The Global Impact Of Zoonoses

Statistics indicate that more than 15% of the human population will pick up a zoonotic infection at some stage of their lives. Veterinary specialist in public health Dr Jan H du Preez takes a closer look at the threats presented by some of the more common zoonoses across the world.

- Dr Jan H du Preez

Scientists estimate that no fewer than six out of 10 infectious diseases in humans are zoonoses.

The majority of zoonoses come from livestock, including cattle, chickens, pigs, goats, sheep and camels, as well as pets. More than 200 zoonoses are recognised worldwide.

THREAT OF RABIES

This horrifying viral disease is deadly for both animals and humans; it kills more than 55 000 people across the world annually.

Dogs are the source of up to 99% of human rabies deaths. Forty percent of people bitten by suspected rabid animals are children under 15 years of age. Every year, more than 15 million people worldwide receive a post-bite vaccination, which is estimated to prevent thousands of rabies deaths a year. Rabies is present on all continents except Antarctica, but more than 95% of human deaths from the disease occur in Asia and Africa. All warm-blooded animals with fur may be carriers and transmit the virus.

In South Africa alone, more than R70 million a year is spent on post-exposure prophylactic rabies treatment. Worldwide, rabies causes annual losses to the livestock sector estimated at US$512 million (about R6,3 billion).

ZOONOTIC INFLUENZA

Avian and swine influenza are viral zoonoses. Human infection can occur after direct or indirect contact with infected poultry or pigs. Some people with animal influenza develop serious and potentially life threatening complications, such as pneumonia. The most infamous pandemic was the so-called Spanish flu, caused by an avian influenza virus that killed tens of millions of people in 1918 and 1919.

TOXOPLASMOSIS: A DANGER IN PREGNANCY