“Zoonoses Within Our Living Environment”
Date: Sat.19th July 13:30 ~ 16:30
Venue: Waraku Meeting Room
Organiser: Society for Zoonoses Research
Purpose: As well as for cats and dogs, many pet animals such as small birds, reptiles (turtles, snakes, lizards etc.), amphibian (flogs, salamanders etc.), and tropical fish are raised in human society. We are organizing six lectures, within the symposium “Zoonoses around living environment” namely 1. Current trends of zoonoses, 2. Rabies, 3. Salmonellosis, 4. Dermatophytosis, 5. Echinococcosis, 6. Control of infectious diseases. We hope the symposium will bring correct awareness about zoonoses for our happy lives with pets.
Dogs and cats have been human companions for more than 10,000 years. They have been sharing our environment and have gained a major status as “pets” in our modern and urbanized society. As well as for cats and dogs, many pet animals such as small birds, reptiles (turtles, snakes, lizards etc.), amphibian (frogs, salamanders etc.), and tropical fish are also raised in human society. Especially cats and dogs are more and more considered as “family members” or “companions” within households; not to mention sometimes as substitutes to children. Pet dog and cat populations have substantially increased in the developed countries and it is estimated that they are present in more than 40% of households in Japan (2013 estimated dog population: 10 million, estimated cat population: 9.7 million). However, they still can serve as a source of human infection by various pathogens, including viruses, bacteria, parasites and fungi.
We are organizing six lectures, namely 1. Current trends of zoonoses, 2. Rabies, 3. Salmonellosis, 4. Dermatophytosis, 5. Echinococcosis, 6. Control of infectious diseases in the symposium “Zoonoses around living environment”. We hope the symposium will bring correct awareness about zoonoses for our happy lives with pets.
“Current Trends in Zoonotic Diseases in Japan”
A succession of public health-related concerns have been reported in recent years, many of which are categorized as zoonotic diseases – infectious diseases that spread between animals and humans – such as the outbreak of Severe Acute Respiratory Syndrome (SARS), caused by the SARS coronavirus, which occurred in 2003, the pandemic influenza virus that appeared in 2009, and the out
break of rabies that marked the reappearance of the disease in Taiwan after an absence of over fifty years.
In Japan, patient surveillance is carried out for the purpose of understanding the occurrence of disease trends. According to changes in patient reports, as identified by this surveillance, and from the food poisoning surveillance, the food poisoning occurrence situation can be ascertained. The majority of zoonotic disease cases in Japan are largely the result of food-borne infections such as enterohemorrhagic Escherichia coli (EHEC) and Salmonella. While the bacteria causing these infections are classified principally as microorganisms causing food poisoning, they can also be spread by zoonotic means. On the other hand, diseases can occur primarily as a result of zoonotic infections, such as scrub typhus or Japanese spotted fever which is transmitted by trombiculid mites or ticks and arthropod-borne infections transmitted by mosquitoes (e.g. Japanese encephalitis). These diseases result from the transmission of pathogens when infected arthropods bite humans, and such cases occur in Japan every year.
In addition, in recent years, there have been case reports of patients who were infected overseas but whose disease developed in Japan upon return from their travels, including a rabies case in 2006 and dengue cases. As Japan is an island nation, it has been possible to prevent rabies importation through the use of strict quarantine laws, rabies vaccination, and animal registration. However, the rabies situation in neighboring countries indicates that Japan remains at risk of importing this infection. In my talk, I would like to discuss the recent zoonotic disease situation in Japan.
Japan has been rabies free for more than half a century. The last cases of indigenous human and animal rabies were in 1954 and 1957, respectively. In 1970, a college student suffered from rabies in Tokyo after a trip to Nepal where he had been bitten by a stray dog. In November 2006, two cases of imported rabies occurred in succession after a 36-year absence (http://idsc.nih.go.jp/iasr/28/325/tpc325.html). Nowadays, in Japan, under the Rabies Prevention Law (MHLW, 1950), the Infectious Diseases Control Law (MHLW, 1998) and the Domestic Animal Infectious Diseases Control Law (MAFF, 1951) substantive efforts to prevent rabies have been adopted by central and local governments, veterinarians, and physicians (e.g. the registration and control of stray dogs, rabies diagnosis in suspected cases, appropriate PEP for humans, import and export quarantine of animals, notification system for the importation of animals, rabies vaccination of dogs). A follow-up amendment and drill of measures and a contingency plan has also been deemed necessary, because any inappropriate public health response or delay at an early stage of rabies cases, even in doubt, leads to unnecessary, excessive social anxiety. In fact, two imported human rabies cases reported in Kyoto and Yokohama in November 2006 were dealt with in accordance with The Guideline for Rabies in 2001 (MHLW) in terms of the initial response and medical practice. Recently, a Guideline for Rabies Control in Japan 2013 was also released focusing on an action plan after the confirmation of rabid animals in Japan. However, the awareness program of people giving the precisive information and a day life with owned pets and other animals in peace could be very important for maintaining a rabies free status in Japan. In this regards, the recent topics of rabies in the world, especially focused on Asia, is introduced for the understanding of why we need the prevention of rabies in Japan.
Salmonella is known to be the causative agent of foodborne disease or zoonoses in humans and animals. Salmonella infection in humans commonly causes fever, stomachache and diarrhea. Salmonella distribute in mammal, birds, reptiles, amphibian and environment. Human patients have been infected with Salmonella from dogs and cats. However, recently, the popularity of reptiles as pets has been increasing in developed countries, such as the United States, Japan and European countries. This has led to an increase in the number of reptile-associated human Salmonella infections. The Ministry of Health, Labour and Welfare of Japan issued alerts on the risk of Salmonella infection from pet reptiles in 2005 and 2013. We have clarified that reptiles carry Salmonella as a part of the normal bacterial flora in their intestine at a high rate and the vertical infection of Salmonella is organized in reptiles. To date, no suitable eradication method of Salmonella from reptiles has been developed. Therefore, young children and old people, who have high sensitivity to Salmonella, should avoid contact with reptiles and we should pay close attention to keeping and handling pet reptiles. In this lecture, I’d like to introduce our research about epidemiology and the ecology of Salmonella in reptiles.
Cutaneous Fungal Infections Common to Human and Animals
Zoonotic dermatophytoses caused by contact with infected subjects are well known. The representative causative fungal species originated from animals are Microsporum canis and Trichophyton mentagrophytes. Latent infections of dermatophytoses in animals may cause human diseases. Usually primary hosts show slight or mild symptoms, however, it takes a more severe form in other animal species. For example, Kerion Celsi caused by M. canis originated from animals shows severe symptoms in humans. Interestingly, brown rats in urban areas harbor T. mentagrophytes which is the causative agent of ringworm and tinea pedis in humans, and ringworm in exotic pets and companion animals. On the other hand, T. rubrum originated from humans causes infection to animals. Therefore, we should notice that humans become infectious sources to animals in dermatophytoses.
Dermatophyte related species also cause infections in both animals and humans. I experienced a case of Chrysosporium sp. infection in a pigeon causing it to de-feather, and a case of refractory dermatitis in a cat by Arthrographis karlae. The above fungal species sometimes developed to systemic infections in immunocompromized hosts. I would like to recommend paying attention to nursing the infected animals.
We should also mind cutaneous histoplasmosis caused by a highly pathogenic fungal specie: Histoplasma capsulatum. Infections caused by highly pathogenic micro-organisms can lead to death even in healthy individuals. Conventionally, histoplasmosis had been treated as imported mycosis; however, autochthonous cases in humans, dogs and a cat were reported in Japan. The genotypes of the fungi in cutaneous histoplasmosis in our country are identical to those in equine pseudofarcy controlled by the Act on Domestic Animal Infectious Diseases Control as equine notifiable infectious disease. Then, contagious infections are undeniable and systemic infections may occur in severe cases. There were more than 30 thousand equine cases before World War II. Therefore, any region where horses were once raised should be regarded as an endemic area.
Parasite: Echinococcus spp.
Echinococcus is a genus of cestodes, which transmits between carnivores as definitive hosts and ungulates and rodents as intermediate hosts causing serious parasitic zoonoses. While Echinococcus multilocularis causes severe problems in Japan at present, E. granulosus are only found in a few imported cattle.
Echinococcus granulosus transmits between dogs and livestock around the world. The parasites were recorded in a few humans in 19th century Japan.
At present E. multilocularis transmits actively in foxes and wild rodents, but has accidentally infected pigs, humans and zoo monkeys as intermediate hosts in Hokkaido. The larvae proliferate in the liver. While the distribution of the parasite in Japan is restricted to Hokkaido, the prevalence in foxes reached to 40%. About 20 new patients were reported every year. In humans the unlimited proliferation of the larvae lead a lethal process.
While foxes are considered to be the main definitive host of E. multilocularis, dogs are also highly susceptible hosts. While the prevalence of the parasite in dogs is less than 1%, dogs contact intimately with human and discharge eggs of the parasite with their feces. Dogs are suspected as a significant source of infection to humans. Because infected dogs do not show any specific symptom, proper examinations are needed for the diagnosis. The diagnostic methods for canine echinococcosis are established . While canine echinococcosis is a reportable disease in Japan, the number of examined animals is extremely few. In several towns and villages, inhabitants are distributing baits with anthelmintic during no-snow seasons for the control of Echinococcus infection in wild foxes. Oval contaminations of these areas are reduced after bait distribution. In Hokkaido most inhabitants are unconcerned about echinococcosis. The number of inhabitants, who have a medical examination for the disease, is reducing as years pass.
Measures Taken Against Zoonosis in our Country
Deputy Director, Tuberculosis and Infectious Disease Control Division, Health Service Bureau, Ministry of Health, Labour and Welfare
Last year, 2013, saw the occurrence of a wide range of zoonoses (diseases transmitted from animals). Firstly, during January, the first case of SFTS (severe fever with thrombocytopenia syndrome) which had never previously been reported in Japan was confirmed. The disease is transmitted by ticks inhabiting outdoors. Furthermore in China, since March, there have been hundreds of cases of H7N9 avian flu in human patients. The cause of these infections is said to be connected to live bird markets and the handling of birds. Then, additionally, ther
e have been reports from Arabian Peninsula countries of MERS (Middle East respiratory syndrome) patients. The cause, as at the time of writing, remains unclear although there is speculation of a link to dromedaries (Arabian camels). Furthermore, Taiwan, which has been rabies-free for more than 50 years discovered rabies within the wild ferret badger population. As well as such cases of previously unknown emerging diseases, or re-emerging diseases (thought to have been eradicated but now making a come-back), there are many zoonoses transmitted by our pets that are now becoming a daily problem. In order to avoid such transmissions, it is now extremely important for people to follow a few simple rules such as, 1) avoiding excessively-close contact with animals, e.g. feeding them mouth to mouth, 2) washing our hands after touching animals, and 3) not keeping a wild animal in the house – indeed, not touching animals in the wild at all. Japan’s Ministry of Health, Labour and Welfare is making efforts to heighten the public’s awareness and knowledge of zoonoses by publishing and distributing posters, fliers and handbooks. The Ministry is also taking other measures to counter zoonosis incidents from various other angles. For this symposium I will be introducing information about such measures.