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Lactic acid bacteria, vaccines, hand-washing eyed as preventative measures for influenza

Iwate Medical University professor Kiyomi Sakata (Mainichi)

Influenza and cold season is now upon us, and as serious cases may become fatal, these conditions must be taken seriously. To this end, a seminar was recently held in Tokyo featuring talks by three experts regarding prevention of disease infection -- as well as a strain of lactic acid bacteria that has been found useful for combatting influenza.

    A disease that has resulted in a surprisingly high number of recent fatalities is pneumonia, which is caused primarily by bacteria and viruses. According to statistics on disease-related fatalities that were released by the Ministry of Health, Labor and Welfare, a total of 119,600 individuals passed away from pneumonia last year, which was second only to cancer at 368,100, and heart disease at 196,900.

    An increasing number of deaths from pneumonia and influenza tend to occur during the winter months of January and February. According to health ministry statistics, 1,391 individuals died from influenza this year in January alone.

    Norio Yamamoto, an associate professor with the Department of Infection Control Science at the Juntendo University Graduate School of Medicine, points out that as opposed to a normal cold, special caution must be taken with respect to influenza since the symptoms of high fever and all-over body aches may be accompanied by additional complications such as bronchitis and pneumonia.

    And while advance vaccinations are useful for preventing the aggravation of influenza, these are not always effective due to the fact that the genetic composition of the virus often changes. While several medications do exist that prevent the virus' proliferation, moreover, the appearance of drug-resistant influenza viruses has also become problematic.

    "The response to influenza must not be restricted to one singular method," notes Dr. Yamamoto. "It is critical that as many prevention and treatment methods as possible be utilized." He adds that in addition to vaccinations, basic precautions such as hand-washing should also be taken.

    Recently gaining attention as a preventative measure in this regard is lactococcus lactis JCM5805, a strain of lactic acid bacteria that was discovered by Kirin Co.

    When a virus invades the human body, immune system cells such as natural killer cells and killer T cells head toward the virus in order to drive it out. Lactococcus lactis JCM5805 works to directly activate plasmacytoid dendritic cells (pDCs), which are immune system cells that serve a sort of control tower function to stimulate other immune system cells.

    In an experiment whereby mice were infected with pneumonia, it was confirmed that the survival rate had risen among those mice that had been administered lactococcus lactis JCM5805.

    Tokai University subsequently conducted a separate experiment in order to determine whether or not ingesting lactococcus lactis JCM5805 would in fact prevent colds and influenza in human beings. The university divided a total of 657 participants aged 18 to 39 into two groups -- one of which was administered the strain of lactic acid bacteria, and the other of which was given a placebo that did not include it. The symptoms among the members of the two groups were then compared after 12 weeks.

    The results of the experiment showed that the rate of contracting colds and influenza was 28.8 percent among those who had been administered the lactococcus lactis JCM5805, which was lower than those who had ingested the placebo, at 37.1 percent.

    While this figure does not represent a significant statistical difference, the symptoms of severe sore throat and coughing were clearly reduced among the members of the group that had ingested the lactic acid bacteria.

    "We can say that administering lactococcus lactis JCM5805 resulted in a lessening of the severe symptoms associated with influenza and common colds," commented Naoaki Ishii, a medical school professor at Tokai University who announced the findings of the experiment.

    A similar human experiment was conducted this year between January and March at a total of 10 elementary schools and one middle school in the town of Shizukuishi, Iwate Prefecture.

    Three times per week, the total of 1,253 students attending the 11 schools were given yogurt drinks that included a dose of lactococcus lactis JCM5805 along with their lunch that had been provided free-of-charge by Koiwai Dairy Products Co., which has a factory located in the town. A study was subsequently conducted to see if there was a difference in the rate of contracting influenza as compared with children and students from seven surrounding cities and towns.

    Since six among the seven nearby municipalities suffered influenza epidemics, the comparison was conducted between the town of Shizukuishi and another town known as "A" -- neither of which saw widespread outbreaks of influenza.

    The results of the experiment revealed that while the maximum disease rate in town A was 7.29 percent, the figure in Shizukuishi was comparatively lower, at 5.18 percent. The rate was also significantly lower, moreover, during the actual period when the students were ingesting the lactic acid bacteria.

    "The study revealed the possibility that consuming a yogurt drink three times weekly that contains lactococcus lactis JCM5805 reduces the risk of contracting influenza by around 30 percent," notes Kiyomi Sakata, a professor in the department of Public Health in the School of Medicine at Iwate Medical University, who reported the findings of the study during a meeting of the Japanese Society of Public Health.

    In order to help prevent colds and influenza, then, a lineup of basic prevention strategies should be employed that includes vaccinations, hand-washing, gargling, and consuming lactic acid bacteria drinks.

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