Guinea pigs are making people ill, a report stated earlier this month.
In three years, at least as many people have been taken to hospital after developing life-threatening pneumonia from their furry friends.
Most guinea pigs likely harbour the bacteria responsible for the inflammatory lung condition, which is detectable by the animals developing pink eye.
Dr Steven Gordon, chair of infectious disease at the Cleveland Clinic, who was not involved in the study, said: ‘We love our pets, but we’ve got to be smart about pets and hygiene.
‘We should be washing our hands after pet contact, and certain high-risk people – like those with compromised immune systems – should avoid contact with pets.’
‘This study is a paradigm shifter’
Researchers from around the world analyzed data from a study that has monitored 246 infants with Toxoplasma gondii-related disease since 1981.
Results reveal a link between the parasite and almost 1,200 human genes that are associated with cancer.
Protein fragments from children with severe forms of the disease are also linked to Alzheimer’s, Parkinson’s and epilepsy.
The parasite is thought to increase the risk of these conditions by releasing proteins that alter communication between brain cells.
Dr Steindler said: ‘This study is a paradigm shifter.’
Only pregnant women are currently advised to avoid cat faeces, which often contain Toxoplasma gondii, as the parasite is known to cause miscarriages, still births and damage to foetus’ development.
Infections often seem harmless, with few people experiencing symptoms and just a few showing signs of mild flu.
Other factors may be at play
Yet, the researchers add other factors aside from Toxoplasma gondii infection likely also influence a person’s risk of developing such diseases.
They wrote: ‘We hypothesise that disease occurs in the presence of the relevant susceptibility genes, parasite genotype and other innate and environmental factors such as other infections, the microbiome or stress that influence immune responses.’
Dr Steindler added: ‘At the same time, we have to translate aspects of this study into preventive treatments that include everything from drugs to diet to lifestyle, in order to delay disease onset and progression.’
The findings were published in the journal Nature.