Question: Will an OCP detect all parasites?

Claire Bourke answered on 16 Jun 2016:

Hi Adam, am I right in thinking that you mean the ova, cysts and parasites exam when you say OCP? If so, then Linda is right, because this test is designed to look in poo, it will only detect parasites, cysts and eggs that pass through the gut and not those found elsewhere. It is often a good start if there is evidence of an infection in the gut though (e.g. blood in the stool, bloating etc.).

During my PhD I used poo and urine samples to identify parasitic worms in the gut and these can actually be quite tricky to identify under a microscope. As you might imagine, there is lots of other stuff (food, fibre, fat droplets etc.) in a poo sample besides parasites, so it can be a challenge to see evidence of parasites and spot which one is which. This is particularly the case if someone has a very light infection/few parasites because that means that there are fewer eggs, cysts and parasites to spot. To increase the accuracy of detection in these cases it is often better to collect more than one sample on multiple different days to make doubly sure!