Hantavirus infection in Taiwan: The experience of a geographically unique area

Abstract

Hantaviruses are rodent-borne viruses, and they, mainly the Hantaan (HTN) serotype, are the causative agents of a group of febrile nephropathies known as "hemorrhagic fever with renal syndrome (HFRS). " Despite the fact that HFRS is frequently reported in China, with an annual incidence of 50,000-100,000 cases, one puzzling observation that no local case of HFRS has been confirmed in Taiwan has yet to be explained. We hypothesized that the hantavirus strain prevailing in Taiwan mainly belongs to the mild strain, the Seoul (SEO) strain, and the absence of severe disease was related to the absence of HTN. To test these hypotheses, this epidemiologic study was performed, including a seroprevalence survey and phylogenetic analysis on hantavirus isolated from the rodent population trapped in major seaports, rural, and mountainous areas of Taiwan. This study also included rodents and viruses from two isolated islands, Kinmen and Matzu, which are geographically adjacent to the east coast of mainland China. There were a total of 5,461 rodents of 16 species captured, and R. norvegicus was the most common species, with an antibody prevalence much higher in international seaports (20%) than in rural regions (approximately 5%) and intermediate in some domestic seaports. By reverse transcriptase polymerase chain reaction (RT-PCR), 33.9% of the seropositive R. norvegicus were found to have amplifiable hantavirus sequences in their lung tissues, and subsequent phylogenetic analyses indicated that almost all hantavirus in Taiwan was most closely related to the prototype SEO strain, and no HTN strain was recovered from any rodent species indigenous to Taiwan. The seroprevalence of SEO infection in R. norvegicus on Kinmen and Matzu was also different from that in southern provinces of China but closely resembled that in seaports in Taiwan, and the SEO identified was genetically linked to Taiwanese SEO strains. These results substantiate our hypotheses, and suggest that the epidemiology of hantavirus infection in Taiwan are different from that in China, where the HTN and SEO strains and HFRS concurrently prevail.

Seaport as a source of hantavirus: A study on isolated isles

“…In Kinmen and Lienchiang Counties, R. losea was the most common one captured in this study. This finding confirmed the results obtained by Chin et al (2000). Among the remote and offshore isles of Taiwan, the highest seroprevalence of hantavirus in the small mammals has been demonstrated on the Orchid Islets (21.4%) in southeast Taiwan (Kao et al 1996).…”

“…However, only negative results were obtained after examination on 202 animals in another survey (Chin et al 2000). The seroprevalences in Kinmen, Lienchiang, Penghu, and Shaolouchous have been reported to be 2.1%, 11.6%, 5.4%, and 9.5%, respectively (Chin et al 2000). In this study, the seroprevalence in Kinmen and Lienchiang were respectively found to be 3.8% and 3.9%.…”

“…In 2000, some 5461 rodents were captured from major seaports, rural, mountainous areas, and isolated islands of Taiwan and screened for hantavirus antibodies. Although the overall seroprevalence was 8.9%, the antibody prevalence was significantly higher in international seaports (20%) than in rural regions (approximately 5%) (Chin et al 2000).…”

“…On Taiwan proper, the hantavirus virus antibodies have been detected in small mammals and human subjects. In small mammals, the seroprevalence had been reported to range from 4 -22% (LeDuc et al 1986;Liu et al 1996;Wu et al 1996;Chen et al 1998;Chin et al 2000). Rattus norvegicus was the most common one captured in Taiwan and this rodent species has the high seroprevalence of 22.0% (Chin et al 2000).…”

“…Among the remote and offshore isles of Taiwan, the highest seroprevalence of hantavirus in the small mammals has been demonstrated on the Orchid Islets (21.4%) in southeast Taiwan (Kao et al 1996). However, only negative results were obtained after examination on 202 animals in another survey (Chin et al 2000). The seroprevalences in Kinmen, Lienchiang, Penghu, and Shaolouchous have been reported to be 2.1%, 11.6%, 5.4%, and 9.5%, respectively (Chin et al 2000).…”