Eurosurveillance - Volume 7, Issue 12, 01 December 2002

A large outbreak of influenza-like illness occurred in Madagascar during July–August 2002. The very sharp increase in the number of cases over a short period of time led health authorities to suspect the appearance of a particularly virulent new influenza virus strain. This triggered immediate international reaction, and a WHO international team assisted local health authorities investigate and control the outbreak. Fortunately preliminary investigation found the virus strain involved was the known A/Panama/2007/99 type, which has been circulating worldwide for several years.

Preliminary investigation found that a large outbreak of influenza-like illness occurred in Madagascar during July–August 2002, with 30 304 cases and 754 deaths reported. Most cases were reported from the highland regions of Fianarantsoa Province, in centre Madagascar. The majority of the cases lived in rural areas, and children under five years and adults 60 years and older were the most affected. The outbreak was attributable to an A/Panama/2007/99-like (H3N2) virus, which has been circulating worldwide for several years.

A local sentinel network of general practitioners has been established in the north west of England for the surveillance of influenza. In the 2001–02 winter, consultation rates for influenza-like-illness (ILI) were low but the surveillance network was able to demonstrate sub-regional variations in the timing of peak influenza activity, and the infection of different age groups. This suggests the network can contribute to better planning to winter pressures on the North West health service.

According to a national survey in Germany, the influenza virological surveillance can be improved when sentinel practitioners take throat swabs specimens only from patients who consult early after the disease onset (ie, within 48 hours), and when they use the strict clinical case definition of influenza-like illness. PCR should be used for primary detection of influenza viruses.

Seasonal outbreaks of influenza exert a considerable burden on health services, and are notorious for their variability from year to year. Making use of historical data from the Scottish sentinelle surveillance since 1972, a potential candidate model has been derived based on simple linear regression. It was applied with a measure of success in the 1999–2000 winter season.

In Geneva, Switzerland, the Spanish flu epidemic affected more than 50% of the population. The mortality was higher among those aged between 20–49 years and among men. The socioeconomic impact was very important, as the outbreak led to severe dysfunctions, including in health services. This epidemic shows the socio-economical burden that may be associated with influenza and highlights the need for pandemic preparedness.