Non-influenza Respiratory Pathogens in Mongolia: Results of multiplex real-time Polymerase Chain Reaction (mx-rt-PCR) surveillance in 2008-2013 1, 2,
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P.Nymadawa Ch.Maitsetseg , S.Tsatsral 1 Mongolian Academy of Medical Sciences, 2 National Influenza Center, National Center of Communicable Diseases, Ministry of Health, Mongolia
Background Acute respiratory infections (ARI) are the leading cause of human morbidity and mortality globally. The control activities of ARI are complicated with the multiple pathogens causing a disease with similar clinical expressions. A screening of respiratory samples collected from ARI patients in Mongolia in 2003-2007 with the “classical” MDCK cell culture yielded only 9.8% (691/7,073) influenza viruses [B.Darma et al., 2009] leaving the vast majority of ARI cases with unknown etiology. The aim of this study is to test a current nucleic acid based multiplex technology to study the etiology of ARI in Mongolia.
Materials and Methods We have studied 2,515 archival samples tested negative for influenza viruses by rt-PCR, kept in the National Influenza Center, National Center of Communicable Diseases, Mongolia (NIC), collected from patients with ARI by sentinel surveillance sites all over the country from November 2008 through March 2013. The nucleic acids were isolated from the respiratory samples by NucliSENS Minimag, bioMerieux, France and specific pathogens were detected by ABI Fast Real Time PCR System 7500, Applied Biosystems, USA with a mx-rt-PCR assay for simultaneous detection and identification of 19 respiratory pathogens: respiratory syncytial virus (RSV), human rhinovirus (HuRhV), parainfluenza viruses (PIV: types I, II, III, and IV), influenza viruses (IV: types A and B, A/H1N1pdm), human metapneumovirus (HuMpV), enterovirus (EV), parechovirus (PEV) human bocavirus (HuBV), human coronaviruses (HuCoV: strains HCoV-43, HCoV-63, HCoV-229, and HCoV-HKU), adenovirus (AdV), Mycoplasma pneumonia (MyP) using “FTD Respiratory Test Kit” (Fast-Track Diagnostics, Luxembourg).
Results We have detected totally 1,490 pathogens from the tested samples, among them 269 (18%) HuRhV, 253 (17%) RSV, 191 (12.8%) PIV, 190 (12.7%) HuCoV, 144 (9.7%) HuBV), 122 (8.2%) IV-A, 117 (7.8%) HuMV, 104 (7.0%) AdV, 55 (3.7%) EV, 22 (1.5%) MyP, 18 (1.2%) IV-B and 5 (0.3%) PEV (Figure 1). 209 (8.3%) of samples has yielded more than 2 pathogens (coinfection). 1,092 (43.4%) samples were from outpatient population and 1423 (56.6%) – from the hospitalized patients yielding slightly higher virus detection in the outpatient samples (51.6% vs 50%). The dominating viruses detected were: HuRhV (21.1%), HuCoV (14.7%) and PIV (11.6%) among 653 pathogens from outpatient samples, whereas RSV (21.5%), HuRhV (15.6%) and PIV (13.7%) among 839 pathogens from inpatient samples (Figure 2).
Figure 1. Percentage of pathogens detected from ARI samples in Mongolia in 2008-2013
Figure 2. Percentage of pathogens detected in outpatient samples and from hospitalized patients
The virus detection was significantly higher (p ≤0.001) in young age groups 0-5 (56%=964/1,715) and 6-10 (53%=125/236) years in comparison to the older age groups (33.3%=188/564) (Figure 3).
Figure 3. Percentage of detected respiratory pathogens in different age groups
Analysis of monthly distribution of average detection rates for individual pathogens has revealed different patterns: PIV, RSV, HuMV caused outbreaks 2 times in a year in October-December, and in March-May (Figure 4A); HuCoV, HuBV detected usually in October-January (Figure 4B); IV – prevailed in December-February (Figure 4C); PEV – detected mostly in JulySeptember; whereas HuRhV, AdV, EV and MyP were detected year around (Figure 4D). A.
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Figure 4. Distribution of detected respiratory pathogens per month (average for four years)
Conclusion The detection rate of respiratory pathogens in respiratory samples from ARI patients can be significantly improved with multiplex rt-PCR method and it is recommendable to introduce it into the routine virological surveillance for ARI.
Acknowledgement The authors express their thank to CDC USA for supporting of routine influenza surveillance activity in Mongolia through the Cooperative Agreement Project “Developing Sustainable Influenza Surveillance Network” IU511P000331 Presenting author: Prof. P.Nymadwa, MD, PhD, DSc(Med) E-Mail:
[email protected] PBN: P2-639 Abstract number: 5027
