Twenty‐five years of acanthamoeba diagnostics in Austria

AbstractAcanthamoeba spp. are ubiquitous free‐living amoebae and do not need a host. They can, however, cause disease upon accidental contact with a potential host. The most common Acanthamoeba infection in humans is the so‐called Acanthamoeba keratitis (AK), occurring mainly in contact lens wearers.The first case of AK was reported in the early seventies and in the mid‐eighties the association between AK and contact lens wear was discovered. Today, acanthamoebae are among the most important causative agents of keratitis in contact lens wearers. AK often shows a severe progression, which is due to a lack of awareness but also to the lack of specific treatment. The dormant cysts pose a particular problem, often residing within the tissue and leading to reinfection after termination of treatment. In industrialized countries the annual incidence of AK lies between 0.1–1 cases per 100 000 inhabitants, with a marked regional variation depending on contact lens wear habits and mode of water supply.Our institution is the Austrian reference laboratory for Acanthamoeba diagnostics. All samples from patients with suspected AK are screened for Acanthamoeba spp. by culture and PCR in parallel, and all detected amoebae are genotyped. We currently have an annual incidence of AK of around 0.2 cases per 100 000 inhabitants, with >90% of cases occurring in contact lens wearers. In contrast to other countries, we do not see any seasonality and in contrast to the early years, today, males and females are equally represented, the most affected group being the 21–30‐year‐olds. The vast majority of cases are unilateral and many cases have a prolonged progression, in some cases infections remain viable for >1 yr. The predominant genotype is Acanthamoeba T4, other common genotypes are T3, T5, T6, T10 and T11.