Report on influenza viruses received and tested by the Melbourne WHO Collaborating Centre for Reference and Research on Influenza during 2022.

As part of its role in the World Health Organization's (WHO) Global Influenza Surveillance and Response System (GISRS), the WHO Collaborating Centre for Reference and Research on Influenza in Melbourne received a record total of 12,073 human influenza positive samples during 2022. Viruses were analysed for their antigenic, genetic and antiviral susceptibility properties. Selected viruses were propagated in qualified cells or embryonated hen's eggs for potential use in seasonal influenza virus vaccines. In 2022, influenza A(H3N2) viruses predominated over influenza A(H1N1)pdm09 and B viruses, accounting for 77% of all viruses analysed. The majority of A(H1N1)pdm09, A(H3N2) and influenza B viruses analysed at the Centre were found to be antigenically and genetically similar to the respective WHO recommended vaccine strains for the southern hemisphere in 2022. Of 3,372 samples tested for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir, two A(H1N1)pdm09 viruses showed highly reduced inhibition against oseltamivir.

Risk of latent and active tuberculosis infection in travellers: a systematic review and meta-analysis.

INTRODUCTION: Achieving tuberculosis (TB) elimination in low TB incidence countries requires identification and treatment of individuals at risk for latent TB infection (LTBI). Persons travelling to high TB incidence countries are potentially at risk for TB exposure. This systematic review and meta-analysis estimates incident LTBI and active TB among individuals travelling from low to higher TB incidence countries. METHODS: Five electronic databases were searched from inception to 18 February 2020. We identified incident LTBI and active TB among individuals travelling from low (<10 cases/100 000 population) to intermediate (10-100/100 000) or high (>100/100 000) TB incidence countries. We conducted a meta-analysis and meta-regression using a random effects model of log-transformed proportions (cumulative incidence). Subgroup analyses investigated the impact of travel duration, travel purpose and TB incidence in the destination country. RESULTS: Our search identified 799 studies, 120 underwent full-text review, and 10 studies were included. These studies included 1 154 673 travellers observed between 1994 and 2013, comprising 443 health care workers (HCW), 1 068 636 military personnel and 85 594 general travellers/volunteers. We did not identify any studies that estimated incidence of LTBI or active TB among people travelling to visit friends and relatives (VFRs). The overall cumulative incidence of LTBI was 2.3%, with considerable heterogeneity. Among individuals travelling for a mean/median of up to 6 months, HCWs had the highest cumulative incidence of LTBI (4.3%), whereas the risk was lower for military (2.5%) and general travellers/volunteers (1.6%). Meta-regression did not identify a difference in incident LTBI based on travel duration and TB incidence in the destination country. Five studies reported cases of active TB, with an overall pooled estimate of 120.7 cases per 100 000 travellers. CONCLUSIONS: We found that travelling HCWs were at highest risk of developing LTBI. Individual risk activities and travel purpose were most associated with risk of TB infection acquired during travel.

Seroepidemiology of melioidosis in children from a remote region of Papua New Guinea.

BACKGROUND: The Balimo region in Papua New Guinea has previously been identified as melioidosis-endemic with a predilection for children. Where health resources are scarce, seroepidemiology can be used to assess exposure to Burkholderia pseudomallei and therefore risk of acquiring melioidosis. METHODS: Logistic regression was used to determine associations between indirect haemagglutination assay (IHA) seroreactivity with environmental and demographic/cultural factors to aid in determining risk factors associated with exposure to B. pseudomallei in children. RESULTS: Of the 968 participants, 92.9% (899/968) were children, representing the majority of the community school population in the immediate Balimo region. Of these, 24.6% (221/899) were seropositive. Bathing in the lagoon (OR=2.679), drinking from the well or lagoon (OR=1.474), and being a member of the Siboko (OR=1.914) or Wagumisi (OR=1.942) clans were significantly associated with seropositivity. In the multivariate analysis, drinking from a well or lagoon (OR=1.713), and the Siboko (OR=2.341) and Wabadala (OR=2.022) clans were associated with seropositivity. CONCLUSIONS: This study in children supports observations that interactions with groundwater in this region are risk factors in acquiring melioidosis. Public health measures intended to limit this exposure may help reduce the risk of acquiring melioidosis in this remote community. Associations with clan structure may provide more cultural specific insights, however this requires further elucidation.