Significance of major international seaports in the distribution of murine typhus in Taiwan

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.

The Spatial and Social Patterning of Property and Violent Crime in Toronto Neighbourhoods: A Spatial-Quantitative Approach

“…Figure 4 shows the spatial distribution of pseudo t-values for the intercept and each independent variables in the study area. Pseudo t is calculated by dividing coefficient estimate by the standard error, with significance (p < 0.05) defined as a pseudo t-value > 1.96 (positive relationship) or <−1.96 (negative relationship) [51,[53][54][55]. Non-significant relationships are represented in yellow in Figure 4, with significant positive relationships in red/orange, and significant negative relationships in green/light green.…”

The Re-Emergence and Emergence of Vector-Borne Rickettsioses in Taiwan

“…Not unlike scrub typhus, males were more frequently infected with R. typhi than females (>2:1), although most cases occurred in those aged 50 to 59 (27%) with a mean age of 50 years, compared to 60 to 69 years for scrub typhus, while murine typhus cases similarly demonstrated a significant positive correlation with monthly average temperature ( r 2 = 0.747, p = 0.005) in most cases from May to August [ 53 ]. Likewise, Kuo et al [ 73 ] recently analyzed murine typhus cases confirmed by the Taiwan CDC from 2000 to 2014, and revealed the highest IR in the 50 to 59-year age stratum and increased IR during May to August.…”

“…Murine typhus most commonly occurs in warm coastal areas where rodents and their fleas flourish [ 77 ], explaining the distribution of murine typhus in Taiwan (i.e., in western coastal districts/townships). In fact, in a geographically weighted regression model, Kuo et al [ 73 ] found that risk for murine typhus increases with increasing proximity to operating seaports, particularly in districts near Kaohsiung and Taichung international seaports. Chien et al [ 67 ] conducted a field survey of small mammals and their ectoparasites at international ports around Taiwan and its offshore islands from 2004 to 2011.…”

Climate factors driven typhus group rickettsiosis incidence dynamics in Xishuangbanna Dai autonomous prefecture of Yunnan province in China, 2005–2017

“…There were some previous studies suggesting that TGR incidence was related to meteorological factors. Kuo et al found murine typhus was negative related to precipitation and temperature after controlling the distance of operating international seaports using a Bayesian negative binomial conditionally autoregressive model [11]. Li et al reported that TGR incidence was positive associated with precipitation and temperature using Pearson correlation analysis [17].…”

“…In recent years, many regions have reported murine typhus cases with severe complications, such as pneumonia, pancreatitis, and septic shock [8][9][10]. There are only a few regions still monitor murine typhus, such as Texas, Hawaii, California and Taiwan [7,11]. Moreover, murine typhus poses a threat to the health of travelers, and travel destinations primarily locate in Southeast Asia, Africa and America [12].…”