Epidemiological update: increase in reporting of human cases of A(H5N1) influenza, Egypt, 9 April 2015

​In Egypt, as of 6 April 2015, the Ministry of Health and Population has reported 134 human cases of influenza A(H5N1), including 38 deaths. Since 2006, Egypt has reported 336 human cases, according to the World Health Organization (WHO)/Food and Agriculture Organization of the United Nations (FAO).

The number of laboratory-confirmed human cases of avian influenza A(H5N1) virus infection in Egypt with onsets of illness from January to March 2015 is the highest reported for a three-month period since the start of the epidemic in 2006. New cases have been reported every month since the surge that started in November 2014 (Figure). No similar surge in cases has been reported in any other country.

As communicated by WHO, during the recent surge (November 2014 to March 2015), cases have been reported from 21 of the 29 Egyptian governorates. Females represented 60% of the cases. The number of fatal cases in Egypt in 2015 is the highest ever reported (Table). The case–fatality rate for 2015 so far is 28%, although, for recent cases, the final outcomes may not yet be known. There appears to have been no discernible trend in the case–fatality rate between 2006 and 2015. According to the WHO Regional Office for the Eastern Mediterranean (EMRO), despite the recent surge in human cases, the demographic and epidemiological characteristics of the recently reported cases do not significantly differ from previous periods.

The increase in human cases in Egypt may be attributed to several factors, including increased circulation of influenza A(H5N1) viruses in poultry, lower public health awareness of risks in middle and upper Egypt, seasonal factors such as closer proximity to poultry because of cold weather and possibly longer survival of the viruses in the environment. A high-level joint WHO/FAO/OIE mission to Egypt was conducted in March 2015 to assess the risks associated with the influenza A(H5N1) viruses and to recommend control measures.

Figure: Distribution of human influenza A(H5N1) cases in Egypt, by month and year, March 2006 to March 2015

Source FAO Emergency Prevention System (EMPRES)

 

Table: Number of human influenza A(H5N1) cases and deaths in Egypt, by year

 * First three months only

ECDC assessment

This ongoing outbreak of influenza A(H5N1) among poultry and humans in Egypt has now caused more cases during one season than has been reported from any other country globally. The virus belongs to a clade that appears to have been restricted to transmission in Egypt and neighbouring countries for several years. An emergence of a novel cluster within this clade was recently reported, which might explain the increase in poultry infections and/or human cases. No publicly available evidence is available to rule out ongoing human-to-human transmission in smaller clusters of cases and detailed epidemiological studies are urgently needed.

The conclusions from the ECDC Rapid Risk Assessment published on 13 March 2015 remain valid.

The increase in human cases of A(H5N1) infection during the winter months 2014–2015 may be due to an increase in the circulation of A(H5N1) among backyard poultry and exposure to infected poultry across Egypt. Identification of such sporadic cases or small clusters is not unexpected as avian influenza A(H5N1) viruses are known to be circulating there among poultry. Strict implementation of control measures to reduce and eliminate infection in poultry is essential for reducing the risk of zoonotic transmission and human cases. Enhanced human infectivity of the circulating virus and the protection conferred by the poultry vaccines currently in use should be further investigated. Surveillance in poultry as well as in humans needs to be strengthened and, ideally, coordinated. Intervention programmes to reduce virus circulation in the country should be reinforced. Travellers visiting Egypt should avoid direct contact with poultry and birds or uncooked/untreated poultry products.