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Open Access Research article

Respiratory viruses associated with patients older than 50 years presenting with ILI in Senegal, 2009 to 2011

Ndongo Dia1, Vincent Richard2, Davy Kiori1, El Hadj Abdoul Khadir Cisse1, Fatoumata Diène Sarr2, Abdourahmane Faye1, Déborah G Goudiaby1, Ousmane M Diop1 and Mbayame N Niang1*

Author Affiliations

1 Unit of Medical Virology, Institut Pasteur de Dakar, Unité de Virologie Médicale, Dakar, BP; 220, Dakar, Senegal

2 Institut Pasteur de Dakar, Unité d’Epidémiologie des maladies infectieuses, Dakar, Sénégal

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BMC Infectious Diseases 2014, 14:189  doi:10.1186/1471-2334-14-189

Published: 8 April 2014

Abstract

Background

In Africa, especially in West Africa, studies about the prevalence and diversity of respiratory viruses (influenza and others) in elderly people are largely lacking. In studies done elsewhere, it is well established that older people, when compared with younger adults, are at greater risk of significant morbidity and mortality from complications arising from influenza. The main aim of this study was to determine the prevalence and the diversity of respiratory viruses associated with ILI cases in adults over 50 years old in Senegal.

Methods

The recruitment period of this study was from January 2009 to December 2011. 232 patients aged 50 years and above presenting ILI cases were enrolled. Nasal-pharyngeal and/or oral pharyngeal swabs were collected from patients. RNA was extracted from 200 μl of each sample followed by a two-step real-time RT-PCR. The Anyplex™ II RV16 Detection kit was used for viral detection. The kit enabled the simultaneous detection of the presence of 16 respiratory viruses.

Results

150 viruses were detected: influenza viruses (44.7%) and rhinoviruses (26.7%) were the most prevalent. We detected 13 human parainfluenza viruses (8.7%), 7 human respiratory syncytial viruses (4.7%), 6 coronaviruses (4%), 5 human metapneumoviruses (3.3%), 5 human adenoviruses (3.3%) and 1 human bocavirus (0.7%). 14 cases (6%) of dual virus infections and one triple viral detection case were encountered. 56 (56.6%) viruses detected were found in the 50-64 year old age group, 59 (76.6%; P < 0.001) from 65–74 year old age group and 35 (62.5%) were detected in the ≥75 year old age group. The viral co-infections were more frequent in the 65-74 age group (9/15).

Conclusions

This pilot study demonstrates a variety of respiratory viruses in the elderly. It also highlights a high prevalence of these viruses in this age group. We speculate from these results that the impact of respiratory viruses other than influenza on the elderly has been considerably underestimated. A more exhaustive study seems necessary in order to provide a more complete picture of the burden of respiratory viruses on morbidity among adults over 50 years old in the sub-Saharan context.

Keywords:
Influenza; Respiratory virus; Elderly; Prevalence; Diversity