Infectious diseases

To the Editor:Hepatitis E virus (HEV) genotype 3, the most common genotype in high income countries, is transmitted by ingestion of high risk food — including pork, deer and shellfish — and by blood transfusion. Rural residence, travel to hyperendemic areas (eg, southern Europe) and animal exposure are other risk factors.1 Both de novo and reactivated HEV infection can lead to chronic infection in up to 60% of immunocompromised patients, particularly in solid organ transplant (SOT) recipients.1,2 Moreover, 10% of patients who are chronically infected develop cirrhosis.1 In a 2013 study, the seroprevalence of HEV in Australian blood donors was 5.99%.3 Autochthonous transmission in Australia, including one patient who was a liver transplant recipient, is well documented.4,5 However, the seroprevalence and rate of chronic HEV infection in SOT recipients in Australia are unknown. We carried out a study to investigate this in an Australian tertiary hospital. In phase 1 of our study, we recruited renal transplant recipients attending routine outpatient follow-up in 2014–15; phase 2 was limited to seropositive participants from phase 1. The study was approved by the Northern Sydney Local Health District Human Research Ethics Committee (LNR/14/HAWKE/300). Seventy-four patients consented to participate in phase 1, and post-transplant stored serum was tested for HEV IgG. Six participants were HEV IgG positive. One seropositive participant died of invasive fungal infection before phase 2. The remaining five participants who were seropositive consented to phase 2, of whom one was HEV IgM positive. We tested plasma for HEV RNA and no phase 2 participants had evidence of ongoing chronic infection. While our study had limitations and we did not identify any participant with chronic infection, it is important to note that Australian SOT recipients are exposed to HEV and are at risk of chronic infection. Effective therapy for chronic HEV is available; therefore, we recommend that SOT recipients who have abnormal liver function tests should be tested for HEV RNA in blood to maximise early diagnosis. In addition, with respect to risk mitigation, previous Australian research supports a link between local pork consumption and HEV infection,4 and French guidelines suggest that SOT recipients should avoid consuming food containing pork liver.6 We believe that similar advice should be given to SOT recipients in Australia. Moreover, consideration should be given to screening donated blood in Australia for HEV RNA, as done in France and the United Kingdom, with experts calling for such screening across the European Union.7,8 The Australian Red Cross Blood Service has undertaken a large scale screening study of donated plasma for HEV RNA to estimate the local risk of HEV transmission by blood transfusion, with results currently pending.9

James P Newcombe · Stella McGinn · Bruce Wong · Archie Darbar · George Kotsiou

To the Editor:We report an extensive investigation into a cluster of five confirmed cases of Legionnaires’ disease in Sydney’s Inner West in May 2016. The patients were aged 62–89 years, four were men, all were ex-smokers, and four had significant comorbidities, such as immunosuppression. Hospitalisations lasted a median of 6 days and one patient died. All patients tested positive for Legionella pneumophila serogroup 1 urinary antigens; however, L. pneumophila was isolated by culture in only one patient. Patients were interviewed to obtain the histories of where they had been in the 2–10 days before the onset of symptoms (the incubation period), and then, to identify the focus for our environmental investigation, we mapped the locations against water source locations.1 Local councils assisted in the collection of water samples: 86 samples were obtained from cooling towers and 15 from other sites, such as fountains. At the time of sampling, requests were made for immediate cleaning of all visibly unclean air conditioning cooling towers or those with cloudy water. Only one sample tested positive for Legionella: a fountain with a low positive result of Legionella anisa. If Legionella isolates are genetically indistinguishable, the genomic sequencing of clinical and environmental samples is a useful tool that can link cases to each other and to an environmental source. In this investigation, L. pneumophila was cultured in only one case and in no environmental samples; therefore, we could not link cases to each other or to an environmental source by genotyping, leaving the possibility that cases were unrelated and sporadic. Despite this investigation, no environmental source for these infections was identified. It is uncommon in an investigation of this size to not detect L. pneumophila in any cooling towers — a routine New South Wales survey found L. pneumophila in 2% of cooling towers in a non-outbreak situation.2 Possible explanations for not detecting Legionella include low sensitivity of sampling at one point in time, incidental and possibly unrelated cleaning of the source cooling tower before sampling, or underestimating the distance that contaminated aerosols may travel, meaning that the source cooling tower was not sampled.3 No further cases with similar exposures were reported in the period immediately after the environmental investigation. This suggests that the extensive public health interventions taken at the time to remedy the problems identified may have been effective, or that incidental cleaning of cooling towers before our sampling may have eliminated the potential source.

Marianne Dowsett · Emma Quinn · Leena Gupta

Antimicrobial agents play a central role in modern health care, especially in the hospital setting

John D Turnidge · Karin Thursky · Caroline S Chen · Vicki R McNeil · Irene J Wilkinson

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Leon J Worth · Ann L Bull · Michael J Richards

In reply

Naomi Runnegar · Damin Si · John Marquess

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Martyn D Kirk · Stephanie Davis · Kerri Viney