Application of a comprehensive approach to pathogen screening in a stowaway rat on an airplane

In April 2017, a rat was observed on an airplane during a flight from Miami (USA) to Berlin (Germany). After landing in Berlin, significant efforts were made to trap the rat and disinfect the airplane. As rats are known reservoir hosts for a variety of zoonotic pathogens, this event necessitated the establishment of a standard workflow for the detection of rodent-borne pathogens. Tissue and blood samples were collected to screen for zoonotic pathogens and other known and novel infectious agents using an array of open-view methods (cultivation and characterization of bacteria, high-throughput sequencing) and pathogen-specific methods (e.g. PCR, RT-PCR and multiplex serology). The black rat (Rattus rattus), as confirmed by mtDNA sequences, carried several infectious agents. Cultivation experiments revealed the presence of seven bacterial and two fungal genera. In addition, a methicillin-susceptible Staphylococcus aureus strain of MLST-CC45 was detected by culture-based approaches, and its full genome was sequenced. High-throughput sequencing identified novel picobirnaviruses and various bacterial genera, the majority of which represent commensals rather than pathogens. Despite the diversity of bacterial, viral, and fungal species that can be expected in wild rats, only a few zoonotic and non-zoonotic pathogens were detected in the stowaway rat. Nonetheless, this incident highlights the potential of international (and cross-continental) dissemination of pathogens and the need for a standardized workflow to provide comprehensive coverage of the diversity of microorganisms in such animals.