First case of Oropouche fever detected in the international border region of the Colombian Amazon: clinical characteristics and molecular diagnosis.

OBJECTIVES: We report the first case of Oropouche fever detected in the border region of Colombia. METHODS: Using a multiplex real-time polymerase chain reaction (PCR), genetic sequencing and clinical characteristics during the dengue epidemic in 2019, a total of 175 samples were analysed, from cases notified to the system epidemiological surveillance such as dengue. FINDINGS: The Oropouche virus (OROV) isolate from Leticia belongs to lineage 2 according to both M and S genome segments maximum likelihood (ML) analysis, shares a common ancestor with samples obtained in Esmeraldas, Ecuador and Turbaco, Colombia. The patient: a woman resident in the border neighbourhood of the municipality of Leticia had the following symptoms: fever, headache, retro-orbital pain and myalgias. MAIN CONCLUSION: This cross-border surveillance can be useful to give an alert about the entry or exit of arboviruses circulation in the region, which are often underreported in public health surveillance systems.

Deep Sequencing Reveals Occult Mansonellosis Coinfections in Residents From the Brazilian Amazon Village of São Gabriel da Cachoeira.

Mansonella ozzardi and Mansonella perstans infections both cause mansonellosis but are usually treated differently. Using a real-time polymerase chain reaction assay and deep sequencing, we reveal the presence of mansonellosis coinfections that were undetectable by standard diagnostic methods. Our results confirm mansonellosis coinfections and have important implications for the disease's treatment and diagnosis.

Genomic and phylogenetic characterisation of an imported case of SARS-CoV-2 in Amazonas State, Brazil.

A new coronavirus [severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)] is currently causing a life-threatening pandemic. In this study, we report the complete genome sequencing and genetic characterisation of a SARS-CoV-2 detected in Manaus, Amazonas, Brazil, and the protocol we designed to generate high-quality SARS-CoV-2 full genome data. The isolate was obtained from an asymptomatic carrier returning from Madrid, Spain. Nucleotide sequence analysis showed a total of nine mutations in comparison with the original human case in Wuhan, China, and support this case as belonging to the recently proposed lineage A.2. Phylogeographic analysis further confirmed the likely European origin of this case. To our knowledge, this is the first SARS-CoV-2 genome obtained from the North Brazilian Region. We believe that the information generated in this study may contribute to the ongoing efforts toward the SARS-CoV-2 emergence.

Resurgence of Vaccine-Preventable Diseases in Venezuela as a Regional Public Health Threat in the Americas.

Venezuela's tumbling economy and authoritarian rule have precipitated an unprecedented humanitarian crisis. Hyperinflation rates now exceed 45,000%, and Venezuela's health system is in free fall. The country is experiencing a massive exodus of biomedical scientists and qualified healthcare professionals. Reemergence of arthropod-borne and vaccine-preventable diseases has sparked serious epidemics that also affect neighboring countries. In this article, we discuss the ongoing epidemics of measles and diphtheria in Venezuela and their disproportionate impact on indigenous populations. We also discuss the potential for reemergence of poliomyelitis and conclude that action to halt the spread of vaccine-preventable diseases within Venezuela is a matter of urgency for the country and the region. We further provide specific recommendations for addressing this crisis.

Detection of Mansonella ozzardi among blood donors from highly endemic interior cities of Amazonas state, northern Brazil.

BACKGROUND: In the Brazilian Amazon, the filarial nematode Mansonella ozzardi co-exists with malaria parasites and thick blood smear microscopy is considered the diagnostic gold standard. Transfusion of M. ozzardi microfilariae does not establish new infections, however microfilariae can survive approximately 2 years in blood-recipients with unknown risk of pathology. Data on transfusion-transmitted filariasis are lacking. This study investigated M. ozzardi parasitemias in blood donors from decentralized centers of "Fundação Hematologia e Hemoterapia do Estado do Amazonas/HEMOAM," Northern Brazil. STUDY DESIGN AND METHODS: Cross-sectional investigation employing blood smear microscopy (n = 356) and qualitative nested-M. ozzardi-PCR (227 out of 356) in donor candidates from 19 hemocenters in interior/rural municipalities of Amazonas state. FINDINGS: Participants were mostly young males. Positivity by microscopy was 7.9% (28 out of 356) and 23.8% by M. ozzardi-PCR (54 out of 227). Parasitaemias were found in 16 out of 19 municipalities. In 54 M. ozzardi-positives, 24 were ineligible; among 30 that donated, 27 were interdicted by seropositivity (22 anti-HBc, 3 anti-HBc + HBsAg, 1 Chagas+malaria, 1 VDRL). Seropositivty was higher in M. ozzardi-PCR-positives vs M. ozzardi-PCR-negatives (OR = 15.8, 95% CI 4.5-56.1, p < 0.0001). Three M. ozzardi contaminated blood units were transfused, but no follow-up information on the recipients is available. MAIN CONCLUSIONS: Our study provides important baseline data on M. ozzardi among blood donors from the Brazilian Amazon. Further investigations in endemic areas are necessary to clarify possible association between M. ozzardi and other infections and also to elucidate whether there is any significant clinical effect upon transfusion of contaminated blood.

Molecular Verification of New World Mansonella perstans Parasitemias.

We obtained ribosomal and mitochondrial DNA sequences from residents of Amazonas state, Brazil, with Mansonella parasitemias. Phylogenetic analysis of these sequences confirm that M. ozzardi and M. perstans parasites occur in sympatry and reveal the close relationship between M. perstans in Africa and Brazil, providing insights into the parasite's New World origins.

Mosquito-Disseminated Insecticide for Citywide Vector Control and Its Potential to Block Arbovirus Epidemics: Entomological Observations and Modeling Results from Amazonian Brazil.

BACKGROUND: Mosquito-borne viruses threaten public health worldwide. When the ratio of competent vectors to susceptible humans is low enough, the virus's basic reproductive number (R0) falls below 1.0 (each case generating, on average, <1.0 additional case) and the infection fades out from the population. Conventional mosquito control tactics, however, seldom yield R0 < 1.0. A promising alternative uses mosquitoes to disseminate a potent growth-regulator larvicide, pyriproxyfen (PPF), to aquatic larval habitats; this kills most mosquito juveniles and substantially reduces adult mosquito emergence. We tested mosquito-disseminated PPF in Manacapuru, a 60,000-inhabitant city (~650 ha) in Amazonian Brazil. METHODS AND FINDINGS: We sampled juvenile mosquitoes monthly in 100 dwellings over four periods in February 2014-January 2016: 12 baseline months, 5 mo of citywide PPF dissemination, 3 mo of focal PPF dissemination around Aedes-infested dwellings, and 3 mo after dissemination ended. We caught 19,434 juvenile mosquitoes (66% Aedes albopictus, 28% Ae. aegypti) in 8,271 trap-months. Using generalized linear mixed models, we estimated intervention effects on juvenile catch and adult emergence while adjusting for dwelling-level clustering, unequal sampling effort, and weather-related confounders. Following PPF dissemination, Aedes juvenile catch decreased by 79%-92% and juvenile mortality increased from 2%-7% to 80%-90%. Mean adult Aedes emergence fell from 1,077 per month (range 653-1,635) at baseline to 50.4 per month during PPF dissemination (range 2-117). Female Aedes emergence dropped by 96%-98%, such that the number of females emerging per person decreased to 0.06 females per person-month (range 0.002-0.129). Deterministic models predict, under plausible biological-epidemiological scenarios, that the R0 of typical Aedes-borne viruses would fall from 3-45 at baseline to 0.004-0.06 during PPF dissemination. The main limitations of our study were that it was a before-after trial lacking truly independent replicates and that we did not measure mosquito-borne virus transmission empirically. CONCLUSIONS: Mosquito-disseminated PPF has potential to block mosquito-borne virus transmission citywide, even under adverse scenarios. Our results signal new avenues for mosquito-borne disease prevention, likely including the effective control of Aedes-borne dengue, Zika, and chikungunya epidemics. Cluster-randomized controlled trials will help determine whether mosquito-disseminated PPF can, as our findings suggest, develop into a major tool for improving global public health.

The mitogenome of Onchocerca volvulus from the Brazilian Amazonia focus.

We report here the first complete mitochondria genome of Onchocerca volvulus from a focus outside of Africa. An O. volvulus mitogenome from the Brazilian Amazonia focus was obtained using a combination of high-throughput and Sanger sequencing technologies. Comparisons made between this mitochondrial genome and publicly available mitochondrial sequences identified 46 variant nucleotide positions and suggested that our Brazilian mitogenome is more closely related to Cameroon-origin mitochondria than West African-origin mitochondria. As well as providing insights into the origins of Latin American onchocerciasis, the Brazilian Amazonia focus mitogenome may also have value as an epidemiological resource.

Outstanding insecurities concerning the use of an Ov16-based ELISA in the Amazonia onchocerciasis focus.

In a recent issue of Memórias do Instituto Oswaldo Cruz, published in Rio de Janeiro in February 2014 (109: 87-92), Adami et al. have published a survey reporting Mansonella parasite prevalence in the Amazon Region. This report makes a useful contribution to the existing knowledge of filarial parasite distribution within the Amazon area, parasite prevalence rates in relation to age and occupation and provides observations on the possible clinical impact of Mansonella ozzardi. Their publication also provides an account of what appears to be a novel ELISA that has recently been used in the Simuliidae and Onchocerciasis Laboratory of the Oswaldo Cruz Institute, Rio de Janeiro, Brazil. We are concerned that the publication of this ELISA may have created an excessively positive impression of the effectiveness of the onchocerciasis recrudescence serological surveillance tools that are presently available for use in the Amazonia onchocerciasis focus. In this letter we have, thus, sought to highlight some of the limitations of this ELISA and suggest how continuing insecurities concerning the detection of antibodies to Onchocerca volvulus within the Amazonia onchocerciasis focus might be minimised.

Evaluation of Aedes aegypti control intervention with pyriproxyfen by lcWGS in Manacapuru, Amazonas, Brazil.

BACKGROUND: Ae. aegypti mosquitoes are considered a global threat to public health due to its ability to transmit arboviruses such as yellow fever, dengue, Zika and Chikungunya to humans. The lack of effective arboviral vaccines and etiological treatments make vector control strategies fundamental in interrupting the transmission cycle of these pathogens. This study evaluated Ae. aegypti mosquito populations pre- and post-intervention period with disseminating stations of the larvicide pyriproxyfen to understand its potential influence on the genetic structure and population diversity of these vectors. METHODOLOGY/PRINCIPAL FINDINGS: This study was conducted in Manacapuru city, Amazonas, Brazil, where 1,000 pyriproxyfen dissemination stations were deployed and monitored from FEB/2014 to FEB/2015 (pre-intervention) and AUG/2015 to JAN/2016 (post-intervention). Low-coverage whole genome sequencing of 36 individuals was performed, revealing significant stratification between pre- and post-intervention groups (pairwise FST estimate of 0.1126; p-value < 0.033). Tajima's D estimates were -3.25 and -3.07 (both p-value < 0.01) for pre- and post-intervention groups, respectively. Molecular diversity estimates (Theta(S) and Theta(Pi)) also showed divergences between pre- and post-intervention groups. PCA and K-means analysis showed clustering for SNP frequency matrix and SNP genotype matrix, respectively, being both mainly represented by the first principal component. PCA and K-means clustering also showed significant results that corroborate the impact of pyriproxyfen intervention on genetic structure populations of Ae. aegypti mosquitoes. CONCLUSIONS/SIGNIFICANCE: The results revealed a bottleneck effect and reduced mosquito populations during intervention, followed by reintroduction from adjacent and unaffected populations by this vector. We highlighted that low-coverage whole genome sequencing can contribute to genetic and structure population data, and also generate important information to aid in genomic and epidemiological surveillance.

Mosquito-disseminated pyriproxyfen for mosquito-borne disease control in Belo Horizonte, Brazil: a pragmatic, before-after control-intervention paired-series trial.

BACKGROUND: Mosquitoes transmit important human pathogens, including dengue virus, but are notoriously hard to control. Mosquito-disseminated pyriproxyfen (MDPPF) uses the mosquitoes themselves to transfer particles of pyriproxyfen, a potent larvicide and pupicide, from lure dissemination stations to untreated larval habitats. MDPPF can reduce mosquito densities, but possible epidemiological effects remain to be measured. We aimed to investigate whether MDPPF can help curb mosquito-borne disease transmission. METHODS: In this pragmatic, before-after control-intervention paired-series (BACIPS) trial conducted in Belo Horizonte, Brazil, municipal vector-control staff deployed, then serviced monthly (from November, 2017, to December, 2019), 2481 pyriproxyfen dissemination stations in a nine-neighbourhood cluster with a history of high dengue endemicity; nine adjacent neighbourhoods were designated as a buffer area, and the remaining 258 city neighbourhoods as the control area. The primary epidemiological outcome of the trial was dengue incidence. Based on official dengue-notification records broken down by week and neighbourhood (ie, week-neighbourhood case counts; N=265 162 cases in total) from Jan 1, 2016, to Dec 31, 2019, we estimated intervention effects on incidence using a BACIPS approach and negative-binomial generalised linear mixed models (GLMMs). Zika and chikungunya cases were too rare to be assessed with confidence. FINDINGS: Week-neighbourhood dengue incidence ranged from 0 to 379·5 cases per 10 000 residents, with epidemic outbreaks recorded in 2016 and 2019. Intention-to-treat, BACIPS-GLMM adjusted estimates indicate that MDPPF deployment was associated with a net 29% (95% CI 21-36; p=4·7 × 10-10) average decrease of dengue incidence in intervention neighbourhoods and a net 21% (12-30; p=2·7 × 10-5) average decrease in buffer neighbourhoods. In contrast, and due in part to larger uncertainties, average incidence rates were statistically indistinguishable across areas before the intervention (intervention area p=0·47; buffer area p=0·11) and across trial periods in control neighbourhoods (p=0·74). Hence, in the all-too-common scenario of a 100 000-case outbreak, public health managers could expect MDPPF to reduce the strain on the health-care system by at least about 29 000 (21 000-36 000) symptomatic cases. INTERPRETATION: Our results suggest that MDPPF can help prevent dengue under the many operational constraints of real-world vector-control interventions and despite incomplete coverage and potential dilution of intervention effects. MDPPF holds promise as an additional tool for dengue control. FUNDING: Coordenação-Geral de Vigilância de Arboviroses, Secretaria de Vigilância em Saúde e Ambiente, Ministry of Health, Brazil, Secretaria Municipal de Saúde de Belo Horizonte, Brazil, and Fundação de Amparo à Pesquisa do Estado do Amazonas, Brazil.

Diflubenzuron larvicide auto-dissemination: A modeling study.

Proposing substitutes for Pyriproxyfen (PPF) in the auto-dissemination strategy is essential to ensure the continuity of the strategy in the field, especially in the case of the emergence of populations resistant to this larvicide. One possible substitute among the compounds already in use in Brazil is the larvicide Diflubenzuron (DFB). The equation that defines the proportion of oviposition sites (habitats) contaminated by the auto-dissemination strategy was modified to account for the number of visits required to reach the necessary concentration of DFB for contamination, considering scenarios with varying numbers of oviposition sites and mosquito densities. The dissemination was evaluated in oviposition sites of 2 L, 1.5 L, 1 L, 0.5 L, 0.2 L, and 0.1 L. The minimum concentration of active ingredient (a.i) of DFB required for a commercial product to contaminate at least 50% of oviposition sites was also investigated, along with the impact of other vector control methods, such as the removal/destruction of oviposition sites and the use of insecticides to kill adult 'females, on the auto-dissemination approach. The use of pure DFB compounds enabled contamination efficiency of more than 50% in oviposition sites with a volume of less than 2 L in scenarios with fewer oviposition sites. On the other hand, with the use of the commonly used concentration of the product, similar efficacy was only achieved in oviposition sites of 0.1 L and 0.2 L in medium and high infestation scenarios. Strategies that reduce the number of available oviposition sites work synergistically with the auto-dissemination strategy, making it possible to use less concentrated products and contaminated sites of larger volume. The strategy proved to be resilient in situations of insecticide application according to the concentration of DFB used, abundance of females, and low number of oviposition sites. Increasing the number of dissemination traps on the field also contributes to better results, especially for oviposition sites of 0.5 L and 1 L. The results of the model obtained under the stipulated conditions provide further support for the potential use of DFB as a substitute for PPF in the auto-dissemination strategy.

Impact of Long-Term Pyriproxyfen Exposure on the Genetic Structure and Diversity of Aedes aegypti and Aedes albopictus in Manaus, Amazonas, Brazil.

Aedes aegypti and Aedes albopictus are responsible for transmitting major human arboviruses such as Dengue, Zika, and Chikungunya, posing a global threat to public health. The lack of etiological treatments and efficient vaccines makes vector control strategies essential for reducing vector population density and interrupting the pathogen transmission cycle. This study evaluated the impact of long-term pyriproxyfen exposure on the genetic structure and diversity of Ae. aegypti and Ae. albopictus mosquito populations. The study was conducted in Manaus, Amazonas, Brazil, where pyriproxyfen dissemination stations have been monitored since 2014 up to the present day. Double digest restriction-site associated DNA sequencing was performed, revealing that despite significant local population reductions by dissemination stations with pyriproxyfen in various locations in Brazil, focal intervention has no significant impact on the population stratification of these vectors in urban scenarios. The genetic structuring level of Ae. aegypti suggests it is more stratified and directly affected by pyriproxyfen intervention, while for Ae. albopictus exhibits a more homogeneous and less structured population. The results suggest that although slight differences are observed among mosquito subpopulations, intervention focused on neighborhoods in a capital city is not efficient in terms of genetic structuring, indicating that larger-scale pyriproxyfen interventions should be considered for more effective urban mosquito control.

Corrigendum: Implementing a provisional overarching intervention for COVID-19 monitoring and control in the Brazil-Colombia-Peru frontier.

[This corrects the article DOI: 10.3389/fpubh.2023.1330347.].

Detection of DENV-4 genotype I from mosquitoes collected in the city of Manaus, Brazil.

BACKGROUND: Dengue epidemics have been reported in Brazil since 1981. In Manaus, a large city in the Amazon region, dengue is endemic with all four-virus serotypes (DENV-1, -2, -3, and -4) simultaneously causing human disease. In 2008, during a surveillance of dengue virus in mosquitoes in the district of Tancredo Neves in Manaus, 260 mosquitoes of Aedes genus were captured, identified and grouped into pools of 10 mosquitoes. FINDINGS: RNA extracts of mosquito pools were tested by a RT-Hemi-Nested-PCR for detection of flaviviruses. One amplicon of 222 bp, compatible with dengue virus serotype 4, was obtained from a pool of Aedes aegypti. The nucleotide sequence of the amplicon indicated that the mosquitoes were infected with DENV-4 of genotype I. This virus of Asian origin has been described in Manaus in 2008 infecting acute febrile illness patients. CONCLUSION: This is the first report of dengue virus serotype 4 genotype I infecting Aedes aegypti in the Americas.

Implementing a provisional overarching intervention for COVID-19 monitoring and control in the Brazil-Colombia-Peru frontier.

Introduction: he challenge was to provide comprehensive health resources to a remote and underserved population living in the Brazil-Colombia-Peru border, amid the most disruptive global crisis of the century. Methods: In August 2021, Fundação Oswaldo Cruz Amazonia (FIOCRUZ Amazônia) and partner collaborators implemented an overarching provisional program for SARS-CoV-2 detection and lineages characterization, training of laboratory personnel and healthcare providers, donation of diagnostic supplies and personal protective equipment, and COVID-19 vaccination. The expedition was conducted at the Port of Tabatinga, a busy terminal with an intense flux of people arriving and departing in boats of all sizes, located in the Amazon River basin. Local government, non-profit organizations, private companies, and other stakeholders supported the intervention. Results: The expedition was accomplished in a convergence point, where migrant workers, traders, army personnel, people living in urban areas, and people from small villages living in riversides and indigenous territories are in close and frequent contact, with widespread cross-border movement. Using a boat as a provisional lab and storage facility, the intervention provided clinical and laboratory monitoring for 891 participants; vaccination for 536 individuals; personal protective equipment for 200 healthcare providers; diagnostic supplies for 1,000 COVID-19 rapid tests; training for 42 community health agents on personal protection, rapid test execution, and pulse oximeter management; and hands-on training for four lab technicians on molecular diagnosis. Discussion: Our experience demonstrates that multilateral initiatives can counterweigh the scarcity of health resources in underserved regions. Moreover, provisional programs can have a long-lasting effect if investments are also provided for local capacity building.

Declining prevalence of hepatitis A virus antibodies among children from low socioeconomic groups reinforces the need for the implementation of hepatitis A vaccination in Brazil.

Age-related seroprevalence studies that have been conducted in Brazil have indicated a transition from a high to a medium endemicity of hepatitis A virus (HAV) infection in the population. However, most of these studies have focused on urban populations that experience lower incidence rates of HAV infection. In the current study, the prevalence of anti-HAV antibodies was investigated in children with a low socioeconomic status (SES) that live on the periphery of three capital cities in Brazil. A total of 1,162 dried blood spot samples were collected from individuals whose ages ranged from one-18 years and tested for anti-HAV antibodies. A large number of children under five years old (74.1-90%) were identified to be susceptible to HAV infection. The anti-HAV antibody prevalence reached ≥ 50% among those that were 10-14 years of age or older. The anti-HAV prevalence rates observed were characteristics of regions with intermediate level of hepatitis A endemicity. These data indicated that a large proportion of children with a low SES that live at the periphery of urban cities might be at risk of contracting an HAV infection. The hepatitis A vaccine that is currently offered in Brazil is only available for high-risk groups or at private clinics and is unaffordable for individuals with a lower SES. The results from this study suggest that the hepatitis A vaccine should be included in the Brazilian National Program for Immunisation.

Molecular detection of Mansonella mariae incriminates Simulium oyapockense as a potentially important bridge vector for Amazon-region zoonoses.

OBJECTIVE: To assess the emergent zoonotic disease risk posed by the voracious human-biting blackfly species Simulium oyapockense in the peripheral regions of an expanding urban centre situated deep in the Brazilian Amazon rainforest. METHODS: We performed nine human landing catches at three periurban sites surrounding the Brazilian Amazon town of São Gabriel da Cachoeira. Using the detection of non-human primate filarial parasites as an indicator of the zoonotic disease threat posed by a biting insect, we screened 3328 S. oyapockense blackflies for the presence of zoonotic filarial DNA with an ITS-1 PCR assay and Sanger sequencing. RESULTS: Between 98 and 100% of the biting insects captured during our nine collections were identified as S. oyapockense; at our three collection sites and during our three seasonally-distinct collections this species was captured at rates between 28 and 294 blackflies per hour. PCR screening of the march-collected S. oyapockense detected infectious-stage (L3) Mansonella mariae parasites (which are only known to infect non-human primates) in >0.15% of the tested head samples. CONCLUSIONS: Our results show that residents of the periurban regions of São Gabriel da Cachoeira are routinely exposed to the bites of S. oyapockense blackflies which have previously fed on non-human primates.

Gestational malaria associated to Plasmodium vivax and Plasmodium falciparum placental mixed-infection followed by foetal loss: a case report from an unstable transmission area in Brazil.

Gestational malaria is a multi-factorial syndrome leading to poor outcomes for both the mother and foetus. Although an unusual increasing in the number of hospitalizations caused by Plasmodium vivax has been reported in Brazil, mortality is rarely observed. This is a report of a gestational malaria case that occurred in the city of Manaus (Amazonas State, Brazil) and resulted in foetal loss. The patient presented placental mixed-infection by Plasmodium vivax and Plasmodium falciparum after diagnosis by nested-PCR, however microscopic analysis failed to detect P. falciparum in the peripheral blood. Furthermore, as the patient did not receive proper treatment for P. falciparum and hospitalization occurred soon after drug treatment, it seems that P. falciparum pathology was modulated by the concurrent presence of P. vivax. Collectively, this case confirms the tropism towards the placenta by both of these species of parasites, reinforces the notion that co-existence of distinct malaria parasites interferes on diseases' outcomes, and opens discussions regarding diagnostic methods, malaria treatment during pregnancy and prenatal care for women living in unstable transmission areas of malaria, such as the Brazilian Amazon.