Zoonotic diseases are infections other than those transmitted to humans from animals including birds. In Japan, control measures on zoonotic diseases (legally called "infectious diseases of animal origin") have been strengthened officially under the law on infectious diseases {Law on the prevention of infectious diseases and the treatment of patients infected with infectious diseases"} enacted in 1999 (amended in 2003). Furthermore in August 2005 infection control measures regarding animals in Japan including imported animals were reinforced due to the risks posed by importing animals infected with plague and rabies (Ministry of Health, Labour and Welfare, National Institute of Infectious Diseases: Infectious Agents Surveillance Report (IASR), 26, 196-198, 2005).
  We have introduced so far the following 14 zoonotic diseases in this monthly topic publication (World Focus), namely Echinococcus (W/F No.7), West Nile encephalitis (No.13), Weil's disease (No.27), Tsutsugamushi disease (No.37, 54), Q fever (No.40), Lyme disease (No.46), SARS (No.47), cat-scratch disease (No.50), rabies (No.55, 77), bovine spongiform encephalopathy (No.56), turalemia (No.71), tick-borne encephalitis (No.78). In addition, we have introduced Chagas's disease, which is endemic in South America (No.52), and zoonotic diseases that are considered as a problem in zoos (No.58).
  The Ministry of Health, Labour and Welfare has been reporting the annual variations in the "number of patients infected with diseases of animal origin in Japan" since the enactment of the Law on Infectious Diseases in 1999 (Table 1). We will update information here on the five major zoonotic diseases that are currently attracting the people's attention, together with commentaries based on the latest information published in Nature, Lancet, etc.
Highly pathogenic avian influenza
  This disease was added in 2003 to the list of reported communicable diseases that must be notified to the health authorities. Fortunately no human cases have been found in Japan, although many poultry cases due to H5N1 virus were reported in 2004. Also, cases with weak pathogenicity (H5N2) recently occurred in poultry in Ibaraki and Saitama prefectures. On the other hand, the Ministry of Environment is carrying on surveys on wild birds, and recently it tested approximately 700 specimens collected in nine prefectures in Japan in February 2006 (Chiba prefecture, Ibaraki prefecture, Nagasaki prefecture, Niigata prefecture, Fukushima prefecture, Okinawa prefecture, etc.). As a result, the ministry reported that no highly pathogenic avian influenza was detected in any of the specimens collected from those areas (http://www.env.go.jp). However, cases of dead birds have recently been reported in the United Kingdom. According to WHO's reports (as of April 21, 2006), there are 204 human confirmed cases and 113 fatalities all over the world. Therefore thorough control measures will be needed in Japan, too.
Tsutsugamushi disease and Japanese spotted fever
  These two infections are caused by tick bites. The number of patients afflicted with Tsutsugamushi disease has been showing a tendency to decrease over the last few years. However, it constitutes the most important category amongst zoonotic diseases. By contrast, cases of Japanese spotted fever tend to increase, and the areas where patients contract the disease are expanding. Patients contract Tsutsugamushi disease as early as in spring in Northeastern Japan, though the cases are generally concentrated in fall. The incidence of Japanese spotted fever is reported during March to December with a peak in summer. These diseases may also be contracted when collecting edible wild plants and hiking (IASR 27 No.2, 1-2, 2006).

Hepatitis E
  This disease was legally designated in 2003 as an infectious disease to be notified to the health authorities. Over 30 patients were reported in 2004. The infection causes acute hepatitis, but it does not become chronic. Although clinical symptoms are accompanied by jaundice after infection by the oral route, the frequency of inapparent infection is also high. In case pregnant women contract the infection during the third week of pregnancy, the fatality rate in fetuses reportedly reaches 20%. Outbreaks often occur in developing countries and the disease was generally considered as an imported infection. However, it also occurs in Japan when consuming wild boar liver and raw deer meat. Since hepatitis E virus genes have been detected also in marketed pork liver, one should be careful and avoid the consumption of insufficiently heated offal.
Bovine spongiform encephalopathy (BSE)
  Over four years have elapsed since the first case of BSE was discovered in Japan. As regards the source and the route of BSE infection in Japan, a BSE epidemiological study team of the Ministry of Agriculture, Forestry and Fisheries carried on a study on seven cases of BSE that occurred in Japan up to September 2003. According to the team's report, the source of infection was confined to 33 cows that were imported from the UK in 1982 or in 1987. The team assumed that the infected cows may have been recycled as meat and bone meal or that the disease may have been caused by a BSE pathogen contained in meat and bone meal imported from Italy before 1990. As regards the route of infection, the team presumed the possibility of mixing the feeds for cows with contaminated feeds for pigs and poultry.
  Japan is implementing measures regarding the safety of edible meat under the most severe international constrain. Measures to prevent the spread of BSE are also carried out efficiently in Japan. It will be necessary to continue to take thorough control measures in order to prevent the penetration of BSE from foreign countries.