Page 609 - The Veterinary Laboratory and Field Manual 3rd Edition

546 Glossary

One Health – Over the past decades numerous Population at risk – The population of animals
organizations have recognized the need to inte- which are identified as those likely to develop a
grate human and animal health, and the health disease.
of the environment, and have taken steps to Prevalence – The number of animals which
develop new programs and form new partner- have developed a disease (diagnosed on the basis
ships to support that integration. The concept of clinical signs or by laboratory tests) in a stated
of ‘One Health’ is not new and essentially refers population at a given time. This is regardless of
to an integrated multidisciplinary approach to when the illness began. The prevalence rate is
solving complex health problems that impact, defined as the number of positive cases divided
or are impacted by, animals, humans and the by the number of animals in the population
environment.
tested at a given point in time.
Pandemic – An epidemic (a sudden outbreak)
that becomes very widespread and affects a Probability – The likelihood of an event occur-
whole region, a continent, or the world. ring.
Risk – The potential that a chosen activity or
Pathogen – An agent that causes disease, espe- action will result in an undesirable consequence.
cially a living microorganism, such as a virus, Almost any human endeavour carries some
bacterium or fungus or an endo/ectoparasite. risk, but some are much riskier than others.
Some pathogens are obligate (that is, nearly Essentially, risk = likelihood × consequence.
always cause disease) and others are opportunis-
tic (that is, cause disease only when the host’s Risk assessment – The identification, evalua-
immunity is compromised). Pathogens can be tion and estimation of the likely risk associated
transmitted via various routes from one host to with an action, event or procedure. Typically, in
another including the faecal-oral route, by aero- animal health, this consists of hazard identifica-
sol, by direct and indirect contact (that is, via the tion and characterization, a release assessment,
environment) and by arthropod vectors. exposure assessment and then risk characteriza-
tion. Risk Analysis includes risk assessment,
PCR – Polymerase chain reaction is a technique
in molecular genetics that permits the analy- risk communication and risk management. Risk
sis of a short sequence of DNA (or RNA) even assessments are an important part of developing
in samples containing only minute quantities risk mitigation recommendations to ensure that
of genetic material. PCR is used to reproduce biosafety and biosecurity requirements are met
(amplify) selected sections of DNA or RNA for both in the field and in the laboratory.
analysis. PCR technology is now quite varied Sanitary and Phytosanitary (SPS) Agreement
and widely available but although PCR is a sen- – see http://www.wto.org/english/tratop_e/sps_
sitive tool for diagnostics the results are only e/sps_e.htm.
reliable if the correct conditions are available to
undertake testing. It should be noted that the WHO – World Health Organization of the
presence of genetic material in a sample from United Nations see http://www.who.int/en/.
a case doesn’t indicate a diagnosis unless the Zoonotic disease – An infectious disease that
findings are consistent with the clinical find- can be transmitted from animals to humans.
ings, that is, a PCR positive reaction doesn’t A significant number of infectious diseases,
necessarily indicate that a live pathogen is including those caused by viruses, bacteria and
present. parasites, can be transmitted from animals to

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