Rabies virus in Taiwan, China is not an alien virus that took root a century ago; active surveillance is needed to avoid a threat like MERS
The MERS virus is bearing down ferociously, and neighboring South Korea has already fallen; some scholars have pointed out that the virus came from camels or bats, and although this has not been confirmed, it nonetheless highlights the threat of zoonotic diseases. In 2013, Taiwan discovered another zoonotic disease - rabies. A National Taiwan University team detected rabies virus in ferret-badgers, the first finding in 52 years, and agricultural authorities at one point suspected the virus had been brought in by animals smuggled from China, but after academia compared virus strains from various countries, it was confirmed that a native virus had existed in Taiwan a hundred years ago.
Last year the Endemic Species Research Institute analyzed the gene sequences of Chinese and Taiwanese ferret-badgers and found that they differ greatly from each other, so the possibility of smuggled Chinese ferret-badgers is small; the virus should have been lurking in Taiwan for some time, and re-testing ferret-badger carcasses preserved from 2010 also found rabies virus, further confirming that the virus had long since taken root locally. Because testing only began in recent years did it gain attention; it was not a sudden major outbreak. The government is urged to face up to the local origin of the virus, invest in wildlife surveillance, and establish a prevention and control network.
Chinese and Taiwanese ferret-badgers differ greatly genetically; rabies virus took root locally long ago
The year before last, Taiwan saw its first rabies case in half a century, and as of now a total of 462 ferret-badgers, 1 house shrew (Suncus murinus), 1 puppy, and 5 masked palm civets (Paguma larvata) have been confirmed. To clarify the origin of the virus, National Taiwan University and the Animal Health Research Institute of the Council of Agriculture analyzed the virus's nucleic acid sequences and evolutionary relationships, while the Council of Agriculture's Endemic Species Research Institute took a different path, examining the gene sequences of Taiwanese and Chinese ferret-badgers to study whether Chinese ferret-badgers had ever been introduced into Taiwan and thereby brought the virus.
The Endemic Species Research Institute obtained data on Chinese ferret-badgers from the public gene and virus database website GenBank, then collected 67 ferret-badgers native to Taiwan and performed mitochondrial COI sequencing, of which 47 were infected with rabies.
The research team identified a total of 16 genotypes, with 47 individuals belonging to the same type, of which 33 were infected with rabies, spread across northern, central, southern, and eastern Taiwan. However, the genetic difference among individual Taiwanese ferret-badgers was only 0.27%, while the average difference from China was 2.94%, a difference of 10.9 times.
The team also analyzed the mitochondrial COII sequences of another 343 ferret-badgers native to Taiwan and reached the same conclusion: the average difference from Chinese ferret-badgers reached 4.34%, far higher than the 0.45% difference among local populations. Therefore the research team judged that Taiwanese and Chinese ferret-badgers had diverged over a long period, and the probability of Chinese ferret-badgers being introduced into Taiwan's wild is not high.
Researcher Chang Shih-wei said that scholars had previously analyzed the virus's nucleic acid sequences and confirmed that the rabies virus that broke out in Taiwan last year did not come from China, and this study provides indirect evidence supporting that claim.
Tsai Chi-li believes that ferret-badger meat does not taste good, and Taiwan already has plenty of them, so there is no need to smuggle them. "Taiwan's rabies virus has existed for at least 1,200 years; who exactly brought it is no longer traceable, but it was definitely not brought by Chiang Kai-shek."
As early as 2010, ferret-badgers were already infected with rabies virus
If it has existed for so long, why the major outbreak in 2013?
Chang Shih-wei believes the talk of a major outbreak is incorrect. The virus had long existed in Taiwan; it was only because a National Taiwan University research team happened to detect it that the outside world became aware. The Endemic Species Research Institute later tested ferret-badger specimens from after 2010 and found they had long been infected with rabies. "The epidemic definitely did not begin only in 2013."
Researcher Tsai Chi-li said that many people often pick up ferret-badgers killed by cars, but normal ferret-badgers should not run onto the road for no reason; it may be that abnormal behavior from rabies infection led them to be treated as "roadkill," and moreover infected ferret-badgers in Taiwan show no obvious aggressive behavior, only circling in place, and are often misdiagnosed as "canine distemper" - which is why rabies was discovered so late.
The rise of zoonotic diseases: only by clarifying the problem can the right remedy be applied
Although the origin of rabies cannot be traced, it reminds people to face up to the threat of zoonotic diseases. The ancient HIV AIDS virus, the H5N1 avian influenza that caused heavy losses in Taiwan, the terrifying SARS, and Ebola all first appeared in animals and gradually evolved into zoonotic diseases, and the recently emerging MERS has also been said to come from bats or camels.
Tsai Chi-li believes that Taiwan often blames China for both good and bad things. Now evidence from all sides indicates that the rabies virus has long existed locally. "We should generously acknowledge that the rabies virus is a local lineage, then see how to prevent and control it and solve the problem."
Professor Chen Chen-chih of National Pingtung University of Science and Technology, who has long focused on wildlife epidemiology, previously said in an interview with NewsMarket that no matter what the origin of the rabies virus, it highlights that Taiwan's wildlife surveillance is not sound enough, and ferret-badgers are mostly sent for testing only after they have died. "But more important is to understand how the virus changes within wild animals and to identify the various possible influencing factors, such as time, season, and space, in order to manage the disease."
In addition to ferret-badgers, Taiwan also has 5 cases of masked palm civets infected with rabies, but Tsai Chi-li believes these should just be accidents; the focus should still go back to ferret-badgers, since after all ferret-badgers have the highest number of infections. Currently other research teams have analyzed the kinship relationships of Taiwan's ferret-badger populations and drawn up prevention and control strategies for different regions, making full use of limited manpower.