Spread of Disease

Spread of Disease

The movement of large numbers of animals across long distances also brings together many diseases that were previously confined to a species or place, and in some cases both. One reason that captive bred birds cannot be re-introduced into wild populations is because birds in the pet trade have been exposed to a variety of diseases that could wipe out natural populations that have no immunity to them.

Animal to Human Diseases (Zoonoses )

With the growth of the wildlife trade, the number of diseases spread by animals to humans, known as Zoonoses, has also increased. Animals and people are now vulnerable to new diseases, parasites, viruses and funguses to which they had not been previously exposed.


In 2003, Severe Acute Respiratory Syndrome (SARS) brought Hong Kong to a standstill. The disease was brought into the territory by an infected Mainland doctor and almost 300 people in Hong Kong died from the virus shortly after.

The source of the virus remains unknown – it is believed to have originated in the horseshoe bat – but at the time the virus was found in 5 Palm Civets (Paguma larvata) and a raccoon dog in a wildlife meat market in Guangdong, south China. A Chinese Ferret Badger from the market was found to carry the antibodies from the disease. Scientists speculate that the virus jumped from these animals to humans and were subsequently spread by wild animal traders to their patron.

Avian Influenza (H5N1)

There are many strains of Avian flu but most do not cause human deaths. However, in 2001 and 2002, the H5N1 strain caused severe disease and many deaths. Most of those who died were in close contact with poultry but wild birds were also found to carry the disease. Due to highly intensive farming methods, millions of chickens had to be killed to stop the spread of the disease; a million chickens were slaughtered each time H5N1 was detected in Hong Kong in 2001 and 2002.

The Risk of Salmonella

Salmonella can be contracted in many ways (e.g. eating unhygienically prepared food) and it is not unheard of for children to fall sick after handling reptiles that carry the disease naturally in their intestines. Salmonella infections are particularly serious in babies, children and people with weak immune systems. Most people experience symptoms similar to a bad case of food poisoning- diarrhoea, fever and stomach cramps – but in severe cases, it can lead to septicaemia (blood poisoning) and meningitis (swelling of the brain membrane).

In the 1970s, salmonella was consistently found in in the faeces of small turtles, leading to a ban on their trade in the US. The Communicable Disease Centre in the United States has seen a sharp increase in salmonella cases with the growing popularity of keeping reptiles as pets and recommends they are not kept as classroom pets.