Uncovering Hidden Global Health Risks from a Transatlantic Stowaway Rat

In 2017, passengers aboard a flight from Miami to Berlin encountered an unexpected traveler—a rat that had stowed away during transit. The rodent was captured after landing and handed over to researchers at the Friedrich-Loeffler-Institut (FLI). This incident served as a critical opportunity for scientists from the German Center for Infection Research (DZIF) and the 'Rodent-borne Pathogens (NaÜPa-net)' network to investigate the potential health risks posed by such animal travelers.

The team conducted thorough laboratory analyses on the rat, which was believed to have possibly traveled from Dubai before reaching Berlin. Although the pathogen screening found only a few microbes, notably lacking the most dangerous rat-borne pathogens like hantaviruses or leptospira bacteria, the study revealed important insights. Notably, a strain of Staphylococcus aureus closely related to human variants was discovered in the rat, indicating recent exchange of microbes between humans and rodents, and highlighting the potential for rats to act as vectors in spreading pathogens.

The research utilized a comprehensive approach, including bacterial cultures, high-throughput sequencing, PCR, RT-PCR, and serology. The findings showed the absence of high-risk pathogens, suggesting the immediate risk to passengers was low. However, the detection of bacteria similar to human strains underscores how easily microbes can transfer between humans and rats, especially in global transit hubs.

This case exemplifies how rats, particularly species like Rattus rattus and Rattus norvegicus, have traveled alongside humans for centuries, now facilitated by modern air travel. The ability of rats to carry dangerous zoonotic agents such as leptospira, rat-bite fever pathogens, Seoul orthohantavirus, and hepatitis E virus presents ongoing risks. With millions of flights annually, the chances of unintentional transport increase, emphasizing the need for standardized detection and containment procedures.

The study advocates for immediate capture and containment of any animals found aboard aircraft, in compliance with international regulations, coupled with thorough pathogen screening. Establishing such protocols can help prevent outbreaks and facilitate rapid response if a hazardous pathogen is detected. Additionally, genetically analyzing the origin of such animals can serve as an essential part of ecosystem health monitoring.

In summary, this incident and subsequent research demonstrate the immense connectivity of our world and underscore the importance of vigilance against the hidden spread of infectious diseases. As rats continue to traverse continents, they serve as indicators of ecosystem health—reminding us of the ongoing need for integrated health strategies to mitigate global infectious disease risks.