Do humans spread zoonotic enteric bacteria in Antarctica?

Reports of enteric bacteria in Antarctic wildlife have suggested its spread from people to seabirds and seals, but evidence is scarce and fragmentary. We investigated the occurrence of zoonotic enteric bacteria in seabirds across the Antarctic and subantarctic region; for comparison purposes, in addition to seabirds, poultry in a subantarctic island was also sampled. Three findings suggest reverse zoonosis from humans to seabirds: the detection of a zoonotic Salmonella serovar (ser. Enteritidis) and Campylobacter species (e.g. C. jejuni), typical of human infections; the resistance of C. lari isolates to ciprofloxacin and enrofloxacin, antibiotics commonly used in human and veterinary medicine; and most importantly, the presence of C. jejuni genotypes mostly found in humans and domestic animals but rarely or never found in wild birds so far. We also show further spread of zoonotic agents among Antarctic wildlife is facilitated by substantial connectivity among populations of opportunistic seabirds, notably skuas (Stercorarius). Our results highlight the need for even stricter biosecurity measures to limit human impacts in Antarctica.