Hi Nikkita
that’s a good question, but very difficult to answer. It is easier to answer the question how many people are infected with parasites, and even that is difficult as it would be too difficult and expensive to test everyone with diagnostic tests, but luckily we have epidemiologists like Mark who can do this sort of calculation. Bearing in mind that already being infected with a parasite does not protect you against being re-infected, I would say that a few hundred million people may get infected and re-infected on a daily basis, but it’s difficult to give a precise estimate. Maybe my colleagues can comment on this.
Hi Nikkita
Thanks for passing this one to me Franco – no pressure. The incidence rate is a measure of the rate of transmission of a parasite over time. This is expressed differently for different parasites. So for malaria it is often the ‘entomological inoculation rate’ which is the number of bites from an infected mosquito per unit time. This can range from 0 per night to several per night depending on where someone lives. Sometimes the incidence is referred to as ‘force of infection’ which is measure of the number of parasites entering the host per unit time. It has been estimated that approx 200 million people get malaria per year, so you can work out what means per day. When applied to worm infections, this might be a fairly small number per-capita. But multiply a small probability by a large number of potential hosts and you still get huge number in the millions most likely.
Comments
Mark commented on :
Hi Nikkita
Thanks for passing this one to me Franco – no pressure. The incidence rate is a measure of the rate of transmission of a parasite over time. This is expressed differently for different parasites. So for malaria it is often the ‘entomological inoculation rate’ which is the number of bites from an infected mosquito per unit time. This can range from 0 per night to several per night depending on where someone lives. Sometimes the incidence is referred to as ‘force of infection’ which is measure of the number of parasites entering the host per unit time. It has been estimated that approx 200 million people get malaria per year, so you can work out what means per day. When applied to worm infections, this might be a fairly small number per-capita. But multiply a small probability by a large number of potential hosts and you still get huge number in the millions most likely.
Franco commented on :
I feel guilty now Mark – I ‘liked’ your answer in compensation!