Sabethes species mosquitoes. We investigated potential routes of mosquito-borne virus exchange between urban and sylvatic transmission cycles by characterizing mosquito communities in three urban forest parks that receive heavy traffic from both humans and monkeys in Manaus, Brazil. Parks were stratified by both distance from the urban-forest edge (0, 50, 100, and 500 m) and relative Normalized Difference Vegetation Index (NDVI) (low, medium, or high), and mosquitoes were sampled at randomly selected sites within each stratum using BG-Sentinel traps. Additionally, temperature, relative humidity, and other environmental data were collected at each site. A total of 1,172 mosquitoes were collected from 184 sites sampled in 2018, of which 98 sites were resampled in 2019. Using park as the unit of replication (i.e. 3 replicates per sampling stratum), a two-way ANOVA showed no effect of distance or NDVI on the mean number of identified species (P > 0.05 for both comparisons) or on species diversity as measured by the Shannon-Wiener diversity index (P > 0.10 for both comparisons). However, the Morisita overlap index revealed that mosquito communities changed substantially with increasing distance from edge, with communities at 0 m and 500 m being quite distinct. Aedes albopictus and Ae. aegypti penetrated at least 100 m into the forest, while forest specialists including Haemagogus janthinomys, Sabethes glaucodaemon, and Sa. tridentatus were detected in low numbers within 100 m from the forest edge. Trichoprosopon digitatum and Psorophora amazonica were among the most abundant species collected, and both showed distributions extending from the forest edge to its interior. Our results show overlapping distributions of urban and forest mosquitoes at park edges, which highlights the risk of arbovirus exchange via multiple bridge vectors in Brazilian urban forest parks. These parks may also provide refugia for both Ae. albopictus and Ae. aegypti from mosquito control programs.

Composition of sand fly fauna (Diptera: Psychodidae) and detection of Leishmania DNA (Kinetoplastida: Trypanosomatidae) in different ecotopes from a rural settlement in the central Amazon, Brazil.

BACKGROUND: Phlebotomine sand flies (Diptera: Psychodidae) are vectors of Leishmania species, the etiological agents of leishmaniasis, which is one of the most important emerging infectious diseases in the Americas. In the state of Amazonas in Brazil, anthropogenic activities encourage the presence of these insects around rural homes. The present study aimed to describe the composition and distribution of sand fly species diversity among the ecotopes (intradomicile, peridomicile and forest) in an area of American cutaneous leishmaniasis transmission and detect natural infection with Leishmania DNA to evaluate which vectors are inside houses and whether the presence of possible vectors represents a hazard of transmission. RESULTS: Phlebotomine sand flies were collected using light traps. A total of 2469 specimens representing 54 species, predominantly females (71.2%), were collected from four sites. Polymerase chain reaction analysis was performed on 670 samples to detect Leishmania DNA. Most of the samples (79.5%) were collected in the forest, with areas closer to rural dwellings yielding a greater abundance of suspected or proven vectors and a larger number of species containing Leishmania DNA. Nyssomyia umbratilis and Bichromomyia flaviscutellata were found near rural homes, and Ny. umbratilis was also found inside homes. Leishmania DNA was detected in different species of sand flies in all ecotopes, including species with no previous record of natural infection. CONCLUSIONS: There is no evidence that vectors of American cutaneous leishmaniasis are becoming established inside homes, but there are sand flies, including Ny. umbratilis and other possible vectors, in environments characterized by a human presence. These species continue to be predominant in the forest but are prevalent in areas closer to ecotopes with a greater human presence. The existence of proven or suspected vectors in this ecotope is due to the structural organization of rural settlements and may represent a hazard of transmission. Although the detection of Leishmania DNA in species that were not previously considered vectors does not mean that they are transmitting the parasite, it does show that the parasite is circulating in ecotopes where these species are found.

Implication of Tityus apiacas (Lourenco, 2002) in scorpion envenomations in the Southern Amazon border, Brazil.

Herein, four cases of scorpion stings caused by Tityus apiacas recorded from the municipality of Apuí, in the southern region of the Brazilian Amazon, are described. Patients showed systemic clinical manifestations, described as unusual, involuntary, and generalized tingling and numbness, reported by patients as an electric shock sensation, lasting up to 24 hours after the sting. All patients described local pain and sensation, along with other clinical symptoms including local edema and erythema. Systemic manifestations were not life threatening. Antivenom therapy was administered to all patients, who were discharged without complaints.

Implication of Tityus apiacas (Lourenco, 2002) in scorpion envenomations in the Southern Amazon border, Brazil

Abstract Herein, four cases of scorpion stings caused by Tityus apiacas recorded from the municipality of Apuí, in the southern region of the Brazilian Amazon, are described. Patients showed systemic clinical manifestations, described as unusual, involuntary, and generalized tingling and numbness, reported by patients as an electric shock sensation, lasting up to 24 hours after the sting. All patients described local pain and sensation, along with other clinical symptoms including local edema and erythema. Systemic manifestations were not life threatening. Antivenom therapy was administered to all patients, who were discharged without complaints.

Scorpion envenoming caused by Tityus cf. silvestris evolving with severe muscle spasms in the Brazilian Amazon.

Scorpion stings are a public health problem in the Brazilian Amazon. However, detailed clinical characterization with the proper animal identification is scarce. Here we report a confirmed case of envenoming by Tityus cf. silvestris in the Brazilian Amazon. The case evolved with generalized muscle spasms and was treated with antivenom and supportive therapy, requiring intensive care unit admission. The patient evolved favourably and was discharged after 9 days of hospitalization.

A profile of scorpionism, including the species of scorpions involved, in the State of Amazonas, Brazil.

INTRODUCTION: This study investigated scorpionism profile in the State of Amazonas, Brazil. METHODS: Data referring to stinging incidents were obtained from the National Databank of Major Causes of Morbidity. Information on the scorpion species involved was obtained from the Amazonas State health units. RESULTS: Amazonas has a scorpionism rate of 8.14 cases/100,000 inhabitants. Some municipalities (e.g., Apuí) presented higher rates (273 cases/100,000 inhabitants). Most species involved in envenomation belonged to the genus Tityus. CONCLUSIONS: Our results reaffirm the notion of scorpionism being a public health hazard and provide data that can guide public policy aimed at scorpionism prevention and treatment.

Chagas disease in the State of Amazonas: history, epidemiological evolution, risks of endemicity and future perspectives.

Chagas disease (CD) is a parasitic infection that originated in the Americas and is caused by Trypanosoma cruzi. In the last few years, the disease has spread to countries in North America, Asia and Europe due to the migration of Latin Americans. In the Brazilian Amazon, CD has an endemic transmission, especially in the Rio Negro region, where an occupational hazard was described for piaçaveiros (piassaba gatherers). In the State of Amazonas, the first chagasic infection was reported in 1977, and the first acute CD case was recorded in 1980. After initiatives to integrate acute CD diagnostics with the malaria laboratories network, reports of acute CD cases have increased. Most of these cases are associated with oral transmission by the consumption of contaminated food. Chronic cases have also been diagnosed, mostly in the indeterminate form. These cases were detected by serological surveys in cardiologic outpatient clinics and during blood donor screening. Considering that the control mechanisms adopted in Brazil's classic transmission areas are not fully applicable in the Amazon, it is important to understand the disease behavior in this region, both in the acute and chronic cases. Therefore, the pursuit of control measures for the Amazon region should be a priority given that CD represents a challenge to preserving the way of life of the Amazon's inhabitants.

Chagas disease in the State of Amazonas: history, epidemiological evolution, risks of endemicity and future perspectives

Chagas disease (CD) is a parasitic infection that originated in the Americas and is caused by Trypanosoma cruzi. In the last few years, the disease has spread to countries in North America, Asia and Europe due to the migration of Latin Americans. In the Brazilian Amazon, CD has an endemic transmission, especially in the Rio Negro region, where an occupational hazard was described for piaçaveiros (piassaba gatherers). In the State of Amazonas, the first chagasic infection was reported in 1977, and the first acute CD case was recorded in 1980. After initiatives to integrate acute CD diagnostics with the malaria laboratories network, reports of acute CD cases have increased. Most of these cases are associated with oral transmission by the consumption of contaminated food. Chronic cases have also been diagnosed, mostly in the indeterminate form. These cases were detected by serological surveys in cardiologic outpatient clinics and during blood donor screening. Considering that the control mechanisms adopted in Brazil's classic transmission areas are not fully applicable in the Amazon, it is important to understand the disease behavior in this region, both in the acute and chronic cases. Therefore, the pursuit of control measures for the Amazon region should be a priority given that CD represents a challenge to preserving the way of life of the Amazon's inhabitants.

Description of Trichophoromyia uniniensis, a new phlebotomine species (Diptera: Psychodidae: Phlebotominae) of Amazonas State, Brazil.

BACKGROUND: A new species of phlebotomine sand flies belonging to Trichophoromyia Barretto, 1962 genus is described, based on males collected in Jaú National Park, Amazonas state, Brazil. METHODS: The Sand flies were mounted in Canada balsam. They were measured with a binocular Olympus CH-2 microscope with the aid of a micrometer objective and the drawings were done with the help of a camera lucida. RESULTS: This new species named Trichophoromyia uniniensis sp. nov. is closely related to Trichophoromyia omagua (Martins, Llanos & Silva, 1976). The former can be distinguished from the latter by the shape of its paramere that has the lower apical region turned up in the new species. CONCLUSION: With the new species here described a total of 39 species belonging to the Trichophoromyia genus are now known, most of them present in the Amazon rainforest.

[Series of acute Chagas' disease cases attended at a tertiary-level clinic in Manaus, State of Amazonas, from 1980 to 2006]. / Série de casos agudos de doença de Chagas atendidos num serviço terciário de Manaus, Estado do Amazonas, de 1980 a 2006.

INTRODUCTION: Chagas disease is an emerging and neglected problem in the Brazilian Amazon region. METHODS: This study describes a series of acute autochthonous cases of Chagas disease that were attended at the Tropical Medicine Foundation of Amazonas, Manaus, between 1980 and 2006. RESULTS: Twenty-nine cases were recorded: 19 (65.5%) were male and 10 (34.5%) cases were female. Fifteen (51.7%) were isolated cases and 14 (48.3%) were from outbreaks. The commonest signs and symptoms were fever, fatigue, headache, myalgia, chills, pallor, dyspnea and edema of the face and lower limbs. No deaths were recorded. CONCLUSIONS: The disease occurred frequently among young people. The parasitological methods showed high sensitivity.

Série de casos agudos de doença de Chagas atendidos num serviço terciário de Manaus, Estado do Amazonas, de 1980 a 2006 / Series of acute Chagas' disease cases attended at a tertiary-level clinic in Manaus, State of Amazonas, from 1980 to 2006

INTRODUÇÃO: A doença de Chagas é um problema emergente e negligenciado na Região Amazônica. MÉTODOS: Descreve-se uma série de casos agudos autóctones de doença de Chagas atendidos na Fundação de Medicina Tropical do Amazonas, Manaus, de 1980 a 2006. RESULTADOS: Registraram-se 29 casos, sendo 19 do sexo masculino e 10 casos do sexo feminino. Quinze eram casos isolados e 14 provenientes de surtos. Os sinais/sintomas mais freqüentes foram febre, fadiga, cefaléia, mialgia, calafrios, palidez, dispnéia e edema de face e de membros inferiores. Não foi registrado nenhum óbito. CONCLUSÕES: A doença incidiu com frequência em jovens. Os métodos parasitológicos mostraram elevada sensibilidade.

INTRODUCTION: Chagas disease is an emerging and neglected problem in the Brazilian Amazon region. METHODS: This study describes a series of acute autochthonous cases of Chagas disease that were attended at the Tropical Medicine Foundation of Amazonas, Manaus, between 1980 and 2006. RESULTS: Twenty-nine cases were recorded: 19 (65.5 percent) were male and 10 (34.5 percent) cases were female. Fifteen (51.7 percent) were isolated cases and 14 (48.3 percent) were from outbreaks. The commonest signs and symptoms were fever, fatigue, headache, myalgia, chills, pallor, dyspnea and edema of the face and lower limbs. No deaths were recorded. CONCLUSIONS: The disease occurred frequently among young people. The parasitological methods showed high sensitivity.

Ocorrência de triatomíneos em ambientes silvestres e domiciliares do município de Manaus, Estado do Amazonas / Occurrences of triatomines in wild and domestic environments in the municipality of Manaus, State of Amazonas

A análise da distribuição de triatomíneos é essencial para a formulação de estratégias de controle da doença de Chagas na Região Amazônica. Neste trabalho, apresentam-se os resultados de capturas realizadas em ambientes silvestres e artificiais, em localidades rurais e urbanas de Manaus, Amazonas. Dos 115 triatomíneos coletados, 85 (73,9 por cento) são da espécie Rhodnius pictipes, 25 (21,7 por cento) de Rhodnius robustus e cinco (4,4 por cento) de Panstrongylus geniculatus. A taxa de infecção natural por flagelados foi de 5,9 por cento para Rhodnius pictipes e 8 por cento para Rhodnius robustus. Nenhum exemplar de Panstrongylus geniculatus estava infectado. Todos os exemplares infectados eram oriundos de fragmentos de matas da zona urbana. Verificou-se que 106 (92,2 por cento) triatomíneos foram coletados no ambiente silvestre e nove (7,8 por cento) nas unidades domiciliares pela busca ativa. O gênero Rhodnius predominou nitidamente no ambiente silvestre. Os exemplares de Panstrongylus geniculatus, todos adultos, foram coletados no intradomicílio. Não foram encontrados indícios de colonização domiciliar por triatomíneos.

Analysis of the distribution of triatomines is essential for formulating control strategies for Chagas disease in the Amazon region. In this paper, the results from trapping in wild and artificial environments in rural and urban localities in Manaus, Amazonas, are presented. Out of the 115 triatomines collected, 85 (73.9 percent) were of the species Rhodnius pictipes, 25 (21.7 percent) of Rhodnius robustus and five (4.4 percent) of Panstrongylus geniculatus. The rate of natural infection by flagellates was 5.9 percent for Rhodnius pictipes and 8 percent for Rhodnius robustus. None of the specimens of Panstrongylus geniculatus were infected. All of the infected specimens were from forest fragments in the urban zone. It was found that 106 insects (92.2 percent) were collected from the forest environment and nine (7.8 percent) in households, by means of the active search. The genus Rhodnius clearly predominated in the wild environment. The specimens of Panstrongylus geniculatus (all adults) were collected inside homes. There were no signs of domestic colonization by triatomines.

[Aedes aegypti and associated fauna in the rural zone of Manaus, in the Brazilian Amazon]. / Aedes aegypti e fauna associada em área rural de Manaus, na Amazônia brasileira.

After detecting Aedes aegypti larvae in the rural zone of Manaus, entomological surveillance was carried out over two consecutive years in order to notify occurrences of this species in that area. The tool of entomological surveillance has an important role among the preventive measures against diseases transmitted by insects, particularly arbovirosis.

Aedes aegypti e fauna associada em área rural de Manaus, na Amazônia brasileira / Aedes aegypti and associated fauna in the rural zone of Manaus, in the Brazilian Amazon

Após detectar larvas de Aedes aegypti em área rural de Manaus, realizou-se durante dois anos consecutivos um trabalho de notificação da ocorrência dessa espécie naquela área, através da vigilância entomológica, ferramenta que representa um importante papel entre as medidas preventivas contra doenças de transmissão por insetos em particular as arboviroses.

After detecting Aedes aegypti larvae in the rural zone of Manaus, entomological surveillance was carried out over two consecutive years in order to notify occurrences of this species in that area. The tool of entomological surveillance has an important role among the preventive measures against diseases transmitted by insects, particularly arbovirosis.