Risk factors for febrile respiratory illness and mono-viral infections in a semi-closed military environment: a case-control study

The "timeless" use of influenza-like illness criteria for influenza detection in the tropics

OBJECTIVE

We assessed the performance of influenza-like illness (ILI) case definitions by the Centers for Disease Control and Prevention (CDC), European Centers for Disease Control and Prevention and World Health Organization (WHO) in the tropics where seasonal patterns of respiratory viruses in acute upper respiratory tract infections (AURTIs) are ill-defined.

METHODS

Clinical data and samples for respiratory multiplex polymerase chain reaction test were collected from 717 consecutive patients attending an emergency department in Singapore for uncomplicated AURTI in 2016-2018.

RESULTS

Influenza (20.6%), rhinoviruses (14.4%), and coronaviruses (3.6%) were the most common viral pathogens identified. Biannual peaks with year-round activity were identified for influenza. Although higher rhinovirus activity was observed in inter-influenza seasonal periods, rhinoviruses and coronaviruses circulated year-round without distinct seasonal patterns. During high influenza activity months, the CDC and WHO ILI case definitions had moderate-to-high positive likelihood ratio (LR+) of 3.8-6.8 and 4.5-10.7, respectively, for ruling in influenza. They had moderately-high LR + of 3.3-3.8 and 3.9-4.6 for diagnosing influenza during other months. The ILI case definitions had high specificity (77.2%-85.4%) for rhinoviruses and coronaviruses.

CONCLUSION

The CDC and WHO ILI case definitions can be applied to clinically diagnose influenza in the tropics, regardless of the time of the year.

Evidence for Cross-Protection Against Subsequent Febrile Respiratory Illness Episodes From Prior Infections by Different Viruses Among Singapore Military Recruits 2009-2014

Background

Few studies have evaluated the relative cross-protection conferred by infection with different groups of viruses through studies of sequential infections in humans. We investigated the presence of short-lived relative cross-protection conferred by specific prior viral infections against subsequent febrile respiratory illness (FRI).

Methods

Men enlisted in basic military training between December 2009 and December 2014 were recruited, with the first FRI as the study entry point. ResPlex II assays and real-time polymerase chain reaction assays were used to detect viral pathogens in nasal wash samples, and survival analyses were performed to determine whether infection with particular viruses conferred short-lived relative cross-protection against FRI.

Results

Prior infection with adenovirus (hazard ratio [HR], 0.24; 95% confidence interval [CI], .14–.44) or influenza virus (HR, 0.52; 95% CI, .38–.73) conferred relative protection against subsequent FRI episode. Results were statistically significant even after adjustment for the interval between enlistment and FRI (P < .001). Adenovirus-positive participants with FRI episodes tended to be protected against subsequent infection with adenovirus, coronavirus, enterovirus/rhinovirus, and influenza virus (P = .062–.093), while men with influenza virus–positive FRI episodes tended be protected against subsequent infection with adenovirus (P = .044) and influenza virus (P = .081).

Conclusion

Prior adenovirus or influenza virus infection conferred cross-protection against subsequent FRI episodes relative to prior infection due to other circulating viruses.

Cigarette smoking and the occurrence of influenza - Systematic review

OBJECTIVES

The association of current smoking with influenza infection is not widely recognised. The aim of this systematic review was to summarise published evidence and quantify the risk of influenza infection in tobacco smokers compared to non-smokers.

METHODS

We systematically searched MEDLINE, EMBASE, CINAHL, LILACS and Web of Science, from inception to 7 November 2017, to identify relevant randomised control trials, cohort and case-control studies. Study quality was assessed using the Newcastle-Ottawa Scale. We included studies defining influenza as a clinical syndrome and those using confirmatory microbiological tests. Pooled odds ratios (ORs) were estimated by using random effects model.

RESULTS

The mean quality score across the nine included studies (n = 40,685 participants) was 5.4 of 9 (SD 1.07). Current smokers were over 5 times more likely to develop laboratory-confirmed influenza than non-smokers (pooled OR 5.69 (95% CI 2.79-11.60), 3 studies). For studies reporting the occurrence of an influenza-like illness (ILI), current smokers were 34% more likely to develop ILI than non-smokers (pooled OR 1.34 (95% CI 1.13-1.59), 6 studies).

CONCLUSION

Current smokers have an increased risk of developing influenza compared to non-smokers. The association was strongest in studies examining cases with laboratory confirmed influenza.

Impact of an alternating first-line antibiotics strategy in febrile neutropenia

Background

Rising antibiotic resistance poses a challenge to the management of febrile neutropenia in patients with haematological malignancies receiving chemotherapy.

Aim

We studied an alternating first-line antibiotic strategy to determine its impact on all-cause mortality and bacteremia rates in patients with febrile neutropenia.

Methods

An alternating first-line antibiotic strategy was established in mid-2013. Data for 2012 (before strategy implementation) and 2014 (post-strategy implementation) were compared. Antibiotic Heterogeneity Index (AHI) for each of the two time-periods was also calculated.

Findings

There were 2012 admissions (26082 patient-days) in 2012 and 1843 admissions (24331 patient-days) in 2014. There was no significant difference in the baseline characteristics of patients in the two groups. The defined daily doses (DDD) of cefepime (CEF) fell while the DDD of piperacillin-tazobactam (PTZ) rose in 2014 compared with 2012. Vancomycin DDD fell in 2014. The AHI was 0.466 in 2012 and 0.582 in 2014. The difference in all-cause mortality was not statistically significant. There was no difference in rates of bacteremia with CEF-resistant, PTZ-resistant and carbapenem-resistant gram-negative organisms in the two groups. Rates of new cases of Methicillin-resistant Staphylococcus aureus (MRSA) were 2.38/1000 and 2.59/1000 patient-days in 2012 and 2014 respectively. Rates of new cases of Vancomycin-resistant Enterococcus (VRE) were 1.84/1000 and 1.81/1000 patient-days in 2012 and 2014 respectively. There was no Carbapenem-resistant Enterobacteriaceae (CRE) bacteremia in 2012 and 1 in 2014.

Conclusion

An alternating first-line antibiotic strategy resulted in an increase in antibiotic heterogeneity, without increasing mortality. There was also no significant increase in bacteremia rates.

Surveillance for respiratory infectious diseases caused by 6 common viruses in a recruit training site in the Northern region of China

BACKGROUND

Recruit training sites are places with a high incidence of respiratory infectious diseases. Effective surveillance for acute respiratory infectious diseases in a recruit training site is an important way to prevent disease outbreaks.

METHODS

Eight hundred recruits (722 males and 78 females) enlisted in autumn 2015 received a background survey within 24 h of settlement at the recruit training site, including their general personal information, vaccination history, mental status and clinical symptoms. Then, nasopharyngeal swabs of these recruits were collected to detect common respiratory pathogens [influenza virus type A, influenza virus type B, adenovirus (Adv), human respiratory syncytial virus, human bocavirus and human metapneumovirus] by PCR. In addition, fasting venous blood was collected in the morning for adenovirus IgG antibody detection. During the three months of training, the recruits were monitored for symptoms of respiratory infection, and nasopharyngeal swabs were collected from those with an axillary temperature ≥38 °C and other respiratory symptoms within 4 h of symptom onset. Samples were further examined by PCR.

RESULTS

Among the 795 effective nasopharyngeal swab samples collected during survey, two cases of group C type 1 adenovirus were identified by PCR. During the 3 months of training, fever and respiratory symptoms occurred in 39 recruits (incidence rate of 4.9%) and 5 cases of adenovirus were detected (positive rate of 12.8%). Genotyping showed 3 cases of type 4 adenovirus and 2 of type 3 adenovirus. No type 7, 14 or 55 adenovirus was detected. The Adv-IgG positive rate of recruits was 48.2%. Among the 5 Adv positive cases with fever and respiratory symptoms, 4 were Adv-IgG positive.

CONCLUSION

The pathogen carrier rate in recruits was low, and only group C adenovirus, which causes mild infection in humans, was detected. No respiratory outbreak was observed at the recruit training site, and sporadic cases were mainly caused by type 3 and type 4 adenoviruses.