Ciprofloxacin-resistant shigellosis outbreaks among men who have sex with men (MSM) have not been reported in Asia. During 3 March to 6 May 2015, the Notifiable Disease Surveillance System detected nine non-imported Shigella sonnei infections among human immunodeficiency virus (HIV) -infected Taiwanese MSM. We conducted a molecular epidemiological investigation using a 1 : 5 matched case-control study and laboratory characterizations for the isolates. Of the nine patients, four reported engagement in oral-anal sex before illness onset. Shigellosis was associated with a syphilis report within 12 months (adjusted odds ratio (aOR) 8.6; 95% CI 1.05-70.3) and no HIV outpatient follow-up within 12 months (aOR 22.3; 95% CI 2.5-201). Shigella sonnei isolates from the nine patients were all ciprofloxacin-resistant and the resistance was associated with S83L and D87G mutations in gyrA and S80I mutation in parC. The nine outbreak isolates were discriminated into two closely related pulsed-field gel electrophoresis (PFGE) genotypes and seven 8-locus multilocus variable-number tandem repeat analysis (MLVA8) types that suggest multiple sources of infections for the outbreak and possible under-recognition of infection among Taiwanese MSM. The outbreak isolates were characterized to be variants of the intercontinentally transmitted SS18.1 clone, which falls into the globally prevalent phylogenetic sub-lineage IIIb. Inter-database pattern similarity searching indicated that the two PFGE genotypes had emerged in the USA and Japan. The epidemiological characteristics of this outbreak suggest roles of risky sexual behaviours or networks in S. sonnei transmission. We urge enhanced surveillance and risk-reduction interventions regionally against the interplay of HIV and shigellosis among MSM.

Chemsex is a new risk factor for shigellosis among MSM living with HIV, as identified in the 2015-2016 outbreak. Additional risk factors include poppers use, sexual risk behaviours and high pVL. Further studies on chemsex among MSM, which is a rising public health concern, are urgently required.

The present study aimed to evaluate the association between influenza vaccination and the secondary prevention of cardiovascular disease (CVD) among elderly persons. This retrospective cohort study used the Geriatric Dataset of Taiwan’s National Health Insurance Research Database (2000–2013). Patients aged ≥ 65 years who had been hospitalized for the first episodes of myocardial infarction were eligible. The vaccinated cohort comprised patients who received one dose of influenza vaccine within 180 days after discharge. The unvaccinated cohort included those who did not receive influenza vaccination and was propensity score–matched (1:1) for known CVD risk factors. All-cause death, acute myocardial infarction or cardiovascular death, and hospitalization for heart failure were assessed 1 year after the 181 st day after hospital discharge. Compared with the matched cohort ( n = 4,350), the vaccinated cohort ( n = 4,350) had significantly lower incidences of all-cause death (hazard ratios [HR] 0.82, 95% CI [confidence interval] 0.73–0.92), myocardial infarction or cardiovascular death (HR 0.84, 95% CI 0.74–0.96), and hospitalization for heart failure (HR 0.83, 95% CI 0.74–0.92). The association between influenza vaccination and reduction of CVDs was similar across different subgroups. Cumulative incidence curves of the CVDs of interest for the two cohorts separated within the initial 3 months of follow-up ( P < 0.05). Influenza vaccination was associated with a reduced risk of CVD in the elderly population with previous myocardial infarction.

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