Travel and infection: The global mixing bowl

"Healthy travellers to countries where carbapenemases-producing Enterobacteriaceae (CPE) are endemic might be at risk for their acquisition, even without contact with the local healthcare system." So begins a recent Eurosurveillance report by Ruppé and coworkers describing acquisition of CPE by healthy travelers to India. The study describes data from the VOYAG-R project, which has many objectives, including measuring the rate of acquisition of multidrug-resistant Enterobacteriaceae (MRE) in people returning from travel Latin America, Sub-Saharan Africa, and Asia and the length of MRE carriage after trips. 

CRE was the topic of a previous blog post; such pathogens are associated with significant morbidity and mortality (especially in transplant patients and those with hematological malignancies) and are increasing in incidence globally. They are difficult to detect and treat, and are important in hospital infection prevention. The Ruppé et al study reports the acquisition of CPE in three healthy French travelers returning from India. The travelers reported no contact with hospitals or healthcare centers while traveling, leading the authors to conclude that the findings are "worrisome as they attest to the development of a community reservoir for CPE, at least in India."

The study illustrates many important issues, including that those traveling to high prevalence regions are at risk for becoming colonized with CPE. Once colonized, they can carry CPE back to their origination. One can think of such regions has having a high epidemiologic weight for the global propagation of CPE. Such movement of CPE and related pathogens has been described previously. In one example, importation of MRE strains producing NDM-1, OXA-48, and ESBL into the Netherlands after a patient received healthcare in Egypt was observed. In other cases, the acquisition of CPE cannot necessarily be attributed to travel or other risk factors, but what is clear is that such pathogens have spread over large distances and are now regularly observed in many areas. 

Other pathogens are known to exhibit transient colonization, though data are frequently rare and highly variable. The picture of latent introduction of CPE is probably also relevant for other bacteria of interest in hospital epidemiology. Such a picture highlights the need for surveillance, yes, but also for effective hospital infection prevention and control. As has been pointed out, this can be difficult, especially for CRE. We need a better understanding of the mechanical pathways of infection in order to design and implement better prevention practices. 

(image source: Wikipedia)