Ian Le Guillou at Understanding Animal Research (UAR) tells us how infectious diseases jump between species. These jumps often happen because of things that humans do. Sometimes, the disease jumps to us. Diseases that can infect humans and also other species are called zoonoses.
I like UAR. These people are doing something that I’d long wanted to happen – talking sensibly about animal work in labs. So I’m a little frustrated to find a few errors in Dr Le Guillou’s article. Only small errors, which you might not notice unless you’ve written a PhD thesis about Toxoplasma gondii as I did. For example, Dr Le Guillou says that Toxo prevalence in humans is 50% and it isn’t. Unless new data has been published, the best estimate we have is that it’s about 30%.
Picky? Moi? Yes I’m picky. But apart from the picky bits, I like this article. Diseases which jump host species can be truly devastating. Dr Le Guillou gives examples in mammals and amphibians but it’s much wider too. Some of the emerging tree diseases have jumped from tree to tree. Crop diseases jump species too, and I haven’t even started on arthropod diseases.
Science on the Land 
Hello Sam, you’re right to be picky in this instance. The difference between 30% and 50% simply in terms of the UK population is around 12 million people. And on a global level 1.2 billion people – and in my book that’s an unacceptable error!
I’d be very interested to read any future post on transmission of pathogens from species to species and how human intervention has affected the balance one way or another.
Yes it’s a lot of people. I’m emailing Dr Le Guillou now – he may have used more up-to-date sources about Toxo than the ones I know.
Yes, I’ll write more about interspecific disease transfer. Including the article you emailed to me yesterday.
I contacted Ian Le Guillou. He says that the 50% figure was supposed to say 30-50% but somehow it got edited down to a simple 50%. His source was http://www.toxoplasmosis.org/infotox.html I don’t know that guide’s author but it’s good, getting its facts right and explaining them clearly.
It’s kind of scary that an editing ‘anomaly’ can add 1.2 billion people to a statisitic!
Yes it is.