Epidemiology of influenza in West Africa after the 2009 influenza A(H1N1) pandemic, 2010–2012

Nzussouo, Ndahwouh Talla; Duque, Jazmin; Adedeji, Adebayo; Coulibaly, Daouda; Sow, Samba O.; Tarnagda, Zékiba; Maman, Issaka; Lagaré, Adamou; Makaya, Sonia; Elkory, Mohamed Brahim; Adje, Herve Kadjo; Shilo, Paul Alhassan; Tamboura, Boubou; Cissé, Assana; Badziklou, Kossi; Maïnassara, Halima Boubacar; Bara, Ahmed Ould; Keita, Adama Mamby; Williams, Tracy Ann; Moen, Ann; Widdowson, Marc‐Alain; McMorrow, Meredith

doi:10.1186/s12879-017-2839-1

Cited by 23 publications

(31 citation statements)

References 24 publications

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“…In mild cases of infection (ILI), the frequency of influenza cases was 24.8% as compared to 18.7% in severe cases (SARI). Higher proportions of positive influenza cases in ILI as compared to SARI have as well been reported by Mainassara et al in Niger as well as several other West African countries [8, 12, 13]. We noted that lower influenza positivity rate in SARI patients could be attributed to delayed presentation in hospitals resulting in reduced viral loads and lower detection rates as suggested by Dalhatu et al [8].…”

Section: Discussionsupporting

confidence: 83%

“…These results are contradictory to reports from Manirakiza et al in Central Africa Republic where infants aged 0–6 months (8.8%) and people aged 15–50 years (11.0%) had higher proportions of influenza cases [11]. A similar report by Nzussouo et al from West African countries reported that majority of ILI and SARI case-patients testing positive for influenza viruses were children aged 0–4 years [12]. In the latter, higher rates of influenza-associated illness in the 0–4 years age group can be attributed to a selection bias since more than 70% of samples collected were from children aged 0–14 years.…”

Section: Discussionmentioning

confidence: 59%

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Circulation of influenza virus from 2009 to 2018 in Cameroon: 10 years of surveillance data

et al. 2019

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Since the recent emergence of several subtypes of influenza viruses with pandemic potentials, there has been growing interest on the control of this infection worldwide. This study aimed to describe the 10 years of influenza activity in Cameroon between January 2009 and December 2018. Respiratory samples were collected from sentinel sites responsible for influenza surveillance in Cameroon and analyzed for the presence of influenza. Globally, 9 of the 10 administrative regions of the country were represented with at least 1 year of data. A total of 11816 respiratory samples were collected and influenza virus detection rate was 24.0%. The most represented age group was the 0–1 years representing more than 40% of the collected samples and possessing the lowest proportion of influenza cases (16.2%). Meanwhile higher proportions of influenza positive cases was found in the 2–4, 5–14 and 15–49 years age group at ≥29%. Among outpatients, the frequency of influenza virus was 24.8% while in hospitalized patients, 18.7% of samples were positive for influenza virus. We noted year-round circulation of influenza virus in Cameroon with 2 peaks in activity: a major peak in the months of September to December and a minor peak in the months of March to July. Antigenic characterization of influenza isolates showed 37.5% (6/16) vaccine match between the predominant Cameroon strains and the Northern hemisphere vaccine strains with majority of vaccine match observed in influenza B/Victoria subtype (4/6; 66.7%). Data collected from this surveillance system is essential to add to global information on the spread of influenza.

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Section: Discussionsupporting

confidence: 83%

Section: Discussionmentioning

confidence: 59%

Circulation of influenza virus from 2009 to 2018 in Cameroon: 10 years of surveillance data

et al. 2019

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“…Seasonality patterns of influenza in eastern Africa including Ethiopia, have not been clearly established [13]. However, some evidences from different studies indicated that Influenza A (H1N1) pdm2009, Seasonal Influenza A (H3N2) and Influenza B are circulating in different countries of sub-Saharan Africa [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Burden and seasonality of medically attended influenza like illness (ILI) in Ethiopia, 2012 to 2017

et al. 2020

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Background: The influenza virus spreads rapidly around the world in seasonal epidemics, resulting in significant morbidity and mortality. Influenza-related incidence data are limited in many countries in Africa despite established sentinel surveillance. This study aimed to address the information gap by estimating the burden and seasonality of medically attended influenza like illness in Ethiopia. Method: Influenza sentinel surveillance data collected from 3 influenza like illness (ILI) and 5 Severe Acute Respiratory Illness (SARI) sites from 2012 to 2017 was used for analysis. Descriptive statistics were applied for simple analysis. The proportion of medically attended influenza positive cases and incidence rate of ILI was determined using total admitted patients and catchment area population. Seasonality was estimated based on weekly trend of ILI and predicted threshold was done by applying the "Moving Epidemic Method (MEM)". Result: A total of 5715 medically attended influenza suspected patients who fulfills ILI and SARI case definition (77% ILI and 23% SARI) was enrolled. Laboratory confirmed influenza virus (influenza positive case) among ILI and SARI suspected case was 25% (1130/4426) and 3% (36/1289). Of which, 65% were influenza type A. The predominantly circulating influenza subtype were seasonal influenza A(H3N2) (n = 455, 60%) and Influenza A(H1N1)pdm09 (n = 293, 38.81%). The estimated mean annual influenza positive case proportion and ILI incidence rate was 160.04 and 52.48 per 100,000 population. The Incidence rate of ILI was higher in the age group of 15-44 years of age ['Incidence rate (R) = 254.6 per 100,000 population', 95% CI; 173.65, 335.55] and 5-14 years of age [R = 49.5, CI 95%; 31.47, 130.43]. The seasonality of influenza has two peak seasons; in a period from October-December and from April-June. Conclusion: Significant morbidity of influenza like illness was observed with two peak seasons of the year and seasonal influenza A (H3N2) remains the predominantly circulating influenza subtype. Further study need to be considered to identify potential risks and improving the surveillance system to continue early detection and monitoring of circulating influenza virus in the country has paramount importance.

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“…Many avian and several mammalian species are susceptible to IAV infections with varying degrees of morbidity and mortality. Among humans, annual influenza morbidity and associated mortality are estimated at 3-5 million and 250,000-500,000, respectively (Talla Nzussouo et al, 2017). In swine, IAV infections cause mild respiratory disease which may predispose to opportunistic bacterial infections causing reduced weight gain during the fattening period and leading to substantial losses in pork production.…”

Section: Introductionmentioning

confidence: 99%

Exposure of domestic swine to influenza A viruses in Ghana suggests unidirectional, reverse zoonotic transmission at the human–animal interface

Ayim-Akonor

Mertens

May

et al. 2020

Zoonoses and Public Health

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Influenza A viruses (IAVs) have both zoonotic and anthroponotic potential and are of public and veterinary importance. Swine are intermediate hosts and ‘mixing vessels’ for generating reassortants, progenies of which may harbour pandemic propensity. Swine handlers are at the highest risk of becoming infected with IAVs from swine but there is little information on the ecology of IAVs at the human–animal interface in Africa. We analysed and characterized nasal and throat swabs from swine and farmers respectively, for IAVs using RT‐qPCR, from swine farms in the Ashanti region, Ghana. Sera were also analysed for IAVs antibodies and serotyped using ELISA and HI assays. IAV was detected in 1.4% (n = 17/1,200) and 2.0% (n = 2/99) of swine and farmers samples, respectively. Viral subtypes H3N2 and H1N1pdm09 were found in human samples. All virus‐positive swine samples were subtyped as H1N1pdm09 phylogenetically clustering closely with H1N1pdm09 that circulated among humans during the study period. Phenotypic markers that confer sensitivity to Oseltamivir were found. Serological prevalence of IAVs in swine and farmers by ELISA was 3.2% (n = 38/1,200) and 18.2% (n = 18/99), respectively. Human H1N1pdm09 and H3N2 antibodies were found in both swine and farmers sera. Indigenous swine influenza A viruses and/or antibodies were not detected in swine or farmers samples. Majority (98%, n = 147/150) of farmers reported of not wearing surgical mask and few (4%, n = 6) reported to wear gloves when working. Most (n = 74, 87.7%) farmers reported of working on the farm when experiencing influenza‐like illness. Poor husbandry and biosafety practices of farmers could facilitate virus transmission across the human–swine interface. Farmers should be educated on the importance of good farm practices to mitigate influenza transmission at the human–animal interface.

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Epidemiology of influenza in West Africa after the 2009 influenza A(H1N1) pandemic, 2010–2012

Cited by 23 publications

References 24 publications

Circulation of influenza virus from 2009 to 2018 in Cameroon: 10 years of surveillance data

Circulation of influenza virus from 2009 to 2018 in Cameroon: 10 years of surveillance data

Burden and seasonality of medically attended influenza like illness (ILI) in Ethiopia, 2012 to 2017

Exposure of domestic swine to influenza A viruses in Ghana suggests unidirectional, reverse zoonotic transmission at the human–animal interface

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