Can parasites affect public health?

Certain parasites are zoonotic, which means they can be transmitted between
animals and humans. These infections are always of concern to the
public and pet owners, but occupational groups are at risks, not least veterinary
surgeons and veterinary nurses, farmers and zoo personnel – indeed
anyone who is in frequent contact with domestic, exotic or wild animals.


Parasitic zoonoses can be due to endo- or ectoparasites and can cause a
variety of mild or serious symptoms in humans – for example, mild as in
the case of skin irritation caused by flea bites, or very serious as in multi-organ
failure seen in advanced Lyme disease, which is transmitted to people
through the bite of a tick usually associated with animals. Because some
of the common parasites that infect small animals (e.g. Toxoplasma and
Toxocara) also infect humans, especially young children, pregnant women
and immuno-suppressed individuals, they pose a public health risk; thus
veterinary surgeons and nurses have a responsibility to inform their clients
about a parasite’s zoonotic potential. Many of these diseases are associated
with faecal contamination of soil, general level of hygiene and food
preparation. Some parasites are considered important biological hazards
in food. Food is an excellent vehicle by which many pathogens (parasites,
bacteria and viruses) can reach an appropriate colonization site in a new
host. 


There is currently a large amount of research activity on the role
of parasites in food safety, including Toxoplasma gondii and Trichinella
spiralis in pork and pork products. Hence, control of many zoonotic parasitic
diseases requires strict attention to personal hygiene and avoidance of
contaminated materials. Furthermore, certain ectoparasites, like fleas and
some mites, are readily transferred to people from pet animals. Throughout
the book the public health implications of various parasitic infections will
be emphasized.