Influenza Surveillance among Outpatients and Inpatients in Morocco, 1996–2009

There is limited information about the epidemiology of influenza in Africa. We describe the epidemiology and seasonality of influenza in Morocco from 1996 to 2009 with particular emphasis on the 2007-2008 and 2008-2009 influenza seasons. Successes and challenges of the enhanced surveillance system introduced in 2007 are also discussed.Virologic sentinel surveillance for influenza virus was initiated in Morocco in 1996 using a network of private practitioners that collected oro-pharyngeal and naso-pharyngeal swabs from outpatients presenting with influenza-like-illness (ILI). The surveillance network expanded over the years to include inpatients presenting with severe acute respiratory illness (SARI) at hospitals and syndromic surveillance for ILI and acute respiratory infection (ARI). Respiratory samples and structured questionnaires were collected from eligible patients, and samples were tested by immunofluorescence assays and by viral isolation for influenza viruses.We obtained a total of 6465 respiratory specimens during 1996 to 2009, of which, 3102 were collected during 2007-2009. Of those, 2249 (72%) were from patients with ILI, and 853 (27%) were from patients with SARI. Among the 3,102 patients, 98 (3%) had laboratory-confirmed influenza, of whom, 85 (87%) had ILI and 13 (13%) had SARI. Among ILI patients, the highest proportion of laboratory-confirmed influenza occurred in children less than 5 years of age (3/169; 2% during 2007-2008 and 23/271; 9% during 2008-2009) and patients 25-59 years of age (8/440; 2% during 2007-2009 and 21/483; 4% during 2008-2009). All SARI patients with influenza were less than 14 years of age. During all surveillance years, influenza virus circulation was seasonal with peak circulation during the winter months of October through April.Influenza results in both mild and severe respiratory infections in Morocco, and accounted for a large proportion of all hospitalizations for severe respiratory illness among children 5 years of age and younger

Influenza surveillance in 15 countries in Africa, 2006-2010

BACKGROUND: In response to the potential threat of an influenza pandemic, several international institutions and governments, in partnership with African countries, invested in the development of epidemiologic and laboratory influenza surveillance capacity in Africa. METHODS: We used a standardized form to collect information on influenza surveillance system characteristics, the number and percent of influenza-positive patients with influenza-like illness (ILI) or severe acute respiratory infections (SARI) and virologic data. RESULTS: Between 2006 and 2010, the number of ILI and SARI sites in 15 African countries increased from 21 to 127 and from 2 to 98, respectively. Influenza was detected in 22% of ILI cases and 10% of SARI cases. Children 0-4 years accounted for 48% all ILI and SARI cases of which 20% and 10 respectively were positive for influenza. Influenza peaks were generally discernible in North and South Africa. Substantial co-circulation of influenza A and B occurred most years. CONCLUSIONS: Influenza is a major cause of respiratory illness in Africa, especially in children. Further strengthening influenza surveillance, along with conducting special studies on influenza burden, cost of illness, and role of other respiratory pathogens will help detect novel influenza viruses and inform and develop targeted influenza prevention policy decisions in the region.The work presented in this manuscript was funded completely or in part by host governments, Institute Pasteur, and cooperative agreements with the U.S. Centers for Disease Control and Prevention and/or the U.S. Department of Defense.http://www.journals.uchicago.edu/toc/jid/currenthb2013ay201

Onset peak and duration of influenza seasons, Morocco, 1996–2009.

<p>Onset peak and duration of influenza seasons, Morocco, 1996–2009.</p

Model coefficient, 95% confidence interval and p-value for the Interrupted Time-Series Regression Analysis for the assessment of the impact of the enhanced surveillance system, Morocco, 1996–2009.

<p>*the slope coefficient represent the expected average increase of number of samples in each consecutive year during the pre-intervention period (1996–2006).</p><p>**the slope coefficient represent the expected average increase of number of samples in each consecutive year during the post intervention period (2007–2009).</p

Observed and predicted (using the Interrupted Time Series Analysis) numbers of samples during the pre- and post-intervention period, Morocco, 1996–2009.

<p>Observed and predicted (using the Interrupted Time Series Analysis) numbers of samples during the pre- and post-intervention period, Morocco, 1996–2009.</p

Proportion of patients with laboratory-confirmed influenza by age group and surveillance network, Morocco, 2007–2009.

<p>*from September 2007 to August 2008.</p><p>**from September 2008 to August 2009.</p

Number of positive influenza samples by type and subtypes and proportion of ILI cases over total consultation in the health unit and private clinic networks by week, Morocco, 2007–2009.

<p>Number of positive influenza samples by type and subtypes and proportion of ILI cases over total consultation in the health unit and private clinic networks by week, Morocco, 2007–2009.</p

Demographic characteristics of influenza-like illness (ILI) and severe acute respiratory illness (SARI) patients, Morocco, 2007–2009.

<p>*from September 2007 to August 2008.</p><p>**from September 2008 to August 2009.</p