Epidemiology of West Nile virus in Africa: An underestimated threat

Mencattelli, Giulia; Ndione, Marie Henriette Dior; Rosà, Roberto; Marini, Giancarlo; Diagne, Cheikh Tidiane; Diagne, Moussa Moïse; Fall, Gamou; Faye, Ousmane; Diallo, Mawlouth; Faye, Oumar; Savini, Giovanni; Rizzoli, Annapaola

doi:10.1371/journal.pntd.0010075

Cited by 59 publications

(53 citation statements)

References 119 publications

(306 reference statements)

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“…Our data confirmed the circulation of genogroup C in Senegal, which clustered with isolates from Central and West Africa as previously described [39]. This genetic link between sequences could be associated with possible virus importations from neighboring countries, human immigrations and food circulation between Central and West African countries, as previously reported for other viruses, such as the West Nile virus and coronaviruses [43,44]. The C2 subgenotype was the most prevalent EV-A71 type among AFP cases from Senegal.…”

Section: Discussionsupporting

confidence: 90%

Molecular Epidemiology of Enterovirus A71 in Surveillance of Acute Flaccid Paralysis Cases in Senegal, 2013–2020

et al. 2022

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Enterovirus A71 (EV-A71) is a non-polio enterovirus that currently represents a major public health concern worldwide. In Africa, only sporadic cases have been reported. Acute flaccid paralysis and environmental surveillance programs have been widely used as strategies for documenting the circulation of polio and non-polio enteroviruses. To date, little is known about the molecular epidemiology of enterovirus A71 in Africa where resources and diagnostic capacities are limited. To fill this gap in Senegal, a total of 521 non-polio enterovirus isolates collected from both acute flaccid paralysis (AFP) and environmental surveillance (ES) programs between 2013 and 2020 were screened for enterovirus A71 using real-time RT-PCR. Positive isolates were sequenced, and genomic data were analyzed using phylogeny. An overall rate of 1.72% (9/521) of the analyzed isolates tested positive for enterovirus A71. All positive isolates originated from the acute flaccid paralysis cases, and 44.4% (4/9) of them were isolated in 2016. The nine newly characterized sequences obtained in our study included eight complete polyprotein sequences and one partial sequence of the VP1 gene, all belonging to the C genogroup. Seven out of the eight complete polyprotein sequences belonged to the C2 subgenotype, while one of them grouped with previous sequences from the C1 subgenotype. The partial VP1 sequence belonged to the C1 subgenotype. Our data provide not only new insights into the recent molecular epidemiology of enterovirus A71 in Senegal but also point to the crucial need to set up specific surveillance programs targeting non-polio enteroviruses at country or regional levels in Africa for rapid identification emerging or re-emerging enteroviruses and better characterization of public health concerns causing acute flaccid paralysis in children such as enterovirus A71. To estimate the real distribution of EV-A71 in Africa, more sero-epidemiological studies should be promoted, particularly in countries where the virus has already been reported.

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Section: Discussionsupporting

confidence: 90%

Molecular Epidemiology of Enterovirus A71 in Surveillance of Acute Flaccid Paralysis Cases in Senegal, 2013–2020

et al. 2022

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“…There is currently an information gap as to the circulation of USUV and WNV in humans in West Africa. For example, concerning WNV, there are more than twenty African countries (including Burkina Faso) in which no seroprevalence study has yet been conducted in humans to measure the extent of the circulation of the virus [ 46 ]. Two studies in Africa have considered the seroprevalence of WNV in blood donors.…”

Section: Discussionmentioning

confidence: 99%

Screening of Circulation of Usutu and West Nile Viruses: A One Health Approach in Humans, Domestic Animals and Mosquitoes in Burkina Faso, West Africa

et al. 2022

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Usutu virus (USUV) and West Nile virus (WNV) are phylogenetically closely related arboviruses. These viruses mainly follow an enzootic cycle involving mosquitoes and birds, but they occasionally infect humans and other mammals, inducing neurotropic disorders. Since the discovery of USUV, only two human cases have been reported in Africa, including one in Burkina Faso in 2004. Since then, no studies have been conducted to measure the extent of the circulation of this virus in Burkina Faso, and no study regarding the circulation of WNV has been conducted. Our study aimed to determine the seroprevalence of USUV and WNV in blood donations and in animals (horses, dogs, chickens and pigeons) and to perform molecular screening in patients with febrile fever and in Culex quinquefasciatus and Aedes aegypti mosquitoes. The prevalence of USUV and WNV was studied by serological (ELISA and microneutralization tests) and molecular analyses (RT-qPCR) of mosquito, dog, domestic bird, horse, and human samples in Burkina Faso between 2019 and 2021. We detected a very active transmission of both viruses in Burkina Faso. WNV and USUV seroprevalence is particularly high in humans (19.16% and 14.17%, respectively) and horses (17.28% and 6.17%). Molecular screening did not detect WNV or USUV in the mosquito or human samples tested. Our study shows an active spread of USUV and WNV in Burkina Faso, especially for WNV. This study highlights the value of developing surveillance programs to better prevent, detect, and alert people to USUV and WNV circulation in both primary and incidental hosts.

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“…Among individuals who develop the neurological disease, mortality can be present, ranging from 4% to 14% [ 1 ]. Due to this high proportion of asymptomatic cases, low mortality rates, and initially limited geographic distribution to the Middle Eastern and Central African regions, WNV has been a largely neglected public health concern [ 1 – 5 ]. However, recent WNV outbreaks recorded since the mid- and late 1990s, together with the increasing number of confirmed human cases, have called for a different perspective on the pathogen [ 2 , 6 – 8 ].…”

Section: Introductionmentioning

confidence: 99%

Host selection and forage ratio in West Nile virus–transmitting Culex mosquitoes: Challenges and knowledge gaps

et al. 2022

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Background To date, no specific therapy or vaccination is available for West Nile virus (WNV) infections in humans; preventive strategies represent the only possibility to control transmission. To focus these strategies, detailed knowledge of the virus dynamics is of paramount importance. However, several aspects of WNV transmission are still unclear, especially regarding the role of potential vertebrate host species. Whereas mosquitoes’ intrinsic characteristics cause them to favour certain hosts (host preference), absolute selection is impossible in natural settings. Conversely, the selection carried out among available hosts and influenced from hosts’ availability and other ecological/environmental factors is defined as host selection. Methodology/Principal findings In July 2022, we searched PubMed database for original articles exploring host selection among WNV-transmitting Culex mosquitoes, the main WNV vector. We considered only original field studies estimating and reporting forage ratio. This index results from the ratio between the proportion of blood meals taken by mosquitoes on potential host species and the hosts’ relative abundance. From the originally retrieved 585 articles, 9 matched the inclusion criteria and were included in this review. All but one of the included studies were conducted in the Americas, six in the United States, and one each in Mexico and Colombia. The remaining study was conducted in Italy. American Robin, Northern Cardinal, and House Finch were the most significantly preferred birds in the Americas, Common Blackbird in Italy. Conclusions/Significance Although ornithophilic, all observed WNV-transmitting mosquitoes presented opportunistic feeding behaviour. All the observed species showed potential to act as bridges for zoonotic diseases, feeding also on humans. All the observed mosquitoes presented host selection patterns and did not feed on hosts as expected by chance alone. The articles observe different species of mosquitoes in different environments. In addition, the way the relative host abundance was determined differed. Finally, this review is not systematic. Therefore, the translation of our results to different settings should be conducted cautiously.

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Epidemiology of West Nile virus in Africa: An underestimated threat

Cited by 59 publications

References 119 publications

Molecular Epidemiology of Enterovirus A71 in Surveillance of Acute Flaccid Paralysis Cases in Senegal, 2013–2020

Molecular Epidemiology of Enterovirus A71 in Surveillance of Acute Flaccid Paralysis Cases in Senegal, 2013–2020

Screening of Circulation of Usutu and West Nile Viruses: A One Health Approach in Humans, Domestic Animals and Mosquitoes in Burkina Faso, West Africa

Host selection and forage ratio in West Nile virus–transmitting Culex mosquitoes: Challenges and knowledge gaps

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