Does an asymptomatic toxoplasmosis infection cause elderly people to become frailer?

The Science Daily website has an article which infers that elderly people who have unknowingly been infected with the Toxoplasma gondii protozoan tend to be frailer in old age than those who haven’t.

Essentially, the scientists found a connection with a higher level of antibodies to Toxoplasma gondii in a person and increased frailty.

But my argument would be this: I don’t think they have proved cause and effect.

Toxoplasma parasite engages in 'identity theft' of immune cell to travel around the host's body
Toxoplasma parasite engages in ‘identity theft’ of immune cell to travel around the host’s body. Image: Professor Antonio Barragan, who led the study. Red marks the Toxoplasma parasite. The nucleus is blue, and the cell’s surface is green.
Two useful tags. Click either to see the articles: Toxic to cats | Dangers to cats

It may be the case that elderly people who are frail for any number of reasons including their inherited genetics, may be more likely to respond to an asymptomatic infection of the Toxoplasma gondii protozoan by producing more antibodies than those who aren’t frail. That would seem to be a reasonable alternative viewpoint. I’m surprised that the scientists did not state that their study appears to be an observational one without proving cause and effect.

Actually, on reading the report more carefully they do state that, “The researchers did not, as they originally hypothesised, find an association between an infection to T. gondii and frailty. I think that’s an admission that there might not be cause and effect which is important in my view because I don’t want to see the domestic cat denigrated unjustifiably.

We know that a lot of people are infected with toxoplasmosis but they have no symptoms throughout their lives. They don’t know that they are infected. But the question is this: does it have any impact on these people and this study infers that it might make them frailer.

They say that in some countries more than 65% of people are infected and these people unknowingly harbour the parasite for life.

And in this survey, they “examined the blood of 601 Spanish and Portuguese adults over 65”. They measured their frailty. They stated that 67% of the people had indications in their blood (seropositive) of a latent infection of Toxoplasma gondii. The slightly concerning data is the high level of the number of humans infected.

Before I finish, I would like to remind people once again that the domestic cat sheds Toxoplasma gondii oocysts once in their life for a short time if they are infected and it is possible that some of these oocysts can find their way inside a human in various ways such as when cleaning up the cat litter tray.

However, it should be strongly emphasised that by far the most common way of being infected by this protozoan is through eating unpasteurised milk, raw vegetables and/or undercooked meat. This point needs to be made protect the domestic cat from abuse.

Note: Toxoplasmosis is a zoonosis as it can be transmitted between and affect cats and humans.

Study title: Toxoplasma gondii IgG Serointensity is Positively Associated with Frailty. Link:

RELATED: Truth about Toxoplasmosis and Cats

Please search using the search box at the top of the site. You are bound to find what you are looking for.

Useful tag. Click to see the articles: Cat behavior

Leave a Comment

Your email address will not be published. Required fields are marked *

follow it link and logo

Note: sources for news articles are carefully selected but the news is often not independently verified.

I welcome and value comments. Please share your thoughts. All comments are currently unmoderated.

This blog is seen in 199 of the world's country's according to Google Analytics which is pretty much the entire world.

Scroll to Top