[EvaH (OP)]

David wants to know:

For some years now, New Scientist and other serials have run articles about infectious diseases causing apparent mental illnesses. For examples: Coxsackie B triggering Type Diabetes, the parasite cats carry that causes mice and humans to take dangerous risks, and every so often a serotype of the sore-throat Streptococcus is blamed for sudden onset OCD. I have treated psychosomatic explanations with deep suspicion for many years now, especially Freudian explanations. Since the Marshall & Warren discovery, few people now believe “stress” causes stomach ulcers, so why persist with simply Psychological treatment for OCD?

What do you think?

[evan_au]

Can infectious diseases cause mental illness?

Yes. Before the introduction of antibiotics, syphilis was a major cause of mental illness.
Even infectious memes like alcohol, ice and pot consumption have been linked to mental conditions.

As for OCD, I am not aware of a specific infectious cause - it may be a more general thing like an autoimmune reaction in susceptible individuals which is not seen in other individuals.

In the absence of a specific known cause (especially if the trigger was an infection which has now healed), all the medical profession can do is to treat the symptoms.
- So if repetitive compulsions are interfering with your quality of life, see a professional
- I heard of an interesting app for OCD which sounded simple and non-threatening
- This app had 2 parts (which could could probably build yourself):
1. A video on your smartphone, showing the patient washing their hands. Whenever the compulsion strikes, just watch the video - you can do it anywhere.
2. Photos of various levels of "dirt" on your smartphone that they can swipe. This desensitises the patient in an environment which is clearly separate from the dirt itself. 
- Apparently, they have had high levels of completion and good results with OCD patients.

Listen or read here: https://www.thenakedscientists.com/articles/interviews/app-shown-help-ocd-symptoms