# Human Parasites **URL:** \ **Category:** Factual Questions\ **Created:** [January 18, 2006, 3:05am UTC](https://boards.straightdope.com/t/human-parasites/340463 "2006-01-18T03:05:11Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![bizzwire](https://avatars.discourse-cdn.com/v4/letter/b/958977/32.png) [@bizzwire](https://boards.straightdope.com/u/bizzwire)\ **Post date:** [January 18, 2006, 3:05am UTC](https://boards.straightdope.com/t/human-parasites/340463/1 "2006-01-18T03:05:11Z")
A comment someone made in one of the countless ID threads has really stuck fast. I forgot who posited it, but the argument went something along the lines of “If the biblical account of creation is to be believed literally, all life forms on the planet were created all at the same time, in their present form. There are several parasites and disease-causing organisms which can only survive/reproduce in a human host. Ergo, Adam and Eve were totally clapped-out.” I don’t want to re-ignite an ID debate, but I am curious: what parasites and other cooties could not exist without humans? ---
**Author:** ![ComeToTheDarkSideWeHaveCookies](https://avatars.discourse-cdn.com/v4/letter/c/e9bcb4/32.png) [@ComeToTheDarkSideWeHaveCookies](https://boards.straightdope.com/u/ComeToTheDarkSideWeHaveCookies)\ **Post date:** [January 18, 2006, 3:22am UTC](https://boards.straightdope.com/t/human-parasites/340463/2 "2006-01-18T03:22:35Z")
[http://www.biosci.ohio-state.edu/~parasite/lifecycles/balantidium\_lifecycle.html](http://www.biosci.ohio-state.edu/~parasite/lifecycles/balantidium_lifecycle.html) [http://www.biosci.ohio-state.edu/~parasite/lifecycles/filaria\_lifecycle.html](http://www.biosci.ohio-state.edu/~parasite/lifecycles/filaria_lifecycle.html) [http://www.biosci.ohio-state.edu/~parasite/lifecycles/capillaria\_lifecycle.html](http://www.biosci.ohio-state.edu/~parasite/lifecycles/capillaria_lifecycle.html) [http://www.biosci.ohio-state.edu/~parasite/lifecycles/enterobius\_lifecycle.html](http://www.biosci.ohio-state.edu/~parasite/lifecycles/enterobius_lifecycle.html) [http://www.biosci.ohio-state.edu/~parasite/lifecycles/fasciolopsis\_lifecycle.html](http://www.biosci.ohio-state.edu/~parasite/lifecycles/fasciolopsis_lifecycle.html) [http://www.biosci.ohio-state.edu/~parasite/lifecycles/heterophyes\_lifecycle.html](http://www.biosci.ohio-state.edu/~parasite/lifecycles/heterophyes_lifecycle.html) [http://www.biosci.ohio-state.edu/~parasite/lifecycles/loa\_lifecycle.html](http://www.biosci.ohio-state.edu/~parasite/lifecycles/loa_lifecycle.html) [http://www.biosci.ohio-state.edu/~parasite/lifecycles/metagonimus\_lifecycle.html](http://www.biosci.ohio-state.edu/~parasite/lifecycles/metagonimus_lifecycle.html) [http://www.biosci.ohio-state.edu/~parasite/lifecycles/paragonimus\_lifecycle.html](http://www.biosci.ohio-state.edu/~parasite/lifecycles/paragonimus_lifecycle.html) [http://www.biosci.ohio-state.edu/~parasite/lifecycles/strongyloides\_lifecycle.html](http://www.biosci.ohio-state.edu/~parasite/lifecycles/strongyloides_lifecycle.html) I haven’t gone through and cross-referenced all of these to see if they all require a human host for their lifecycle, but that is how they’re presented on the Ohio State University site where I got them all. Interesting somewhat related BBC article from 2003: [http://news.bbc.co.uk/2/hi/health/3287733.stm](http://news.bbc.co.uk/2/hi/health/3287733.stm) ---
**Author:** ![Tevildo](https://avatars.discourse-cdn.com/v4/letter/t/b9bd4f/32.png) [@Tevildo](https://boards.straightdope.com/u/Tevildo)\ **Post date:** [January 18, 2006, 3:24am UTC](https://boards.straightdope.com/t/human-parasites/340463/3 "2006-01-18T03:24:32Z")
> [@bizzwire](#): > > I don’t want to re-ignite an ID debate, but I am curious: what parasites and other cooties could not exist without humans? A few obvious candidates from the macroscopic world, before we get into the thousands of human-specific bacteria: Body louse, _Pediculus humanus humanus_ Head louse, _Pediculus humanus capitis_ Crab louse, _Phthirus punis_ The mites _Demodex folliculorum_ and _D. brevis_ The tapeworms _Taenia saginata, T. asiatica_ and _T. solium_. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 18, 2006, 9:57am UTC](https://boards.straightdope.com/t/human-parasites/340463/4 "2006-01-18T09:57:38Z")
There are plenty of diseases to which humans become immune after the infection has run its course; starting from a population of two (or, for that matter, a population of eight in the ark), diseases like measles simply _wouldn’t make it_; they would run their course and become extinct because everybody would be immune before there were new human hosts on the scene to become infected. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [January 18, 2006, 10:10am UTC](https://boards.straightdope.com/t/human-parasites/340463/5 "2006-01-18T10:10:21Z")
> [@Mangetout](#): > > There are plenty of diseases to which humans become immune after the infection has run its course; starting from a population of two (or, for that matter, a population of eight in the ark), diseases like measles simply _wouldn’t make it_; they would run their course and become extinct because everybody would be immune before there were new human hosts on the scene to become infected. Measles is not an obligatory human pathogen. It can infect several of the great apes at the very least. In reality measles itself is simply a slightly mutated form of a normal cow virus. Once again this doesn’t require any stretch to be incorporated into a scenario with only 2 humans 6000 years ago. Just as in relaity it could simply have jumped the species barrier sometime since then. This is why the OP specifically asked for obligatory human parasites, not simply parasites with a single infective window. There was never any need for the first two humans to be acrrying measles, nor would the disiease necesrily be eradicated if the human population were reduced to two. ---
**Author:** ![Fish\_Cheer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fish_cheer/32/17179_2.png) [@Fish\_Cheer](https://boards.straightdope.com/u/Fish_Cheer)\ **Post date:** [January 18, 2006, 10:21am UTC](https://boards.straightdope.com/t/human-parasites/340463/6 "2006-01-18T10:21:15Z")
> [@Tevildo](#): > > A few obvious candidates from the macroscopic world, before we get into the thousands of human-specific bacteria: > > The tapeworms _Taenia saginata, T. asiatica_ and _T. solium_. At least one of these, T. solium, is said to also infect non-human primates. (Warning! PDF File below) [(cite)](http://www.cfsph.iastate.edu/Factsheets/pdfs/taenia.pdf) ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 18, 2006, 10:32am UTC](https://boards.straightdope.com/t/human-parasites/340463/7 "2006-01-18T10:32:57Z")
> [@Blake](#): > > Measles is not an obligatory human pathogen. It can infect several of the great apes at the very least. In reality measles itself is simply a slightly mutated form of a normal cow virus. Once again this doesn’t require any stretch to be incorporated into a scenario with only 2 humans 6000 years ago. Just as in relaity it could simply have jumped the species barrier sometime since then. > > This is why the OP specifically asked for obligatory human parasites, not simply parasites with a single infective window. There was never any need for the first two humans to be acrrying measles, nor would the disiease necesrily be eradicated if the human population were reduced to two. OK, perhaps measles itself was a bad example, but I’m sure there are pathogens (and indeed parasites) that would fall into this category of either killing or rendering immune the pool of hosts faster than they could reproduce.