Ecobiology of Haemagogus leucocelaenus arbovirus vector in the golden lion tamarin translocation area of Rio de Janeiro, Brazil.

Significant pathogens that have resurfaced in humans originate from transmission from animal to human populations. In the Americas, yellow fever cases in humans are usually associated with spillover from non-human primates via mosquitoes. The present study characterized the prevalence of the yellow fever vector Haemagogus leucocelaenus in Rio de Janeiro, Brazil. The Atlantic Forest fragment chosen is an area of translocation of the golden lion tamarin (Leontopithecus rosalia), where 10 ovitraps were installed to collect mosquito eggs in Fazenda Três Irmãos, at Silva Jardim city, from March 2020 to October 2022. A total of 1514 eggs were collected, of which 1153 were viable; 50% belonged to medically important mosquito species and 24% to the yellow fever vector species, Hg. leucocelaenus. The months of December 2020 (n = 252), November 2021 (n = 188), and January 2022 (n = 252) had the highest densities of this vector. Haemagogus leucocelaenus was positively correlated with temperature (r = 0.303) and humidity (r = 0.48), with eggs hatching up to the 15th immersion with higher abundance of females. Implementing mosquito monitoring for arbovirus activity can help protect both the golden lion tamarin and human populations from the threat of arbovirus transmission.

YELLOW ALERT: Persistent Yellow Fever Virus Circulation among Non-Human Primates in Urban Areas of Minas Gerais State, Brazil (2021-2023).

Yellow fever virus (YFV) is the agent of yellow fever (YF), which affects both humans and non-human primates (NHP). Neotropical NHP are highly susceptible to YFV and considered sentinels for YFV circulation. Brazil faced a significant YF outbreak in 2017-2018, with over 2000 human cases and 2000 epizootics cases, mainly in the State of Minas Gerais, Brazil. This study aimed to investigate whether YFV circulation persisted in NHP after the human outbreak had subsided. To this end, NHP carcass samples collected in Minas Gerais from 2021 to 2023 were screened for YFV. RNA was extracted from tissue fragments and used in RT-qPCR targeting the YFV 5'UTR. Liver and lung samples from 166 animals were tested, and the detection of the ß-actin mRNA was used to ensure adequacy of RNA isolation. YFV RNA was detected in the liver of 18 NHP carcasses collected mainly from urban areas in 2021 and 2022. YFV positive NHP were mostly represented by Callithrix, from 5 out of the 12 grouped municipalities (mesoregions) in Minas Gerais state. These findings reveal the continued YFV circulation in NHP in urban areas of Minas Gerais during 2021 and 2022, with the attendant risk of re-establishing the urban YFV cycle.

Neotropical Sylvatic Mosquitoes and Aedes aegypti Are Not Competent to Transmit 17DD Attenuated Yellow Fever Virus from Vaccinated Viremic New World Non-Human Primates.

Beside humans, thousands of non-human primates (NHPs) died during the recent outbreak caused by the yellow fever virus (YFV) in Brazil. Vaccination of NHPs against YFV with the YF 17DD attenuated virus has emerged as a public health strategy, as it would reduce sylvatic transmission while also preserving endangered susceptible species. The hypothesis of establishing an uncontrolled transmission of this attenuated virus in nature was raised. We assessed vector competence of four sylvatic mosquito species, Haemagogus leucocelaenus, Haemagogus janthinomys/capricornii, Sabethes albiprivus, and Sabethes identicus, as well as the urban vector Aedes aegypti for YF 17DD attenuated vaccine virus when fed directly on eleven viremic lion tamarins or artificially challenged with the same virus. No infection was detected in 689 mosquitoes engorged on viremic lion tamarins whose viremia ranged from 1.05 × 103 to 6.61 × 103 FFU/mL, nor in those artificially taking ≤ 1 × 103 PFU/mL. Low viremia presented by YF 17DD-vaccinated New World NHPs combined with the low capacity and null dissemination ability in sylvatic and domestic mosquitoes of this attenuated virus suggest no risk of its transmission in nature. Thus, vaccination of captive and free-living NHPs against YFV is a safe public health strategy.

Yellow fever virus investigation in tissues of vampire bats Desmodus rotundus during a wild yellow fever outbreak in Brazilian Atlantic Forest.

In the last decade a large outbreak of Yellow Fever (YF) has been observed in Brazilian Atlantic Forest region, traditionally a non-endemic area. In this scenario, the role of wild mammal species as YF reservoirs can be questioned, especially the hematophagous bat, Desmodus rotundus. So, the objective of this study was to analyze molecularly the presence of the YF virus (YFV) in hematophagous bats during a YF outbreak in Brazil. Twenty-one samples were collected from seven adult male hematophagous bats D. rotundus. As YFV is considered a viscerotropic and neurotropic virus, samples of liver, kidney and brain were collected and molecularly analyzed using the RT qPCR technique. The animals were captured according to ethical protocols during a YF outbreak in Brazil in 2017, from a region of the Brazilian Atlantic Forest. The results revealed that the analyzed tissue samples were not infected with the YFV. The negative results for this bat species allow us to infer that other animals may be reservoirs of this virus in this ecosystem and they probably have not been identified yet. Therefore, health surveillance actions are essential to monitor the role of wild animals in the YF dissemination in Brazilian Atlantic Forest and alert to the possibility of new geographic amplification of areas where YF occurs. This research encourages the new search about the role of wild animals on YFV transmission and reinforces the importance of epidemiological surveillance in the transmission of human infectious diseases.

Epidemiologic profile and histopathological findings in Neotropical Primates during and after the yellow fever outbreak in Espírito Santo, Brazil.

Yellow fever (YF) is a viral disease whose transmission involves non-human primates (NHP), mosquitoes, and humans. Between 2016 and 2018 occurred the largest YF outbreak in the last 100 years in Brazil. We analyzed epidemiologic profile and geographic distribution of epizootics and described most frequent histopathological findings in NHP that died during YF outbreak in the state of Espírito Santo. We consider 487 epizootics notifications registered at the State Health Department from January 2017 to July 2020. Throughout the state, 51 (65.4%) municipalities reported epizootics, with more cases in central and metropolitan areas. Reverse transcription polymerase chain reaction and immunohistochemistry were laboratory tests performed for diagnosis of yellow fever, with 160 (32.9%) positive results, 314 (64.5%) negative and 13 (2.7%) inconclusive. Histopathological findings were compared statistically between positive and negative animals for YF. The liver was the most affected organ. Hemorrhage, hepatocyte necrosis, steatosis, cholestasis and eosinophilic degeneration were statistically more frequent in positive animals. Tubular necrosis, nephritis, congestion and lymphoid hypoplasia on spleen were statistically correlated to positive animals. Knowledge of pathogenic aspect of YF is necessary to guarantee that samples from Neotropical primates are properly used for YF surveillance purposes, to ensure appropriate diagnoses and subsequent public health responses.

Demographic changes in an Atlantic Forest primate community following a yellow fever outbreak.

We investigated demographic changes in three primate species (Alouatta guariba, Sapajus nigritus, and Callithrix flaviceps) at the Reserva Particular do Patrimônio Natural-Feliciano Miguel Abdala, Caratinga, Minas Gerais, Brazil, following a yellow fever outbreak (YFO) by comparing their population sizes before (2015) and after the outbreak (2017-2018), and by monitoring the size, composition, and reproductive status of groups from 2017 to 2021. Comparisons of pre- and post-YFO census data indicate the A. guariba population declined by 86.6%, from an estimated minimum of 522 individuals to 70 individuals. However, by October 2021, the population had grown to at least 86 individuals, with an adult sex ratio (N = 53) that was female-biased (0.61). Eleven of the 13 groups being monitored systematically were reproductively active with high survivorship to 12 months of age. S. nigritus declined by 40%, from 377 to 226 individuals. The sex ratio of 33 adult S. nigritus is also female-biased (0.71), and at least 8 of 15 groups being monitored are reproductively active. C. flaviceps declined by 80%, from 85 individuals to the 15-17 individuals observed from 2017 to 2021. The female-biased adult sex ratio and presence of infants and juveniles in the A. guariba and S. nigritus groups are encouraging signs, but there is still great concern, especially for C. flaviceps. Continued monitoring of the demographics of these primates is needed as their persistence appears to still be at risk.

Seasonal variation and intra urban heterogeneity of the entomological risk of transmission of dengue and yellow fever in Abidjan, Côte d'Ivoire.

Dengue and yellow fever are prevalent in Côte d'Ivoire and Aedes (Stegomyia) aegypti (Linnaeus), (Diptera: Culicidae), is known as the main vector. We aimed to assess seasonal variation and spatial heterogeneity in the transmission of both arbovirus diseases in Abidjan. Entomological surveys targeting larvae of A. aegypti, were carried out between November 2015 and August 2016 covering the four climatic seasons including a cohort of 100 houses randomly selected in three neighbourhoods. A. aegypti was the predominant species (96.6%) of mosquitoes resulting from the rearing of harvested larvae, and the only vector of dengue and yellow fever recorded during the study period. The highest proportion of water storage containers (45.5%) which represented the major breeding sites infested by the larvae of A. aegypti, was observed in Anoumabo. The house indices >5% and/or Breteau indices >20 recorded in each neighbourhood, during the different climatic seasons, indicated that there was, a high and permanent, heterogeneity in the transmission risk of dengue and yellow fever between the three neighbourhoods. In terms of transmission risk, Anoumabo was the neighbourhood with the highest risk compared to the two others, then, particular attention should be paid to this site in terms of surveillance by vector control programme in Abidjan.

Reemergence of yellow fever virus in southeastern Brazil, 2017-2018: What sparked the spread?

BACKGROUND: The 2017-2018 yellow fever virus (YFV) outbreak in southeastern Brazil marked a reemergence of YFV in urban states that had been YFV-free for nearly a century. Unlike earlier urban YFV transmission, this epidemic was driven by forest mosquitoes. The objective of this study was to evaluate environmental drivers of this outbreak. METHODOLOGY/PRINCIPAL FINDINGS: Using surveillance data from the Brazilian Ministry of Health on human and non-human primate (NHP) cases of YFV, we traced the spatiotemporal progression of the outbreak. We then assessed the epidemic timing in relation to drought using a monthly Standardized Precipitation Evapotranspiration Index (SPEI) and evaluated demographic risk factors for rural or outdoor exposure amongst YFV cases. Finally, we developed a mechanistic framework to map the relationship between drought and YFV. Both human and NHP cases were first identified in a hot, dry, rural area in northern Minas Gerais before spreading southeast into the more cool, wet urban states. Outbreaks coincided with drought in all four southeastern states of Brazil and an extreme drought in Minas Gerais. Confirmed YFV cases had an increased odds of being male (OR 2.6; 95% CI 2.2-3.0), working age (OR: 1.8; 95% CI: 1.5-2.1), and reporting any recent travel (OR: 2.8; 95% CI: 2.3-3.3). Based on this data as well as mosquito and non-human primate biology, we created the "Mono-DrY" mechanistic framework showing how an unusual drought in this region could have amplified YFV transmission at the rural-urban interface and sparked the spread of this epidemic. CONCLUSIONS/SIGNIFICANCE: The 2017-2018 YFV epidemic in Brazil originated in hot, dry rural areas of Minas Gerais before expanding south into urban centers. An unusually severe drought in this region may have created environmental pressures that sparked the reemergence of YFV in Brazil's southeastern cities.

Non-thrombotic pulmonary embolism of brain, liver, or bone marrow tissues associated with traumatic injuries in free-ranging neotropical primates.

From 2016 to 2019, Southeastern Brazil faced an outbreak of yellow fever (YF) affecting both humans and New World primates (NWP). The outbreak was associated with a marked increase in traumatic lesions in NWP in the affected regions. Non-thrombotic pulmonary embolization (NTPE) can be a consequence of massive traumatic events, and it is rarely reported in human and veterinary medicine. Here, we describe NTPE of the brain, liver, and bone marrow in free-ranging NWP, highlighting the epidemiological aspects of these findings and the lesions associated with this condition, including data on traumatic injuries in wild NWP populations during the course of a recent YF outbreak. A total of 1078 NWP were necropsied from January 2017 to July 2019. Gross traumatic injuries were observed in 444 marmosets (44.3%), 10 howler monkeys (23.2%), 9 capuchins (31.0%), 1 titi-monkey (50.0%), and 1 golden lion tamarin (33.3%). NTPE was observed in 10 animals, including 9 marmosets (2.0%) and 1 howler monkey (10.0%). NTPE was identified in the lung and comprised hepatic tissue in 1 case, brain tissue in 1 case, and bone marrow tissue in 8 cases. Although uncommon, it is important to consider NTPE with pulmonary vascular occlusion during the critical care of traumatized NWP. In addition, this study highlights the importance of conservational strategies and environmental education focusing on One Health, not only to protect these free-ranging NWP populations but also to maintain the efficacy of epidemiological surveillance programs.

Absence of yellow fever virus circulation in wildlife rodents from Brazil.

Yellow fever (YF), caused by the yellow fever virus (YFV), is an emerging viral zoonosis that affects humans and non-human primates (NHP). In South America, YF is naturally maintained through enzootic/sylvatic cycles involving NHPs and mosquitoes (Haemagogus and Sabethes). In this study, we retrospectively analyzed wildlife rodents to better understand their role in a potential alternative YF sylvatic cycle. The plaque reduction neutralization test was performed to detect anti-YFV antibodies, while qPCR targeting the NS5 region of flaviviruses and standard PCR targeting the CprM region were applied to detect YFV RNA in tissue and blood samples. YFV was not evidenced in any of the tested samples. These findings provide additional information regarding sylvatic YFV and emphasize the importance of YFV surveillance in wild animals as potential reservoirs/hosts given the well-established enzootic cycle in the studied areas, mainly in the Atlantic Forest.

[Yellow fever prevention and control: assessment of surveillance activities in a previously unaffected area in Brazil]. / Prevenção e controle da febre amarela: avaliação de ações de vigilância em área indene no Brasil.

Following the reemergence of yellow fever in 2014/2015, Brazil recorded its largest yellow fever epidemic in recent decades, mainly affecting the country's Southeast region. Yellow fever is a hemorrhagic viral disease caused by a flavivirus transmitted by sylvatic mosquitos (Haemagogus; Sabethes). In the urban cycle, eradicated in Brazil since 1942, the virus is transmitted by Aedes aegypti. Nonhuman primates are the principal hosts of the virus and constitute "sentinels" in yellow fever surveillance. This article describes the control and prevention activities launched during the yellow fever epidemic in the State of Espírito Santo, Brazil, and the implementation of vaccination, through an ecological study with a spatial approach. The study revealed the lack of detection of epizootics in nonhuman primates by surveillance services in Espírito Santo, with simultaneous detection in humans. The study presented the evolution of vaccination activities, reaching 85% overall coverage for the state in six months, varying widely, from 59% to 122%, between municipalities (counties). Importantly, 55% of the municipalities with timely immunization, considering the interval adopted for this study, did not present human cases. The intensification of surveillance activities, communication between areas, and multidisciplinary teams in managing the epidemic optimized the detection and diagnosis of human cases and allowed control of the epidemic. The study identifies progress and points to some late measures and gaps in surveillance that require improvements.

A partir da reemergência da febre amarela em 2014/2015, o Brasil registrou nos anos sequentes sua maior epidemia de febre amarela das últimas décadas, atingindo principalmente a região sudeste. A febre amarela, doença viral hemorrágica, é causada por um flavivírus, transmitido por mosquitos silvestres (Haemagogus; Sabethes). Na ocorrência do ciclo urbano, erradicado no Brasil desde 1942, a transmissão se dá pelo Aedes aegypti. Primatas não humanos são os principais hospedeiros do vírus e constituem "sentinelas" na vigilância da febre amarela. Este artigo descreve as ações de controle e prevenção desencadeadas durante a epidemia de febre amarela no Estado do Espírito Santo, Brasil, e a implementação da vacinação por meio de um estudo ecológico com abordagem espacial. O estudo evidenciou a falha na detecção de epizootias em primatas não humanos pelos serviços de vigilância do Espírito Santo, sendo simultânea à detecção em humanos. Apresentou a evolução das ações de vacinação, com alcance de 85% de cobertura vacinal geral para o estado em seis meses, sendo heterogênea entre os municípios (de 59% a 122%). Destaca-se que 55% dos municípios com ações de imunização em tempo oportuno, considerando o intervalo adotado para este estudo, não apresentaram casos em humanos. A intensificação das ações de vigilância, interlocução entre as áreas e equipes multidisciplinares na condução da epidemia otimizou a detecção e o diagnóstico dos casos em humanos e viabilizou o controle da epidemia. Foi possível reconhecer avanços, apontar algumas medidas tardias e lacunas na vigilância que necessitam melhorias.

A partir del resurgimiento de la fiebre amarilla en 2014/2015, Brasil registró los años siguientes su mayor epidemia de fiebre amarilla de las últimas décadas, alcanzando principalmente la región sudeste. La fiebre amarilla, enfermedad viral hemorrágica, es causada por un flavivirus, transmitido por mosquitos silvestres (Haemagogus; Sabethes). Respecto a la ocurrencia del ciclo urbano, erradicado en Brasil desde 1942, la transmisión se produce por el Aedes aegypti. Primates no humanos son los principales huéspedes del virus, y constituyen "centinelas" en la vigilancia de la fiebre amarilla. Este artículo describe las acciones de control y prevención desencadenadas durante la epidemia de fiebre amarilla en el Estado de Espírito Santo, Brasil, y la implementación de la vacunación mediante un estudio ecológico con abordaje espacial. El estudio evidenció el fallo en la detección de epizootias en primates no humanos por los servicios de vigilancia de Espírito Santo, siendo simultánea a la detección en humanos. Presentó la evolución de las acciones de vacunación, con alcance de un 85% de cobertura en la vacunación general para el estado en seis meses, siendo heterogénea entre los municipios (de 59% a 122%). Se destaca que un 55% de los municipios con acciones de inmunización en tiempo oportuno, considerando el intervalo adoptado para este estudio, no presentaron casos humanos. La intensificación de las acciones de vigilancia, interlocución entre las áreas y equipos multidisciplinarios en la gestión de la epidemia optimizó la detección y diagnóstico de los casos humanos y viabilizó el control de la epidemia. Fue posible reconocer avances, apuntar algunas medidas tardías y lagunas en la vigilancia que necesitan mejorías.

Prevenção e controle da febre amarela: avaliação de ações de vigilância em área indene no Brasil / Yellow fever prevention and control: assessment of surveillance activities in a previously unaffected area in Brazil / Prevención y control de la fiebre amarilla: evaluación de acciones de vigilancia en un área indemne de Brasil

A partir da reemergência da febre amarela em 2014/2015, o Brasil registrou nos anos sequentes sua maior epidemia de febre amarela das últimas décadas, atingindo principalmente a região sudeste. A febre amarela, doença viral hemorrágica, é causada por um flavivírus, transmitido por mosquitos silvestres (Haemagogus; Sabethes). Na ocorrência do ciclo urbano, erradicado no Brasil desde 1942, a transmissão se dá pelo Aedes aegypti. Primatas não humanos são os principais hospedeiros do vírus e constituem "sentinelas" na vigilância da febre amarela. Este artigo descreve as ações de controle e prevenção desencadeadas durante a epidemia de febre amarela no Estado do Espírito Santo, Brasil, e a implementação da vacinação por meio de um estudo ecológico com abordagem espacial. O estudo evidenciou a falha na detecção de epizootias em primatas não humanos pelos serviços de vigilância do Espírito Santo, sendo simultânea à detecção em humanos. Apresentou a evolução das ações de vacinação, com alcance de 85% de cobertura vacinal geral para o estado em seis meses, sendo heterogênea entre os municípios (de 59% a 122%). Destaca-se que 55% dos municípios com ações de imunização em tempo oportuno, considerando o intervalo adotado para este estudo, não apresentaram casos em humanos. A intensificação das ações de vigilância, interlocução entre as áreas e equipes multidisciplinares na condução da epidemia otimizou a detecção e o diagnóstico dos casos em humanos e viabilizou o controle da epidemia. Foi possível reconhecer avanços, apontar algumas medidas tardias e lacunas na vigilância que necessitam melhorias.

Following the reemergence of yellow fever in 2014/2015, Brazil recorded its largest yellow fever epidemic in recent decades, mainly affecting the country's Southeast region. Yellow fever is a hemorrhagic viral disease caused by a flavivirus transmitted by sylvatic mosquitos (Haemagogus; Sabethes). In the urban cycle, eradicated in Brazil since 1942, the virus is transmitted by Aedes aegypti. Nonhuman primates are the principal hosts of the virus and constitute "sentinels" in yellow fever surveillance. This article describes the control and prevention activities launched during the yellow fever epidemic in the State of Espírito Santo, Brazil, and the implementation of vaccination, through an ecological study with a spatial approach. The study revealed the lack of detection of epizootics in nonhuman primates by surveillance services in Espírito Santo, with simultaneous detection in humans. The study presented the evolution of vaccination activities, reaching 85% overall coverage for the state in six months, varying widely, from 59% to 122%, between municipalities (counties). Importantly, 55% of the municipalities with timely immunization, considering the interval adopted for this study, did not present human cases. The intensification of surveillance activities, communication between areas, and multidisciplinary teams in managing the epidemic optimized the detection and diagnosis of human cases and allowed control of the epidemic. The study identifies progress and points to some late measures and gaps in surveillance that require improvements.

A partir del resurgimiento de la fiebre amarilla en 2014/2015, Brasil registró los años siguientes su mayor epidemia de fiebre amarilla de las últimas décadas, alcanzando principalmente la región sudeste. La fiebre amarilla, enfermedad viral hemorrágica, es causada por un flavivirus, transmitido por mosquitos silvestres (Haemagogus; Sabethes). Respecto a la ocurrencia del ciclo urbano, erradicado en Brasil desde 1942, la transmisión se produce por el Aedes aegypti. Primates no humanos son los principales huéspedes del virus, y constituyen "centinelas" en la vigilancia de la fiebre amarilla. Este artículo describe las acciones de control y prevención desencadenadas durante la epidemia de fiebre amarilla en el Estado de Espírito Santo, Brasil, y la implementación de la vacunación mediante un estudio ecológico con abordaje espacial. El estudio evidenció el fallo en la detección de epizootias en primates no humanos por los servicios de vigilancia de Espírito Santo, siendo simultánea a la detección en humanos. Presentó la evolución de las acciones de vacunación, con alcance de un 85% de cobertura en la vacunación general para el estado en seis meses, siendo heterogénea entre los municipios (de 59% a 122%). Se destaca que un 55% de los municipios con acciones de inmunización en tiempo oportuno, considerando el intervalo adoptado para este estudio, no presentaron casos humanos. La intensificación de las acciones de vigilancia, interlocución entre las áreas y equipos multidisciplinarios en la gestión de la epidemia optimizó la detección y diagnóstico de los casos humanos y viabilizó el control de la epidemia. Fue posible reconocer avances, apuntar algunas medidas tardías y lagunas en la vigilancia que necesitan mejorías.

Dramatic decline in a titi monkey population after the 2016-2018 sylvatic yellow fever outbreak in Brazil.

Platyrrhini are highly vulnerable to the yellow fever (YF) virus. From 2016 to 2018, the Atlantic Forest of southeast Brazil faced its worst sylvatic YF outbreak in about a century, thought to have killed thousands of primates. It is essential to assess the impact of this epidemic on threatened primate assemblages to design effective conservation strategies. In this study, we assessed the impact of the 2016-2018 YF outbreak on a geographically isolated population of Near Threatened black-fronted titi monkeys (Callicebus nigrifrons) in two Atlantic Forest patches of the Santuário do Caraça, MG, Brazil. Extensive preoutbreak monitoring, conducted between 2008 and 2016, revealed that the home range and group sizes of the population remained stable. In 2016, the population size was estimated at 53-57 individuals in 11-12 groups. We conducted monitoring and playback surveys in 2019 and found that the population had decreased by 68% in one forest patch and completely vanished in the other, resulting in a combined decline of 80%. We discuss this severe loss of a previously stable population and conclude that it was highly likely caused by the YF outbreak. The remaining population is at risk of disappearing completely because of its small size and geographic isolation. A systematic population surveys of C. nigrifrons, along other sensible Platyrrhini species, is needed to re-evaluate their current conservation status.

Evaluation of the Diversity of Culicidae Vectors of the Sylvatic Yellow Fever Virus in Atlantic Forest Remnants with the Use of Ovitraps and Bamboo Traps.

Mosquitoes transmit several pathogens in tropical regions, especially in forest areas. The diseases caused by these pathogens include malaria and several arboviruses such as yellow fever. Brazil has the largest endemic area in the world for yellow fever. Many factors can affect the sylvatic cycle of the disease, shifting it into human-inhabited areas. This study aims to examine the oviposition behavior of mosquito species that are effective or potential vectors of the yellow fever virus and which colonize bamboo traps and ovitraps installed at different heights. The positions of the traps in the strata were changed every 15 days. The collection of immature stages (eggs, larvae, and pupae) was performed every 2 weeks for 12 months from August 2018 to July 2019 in the city of Nova Iguaçu, state of Rio de Janeiro, Brazil, in an area near the Tinguá Biological Reserve (REBIO) in the districts of Adrianópolis and Rio D'ouro. Statistical tests were used to compare oviposition at each stratum, and correlation tests showed the relationship between the presence of eggs and immature mosquitoes (larvae and pupae) and temperature, precipitation, and trap type. The diversity was calculated for each trap type and height, as well as the dry and rainy seasons. During the sampling period, 3929 eggs and 4953 larvae and pupae were collected. The traps installed in the high strata remained empty when traps on the ground were installed at the same time, although not when they were installed on their own. The results obtained with this new proposed methodology suggest that diversity is greatest in the rainy season and in bamboo traps for either stratum. Furthermore, this study suggests that mosquitoes begin searching for breeding sites at ground level. Higher levels may be occupied due to the absence or impermanence of other breeding sites.

Yellow Fever as Cause of Death of Titi Monkeys (Callicebus Spp.).

From 2016 to 2018, an epidemic wave of yellow fever (YF) occurred in Brazil, affecting a large number of Platyrrhini monkeys. Titi monkeys (Callicebus spp.) were severely affected yet pathological characterizations are lacking. This study characterized epizootic YF in 43 titi monkeys (Callicebus spp.) with respect to the microscopic lesions in liver, kidney, spleen, heart, brain, and lung, as well as the distribution of immunolabeling for YF virus antigen, and the flaviviral load in the liver. Of 43 titi monkeys examined, 18 (42%) were positive for yellow fever virus (YFV) by immunohistochemistry or reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR). Affected livers had consistent marked panlobular necrotizing hepatitis, lipidosis, and mild inflammation, with intense immunolabeling for YFV mainly in centrilobular hepatocytes (zone 1; P = .05). In the spleen, consistent findings were variable lymphoid depletion (10/11), lymphoid necrosis (lymphocytolysis; 4/11), and immunolabeling for YFV in histiocytic cells (3/16). The main finding in the kidney was multifocal acute necrosis of tubular epithelium (5/7) that was occasionally associated with intracytoplasmic immunolabeling for YFV (6/15). These data indicate that titi monkeys are susceptible to YFV infection, developing severe hepatic lesions and high viral loads, comparable to humans and Alouatta spp. Thus, Callicebus spp. may be reliable sentinels for YF surveillance.

Efficiency of the CO2 -baited omni-directional Fay-Prince trap under semi-field conditions and characterizing response behaviours for the yellow fever mosquito, Aedes aegypti.

Aedes aegypti (L.) (Diptera: Culicidae) is a vector of several serious disease-causing viruses including Dengue, Zika, chikungunya and yellow fever. Effective and efficient trapping methods are essential for meaningful mosquito population and disease-presence surveillance and ultimately, vector control. The Fay-Prince trap (FPT) was developed in the late 1960s as a daytime visual trap for male Ae. aegypti. Since then, its use has been expanded into the trapping of female Ae. aegypti, Aedes albopictus Skuse, other Ae. spp., and Culex spp. The efficiency of the FPT alone and with CO2 was tested under semi-field conditions and the behaviour of responding female Ae. aegypti was characterized. The mean capture efficiency of the FPT with CO2 per 30 min in the greenhouse was 3.07% and the capture rate from the total number of mosquitoes in our semi-field setup was slightly higher at 4.45%. Understanding the behaviours that mosquitoes exhibit during their encounter with particularly a visual trap may recommend trap improvements and contributes to our understanding of host-seeking behaviour and how it might be exploited.

Differential Yellow Fever Susceptibility in New World Nonhuman Primates, Comparison with Humans, and Implications for Surveillance.

A major outbreak of yellow fever (YF) occurred in Brazil during 2016-2018. Epizootics in New World nonhuman primates are sentinel events for YF virus circulation. However, genus-specific susceptibilities and suitability for YF surveillance remain poorly understood. We obtained and compared epidemiologic, histopathologic, immunohistochemical, and molecular results from 93 human and 1,752 primate cases submitted during the recent YF outbreak in Brazil (2017), with the support of the Brazilian National YF Surveillance Program. We detected heterogeneous YF-associated profiles among the various genera of primates we analyzed. Alouatta primates were the most reliable sentinel; Sapajus and Callicebus primates had higher viral loads but lower proportional mortality rates. Callithrix primates were the least sensitive, showing lower viral loads, lower proportional mortality rates, and no demonstrable YF virus antigen or extensive lesions in liver, despite detectable viral RNA. These differences in susceptibility, viral load, and mortality rates should be considered in strategic surveillance of epizootics and control measures for YF.

Yellow fever surveillance challenge: Investigation of a marmoset non-autochthonous case.

Yellow fever (YF) surveillance in Brazil is focused mainly on the detection of epizootic events regarding New World non-human primates (NWNHP). We present a challenging case of a Callitrichidae (Callithrix spp) kept as a domiciliated pet that lived in the urban area of São Paulo municipality and was positive to YF virus by RT-qPCR and immunohistochemistry. After investigation, it was the first occurrence of non-autochthonous YF case of NWNHP described, with probable place of infection in the North shore of São Paulo state. This case illustrates the importance of coordinated laboratorial and field actions, and risks posed by transit of wildlife.

Histopathologic Patterns and Susceptibility of Neotropical Primates Naturally Infected With Yellow Fever Virus.

Yellow fever is an important zoonotic viral disease that can be fatal for both human and nonhuman primates. We evaluated histopathologic changes in free-ranging neotropical primates naturally infected with yellow fever virus (YFV) compared with uninfected cohorts. The most frequent lesions in primates infected with YFV were hepatic changes characterized by midzonal necrosis with lipidosis and mild inflammation including lymphocytes, macrophages, plasma cells, and infrequently neutrophils. Importantly, severe necrotizing hepatic lesions were often observed in Alouatta sp. (howler monkeys), whereas Callithrix sp. (common marmosets) had nearly no hepatic changes. Moderate to severe hepatic necrosis was present in 21/23 (91%) of the YFV-positive Alouatta sp. compared with 10/29 (34%) of the YFV-positive Callithrix sp. (P < .0001; odds ratio = 20). Similarly, hepatitis was more intense in Alouatta sp. compared with Callithrix sp. Furthermore, the frequency of YFV infection was significantly higher in Alouatta sp. compared with Callithrix sp. or Sapajus sp. (capuchin monkeys). Therefore, these data support the notion that Alouatta sp. is highly susceptible to infection and YFV-induced lesions, whereas Callithrix sp. is susceptible to infection but has a lower frequency of YFV-induced lesions.

Yellow fever transmission in non-human primates, Bahia, Northeastern Brazil.

Yellow fever virus (YFV) causes a clinical syndrome of acute hemorrhagic hepatitis. YFV transmission involves non-human primates (NHP), mosquitoes and humans. By late 2016, Brazil experienced the largest YFV outbreak of the last 100 years, with 2050 human confirmed cases, with 681 cases ending in death and 764 confirmed epizootic cases in NHP. Among affected areas, Bahia state in Northeastern was the only region with no autochthonous human cases. By using next generation sequence approach, we investigated the molecular epidemiology of YFV in NHP in Bahia and discuss what factors might have prevented human cases. We investigated 47 YFV positive tissue samples from NHP cases to generate 8 novel YFV genomes. ML phylogenetic tree reconstructions and automated subtyping tools placed the newly generated genomes within the South American genotype I (SA I). Our analysis revealed that the YFV genomes from Bahia formed two distinct well-supported phylogenetic clusters that emerged most likely of an introduction from Minas Gerais and Espírito Santo states. Vegetation coverage analysis performed shows predominantly low to medium vegetation coverage in Bahia state. Together, our findings support the hypothesis of two independent YFV SA-I introductions. We also highlighted the effectiveness of the actions taken by epidemiological surveillance team of the state to prevented human cases.