title: The role of temperature and humidity on seasonal influenza in tropical areas: Guatemala, El Salvador and Panama, 2008-2013.
abstract: BACKGROUND
  The role of meteorological factors on influenza transmission in the tropics is less defined than in the temperate regions. We assessed the association between influenza activity and temperature, specific humidity and rainfall in 6 study areas that included 11 departments or provinces within 3 tropical Central American countries: Guatemala, El Salvador and Panama.
  Logistic regression was used to model the weekly proportion of laboratory-confirmed influenza positive samples during 2008 to 2013 (excluding pandemic year 2009). Meteorological data was obtained from the Tropical Rainfall Measuring Mission satellite and the Global Land Data Assimilation System. We found that specific humidity was positively associated with influenza activity in El Salvador (Odds Ratio (OR) and 95% Confidence Interval of 1.18 (1.07-1.31) and 1.32 (1.08-1.63)) and Panama (OR = 1.44 (1.08-1.93) and 1.97 (1.34-2.93)), but negatively associated with influenza activity in Guatemala (OR = 0.72 (0.6-0.86) and 0.79 (0.69-0.91)). Temperature was negatively associated with influenza in El Salvador's west-central departments (OR = 0.80 (0.7-0.91)) whilst rainfall was positively associated with influenza in Guatemala's central departments (OR = 1.05 (1.01-1.09)) and Panama province (OR = 1.10 (1.05-1.14)). In 4 out of the 6 locations, specific humidity had the highest contribution to the model as compared to temperature and rainfall. The model performed best in estimating 2013 influenza activity in Panama and west-central El Salvador departments (correlation coefficients: 0.5-0.9).
  
  
  CONCLUSIONS
  The findings highlighted the association between influenza activity and specific humidity in these 3 tropical countries. Positive association with humidity was found in El Salvador and Panama. Negative association was found in the more subtropical Guatemala, similar to temperate regions. Of all the study locations, Guatemala had annual mean temperature and specific humidity that were lower than the others.
authors: Goddard Earth Sciences Technology and Research (GESTAR), Universities Space Research Association, Columbia, Maryland, United States of America; Global Change Data Center, Code 610.2, NASA Goddard Space Flight Center, Greenbelt, Maryland, United States of America.
authors: Radina P
authors: RP
authors: Soebiyanto
authors: Influenza Program, Centers for Disease Control and Prevention (CDC) Regional Office for Central America Region, Guatemala City, Guatemala.
authors: Wilfrido
authors: W
authors: Clara
authors: Influenza Unit, Center for Health Studies, Universidad Del Valle de Guatemala, Guatemala City, Guatemala.
authors: Jorge
authors: J
authors: Jara
authors: National Influenza Center, Ministry of Health of Guatemala, Guatemala City, Guatemala.
authors: Leticia
authors: L
authors: Castillo
authors: Health Surveillance Division, Ministry of Health of El Salvador, San Salvador, El Salvador.
authors: Oscar Rene
authors: OR
authors: Sorto
authors: Division of Meteorology, National Environmental Observatories, Ministry of Environment and Natural Resources of El Salvador, San Salvador, El Salvador.
authors: Sidia
authors: S
authors: Marinero
authors: National Influenza Center, Gorgas Memorial Institute of Health Studies, Panama City, Panama.
authors: María E Barnett
authors: ME
authors: de Antinori
authors: Influenza Unit, Center for Health Studies, Universidad Del Valle de Guatemala, Guatemala City, Guatemala.
authors: John P
authors: JP
authors: McCracken
authors: Influenza Division, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, United States of America.
authors: Marc-Alain
authors: MA
authors: Widdowson
authors: Influenza Division, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, United States of America.
authors: Eduardo
authors: E
authors: Azziz-Baumgartner
authors: Global Change Data Center, Code 610.2, NASA Goddard Space Flight Center, Greenbelt, Maryland, United States of America.
authors: Richard K
authors: RK
authors: Kiang
mesh_terms: D006166:Guatemala / Q000453:epidemiology; D006801:Humans; D006813:Humidity; D009980:Influenza A virus / Q000302:isolation & purification*; D007251:Influenza, Human / Q000453:epidemiology* / Q000635:transmission* / Q000821:virology; D008685:Meteorological Concepts; D010176:Panama / Q000453:epidemiology; D012621:Seasons; D013696:Temperature; D013997:Time Factors; D014329:Tropical Climate