Imported melioidosis in the United Kingdom: Increasing incidence but continued under-reporting

Introduction: Melioidosis, caused by the environmentally-acquired bacterium Burkholderia pseudomallei, is increasingly recognised as a globally significant public health problem, although difficult to diagnose and manage. We aimed to review all cases diagnosed in the UK since 2010, when notification became a legal requirement. This was compared with statutory reporting to assess completeness of surveillance. Methods: A novel dataset was compiled comprising routinely collected clinical and demographic details for isolates of B. pseudomallei referred to Public Health England's reference laboratory. Isolates were cross-referenced with an existing database of mandatory reports of B. pseudomallei made under the Health Protection (Notification) Regulations 2010 to determine completeness of surveillance. The literature was also searched for missed non-referred or reported cases. Results: Forty-six UK cases of melioidosis were identified from January 2010-July 2019. The majority of affected patients were male (65.2%); median age was 53. Four had cystic fibrosis. Other co-morbidities were poorly captured by current surveillance mechanisms. Respiratory disease, sepsis and abscess formation were the most common presenting features. Eighteen had acquired infection in Thailand; two cases were associated with travel to Nigeria. 40 UK cases were confirmed as B. pseudomallei by the reference laboratory. Nineteen of the identified cases were not found on the database of notified causative agents. Five patients had been notified with no confirmatory isolate received. Discussion: Discordance between mandatory notification and isolate referral emphasises the challenges in routine epidemiological surveillance, even in a well-resourced, high-income country. The wide variety of presentations highlights the difficulties in clinical diagnosis. Cases identified following travel to Africa add further evidence that the disease is more widespread than previously thought. Sixteen patients required intensive care management, underlining challenges faced in resource limited settings. Individualised pre-travel counselling should be performed in travellers with high-risk comorbidities such as cystic fibrosis.