Introduction from Michael (Admin): I feel that I have to introduce this article by Jo because it is a very complicated area and scientists write in a language which is not easily interpreted by non-scientists. In addition, studies are often a collation of information harvested from other studies and therefore they can compound inaccuracies or create confusion. In my opinion this whole area has become very confused and possibly misleading.
This study essentially is stating that there is an association between cat scratches and depression in the people who look after the cats. The association could be because depressed people are more likely to be scratched rather than the cat scratch causing the depression. That point is very important and needs to be made at the outset. The reason why a depressed person may be more likely to be scratched is because they might be more careless or perhaps have substance abuse problems causing careless handling of their cat(s).
Another interesting aspect of this study is that they appear to have debunked an association between toxoplasmosis and depression which has previously been written about quite a lot. To reiterate: they could not find an association between toxoplasmosis and depression. Also in multi-cat households the owner was less likely to be depressed.
What follows is Jo Singer’s article, to which I have added a few words:
A recent study (not the one I am writing about) performed on 1.3 million patients had showed a strong association between being bitten by a cat and the probability of being diagnosed with depression. The
authors had suggested that infection with cat parasite Toxoplasma could be a likely reason for this association.
The new study revealed that only the group that received cat scratches had a positive effect on depression. Cat biting and toxoplasmosis had no effect on the depression and the number of cats had a negative effect on depression.
The study found an absence of association between toxoplasmosis and depression and a five times stronger association with cat scratching than with cat biting which suggested that the pathogen responsible for mood disorders in animals-injured subjects is probably not the protozoon Toxoplasma gondii, but possibly another organism; the bacteria Bartonella henselae, the agent of cat-scratched disease.
Caveat: As stated an association between depressed people and cat scratches does not automatically mean scratches cause depression.
Bartonella henselae is another infectious zoonotic disease. It is caused by the gram-negative bacterial Bartonella henselae. This disease is commonly referred to as “cat scratch fever“, and is transmitted in cats through contact with flea feces. This bacterium is excreted through the fleas into the feces and is then deposited on the cat’s skin. As the cat grooms itself, he ingests the bacterium which then causes the infection in the cat.
Caveat: dogs can also cause cat scratch fever. This seriously complicates this discussion.
Bartonella symptoms in cats are generally muscle aches, swollen glands and a possible fever. Humans can contract the disease through a scratch or possibly a bite from a cat who is infected. The disease in humans is usually mild; however in some cases a Bartonella infection can become sufficiently serious to warrant a short hospitalization. It is children who are at a higher risk of contracting the disease since they are more likely to play with infected kittens who tend to scratch and bite.
Kitty guardians can reduce the risk of their cats becoming infected with Bartonella through the prudent use of a regular, safe flea prevention program that is recommended by veterinarians. With an easy and simple flea prevention program, you will not only help prevent your cats from contracting Bartonella, but, based on the conclusion that the study reached this may also serve to prevent depression which may be caused through contracting Bartonella.
It will be interesting to learn more about what further studies may reveal about the cause of mental illness. I sincerely hope there are no further associations between cats and mental illness since we all know that having a deep and loving bond with a kitty and our interactions with them often are more effective than psychotropic drugs and there are no negative side effects that are caused by the human-feline bond.
What are your reactions to the study? Tell us in a comment.