No, at the moment, cats cannot be vaccinated for toxoplasmosis. There is a fairly recent study published online on the Science Direct website which provides some insights into the possibilities of a vaccination against this widespread disease. It is entitled, Prospects of toxoplasmosis controlled by cat vaccination (March 2020). I don’t think it’s helpful to go through the study in its entirety but I’ll summarise their conclusion.
They concluded that, “the feasibility of cat vaccination is almost impossible because of the high vaccination coverage needed”. However, they decided that vaccinating cats on farms might have an important effect. The researchers suggested that reducing oocysts-originated infection locally within a meat producing farm would reduce the risk of farm producing contaminated products which would obviously mitigate its contribution as a source to meat born human T. gondii infections.
What they are saying that if there was a cat vaccine against toxoplasmosis it might be viable and useful to use it on a small scale such as on farms but to inoculate cats nationally is almost impossible.
To be clear, there is no current vaccine to protect against toxoplasmosis in human or animals. It’s worth briefly mentioning again the public health considerations of toxoplasmosis.
Public health considerations
About half the human adult population has been exposed to the protozoan parasite in the past based on serological evidence which means based on the presence of antibodies in blood serum. If you’ve got antibodies you’re probably protected against an infection. Pregnant women should take particular precautions if they have a domestic cat companion but they need not give up their cat to a rescue centre as I’m sure most women now realise, as it is a well-discussed topic.
Cats are the only animals to pass on the infectious stage of this parasite through their faeces. It’s worth reminding ourselves that, by a significant factor, most human cases of this disease are contracted by eating raw or undercooked meat, particular lamb or pork. The domestic cat should not be over-vilified because people can do more to protect against the disease by focusing on their food preparation habits such as washing fresh vegetables more carefully. In addition wearing gloves when gardening can help to avoid contact with oocysts in the soil.
And finally, in protection of the domestic cat’s reputation, it should be restated that even if a cat has an active toxoplasmosis infection they are only capable of passing it on for 7 to 10 days in their entire life, when there is an acute infection.
In respect of cat litter trays containing cat faeces, it should also be noted that “It takes anywhere from 1 to 3 days for oocysts shed in the faeces to become infectious – which means the litter box would have to sit unscooped for 1 to 3 days before the infection could be passed on”. I’ve quoted directly from Cat Owner’s Home Button Handbook to put this matter into some sort of perspective. To become infected from a litter tray you would have to touch the faeces with your hand and then touch an opening in your body to transmit the oocysts into your body. You can see that it is quite difficult.
SOME MORE ON CAT VACCINATIONS: