Part of the family but a risk

Pet owners should not only have their pets checked to ensure parasitic diseases are dealt with but also have checkups themselves at hospitals, Liu adds.

Toxoplasma gondii can infect most mammals, including humans, and the symptoms are not obvious - a low fever or lymphadenitis, sleepiness and depression.

The parasite can cause inflammation of the brain and neurological diseases, and can also affect major organs, such as the heart, lungs, liver and eyes.

An unborn child may be infected with the disease via the placenta and, as a result, contract strabismus, epilepsy or be mentally affected, Liu explains.

The disease is fatal to women because it can cause miscarriages or even female sterility, Liu says.

The primary host of the parasite is cats, and the rate of infection via dogs is lower than that for cats.

The disease can be transmitted via ingestion of contaminated cat excrement, such as hand-to-mouth contact after emptying the cat litter.

"Pregnant women should be more careful because they have to eat a lot. They must not touch their pets' excrement and must wash their hands after exposure," Liu says.

Liu also has two further suggestions: don't allow your pet to sleep on the bed and clean the cat litter box as often as possible while wearing gloves.

Children ought to wash their hands before meals and should never share food with pets or touch pets while eating, Liu adds.

Liu's four-district Beijing investigation of more than 2,000 cats in 2009 shows 8 percent were infected with the disease. In 2011, he did a survey among 100 veterinarians, two of whom had toxoplasmosis.

The rate of infection via pets, however, is lower than that of eating undercooked meat or unclean vegetables, Liu says.

"The disease can be prevented if people are careful," Liu concludes.

Beijing resident Li Jing adopted a dog when she was four months pregnant, after reading articles by obstetricians, and was reassured it was all right to have a pet during pregnancy.

"My dog is a great companion. I walked it every day for several months before my son's birth," the 28-year-old says.

She and her husband, Sun Xiang, hope their son, too, will accept the dog as part of the family.

But since the boy is only one month old, the couple is cautious.

"We don't allow the dog to get too close to the baby," Sun says.