Although it is known that febrile respiratory illnesses (FRI) may be caused by multiple respiratory pathogens, there are no population-level studies describing its impact on clinical disease.
Between May 2009 to October 2012, 7733 FRI cases and controls in the Singapore military had clinical data and nasal wash samples collected prospectively and sent for PCR testing. Cases with one pathogen detected (mono-pathogen) were compared with those with two pathogens (dual-pathogen) for differences in basic demographics and clinical presentation using Pearson’s chi-square test and permutation tests.
45.8% had one pathogen detected, while 20.2% had two, 30.9% had no pathogens detected and 3.1% had more than two pathogens. Multiple pathogens were associated with recruits, those with asthma and non-smokers. Influenza A (80.0%), Influenza B (73.0%) and Mycoplasma (70.6%) were most commonly associated with mono-infections while Adenovirus was most commonly associated with dual-infections (62.9%).
The most common virus-virus pair among dual-pathogens was that of Influenza A with Enterovirus; and of bacteria-bacteria pairs, it was Haemophilus influenza (H. influenza) with S. pneumoniae. The top three virus-bacteria observations were H. influenza, paired with Adenovirus, Enterovirus, and Coronavirus respectively.
Influenza A paired with S. pneumoniae had higher proportions of chills and rigors than their respective mono-pathogens (p=0.03, p=0.009). H. influenzae paired with either Enterovirus or Parainfluenzae (p=0.002) had higher proportions of cough with phlegm than their respective mono-pathogens. Although there were observed differences in mean proportions of body temperature, nasal symptoms, sore throat, body aches and joint pains between viral and bacterial mono-infections, there were few differences between distinct dual-infection pairs and their respective mono-infections counterparts.
A substantial number of FRI cases have multiple pathogens detected. Observed clinical differences between cases of dual- infections and mono-infections indicate the likely presence of complex microbial interactions between the various pathogens.
A. Cook, None
J. P. Loh, None
S. H. Ng, None
B. H. Tan, None
C. Gao, None
X. Q. Tan, None
V. Lee, None