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. 2013 Sep 19;8(9):e74064.
doi: 10.1371/journal.pone.0074064. eCollection 2013.

Virological Surveillance of Influenza Viruses during the 2008-09, 2009-10 and 2010-11 Seasons in Tunisia

Awatef El Moussi  1 , Francisco Pozo, Mohamed Ali Ben Hadj Kacem, Juan Ledesma, Maria Teresa Cuevas, Inmaculada Casas, Amine Slim
Affiliations

Virological Surveillance of Influenza Viruses during the 2008-09, 2009-10 and 2010-11 Seasons in Tunisia

Awatef El Moussi et al. PLoS One. .

Abstract

Background: The data contribute to a better understanding of the circulation of influenza viruses especially in North-Africa.

Objective: The objective of this surveillance was to detect severe influenza cases, identify their epidemiological and virological characteristics and assess their impact on the healthcare system.

Method: We describe in this report the findings of laboratory-based surveillance of human cases of influenza virus and other respiratory viruses' infection during three seasons in Tunisia.

Results: The 2008-09 winter influenza season is underway in Tunisia, with co-circulation of influenza A/H3N2 (56.25%), influenza A(H1N1) (32.5%), and a few sporadic influenza B viruses (11.25%). In 2010-11 season the circulating strains are predominantly the 2009 pandemic influenza A(H1N1)pdm09 (70%) and influenza B viruses (22%). And sporadic viruses were sub-typed as A/H3N2 and unsubtyped influenza A, 5% and 3%, respectively. Unlike other countries, highest prevalence of influenza B virus Yamagata-like lineage has been reported in Tunisia (76%) localised into the clade B/Bangladesh/3333/2007. In the pandemic year, influenza A(H1N1)pdm09 predominated over other influenza viruses (95%). Amino acid changes D222G and D222E were detected in the HA gene of A(H1N1)pdm09 virus in two severe cases, one fatal case and one mild case out of 50 influenza A(H1N1)pdm09 viruses studied. The most frequently reported respiratory virus other than influenza in three seasons was RSV (45.29%).

Conclusion: This article summarises the surveillance and epidemiology of influenza viruses and other respiratory viruses, showing how rapid improvements in influenza surveillance were feasible by connecting the existing structure in the health care system for patient records to electronic surveillance system for reporting ILI cases.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Map of ILI sites and population covered by ILI sites in different Tunisian governorates in 2009–2010 season.
Figure 2
Figure 2. Sentinel data of percentage of specimens positive for influenza in comparison with influenza A(H1N1)pdm09_season 2008–2009, 2009–2010 and 2010–2011.
Figure 3
Figure 3. Percentage of consultant in sentinel centre during 2009–2010 and 2010–2011.
Figure 4
Figure 4. Percentage of influenza viruses in season 2008–2009, 2009–2010 and 2010–2011.
Figure 5
Figure 5. Phylogenetic relationship of partial length HA sequences of influenza A(H1N1)pdm09 viruses from fatal, severe and mild cases in Tunisia during 2009–2010/2010–2011 seasons.
Fatal case#; case in care unit+; severe case *; mild case-. The tree was rooted with the vaccine strain A/California/07/2009 (boxed) as outgroup. Branch lengths are drawn to scale. Signature amino acid changes (H1 numbering) are annotated at the nodes of each cluster. Viruses with 222G or 222E changes are marked in the tree.
Figure 6
Figure 6. Phylogenetic comparison of partial length HA sequences of influenza B (Yamagata and Victoria-lineage) from severe and mild cases in Tunisia during 2009–2010 and 2010–2011 seasons.
See this image and copyright information in PMC

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