Cronología de una pandemia: la nueva Influenza A H1N1 en Bogotá, 2009-2010

objectives describing the behaviour of the a h1n1/09 virus related to time, age and gender in patients having suspected infection, medical health care and laboratory diagnosis. method this was a descriptive and retrospective study of patients diagnosed as having the influenza a h1n1/09 virus between april 2009 and july 2010 by the bogotá public health laboratory. results the first cases of a h1n1/09 virus were confirmed since week 17, 2009; positivity increased gradually, reaching maximum expression between weeks 31-36, 2009 (43 % to 53 %) and decreased during the 37th week. the age groups most affected were 6-15 years (35.4 %) and 16-25 years (28 %) (p=0.0044); the lowest percentages were found in children aged less than 1 year (8.7 %) and people older than 65 years (7.2 %) (chi 1.98, p=0.119). the gender ratio was similar: female (18.6 %) and male (17.6 %) (chi 1.82, p=0.1768). conclusions there was a significant increase in influenza a cases during 2009. however, this did not alter the behaviour of the endemic respiratory syncytial virus; on the other hand, the h1n1/09 subtype replaced the seasonal virus circulating amongst the population of bogotá, similarly affecting men and women, mainly young adults. the highest prevalence of cases occurred between august and september 2009.