Swine Flu Day by Day
11 March: First documented symptoms (as of 5 May) in a Mexico City resident who later would be found to have confirmed infection with A(H1N1) swine flu.
30 March: A 10-year-old boy with fever, cold, and vomiting goes to the Naval Medical Center San Diego in California. As part of a clinical study, a nasopharyngeal swab is sent across town to the Naval Health Research Center (NHRC).
1 April: NHRC researchers determine that the boy is likely infected with influenza A, but they cannot subtype the strain. As per protocol, the sample is sent to Marshfield Labs in Wisconsin. HealthMap, a global disease alert system run by academics, flags a news story from Mexico about a strange respiratory outbreak in the state of Veracruz that has claimed two lives.
6 April: Veratect, a Kirkland, Washington-based company that scours news reports for emerging threats, reports in its subscription-only database that local Mexican health officials have declared an alert because of respiratory disease outbreak in La Gloria, Veracruz state, Mexico.
11 April: As per the International Health Regulations (IHR), the World Health Organization (WHO) has a pandemic alert and response network, which relies on designated people or institutions in each member country to report unusual disease patterns. PAHO, a regional office of WHO, asks the Mexican IHR “focal point” to verify the outbreak reported in the news.
12 April: Mexico’s director general of epidemiology confirms to PAHO the existence of acute respiratory infections Studies continue. Mexico’s focal point considers outbreak to be a “potential public health event of international importance” because it meets IHR criteria: severe public health impact and an unusual event.
21 April: Samples from Mexico arrive at PHAC.
22 April: CDC publishes first dispatch in the Morbidity and Mortality Weekly Report (MMWR) about two cases in California. Mexico reports atypical influenza behavior associated with severe pneumonia in various cities. InDRE [Instituto de Diagnóstico y Referencia Epidemiológicos] ships samples to PHACs National Microbiology Laboratory in Winnipeg and CDC.
ProMED’s first report on human cases citing CDC report.
23 April: Samples from Mexico arrive at CDC. PHAC and CDC confirm Mexico cases are the same A(H1N1) of swine origin.
SOURCE: Excerpted and adapted from Cohen (2009).