Pet hazards: Infections you could pick up
Children harassing parents to get a pet is a frequent challenge faced by families around the globe. For those parents who are trying to find an excuse to refuse their child’s request for a pet without seeming inhumane, infections from pets can provide a dignified exit clause. Here are a few of them:
Rabies
This viral infection is justifiably feared. While a whole host of animals can transmit rabies, dog bites are a major source of disease. And despite living in the most technologically advanced age of medicine, rabies, for all intents and purposes, remains incurable.
In other words, people who are exposed to rabies through a dog bite will almost certainly die from a type of brain infection known as encephalitis. The only way to prevent this is by getting a series of injections (antibodies and vaccines) as soon as possible after being bitten.
Pasteurella
Anyone who has worked in the emergency department of a hospital will tell you that injuries arising from dog and cat bites are quite common. In the same way that the human mouth is full of bacteria, so too are the mouths of dogs and cats.
One of the bacteria that they carry is called Pasteurella, named after the famous French microbiologist, Louis Pasteur. If a bite to the hand or leg becomes infected with Pasteurella, it causes a nasty skin infection called cellulitis. But due to Pasteurella’s affinity for deeper tissue, this is often complicated by inflammation of the underlying joints and tendons. Antibiotics are definitely required and sometimes surgery to clean out the joint.
Cat-scratch disease
This is an infection associated with kittens rather than older cats. As the name implies, a scratch from the claw of an excited young cat can inoculate the skin with a bacterium known as Bartonella Henselae. This can lead to a lump forming at the site of the scratch with inflammation of the local lymph nodes (usually in the upper thigh or in the armpit). People can sometimes have fevers and muscle aches. It tends to get better of its own accord, although antibiotics might help.
Worm infections
Dogs and cats can excrete worm eggs in their faeces. Humans, especially small children, can get infected in a couple of ways. First of all, the larvae on the ground can penetrate the skin of one’s feet. This leads to a condition called “cutanea larva migrans” which causes an itchy, migrating rash on that part of the body as the larvae make their way up the leg. In addition, there are little children who eat soil for various reasons. This can lead to a more serious condition called “visceral larva migrans” characterised by fevers, an enlarged liver and an allergic-type rash.
Toxoplasmosis
This parasite is most often acquired by eating undercooked meat; however, cats also excrete toxoplasma in their faeces; therefore, infection in humans can occur through contact with cat faeces. This can occur directly (e.g. by cleaning kitty litter boxes) or indirectly (e.g. through surfaces contaminated by cockroaches that have been in contact with cat faeces). In healthy people, it can cause swelling of the lymph nodes in the neck, fevers and certain types of eye infections.
Psittacosis
Now we move away from mammalian pets and come to our feathered friends. Parrots can transmit an infection called psittacosis. This classically causes pneumonia (a lung infection) which can make people quite sick. Psittacosis is a more likely cause of pneumonia in a parrot owner if the bird is visibly sick e.g. losing feathers or has died recently. People get infected by inhaling the bacterium.
Salmonella
Some people have a penchant for more exotic pets than dogs, cats or birds. Two examples of this are reptiles and amphibians. It is not uncommon, especially in Western countries, for people to keep lizards, frogs, turtles or snakes as pets. These animals can carry Salmonella in their mouth, which is a bacterium that can cause fevers and diarrhoea, especially in young children. People don’t have to be bitten by the pet to become infected.
Fish tank granuloma
Even people with aquariums are at risk of infections. Mycobacterium Marinum a bacterium that lives in fish tanks typically causes a single lump on the hands or arms a couple of weeks after cleaning a fish tank. Occasionally, more lumps can start spreading up the arm. Treatment usually involves a few months of antibiotics.
Conclusion
So there is a snippet of some of the infections we can get from pets. But of course, this shouldn’t be the be all and end all when deciding on whether or not to get a dog or cat. There are so many pros and cons for such an important decision, of which infections are only one. Good luck!
(The writer is an Associate Professor of Medicine at the Australian National University (ANU) and a Specialist in
Infectious Diseases)