Possible Risks and Protective Factors of Upper Respiratory Tract Infections in Healthy Japanese Office Workers

Abstract

Objective: In order to determine the risks and protective factors of upper respiratory tract infections (URTIs) in healthy office workers, we conducted a preliminary epidemiological survey and analysis of saliva parameter levels. Methods: One hundred and forty-six (98 men, 48 women; aged 20-59 years) healthy, full-time office workers in Tokyo and its suburbs participated in a questionnaire survey on lifestyle habits and daily physical condition, including symptoms of URTIs, from October 2012 to March 2013. Salivary parameters (secretory IgA, beta-defensin 2, LL-37, granulysin, lysozyme, cortisol) levels were also measured to analyze the correlation to URTI incidence and lifestyle habits. Results: Both the incidence rate and frequency of URTIs per person during the investigation period were highest among participants in their 50s and lowest among participants in their 30s. Participants who lived with their family showed higher URTI incidence than those who lived alone, while those with exercise habits showed lower URTI incidence. Higher saliva cortisol levels significantly correlated with high URTI incidence, while higher salivary granulysin levels significantly correlated with low URTI incidence. Conclusions: The risk factors of URTI incidence among healthy, full-time office workers include not only aging, but also living with family and higher salivary cortisol levels, and the protective factors are exercise habits and higher salivary granulysin levels.