Workshop Ⅴ “One World, One Health”

Koichi MURATA, PhD,
Professor, College of Bioresource Sciences, Nihon University,
Director, Zoorasia Yokohama Zoological Gardens
President, Japanese Society of Zoo and Wildlife Medicine

Conservation Medicine and Ecological Health

Many of you may never have heard the term “Conservation Medicine.” That is only natural because this field of study was only born in the late 1990’s and the first conference report, which is referred to as the textbook for this new discipline (“Conservation Medicine: Ecological Health in Practice”) was only published in this decade (Alonso et al. 2002). However, inspired by the publication of the textbook, studies related to Conservation Medicine have been evolving rapidly in developed countries.

Conservation Medicine is defined as “a discipline that unites the fields of human health, animal health and ecosystem health” (Tabor, 2002). Conservation Medicine is not based on a health concept that posits human and animal in vertical divisions. It is aimed at horizontal health that can be sustained in interrelationship between humans, animals and the ecosystem, that is to say, “One Health” and conserving Biodiversity that is indispensable. This new field of study can be considered as very pragmatic and interdisciplinary in the way that it links related health and medical study fields and helps sustain the Ecological or Eco-Health.

In Conservation Medicine, countermeasures to control infectious diseases are designed based on an understanding of organic and inorganic host-pathogen interactions and the ecosystem built on their subtle balance.

Emerging Infectious Diseases (EID) are, in particular, caused by human intrusion into the habitats of wild animals and all the more, for this very reason, conservation of Biodiversity is strongly recognized as fundamental to the prevention of those diseases.

Self-medication in primates- prevention and cure
Michael A Huffman, PhD, Associate Professor,
Primate Research Institute, Kyoto University

Chimpanzees and other primates eat a variety of nutritious items including fruits, leaves, young buds on a daily basis. Besides these items, a number of plant parts containing peculiar secondary plant compounds are occasionally eaten. In the recent years, an interest has been shown in understanding the significance of ingesting these nutritionally deplete plant items. One explanation is that these items are used for their pharmacologically active properties. Strong evidence in support of this hypothesis has come from research on African great apes (chimpanzees and gorillas) demonstrating anti-parasitic properties and or relief from parasite related gastro-intestinal upset.
From ecological and parasitological analysis of the behavior of chimpanzees in East Africa it has been shown that the ingestion of extremely bitter juices from the pith of plants or the swallowing of the rough leaves of other species plays an important role in the suppression of parasite infections. Parasites are responsible for a variety of diseases that directly affect the behavior and reproductive capacity of animals. Therefore, it is extremely important that animals should be able to eliminate parasites. It is evident that the effects caused by parasites on the host, and the hosts’ responses to infection are the results of a long evolutionary process. Research has also shown that African great apes do not accidentally ingest these items, but seek these plants out for the curative properties. Interestingly, humans and chimpanzees living in and around the Mahale Mountains National Park of Tanzania select many of the same medicinal plants for use when suffering from similar ailments. From this and other evidence, two explanations can be given. Firstly, they show similar behaviors because they are phylogenetically very close and secondly, humans have traditionally observed the habits of wild animals to obtain valuable new medicines for their own use.
There is hope that the study of self-medicative behaviors in the African great apes and other primates in the wild will provide new methods of healing and new medicinal plants effective in the treatment of the parasite disease in humans, livestock and other domestic animals.

Structure of Animal Communities and Transmission Dynamics of Mosquito Borne Diseases
Yoshio Tsuda
Chief, Laboratory of Taxonomy and Ecology, Department of Medical Entomology, National Institute of Infectious Diseases (NIID)

Mosquito larvae work as scavengers and decompose organic matters in aquatic ecosystems. They are important food resources supporting predator populations in aquatic communities together with other aquatic insects, such as Chironomids, midges, etc. The adult mosquitoes also provide a food source for wild birds, bats, spiders, and ants, among others. Therefore, mosquitoes are an important member of aquatic ecosystems and help maintain the structure and species diversity of animal communities.

Mosquitoes are well known for their blood feeding habits and have unique roles within animal communities. More than 100 mosquito species live in Japan and about 60 of them bite human beings. There are mosquitoes that prefer to feed on wild birds, or on larger mammals, or frogs, even fishes. It is through their blood feeding habits that some mosquito species transmit infectious disease to humans as well as wild animals. Females that have fed on infected animals ingest the pathogen with the blood meal, and transmit it to uninfected animals. The capacity of mosquitoes to transmit pathogens is determined by several biological and ecological characters, such as vector competence, host preference, biting density, feeding pattern, and longevity. The transmission dynamics of the pathogens in animal communities depends largely on the feeding pattern of vector mosquitoes in the communities.

It is important to distinguish the amplifying- and the diluting-vector-animal contacts in order to predict the epidemic of mosquito borne diseases in animal communities. When mosquito borne pathogens are introduced into communities composed of many pathogen hosting animals, vector mosquitoes have a high chance of taking blood meals from host-animals and thus, the amplifying-vector-animal contacts are frequent. Conversely, in animal communities where host animals are rare, a large proportion of vector mosquitoes feed on non pathogen hosting animals, the diluting-vector-animal contacts occurs frequently and thus, the pathogen transmission rate is low. Therefore, we can expect some relationships between community structure and transmission dynamics of mosquito borne diseases within animal communities. Theoretical as well as empirical ecological studies have been conducted to demonstrate the relationships between species diversity and transmission of vector borne diseases.

Mites talk about biodiversity – Ecological significance of
Evolutionarily Significant Units in parasites.
Koichi Goka, PhD,
Invasive Alien Species Research Team
National Institute for Environmental Studies

Biodiversity conservation has been recently a boom in the field of environmental science. We are likely to focus only on visible, beautiful, pretty or stylish animals and plants when we are talking about biodiversity. But also invisible and not beautiful microorganisms are obvious member of biodiversity and take important roles in ecological systems. Notably parasitic organisms have been strong causative agents of evolution and speciation of wildlife through arm race co-evolution between parasites and host species. However, destruction of habitats and biological invasions by the present huge human activities have made co-evolution history between host and parasite collapsed resulting in pandemic of parasites. Also the recent emerging and reemerging disease problems are considered to be results of host switches by infectious viruses those have inhabited within the specific wildlife hosts as symbioses but lost their habitats because of human activities. It must be important process for keeping the symbiotic relationship between human and parasites to understand biodiversity of parasites and co-evolutionary history between hosts and parasites.
Acarian is a representative species group in macro-parasites (=visible parasites). Almost all people only have an unpleasant image for the species group. But the number of species in the group is approximately 50,000 already recorded and is expected to be more than 1,000,000 including never recorded. Furthermore their life history and habitats range widely over free living, parasite, predator and so on. So, we can say acarian is really important member of biodiversity. Here I will introduce the world of co-evolution produced by parasitic mites and their host species and discuss about the significance of biodiversity of miniature organisms, as an acarologist.