Various infectious diseases occur in our immediate environment
     The Japanese are apparently one of the world's most zoo-loving people. There are reportedly over 1,000 zoos in the world, of which in Japan alone the number of zoos and aquariums affiliated with the Japanese Association of Zoo and Aquariums (JAZA) is respectively 90 and 68. Every year zoos draw 40 million visitors and aquariums 27 million visitors, or a total of 67 million people. In terms of simple calculation, more than one Japanese citizen out of two visit zoological gardens and aquariums once a year. In recent years incidents that cannot be unheeded have continuously occurred in these zoos and aquariums drawing large crowds of visitors. These incidents are related to outbreaks of diseases unheard of so far, such as BSE, foot-and-mouth disease, West Nile fever, SARS, highly pathogenic avian influenza, etc.
     The World Health Organization (WHO) is warning us that "we are now on the verge of a world-scale crisis caused by infectious diseases, and no country will be any longer safe." Therefore it is not exaggerated to say that the sanitary environment surrounding us is in a critical situation. In order to cope with this situation, the law on infectious diseases has been revised, monkeys are now subjected to animal quarantine, and the import of prairie dogs, bats and civet cats is now banned.

Zoonosis: infectious diseases common to humans and animals
     Infectious diseases common to humans and animals are called "zoonosis". About 200 different zoonotic diseases have been identified. They are caused by bacteria, fungi, rickettsia, viruses and other etiological agents. There are several equivalent terms in the Japanese language for the word "zoonosis", which are translated into English as "infectious diseases common to humans and domesticated animals", "infectious diseases common to humans and wild animals", "infectious diseases of animal origin", etc. These sicknesses originate from animals, if we consider that they are common not only to domesticated animals and wild animals but also to vertebrates on the whole and that they affect human health. However, infections of human origin that are transmitted by man to animals in zoological gardens may also occur. There is also a risk of misunderstanding that in case of animal-origin infections, the animals constitute a hotbed of pathogens and are dirty and dangerous. Therefore the Infectious Disease Control Committee of the Japan Zoo Aquarium Association has decided to use a term whose English translation is "infectious diseases common to humans and animals", following the original definition that these are infectious diseases common to humans and animals.
     In the past, the main zoonosis observed in Japanese zoological gardens were salmonellosis in reptiles, aspergillosis in penguins, parrot disease in parrots, leptospirosis in rodents, swine erysipelas in dolphins, chlamydiosis in ruminants, echinococcosis and in monkeys, tetanus, etc. There have been cases of zoological gardens affiliated with the Japan Zoo Aquarium Association that were temporarily closed until the visitors' safety could be confirmed, due to infections caused by echinococcosis in gorillas and chlamydiosis in mooses. Fortunately no cases of infection from the animals kept in zoos to the visitors were reported. Nevertheless cases of mass infection of parrot disease amid zookeepers and visitors occurred in December 2002 in facilities with birds on exhibit in zoos not affiliated with the Japan Zoo Aquarium Association. It seems that the disease was brought by newly arrived parrots. This incident taught a lesson reminding us how important are education of zoo keepers on sanitation and public hygiene control including quarantine of imported animals.

Control of infection in zoological gardens
     With the globalization of society, internationalization is also rapidly spreading to zoological gardens all over the world. People can now visit zoos in faraway places thanks to the development of the means of transportation. The number of foreign people visiting the Ueno Zoological Gardens has reached five percent of the total number of visitors. Exchanges of animals between Japanese and foreign zoos are now very active. For this reason, the risk of bringing various infectious diseases into zoos and aquariums has also increased. A cheetah infected with BSE was transferred from a zoo in England to a zoo in France for reproduction, where the animal developed the disease. It is not unusual to transfer rare animals from one country to another for reproduction. However ,this has created risks of propagation of infectious diseases following the transfer of animals.
     No serious accidents should happen if efforts are done to prevent epidemics through thorough basic sanitary precautions and if rapid and appropriate action at the early stage in case of outbreaks is taken to control zoonosis. Putting in place fundamental sanitary measures in collaboration with the related organizations is our responsibility as persons in charge of zoos and aquariums.
     The Japan Zoo Aquarium Association set up in 1999 an Infection Control Committee made up of veterinarians representing each bloc in order to prevent infectious diseases and take action against outbreaks. The Association is also involved in various activities, such as factual surveys of infectious diseases in zoos and aquariums, preparation of action guidelines in response to infection outbreaks, exchange of information on infectious diseases and publicity on these diseases.

SARS, a new form of pneumonia, and highly pathogenic avian influenza
     The stir caused in spring last year by the outbreak of severe acute respiratory syndrome (SARS), atypical pneumonia that started in China, scared the whole world. When the news that civet cats might probably be the source of SARS infection spread, zoos received a lot of inquiries about the safety of these animals they were keeping. The reason is that research institutes in China and Hong Kong had detected from civet cats, raccoons, weasels and badgers used for food in South China a virus whose gene sequence resembled a SARS coronavirus. Reflecting the view that civet cats were the culprits, these animals that were not popular with visitors to zoological gardens received a lot of attention to the point they temporarily drew crowds of onlookers. Fortunately since SARS did not occur in Japan, the zoos were allowed sufficient time to take action.
     Japan has been hit this year by an outbreak of highly pathogenic avian influenza. This disease reportedly broke out in South Korea in December last year, and it was thought that it would not spread to Japan. Nevertheless it eventuated in Yamaguchi prefecture, Japan, last January. The majority of fowls kept in zoological gardens are used for interaction with children. They are left free in zoos for children, as they are small, gentle, and friendly. These are typical animals kept in day nurseries, kindergartens and elementary schools to make children realize the importance of life. However since highly pathogenic avian influenza broke out in Japan, an increasing number of zoos are keeping away chickens from children in order to avoid unnecessary worries. Moreover zoos are urging the public to be careful, encouraging washing hands after touching animals, laying foot mats soaked into disinfectants, prohibiting the transfer of birds to and from other zoos, etc.
     Taking thorough sanitary precautions will almost certainly prevent birds kept in zoos from infection by highly pathogenic avian influenza. Nonetheless the possibility of infection even in case of pet birds remains an undeniable fact. We consider that closing down temporarily facilities showing fowls to the public is a measure inevitable for the protection of the health of the multitude of people visiting zoological gardens.

How to improve the relation between humans and animals
     During the SARS turmoil, civet cats, and during the outbreak of highly pathogenic avian influenza, chickens were dumped on roads. This is a thoughtless attitude. We feel frustrated to see that correct information has not been relayed to people who are worried. In case of zoonosis, both may be either the victimizers or the victims. Unfortunately the animals tend to be considered unilaterally as the culprits. It is feared that the misconception that contacts with many animals carrying pathogens constitute a danger may circulate under the impact of outbreaks of zoonotic diseases. Humans and animals are "members of one team", and zoos are facilities intended for deepening the understanding of animals and nature. Zoonosis is now attracting the attention of the public, and zoological gardens should encourage people to serve as a link between humans and animals in order to build up better relations between them.