Fri, Sep 19, 2014 page3

• Study observes rise in TB cases despite vaccinations

  VIRULENT VIRUS: Research discovered a strain, the ‘modern’ Beijing type, was on the rise and that the many types found reflect the nation’s diverse ethnic origins

  • By Shelley Shan / Staff reporter
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  A recent study by the Nation Health Research Institutes (NHRI) found that the nationwide vaccination against tuberculosis (TB) has become ineffective in containing the spread of the disease, as there has been a sharp increase in patients infected with the most dangerous type of TB.

  The most significant finding was that 85 percent of those infected with TB under 25 years old were infected with the “modern” Beijing strain of the virus, which is the most virulent and drug-resistant among all types of TB.

  The research shows that people can still be infected with TB even after they have received the Bacillus-Calmette-Guerin (BCG) vaccine at birth. National Institute of Infectious Diseases and Vaccinology associate investigator Dou Horng-yunn (杜鴻運) said the phenomenon has caused great concern among disease prevention specialists.

  Dou said that the researchers also found a rapid increase in TB cases among patients aged 15 years old and above.

  The result matched findings from other countries, which show the effectiveness of the vaccine tends to decline drastically about 15 years after inoculation. A second shot of the vaccine would not be effective, he said.

  Dou said that the institute has strived to find a way to address the problem with disease prevention by conducting a series of experiments. He said the team wanted to identify the reasons why patients contracted the Beijing strain of TB, particularly prevalent among young people.

  Dou and his research team studied the data from more than 1,000 TB patients infected since 2005. Their research shows that Taiwan has possibly the most diverse variety of TB virus strains in the world.

  “In China, more than 90 percent of patients with TB had the Bejing strain. Similar situations have occurred in Japan and Korea. However, Taiwan has not only the Beijing strain, but also the East African strain, Latin American-Mediterranean strain and Dutch strain,” he said.

  The research team analyzed the data by categorizing it by age groups, residence and ethnicity. It discovered that the appearance of different variants of TB mirrored the history of Taiwan, in particular the migration of different ethnic groups, colonization by the Dutch, Spaniards, Portuguese and Japanese, as well as interactions between China and Taiwan.

  The arrival of a new ethnic group also brought with it a new strain of the TB virus, the team found.

  Dou said that the Beijing strain of TB has evolved over the years and can be sub-divided into “ancestral” and “modern” types.

  The occurrence of the former can be traced to the Ming Dynasty from 1,368 to 1,644 AD, whereas the latter occurred after World War II.

  The research showed that 56 percent of ethnic-Han infected with TB had the Beijing strain. However, 72 percent of Chinese patients who are also World War II veterans were found to have the modern Bejing strain.

  Aboriginal patients in Hualien were found to have the Dutch strain of TB. Those of the Paiwan Tribe in the south, on the other hand, had TB of the East African strain.

  A few Aboriginal patients in the north were found to have the Latin American-Mediterranean strain of TB.
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