Diseases you could catch from your pet

by Dr. Francesca Brown

Firstly - don't panic!

It is important not to be fearful of these diseases, known as zoonoses (diseases that humans can catch from animals), as provided you are not immunocompromised, common sense hygiene is maintained around your pets, you will remain healthy.

In fact there is a lot of research which suggests that pet owners are healthier than their non-pet owning counterparts.

Common sense hygiene, like washing your hands after handling your cats and before eating, will minimise the chances of contracting one of these zoonotic diseases. It also minimises the chances of some of these diseases being passed from humans to your cats (a reverse zoonosis).


Disease Examples

The list below is not exhaustive but provides brief details of some of the more common zoonoses:


Image source wikimedia commons



This is a protozoan that requires both sheep and cats to complete its life cycle. In cats the infection does not cause any symptoms but in sheep it can cause abortion. There is a vaccination available for sheep but nothing to prevent cats getting infected.

In healthy humans, contact with the parasite causes little more than mild flu symptoms if any symptoms are seen at all. It will usually go undiagnosed and the person will develop antibodies to toxoplasmosis. Approximately 40% of the NZ population have antibodies and are therefore immune due to previous infection. More significant diseases can occur in humans with a suppressed immune system such as those undergoing chemotherapy or that are HIV positive.

Problems arise when a female is infected with toxoplasmosis during pregnancy.  Infection can result in loss of the pregnancy or malformation of the foetus. If you are already immune before you become pregnant (because of prior exposure to toxoplasma), this is not a problem. It is only a problem when your body has never been exposed to the disease and you contract it during pregnancy.

  • Special care must be taken when pregnancy is a possibility, including:
    Do not get a new kitten until the baby is born – cats under 1 year of age are more likely to be shedding infection
  • Do not empty or handle cat litter trays – get someone else to do this
    If you must handle litter trays – wear gloves and a face mask to avoid inhaling infective cysts
  • Handle raw meat carefully, using separate chopping boards for meat and other foods and wash hands thoroughly after handling the meat
  • Cook all meat well – no rare steaks or pink lamb when you are pregnant or trying to conceive
  • If you must garden, garden with gloves on in case of contact with cat faeces.  It would also be good practice to damp down the garden prior to gardenting to prevent dust aerosols.  This is good practice to avoid other potential problems from the soil too. 



Ringworm is not a worm, but in fact a fungus. It looks like a circular lesion on the skin in clinically affected animals and humans, hence the name. Up to 30% of cats are asymptomatic carriers (i.e. carrying the fungus but not showing any outward signs) of ringworm.

The condition causes skin lesions which are mildly itchy. In a healthy person they are treated topically with an anti fungal cream. In immunocompromised humans (such as humans with HIV or undergoing treatment such as chemotherapy which compromises the immune system) systemic treatment (that is medication that gets into the blood stream such as tablets) is likely to be prescribed.

If you suspect you have ringworm see your doctor. It is also advisable to get your cats and dogs checked out by your veterinarian. Your veterinarian will also be able to advise you on decontamination of the environment and an treatment required for your pet.


Visceral Larva Migrans

This is caused by the larva of cat and dog roundworms (Toxocara canis, Toxocara felis and Toxocara leonina). When a human comes into contact with the eggs or larva of this worm and this enters the body, the larva then travels around the body trying to find the dog or cats small intestine.

While doing this, it causes tissue damage as it travels. The larvae can then embed somewhere such as the back of the eye, brain or lung and cause clinical symptoms. This is most common in children because they generally have poorer hygiene habits (they are not so good at washing their hands and put more things in their mouths) than their adult counterparts.

To minimise the risk of infection make sure your dogs and cats are wormed regularly. Ensure your children don't play in soil where cats may have defecated, cover sand pits and practice good hygiene, such as washing your hands after working or playing outside and before eating.


Cutaneous Larva Migrans

This is caused by hookworm larvae. The larvae penetrate and move through the skin if contact occurs and move around just under the skin trying to find the correct location for development.

They are very itchy and it can take sometime for the larvae to die. Again it is more common in children because they are more likely to crawl around in areas that have been contaminated by pet faeces and have poor hygiene habits.

Like with visceral larva migrans, to minimise the risk of infection make sure your cat is wormed regularly, ensure your children don't play in soil where cats may have defecated, cover sand pits and practice good hygiene, such as washing your hands after working or playing outside and before eating.


Cat scratch fever

Cats can carry a bacteria in their claws which causes fever-like symptoms several weeks after the scratch has healed. Initially at the scratch site there might be some inflammation (common with any cat scratch) but by the time the disease shows itself the scratch is usually completely healed and the association is often forgotten.

If you get a scratch from a cat, give the scratch a good scrub and clean with an antibacterial such as chlorhexidine (one of the active ingredients in Savlon(R)). This will minimise the chances of the bacteria getting into the blood stream. If you do develop fever like symptoms a couple of weeks after a cat scratch, it is best to see your doctor and while you are there mention the scratch as it may change the treatment offered.



When cats and dogs bite each other and when they bite humans, they can spread a bacterium that naturally lives in the mouth.  When it gets under the skin, such as after a bite this is when problems occur. These organisms like places with low oxygen content so under the skin is perfect. The bacteria then multiply rapidly and cause an abscess or cellulitis (generalised infection of the underlying tissues).

This infection can spread and become an infection of the whole body. All animal bites should result in an immediate visit to your doctor. Your doctor will usually prescribe antibiotics.  Delaying visiting your doctor following a bite will frequently result in hospitalisation and the need for intravenous antibiotics.

Note: Humans biting each other also has the potential to cause pasteurellosis or similar infections in the skin and the same treatment applies, so this bacterium is not specific to animals!



Fleas prefer a specific host (eg cats or dogs, depending on the flea) but if infestations get big then they start biting other hosts – such as humans. 

For humans this is mainly an irritation as the bites are extremely itchy. Regular, good quality flea control on all animals in your household should prevent this from occurring.




Giardia is a chronic intestinal disease caused by a protozoa.   It occurs worldwide in humans, most domestic mammals and many birds. Infection is common in cats and dogs and is being seen with increasing frequency in New Zealand.

It is a zoonotic disease so it is possible to catch it off your infected cat or dog, if basic hygiene rules are not followed.  It is important to be aware though that most cases of this disease are caught directly from contaminated water sources.  If you have it at the same time as your pet, it is likely that you both had contact with the same water source. 

The infection is passed from animal to animal, person to person, or animal to person by contact with infected faeces either directly (usually as a result of poor hygiene) or indirectly via food or water contaminated with cyst-containing faeces.  Many water sources in New Zealand are now contaminated

Everyday basic hygiene practices should be adhered to such as hand washing after going to the toilet or touching pets and before preparing food.

If you are in an area where Giardia is or may be more prevalent, then drink only boiled or filtered water (unless you know the water source is safe), or bottled carbonated drinks. Avoid ice and beverages made from tap water not known to be safe; and do not eat uncooked or unpeeled fruits and vegetables which may have been grown in contaminated areas.


Campylobacter, which is normally associated with eating undercooked chicken, can also be associated with your companion pets, especially dogs. Recent research has shown that many dogs carry these bacteria asymptomatically (that is without showing any signs of disease) and poor hygiene around your pet dogs, such as not washing your hands after touching your dog and before eating, can result in the spread of campylobacter.

Campylobacter causes severe diarrhoea, vomiting, lethargy and fever and can last for several days.

It is important to remember that if someone in your house is struck down with campylobacter (from poorly cooked chicken for example) then it is also possible to spread it to your dog too.

Routine personal hygiene procedures, such as hand washing before meals, will minimise the chances of contracting this disease.



This is a common zoonosis caused by exposure to an infected animal’s urine. It is more common in pig and cattle owners than dog owners, but can still occur. Leptospirosis in dogs is not currently a problem in the Canterbury area, but disease localities are changing and this may change.  You also need to be aware of it if travelling north of Christchurch and in the North Island. Seek veterinary advice as to whether your dog may be at risk. 

It causes severe flu like symptoms in humans and is extremely debilitating. Very severe cases may result in death. Leptospirosis in humans usually requires hospitalisation. It can take weeks or months to recover and for some people they never fully recover.

Leptospirosis can be prevented by ensuring at risk dogs and livestock, where applicable, are vaccinated. You should also ensure that rodents are well controlled as rodents act as carriers in the leptospirosis life cycle. In addition, ensure that you avoid contact with urine from animals. If you do happen to get some on your hands or elsewhere on your skin, immediately wash your hands using soap, in the usual way.



Avian Chlamydiosis (aka Psittacosis)

Avian chlamydiosis is the main zoonotic disease to be aware of with regards to birds.   This should not be confused with the sexually transmitted disease called chlamydia, which is completely different . 

All bird owners should be aware of the signs of Chlamydiosis (aka Psittacosis) and the human health risks.

The condition is caused by Chlamydia Psittaci. Generalised infections can occur in both birds and mammals, however the majority of human infections originate from birds. All birds can be affected but the most commonly affected include parrots, budgerigars, canaries, finches, pigeons, and poultry. Sudden death, respiratory distress and other signs of general unwellness are seen in birds that are clinically affected. 

If you have a walk in aviary, damp down the dust on the floor before entering to clean up/feed your birds. This helps to prevent aerosolisation of faecal particles which could then be breathing in. 

Ensure that your birds kept in a low stress environment. They should be provided with facilities that are the correct temperature, access to the correct food and water and not be over crowded. 

Seek veterinary attention as soon as you notice your bird is sick and if psittacosis is suspected, then wear a respirator mask when handling and cleaning out your birds. 


Should you have any questions about any of these diseases or anything else to do with your pet, please do not hesitate to contact us on 03 348 9728

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