Abstract
BackgroundInternational seaports are hotspots for disease invasion and pathogens can persist in seaports even after ports are abandoned. Transmitted by fleas infected by Rickettsia typhi, murine typhus, a largely neglected and easily misdiagnosed disease, is known to occur primarily in large seaports. However, the significance of seaports in the occurrence of murine typhus has never been validated quantitatively.Methodology/Principal findingsWe studied the spatial distribution of murine typhus, a notifiable disease, in Taiwan. We investigated whether risk of infection was correlated with distance to international seaports and a collection of environmental and socioeconomic factors, using a Bayesian negative binomial conditionally autoregressive model, followed with geographically weighted regression. Seaports that are currently in use and those that operated in the 19th century for trade with China, but were later abandoned due to siltation were analyzed. A total of 476 human cases of murine typhus were reported during 2000–2014 in the main island of Taiwan, with spatial clustering in districts in southwest and central-west Taiwan. A higher incidence rate (case/population) was associated with a smaller distance to currently in-use international seaports and lower rainfall and temperature, but was uncorrelated with distance to abandoned ports. Geographically weighted regression revealed a geographic heterogeneity in the importance of distance to in-use seaports near the four international seaports of Taiwan.Conclusions/SignificanceOur study suggests that murine typhus is associated with international seaports, especially for those with large trading volume. Thus, one of the costs of global trade in Taiwan might be elevated risks of murine typhus. Globalization has accelerated the spread of infectious diseases, but the burden of disease varies geographically, with regions surrounding major international seaports warranting particular surveillance.
Highlights
Trade is commonly accompanied by the spread of infectious diseases and international seaports have long been hotspots for disease invasion [1]
Globalization has hastened the spread of infectious diseases, with seaports as hotspots for disease invasion
Transmitted by fleas infected with the rickettsia Rickettsia typhi, murine typhus occurs worldwide, but its significance as a common causative agent of illness in tropical regions remains largely neglected
Summary
Trade is commonly accompanied by the spread of infectious diseases and international seaports have long been hotspots for disease invasion [1]. Yellow fever has devastated seaports in the Americas due to the importation of the virus-infected mosquito Aedes aegypti (a competent vector for yellow fever) by ships [4]. Another new disease vector originating in Asia, Aedes albopictus, has spread to seaports in both the Old and New Worlds [5, 6]. One legacy of past shipping events might be continuing circulation of exotic pathogens near receptive seaports; that is, seaports have ceased to function, imported pathogens may persist in proximity to the abandoned seaports, if the conditions are suitable. The significance of seaports in the occurrence of murine typhus has never been validated quantitatively
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