A community-level investigation of the yellow fever virus outbreak in South Omo Zone, South-West Ethiopia, 2012–2014

AbstractBackgroundA yellow fever (YF) outbreak occurred in South Omo Zone, Ethiopia in 2012-2014. This study aimed to analyse historical epidemiological data, to assess the risk for future YF outbreaks through entomological surveillance, including mosquito species identification and molecular screening for arboviruses, and finally to determine the knowledge, attitudes and current preventative practices within the affected communities.Methodology/Principal FindingsFrom October 2012 to March 2014, 165 cases and 62 deaths were reported, principally in rural areas of South Ari region (83.6%), south-west Ethiopia. The majority of patients were 15-44 years old (74.5%) and most case deaths were males (76%). Between June and August 2017, 688 containers were sampled from across 177 households to identify key breeding sites forAedesmosquitoes.Ensete ventricosum(“false banana”) was identified as the primary natural breeding site, and clay pots outside the home as the most productive artificial breeding site. Entomological risk indices from the majority of sites were classified as “high risk” for future outbreaks under current World Health Organization criteria. Adult trapping resulted in the identification of members of theAedes simpsonicomplex in and around households. Screening of adult females revealed no detection of yellow fever virus (YFV) or other arboviruses. 88% of 177 participants had heard of YF, however many participants easily confused transmission and symptoms of YF with malaria, which is also endemic in the area.Conclusions/SignificanceStudy results emphasise the need for further entomological studies to improve our understanding of local vector species and transmission dynamics. Disease surveillance systems and in-country laboratory capacity also need to be strengthened to facilitate more rapid responses to future YF outbreaks.Author SummaryDespite the availability of a highly effective vaccine, yellow fever virus (YFV) remains an important public health problem across Africa and South America due to its high case-fatality rate. This study aimed to assess and reduce the risk for future outbreaks. During this study, historical data analysis was conducted to understand the epidemiology of the recent outbreak in 2012-2014. Entomological surveillance was also carried out, including both mosquito species identification and molecular screening for arboviruses, as well as a household survey to understand the knowledge and attitudes towards yellow fever (YF) within the affected areas and to assess community-level practices for YF prevention. We found a high abundance ofAedes simpsonicomplex in the context of low vaccination coverage. Community knowledge and practice levels were low for reducing potential breeding sites, highlighting the need for increased dissemination of information to community members on how to reduce their risk of exposure to mosquito vectors of arboviruses.

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A community-level investigation following a yellow fever virus outbreak in South Omo Zone, South-West Ethiopia

PeerJ ◽

10.7717/peerj.6466 ◽

2019 ◽

Vol 7 ◽

pp. e6466 ◽

Cited By ~ 3

Author(s):

Ranya Mulchandani ◽

Fekadu Massebo ◽

Fekadu Bocho ◽

Claire L. Jeffries ◽

Thomas Walker ◽

...

Keyword(s):

Yellow Fever ◽

Yellow Fever Virus ◽

Case Fatality ◽

Public Health Problem ◽

Fever Virus ◽

World Health ◽

Effective Vaccine ◽

Breeding Sites ◽

Study Results ◽

South Omo

Background Despite the availability of a highly effective vaccine, yellow fever virus (YFV) remains an important public health problem across Africa and South America due to its high case-fatality rate. This study investigated the historical epidemiology and contemporary entomological and social determinants of a YFV outbreak in South Omo Zone (SOZ), Ethiopia. Methods A YFV outbreak occurred in SOZ, Ethiopia in 2012–2014. Historical epidemiological data were retrieved from the SOZ Health Department and analyzed. Entomological sampling was undertaken in 2017, including mosquito species identification and molecular screening for arboviruses to understand mosquito habitat distribution, and finally current knowledge, attitudes and preventative practices within the affected communities were assessed. Results From October 2012 to March 2014, 165 suspected cases and 62 deaths were reported, principally in rural areas of South Ari region (83.6%). The majority of patients were 15–44 years old (75.8%) and most case deaths were males (76%). Between June and August 2017, 688 containers were sampled across 180 households to identify key breeding sites for Aedes mosquitoes. Ensete ventricosum (“false banana”) and clay pots outside the home were the most productive natural and artificial breeding sites, respectively. Entomological risk indices classified most sites as “high risk” for future outbreaks under current World Health Organization criteria. Adult mosquitoes in houses were identified as members of the Aedes simpsoni complex but no YFV or other arboviruses were detected by PCR. The majority of community members had heard of YFV, however few activities were undertaken to actively reduce mosquito breeding sites. Discussion Study results highlight the potential role vector control could play in mitigating local disease transmission and emphasize the urgent need to strengthen disease surveillance systems and in-country laboratory capacity to facilitate more rapid responses to future YFV outbreaks.

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Yellow Fever Outbreak in Eastern Senegal, 2020–2021

Viruses ◽

10.3390/v13081475 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1475

Author(s):

Moussa Moïse Diagne ◽

Marie Henriette Dior Ndione ◽

Alioune Gaye ◽

Mamadou Aliou Barry ◽

Diawo Diallo ◽

...

Keyword(s):

Yellow Fever ◽

Yellow Fever Virus ◽

Mosquito Species ◽

Virus Transmission ◽

Genomic Analysis ◽

Hemorrhagic Fever ◽

Fever Virus ◽

World Health ◽

Effective Vaccine ◽

Ministry Of Health

Yellow fever virus remains a major threat in low resource countries in South America and Africa despite the existence of an effective vaccine. In Senegal and particularly in the eastern part of the country, periodic sylvatic circulation has been demonstrated with varying degrees of impact on populations in perpetual renewal. We report an outbreak that occurred from October 2020 to February 2021 in eastern Senegal, notified and managed through the synergistic effort yellow fever national surveillance implemented by the Senegalese Ministry of Health in collaboration with the World Health Organization, the countrywide 4S network set up by the Ministry of Health, the Institut Pasteur de Dakar, and the surveillance of arboviruses and hemorrhagic fever viruses in human and vector populations implemented since mid 2020 in eastern Senegal. Virological analyses highlighted the implication of sylvatic mosquito species in virus transmission. Genomic analysis showed a close relationship between the circulating strain in eastern Senegal, 2020, and another one from the West African lineage previously detected and sequenced two years ago from an unvaccinated Dutch traveler who visited the Gambia and Senegal before developing signs after returning to Europe. Moreover, genome analysis identified a 6-nucleotide deletion in the variable domain of the 3′UTR with potential impact on the biology of the viral strain that merits further investigations. Integrated surveillance of yellow fever virus but also of other arboviruses of public health interest is crucial in an ecosystem such as eastern Senegal.

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First confirmed occurrence of the yellow fever virus and dengue virus vector Aedes (Stegomyia) luteocephalus (Newstead, 1907) in Mozambique

Parasites & Vectors ◽

10.1186/s13071-020-04217-9 ◽

2020 ◽

Vol 13 (1) ◽

Author(s):

Ana Paula Abílio ◽

Ayubo Kampango ◽

Eliseu J. Armando ◽

Eduardo S. Gudo ◽

Luís C. B. das Neves ◽

...

Keyword(s):

Dengue Virus ◽

Yellow Fever ◽

Male Genitalia ◽

Yellow Fever Virus ◽

Phylogenetic Analyses ◽

Mosquito Species ◽

Fever Virus ◽

Morphological Identification ◽

Vector Species ◽

Vector Systems

Abstract Background Mozambique, same as many other tropical countries, is at high risk of arthropod-borne virus (arbovirus) diseases and recently two dengue virus (DENV) outbreaks occurred in the northern part of the country. The occurrence of some important vector species, such as Aedes (Stegomyia) aegypti (Linnaeus) and Ae. (Stg.) albopictus (Skuse), besides several other sylvatic vectors, have been reported in the country, which may indicate that the transmission of some arboviruses of public health importance may involve multiple-vector systems. Therefore, knowing the occurrence and distribution of existing and the new important vectors species, is crucial for devising systematic transmission surveillance and vector control approaches. The aim of this study was to map the occurrence and distribution of mosquito species with potential for transmitting arboviruses of human and veterinary relevance in Niassa Province, Northern Mozambique. Methods Field entomological surveys were undertaken in April 2016 in Lago District, Niassa Province, northern Mozambique. Breeding sites of mosquitoes were inspected and immature stages were collected and reared into adult. Mosquitoes in the adult stages were morphologically identified using taxonomic keys. Morphological identification of Aedes (Stegomyia) luteocephalus (Newstead) were later confirmed using dissected male genitalia and molecular based on the phylogenetic analyses of the sequenced barcode (cox1 mtDNA) gene. Results A total of 92 mosquito larvae collected developed into adults. Of these, 16 (17.39%) were morphologically identified as Ae. luteocephalus. The remaining specimens belonged to Ae. (Stg.) aegypti (n = 4, 4.35%), Ae. (Aedimorphus) vittatus (n = 24, 26.09%), Anopheles garnhami (n = 1, 1.09%), Culex (Culiciomyia) nebulosus (n = 28, 30.43%), Eretmapodites subsimplicipes (n = 18, 19.57%) and Toxorhynchites brevipalpis (n = 1, 1.09%), taxa already known to the country. Male genitalia and phylogenetic analyses confirmed the identity of Ae. luteocephalus specimens collected in this study. Conclusions To our knowledge, this is the first detection of Ae. luteocephalus in Mozambican territory, a vector species of yellow fever virus (YFV), Zika virus (ZIKV) and dengue virus (DENV) in Africa. Further studies are encouraged to investigate the role of Ae. luteocephalus in the transmission of arboviral diseases in Mozambique.

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Genetic differentiation in the yellow fever virus vector, Aedes simpsoni complex, in Africa: Sequence variation in the ribosomal DNA internal transcribed spacers of anthropophilic and non-anthropophilic populations

Insect Molecular Biology ◽

10.1046/j.1365-2583.2000.00161.x ◽

2000 ◽

Vol 9 (1) ◽

pp. 85-91 ◽

Cited By ~ 15

Author(s):

L. G. Mukwaya ◽

J. K. Kayondo ◽

M. B. Crabtree ◽

H. M. Savage ◽

B. J. Biggerstaff ◽

...

Keyword(s):

Genetic Differentiation ◽

Yellow Fever ◽

Ribosomal Dna ◽

Sequence Variation ◽

Yellow Fever Virus ◽

Fever Virus ◽

Virus Vector ◽

Internal Transcribed Spacers ◽

Aedes Simpsoni

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What Does the Future Hold for Yellow Fever Virus? (I)

10.20944/preprints201805.0099.v1 ◽

2018 ◽

Author(s):

Raphaëlle Klitting ◽

Ernest A. Gould ◽

Christophe Paupy ◽

Xavier de Lamballerie

Keyword(s):

Yellow Fever ◽

Yellow Fever Virus ◽

Mosquito Species ◽

Central Africa ◽

Fever Virus ◽

Control Measures ◽

Live Attenuated Vaccine ◽

Tropical Regions ◽

The Individual ◽

Vaccination Campaigns

The recent resurgence of yellow fever virus (YFV) activity in the tropical regions of Africa and South America has sparked renewed interest in this infamous arboviral disease. YFV had been a human plague for centuries prior to the identification of its urban transmission vector, the Aedes aegypti mosquito species, and the development of an efficient live-attenuated vaccine, the YF-17D strain. The combination of vector-control measures and vaccination campaigns drastically reduced YFV incidence in humans on many occasions, but the virus never ceased to circulate in the forest, through its sylvatic invertebrate vector(s) and vertebrate host(s). Outbreaks recently reported in Central Africa (2015-2016) and Brazil (since late 2016), reached considerable proportions in terms of spatial distribution and total numbers of cases, with multiple exports, including to China. In turn, questions regarding the likeliness of occurrence of large urban YFV outbreaks in the Americas or of a successful import of YFV to Asia are currently resurfacing. This two-part review describes the current state of knowledge and gaps regarding the molecular biology and transmission dynamics of YFV, along with an overview of the tools that can be used to manage the disease at the individual, local and global levels.

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Haemagogus leucocelaenus (Diptera: Culicidae), the potential wild vector of yellow fever in the border zone of northern Misiones, Argentina

Revista de la Sociedad Entomológica Argentina ◽

10.25085/rsea.800410 ◽

2021 ◽

Vol 80 (04) ◽

pp. 136-141

Author(s):

Julieta A. SICHES ◽

Pablo E. BERROZPE ◽

Gustavo C. ROSSI ◽

Oscar D. SALOMÓN ◽

Juan J. GARCÍA

Keyword(s):

Yellow Fever ◽

Yellow Fever Virus ◽

Virus Transmission ◽

Distribution Patterns ◽

Fever Virus ◽

Border Zone ◽

Wild Populations ◽

Breeding Sites ◽

In The Wild ◽

Primary Vector

Haemagogus leucocelaenus (Diptera: Culicidae) is considered the primary vector of yellow fever virus (Flaviviridae) in wild environments in South America. Previous research has defined Hg. leucocelaenus as a wild species with phytotelmata-type breeding sites. The objective of this study was to report the temporal and space occurrence of Hg. leucocelaenus at the microscale in the wild-periurban fringe through a systematic and spatially stratified sampling using 81 ovitraps between April 2019 and February 2 020 in the locality of Puerto Iguazú, Argentina. Of the total ovitraps, eight were positive for Hg. leucocelaenus, six in the wild environment and two in the periurban environment. Regarding the time distribution, 98.5% of the occurrence was concentrated in November and December 2019 towards the beginning of the rainy season. The results confirm the habitat plasticity of Hg. leucocelaenus and establish the aptitude of artificial containers as a methodology in monitoring studies, since they illustrate the potential of wild populations to deposit fertile eggs in them at least up to 300 m from the wild-periurban fringe. This work is a contribution to determine the temporal and space risk of yellow fever virus transmission in the region, based on the distribution patterns of this species as a function to the ecotone associated with forest borders and climatic variables.

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