Hello student,

To know the answer at first we have to find out all of the sources and causes of those illness.

1. Typhoid disease caused by salmonella typhi bacteria what's the life threatening disease
2. Tetany basically caused because of little amount of potassium or magnesium in our body. Having too much alkaline or acid also can cause this
3. Retainer is caused by clostridium tetani bacteria.
4. Cold is a very common disease among Us which can be done by various viruses
5. Malaria basically caused by the bite of of mosquitoes with the help of plasmodium parasite

So from from the list above we can see all of the illness caused by various kinds of living organisms like virus bacteria parasites, except Tetany.

So so the answer is Tetany

Hope thisI will help you if you have any other doubt comment down below