Investigation of a death related to pandemic influenza H1N1 in the city of Osasco, São Paulo, June, July, 2009

Abstract

 New viral pandemic influenza subtype H1N1 2009, resulting from genetic recombination of swine, avian and human virus, is globally widespread. We present the investigation of the first death related to infection by the H1N1 2009 influenza virus occurring in the State of São Paulo, performed with the aid of EPISUS-SP. Objectives of this study: investigating the first confirmed death in the State and to ascertain the diagnosis; describing the cases according to time, place and person; identifying the index case in the transmission chain with epidemiologic link to the family and investigating and characterizing the possible occurrence of sustained transmission of pandemic influenza H1N1 2009in the city of Osasco, São Paulo. Adolfo Lutz Institute reported the positive results for pandemic influenza in the post-mortem blood collected from the child. This information led us to consider the hypothesis that the index case from the brothers could be the sister. Contacts occurring up to seven days previous to the onset of symptoms in the brothers were identified: 1) family and close friends; 2) school; 3) English school; 4) school bus. Daily activities of the brothers showed they did not go outside the city of Osasco during the period under investigation. MCL was the first death in the city associated to autochthonous pandemic influenza, with no epidemiologic link to imported cases of the disease. Existence of a family outbreak of infection by pandemic influenza H1N1 2009 was ascertained,with nine confirmed cases; probable source of infection was MCL. Sustained transmission of the pandemic influenza virus H1N1 2009 was confirmed in the country. As recommendations deriving from this study, change in case definition was proposed, including autochthonous cases, changes in norms and procedures designed to identify, investigate and manage flu syndrome cases; training of epidemiologic surveillance teams of the cities in order to face possible newpandemics.