Relationship Between Temperature and Influenza: Case Study for the month of March

Influenza, commonly referred to as the ‘flu', is a respiratory virus that causes significant mortality and morbidity during annual epidemics, and is capable of affecting nearly half of the global population during severe pandemics (e.g., the 1918–1920 ‘Spanish Flu' (Potter, 2001). Shortly after the detection of the H1N1 influenza outbreak, a virus infection that started in Mexico in late March and early April 2009. The disease subsequently spread quickly to the United States and other countries and formed the first infectious pandemic of the 21st century (Moghadami, 2012). Patients with high-risk conditions such as diabetes, asthma, pregnancy, cardiovascular diseases, immune suppressive status, obesity, and sickle disease suffered more from this pandemic (Miller, 2009). This study aims at verifying the tendency of the H1N1 influenza in São Paulo city (Brazil) during the period of 2000 to 2004 for march. Monthly data were used from hospitalizations. Hospitalizations data of influenza were obtained from the database of the computer department of the Unified Health System (DATASUS) the list of morbidity of the International Classification of Diseases ICD-10. The trend will be verified through the Mann Kendall test, that is nonparametric trend test. The computer program used for this analysis was the free software R (2.15.0). The Mann-Kendall, initially proposed by Sneyers (1975), considers that, if stability a time series, the succession of values occurs independently, and the probability distribution should always remain the same (simple random number). The p-value associated with the Mann-Kendall test is statistically significant, suggesting the presence of a statistically significant upward trend in in the number of hospitalizations from H1N1 influenza. This fact can be associated with the transition season (summer to autumn), which means that there is an increase in the temperature range. The temperature variation affects humans, since most species is not adapted to the occurrence of major temperature variations.