Epidemiology of respiratory infections among adults in Qatar (2012-2017)

Abstract

Background: Limited data is available about the etiology of influenza like illnesses (ILIs) in Qatar.

Objectives: This study aimed at providing preliminary estimates of influenza and other respiratory infections circulating among adults in Qatar.

Methods: We retrospectively collected data of about 44,000 patients who visited Hamad General Hospital clinics, sentinel sites, and all primary healthcare centers in Qatar between 2012 and 2017. All samples were tested for influenza viruses, whereas about 38,000 samples were tested for influenza and a panel of respiratory viruses using Fast Track Diagnostics (FTD) RT-PCR kit.

Results: Among all ILIs cases, 20,278 (46.5%) tested positive for at least one respiratory pathogen. Influenza virus was predominating (22.6%), followed by human rhinoviruses (HRVs) (9.5%), and human coronaviruses (HCoVs) (5%). A detection rate of 2-3% was recorded for mycoplasma pneumonia, adenoviruses, human parainfluenza viruses (HPIVs), respiratory syncytial virus (RSV), and human metapneumovirus (HMPV). ILIs cases were reported throughout the year, however, influenza, RSV, and HMPV exhibited strong seasonal peaks in the winter, while HRVs circulated more during fall and spring. Elderly (>50 years) had the lowest rates of influenza A (13.9%) and B (4.2%), while presenting the highest rates of RSV (3.4%) and HMPV (3.3%). While males had higher rates of HRVs (11.9%), enteroviruses (1.1%) and MERS CoV (0.2%), females had higher proportions of influenza (26.3%), HPIVs (3.2%) and RSV (3.6%) infections.

Conclusion: This report provides a comprehensive insight about the epidemiology of ILIs among adults in the Qatar, as a representative of Gulf States. These results would help in improvement and optimization of diagnostic procedures, as well as control and prevention of the respiratory infections.

Fig 1. Annual rate of respiratory infections detected from 2012–2017.

The rate of infection per year was calculated as the number of positive cases of each specific virus per the total number of tested samples (n = 43,597 tested for influenza viruses, n = 37929 tested for other viruses). The difference in the infection rate per year was calculated using Pearson Chi2. P-value less than 0.05 is flagged with one star (*). P-value less than 0.01 is flagged with two stars (**). P-value less than 0.001 is flagged with three stars (***). P-value less than 0.0001 is flagged with four stars (****). Ns: not significant.

Fig 2. Monthly distribution of positive cases for at least one respiratory pathogen (2012–2017).

The box plot shows the median mean differences. X: mean. Outer dots: outliers. Bars: standard deviation. The horizontal lines within boxes show the median.

Fig 3. Seasonality of influenza viruses.

The number of positive samples for each influenza type/subtype was calculated per month, from 2012 to 2017. The percentage of positive cases was calculated out of the total tested samples for influenza viruses (n = 43,597).

Fig 4. Seasonality of all ILIs causing pathogens.

The number of positive samples for each pathogen was calculated per month from 2012 to 2017. The percentage of positive cases was calculated out of the total tested samples (n = 37,929).

Fig 5. Rate of ILI infections among males and females.

The difference in the infection rate between the two groups was calculated using Pearson Chi2 and the Fisher Exact test. P-value less than 0.05 is flagged with one star (*). P-value less than 0.01 is flagged with two stars (**). P-value less than 0.001 is flagged with three stars (***). P-value less than 0.0001 is flagged with four stars (****). Ns: not significant.