Aplicação da Técnica de “NESTED PCR” Durante o Período Pré-Patente para Identificação de Schistosoma Mansoni no Hospedeiro Intermediário Biomphalaria Glabrata

Biomphalaria glabrata, molusco de água doce, desempenha um importante papel em Parasitologia Médica, por ser o hospedeiro intermediário de Schistosoma mansoni, tremátode digenético responsável pela schistosomose intestinal. A detecção de moluscos infectados pelo Schistosoma mansoni tem uma grande importância em Saúde pública, porque identifica focos de transmissão da schistosomose. As limitações dos métodos clássicos para o diagnóstico de infecções pré patentes fazem com que os métodos de biologia moleculares sejam vistos como possíveis alternativas através da detecção de ADN do S. mansoni em moluscos hospedeiros. A detecção de sequências específicas de ADN por reacção de polimerase em cadeia (PCR) tem-se verificado ser de extrema importância para a análise genética e diagnóstico de várias doenças infecciosas. Neste estudo foi aplicada a técnica de Nested-PCR, com o objectivo de identificar, no período pré-patente, S. mansoni em moluscos expostos a 1, 5 e 10 miracídios em diferentes períodos de tempo. Foram utilizados moluscos das estirpes albina e selvagem de B. glabrata. Para a realização das técnicas de PCR e de Nested–PCR (NPCR) foram utilizados dois pares de oligonucleótidos desenhados especificamente para detectar o ADN de S. mansoni . Verificou-se amplificação do fragmento de ADN do parasita em 80% das amostras analisadas, independentemente da dose de miracídios e do período de exposição. O método utilizado é altamente sensível, mostrando ser uma ferramenta útil na detecção de hospedeiros intermediários de S. mansoni, consequentemente na identificação de focos de schistosomose intestinal.UNIVERSIDADE NOVA DE LISBOA INSTITUTO DE HIGIENE E MEDICINA TROPICA

The geographical distribution of the malaria vector Anopheles arabiensis in Cabo Verde, 2016–2023

BackgroundIntegrated malaria vector control is crucial to eliminate or reduce infection risk. Understanding vector species distribution, behavior, and environmental factors such as climate, topography, and preferred aquatic habitats is essential.ObjectivesHerein, we aim to compile data from 2016 to 2023 on the primary malaria vector in Cabo Verde to support health surveillance and elimination certification.Materials and methodsMosquitoes larvae were collected using standard sampling tools, and adults using Biogents Sentinel traps, mechanical aspiration and CDC UV light traps, both indoor and in the surroundings of urban and rural areas.ResultsSix hundred fifty-seven specimens of Anopheles gambiae s.l. were identified by morphological methods and PCR-based techniques as Anopheles arabiensis in 12 municipalities from six of the nine inhabited islands, namely, São Vicente, São Nicolau, Maio, Boavista, Santiago, and Santo Antão.ConclusionsWe believe this is the first scientific report of the presence of An. arabiensis on the island of Santo Antão. The Anopheles arabiensis remains the only species in the An. gambiae complex in the Cabo Verde islands. These results offer vital insights for epidemiological surveillance and effective malaria control, especially in light of the recent WHO certification declaring the country malaria-free. However, it is imperative to conduct further studies that comprehensively address epidemiological and entomological aspects, with a special focus on bionomics, genetic determinants of the parasite-vector association, and the characterization of larval habitats. These investigations have the potential to guide a more informed and strategic implementation of malaria vector control measures in Cabo Verde

The geographical distribution of the malaria vector Anopheles arabiensis in Cabo Verde, 2016–2023

Funding Information: The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This research was partially supported by the Cabo Verde State Budget - 65.06.01.04.29.02 - Strengthening the National Public Health Laboratory \u2013 INSP and The Global Fund to Fight AIDS, Tuberculosis and Malaria, through Grant CPV-Z-CCSSIDA, Number 1914, Investing to achieve elimination of malaria and impact against TB and HIV in Cabo Verde. Funding Information: The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This research was partially supported by the Cabo Verde State Budget - 65.06.01.04.29.02 - Strengthening the National Public Health Laboratory \u2013 INSP and The Global Fund to Fight AIDS, Tuberculosis and Malaria, through Grant CPV-Z-CCSSIDA, Number 1914, Investing to achieve elimination of malaria and impact against TB and HIV in Cabo Verde. Acknowledgments Publisher Copyright: Copyright © 2024 Leal, Sousa, Monteiro, Mendonça, Gonçalves and DePina.Background: Integrated malaria vector control is crucial to eliminate or reduce infection risk. Understanding vector species distribution, behavior, and environmental factors such as climate, topography, and preferred aquatic habitats is essential. Objectives: Herein, we aim to compile data from 2016 to 2023 on the primary malaria vector in Cabo Verde to support health surveillance and elimination certification. Materials and methods: Mosquitoes larvae were collected using standard sampling tools, and adults using Biogents Sentinel traps, mechanical aspiration and CDC UV light traps, both indoor and in the surroundings of urban and rural areas. Results: Six hundred fifty-seven specimens of Anopheles gambiae s.l. were identified by morphological methods and PCR-based techniques as Anopheles arabiensis in 12 municipalities from six of the nine inhabited islands, namely, São Vicente, São Nicolau, Maio, Boavista, Santiago, and Santo Antão. Conclusions: We believe this is the first scientific report of the presence of An. arabiensis on the island of Santo Antão. The Anopheles arabiensis remains the only species in the An. gambiae complex in the Cabo Verde islands. These results offer vital insights for epidemiological surveillance and effective malaria control, especially in light of the recent WHO certification declaring the country malaria-free. However, it is imperative to conduct further studies that comprehensively address epidemiological and entomological aspects, with a special focus on bionomics, genetic determinants of the parasite-vector association, and the characterization of larval habitats. These investigations have the potential to guide a more informed and strategic implementation of malaria vector control measures in Cabo Verde.publishersversionpublishe

Factors related to human-vector contact that modify the likelihood of malaria transmission during a contained Plasmodium falciparum outbreak in Praia, Cabo Verde

Background: Determining the reproductive rate and how it varies over time and space (RT) provides important insight to understand transmission of a given disease and inform optimal strategies for controlling or eliminating it. Estimating RT for malaria is difficult partly due to the widespread use of interventions and immunity to disease masking incident infections. A malaria outbreak in Praia, Cabo Verde in 2017 provided a unique opportunity to estimate RT directly, providing a proxy for the intensity of vector-human contact and measure the impact of vector control measures. Methods: Out of 442 confirmed malaria cases reported in 2017 in Praia, 321 (73%) were geolocated and informed this analysis. RT was calculated using the joint likelihood of transmission between two cases, based on the time (serial interval) and physical distance (spatial interval) between them. Log-linear regression was used to estimate factors associated with changes in RT, including the impact of vector control interventions. A geostatistical model was developed to highlight areas receptive to transmission where vector control activities could be focused in future to prevent or interrupt transmission. Results: The RT from individual cases ranged between 0 and 11 with a median serial- and spatial-interval of 34 days [interquartile range (IQR): 17–52] and 1,347 m (IQR: 832–1,985 m), respectively. The number of households receiving indoor residual spraying (IRS) 4 weeks prior was associated with a reduction in RT by 0.84 [95% confidence interval (CI) 0.80–0.89; p-value <0.001] in the peak-and post-epidemic compared to the pre-epidemic period. Conclusions: Identifying the effect of reduced human-vector contact through IRS is essential to determining optimal intervention strategies that modify the likelihood of malaria transmission and can inform optimal intervention strategies to accelerate time to elimination. The distance within which two cases are plausibly linked is important for the potential scale of any reactive interventions as well as classifying infections as imported or introduced and confirming malaria elimination

Enhanced mosquito vectorial capacity underlies the Cape Verde Zika epidemic

International audienceThe explosive emergence of Zika virus (ZIKV) across the Pacific and Americas since 2007 was associated with hundreds of thousands of human cases and severe outcomes, including congenital microcephaly caused by ZIKV infection during pregnancy. Although ZIKV was first isolated in Uganda, Africa has so far been exempt from large-scale ZIKV epidemics, despite widespread susceptibility among African human populations. A possible explanation for this pattern is natural variation among populations of the primary vector of ZIKV, the mosquito Aedes aegypti . Globally invasive populations of Ae . aegypti outside of Africa are considered effective ZIKV vectors because they are human specialists with high intrinsic ZIKV susceptibility, whereas African populations of Ae . aegypti across the species’ native range are predominantly generalists with low intrinsic ZIKV susceptibility, making them less likely to spread viruses in the human population. We test this idea by studying a notable exception to the patterns observed across most of Africa: Cape Verde experienced a large ZIKV outbreak in 2015 to 2016. We find that local Ae . aegypti in Cape Verde have substantial human-specialist ancestry, show a robust behavioral preference for human hosts, and exhibit increased susceptibility to ZIKV infection, consistent with a key role for variation among mosquito populations in ZIKV epidemiology. These findings suggest that similar human-specialist populations of Ae . aegypti in the nearby Sahel region of West Africa, which may be expanding in response to rapid urbanization, could serve as effective vectors for ZIKV in the future

Extensive variation and strain-specificity in dengue virus susceptibility among African Aedes aegypti populations

International audienceAfrican populations of the mosquito Aedes aegypti are usually considered less susceptible to infection by human-pathogenic flaviviruses than globally invasive populations found outside Africa. Although this contrast has been well documented for Zika virus (ZIKV), it is unclear to what extent it is true for dengue virus (DENV), the most prevalent flavivirus of humans. Addressing this question is complicated by substantial genetic diversity among DENV strains, most notably in the form of four genetic types (DENV1 to DENV4), that can lead to genetically specific interactions with mosquito populations. Here, we carried out a survey of DENV susceptibility using a panel of seven field-derived Ae . aegypti colonies from across the African range of the species and a colony from Guadeloupe, French West Indies as non-African reference. We found considerable variation in the ability of African Ae . aegypti populations to acquire and replicate a panel of six DENV strains spanning the four DENV types. Although African Ae . aegypti populations were generally less susceptible than the reference non-African population from Guadeloupe, in several instances some African populations were equally or more susceptible than the Guadeloupe population. Moreover, the relative level of susceptibility between African mosquito populations depended on the DENV strain, indicating genetically specific interactions. We conclude that unlike ZIKV susceptibility, there is no clear-cut dichotomy in DENV susceptibility between African and non-African Ae . aegypti . DENV susceptibility of African Ae . aegypti populations is highly heterogeneous and largely governed by the specific pairing of mosquito population and DENV strain

Genomic Epidemiology of 2015–2016 Zika Virus Outbreak in Cape Verde

International audienceDuring 2015-2016, Cape Verde, an island nation off the coast of West Africa, experienced a Zika virus (ZIKV) outbreak involving 7,580 suspected Zika cases and 18 microcephaly cases. Analysis of the complete genomes of 3 ZIKV isolates from the outbreak indicated the strain was of the Asian (not African) lineage. The Cape Verde ZIKV sequences formed a distinct monophylogenetic group and possessed 1-2 (T659A, I756V) unique amino acid changes in the envelope protein. Phylogeographic and serologic evidence support earlier introduction of this lineage into Cape Verde, possibly from northeast Brazil, between June 2014 and August 2015, suggesting cryptic circulation of the virus before the initial wave of cases were detected in October 2015. These findings underscore the utility of genomic-scale epidemiology for outbreak investigations