Approximately half of all human infectious diseases known today can be classified as emerging thus placing the world in a period of unprecedented infectious disease emergence [1] Zoonoses [2] [3] are diseases which are transferable to humans from animals through infectious agents (e. g. viruses) and the ease of spread of zoonotic disease have implications on human health and disease prevention.
Generally, it can be listed according to the type of their infectious agents—parasites which includes protozoan, cestodes and nematodes. bacteria, viruses, fungi and prions [1] . The potential of humans to act as extra reservoirs for these pathogens necessitates the thorough study on the epidemiology and the potential control of these zoonoses. Zoonotic diseases are in general endemic and usually take place in the natural foci. [4].
Surveillance in natural hosts may be difficult because of the its’ ecologic complexity of zoonoses; technical assistance from different disciplines in ecology, mammalogy, ornithology, and entomology, physiology and epidemiology, may be required for successful research. Geographers and mathematical modelers, are also integrated to the recent surveillance to predict outbreaks using technologically advanced remote sensing system [4].
Zoonotic disease control is highly possible given that there is a thorough understanding of the pathogen’s life cycles and that experts can predict potential outbreaks by controlling activities of delivered at the different stages of life cycles during pre-infection. Zoonoses are not readily eradicated hence control is most important. These control efforts are important because most zoonoses are not amenable to eradication, except perhaps those in areas where animal reservoirs are targeted for vaccination, e. g. , fox rabies in Europe [5].
The Panel Summary from the 2000 Emerging Infectious Diseases Conference in Atlanta, Georgia enumerates the emerging zoonotic disease which are the following (1) Bartonella henselae, (2) Sporothrix schenkii, (3) Capnocytophaga carnimorsus, (4) Echinococcus multilocularis, (5) leishmaniasis, (6) Yersinia pestis (plague), (7) ehrlichisosis, (9) Escherichi coli, (9) Salmonella DT104, (10) Campylobacter spp, (11) Streptococcus iniae, (12) leptospirosis and (13) filoviruses [4]. The recent pandemics on SARS and Avian Bird Flu is caused by Influenza Virus A and coronavirus respectively.
There are about 1415 microorganisms and about 61% of them can cause zoonotic diseases. In view of the fact that most of the emerging pathogens, about seventy-five percent have came from other animals (e. g. mammals), public health sectors should be vigilant against the emergence of new zoonotic diseases. About one-third of the zoonoses can be transferred through human-to-human contact[ 6 ]. Live scale reforestation, wildlife trade and translocation, live animal and bushmeat markets, consumption of exotic foods, development of ecotourism, access to petting zoos, and ownership of exotic pets.
[7]; the domestication of animals as precluded by the ‘increased’ novel interactions between humans and wildlife; the anthropogenic modification of the environment triggering ecological change in the broader level [8] ; Wildlife animals and the contact with them through — wildlife trade and translocation, live animal and bushmeat markets, eating ‘exotic’ foods, ecotourism improvement, accession to petting zoos, and ownership of exotic pets — can also be potential resources for comeback of previously controlled zoonoses [9].
An example of this is the resurfing of Mycobacterium bovis, the causal agent of tuberculosis which is caused by the direct result of spillover from domestic livestock with anthropogenically related factors such as wildlife translocation, and their supplemental feeding [11]. Agricultural expansion affects emergence of zoonotic diseases, and a classic example of this is the Nipah Virus attack in Northern Malaysia in 1998 which had been demonstrated to root from cross-contamination with the pigs.