Detection of influenza virus in rectal swabs of patients admitted in hospital for febrile illnesses in Thailand

Introduction

Influenza virus favours the respiratory tract as its primary site of host entry and replication, and it is transmitted mainly via respiratory secretions. Nasopharyngeal swab is the gold standard specimen type for influenza detection, but several studies have also suggested that the virus replicates in the human gastrointestinal tract.

Methods

A retrospective study was conducted on all patients positive for influenza virus and initially recruited as part of the PREDICT project from 2017 to 2018. The objectives of the study were to investigate whether rectal swab could aid in improving influenza detection, and if there was any correlation between gastrointestinal disturbances and severity of infection, using length of hospital stay as an indicator of severity.

Results

Of the 51 influenza-positive patients, 12 had detectable influenza virus in their rectal swab. Among these 12 rectal swab positive patients, influenza virus was not detected in the nasopharyngeal swab of three of them. Gastrointestinal symptoms were observed for 28.2% patients with a negative rectal swab negative and 25.0% patients with a positive rectal swab. Average length of hospital stay was 4.2 days for rectal swab positive group and 3.7 days for rectal swab negative group. This difference was not statistically significant (p = 0.288).

Conclusions

There is no correlation between influenza virus detection in rectal swab and gastrointestinal disturbances or disease severity, and there is currently insufficient evidence to support replicative ability in the gastrointestinal tract.

Parvalbumin Promoter Methylation Altered in Major Depressive Disorder

Aims: To determine the extent of DNA methylation of parvalbumin gene (PVALB) promoter in major depressive disorder (MDD) patients with and without suicide attempt in comparison with healthy controls. Methods: The extracted DNA from dried blood spots of MDD patients (n = 92) including non-suicidal MDD and suicidal-MDD subgroups (n = 45 and n = 47, respectively) and age-matched control subjects (n = 95) was used for DNA methylation analysis at four CpG sites in the promoter sequence of PVALB by pyrosequencing. Results: The PVALB methylation was significantly increased at CpG2 and decreased at CpG4 in the MDD group compared to the control group, while there was no difference between non-suicidal MDD and suicidal-MDD subgroups. A significant inverse correlation of severity of MDD was indicated only for CpG4. Conclusion: This study provides the first evidence of abnormalities of PVALB promoter methylation in MDD and its correlation with MDD severity indicating a role for epigenetics in this psychiatric disorder.