First US Death

A Mexican toddler who came to the United States for treatment has died in Texas of the swine flu. Texas health officials said the child, a 23-month old Mexican boy, had traveled with his family from Mexico to Brownsville in south Texas. He was brought to Houston after becoming ill and died Monday night. As of April 29, 2009 this remains the only fatality in the US.

Seasonality of the Flu

What is our likely future over the next few months here in the Northern Hemisphere? A few flu basics – Influenza is a seasonal infection in moderate climates. The flu season in the northern hemisphere is between January and April, although infections have occurred as early as December and as late as May. In the southern hemisphere the flu season extends from May to September. The calendar is in our favor – May is almost here. Based on our previous history this indicates the end of influenza is coming to the north. As flu season begins in the southern hemisphere, it is quite possible that swine flu will circulate extensively in that region.

What has happened in prior pandemics? The 1918 pandemic began in March 1918 with an outbreak of a mild respiratory disease in soldiers at Fort Funston, Kansas. Thanks to World War I, it then spread to other military bases in the US and eventually to Europe. These infections were mild and did not receive much attention from the press. At the end of August 1918 a more virulent H1N1 virus emerged which caused a very high mortality – 2.5%. The disease peaked in the fall months September through November. The following spring of 1919 a second disastrous wave of infections took place.

The 1968 pandemic originated in Southern Asia (H3N2) in the summer of 1968 and was responsible for sporadic cases of disease from September through December in the US, England, and Japan. The epidemic spread in the northern hemisphere countries began in December 1968 and ended the end of April 1969. In the southern hemisphere it began in January 1969, ended in October, and returned in June 1970.

Our previous pandemic history and nature of the virus demonstrates the seasonality of pandemic influenza and suggests that the spread of the current swine flu in the north is not imminent.

Call for Action Still Required

This does not negate the need for swift action and planning.  It simply may buy us a bit of time.

Reference – Columbia University Medical Center virology professor, Vincent Racaniello Ph.D.