Freethought & Rationalism Archive

nogods4me · 02-20-2002, 07:22 AM

I have seen posted here on a couple of occaisions the name of a particular disease, carried by a particular insect, that affects only humans. It was being used as an example of the cruelty inherent in a god who would create such a thing. I cannot figure out a quick way to do a search, and was hoping someone here might have the info.

liquid · 02-20-2002, 07:28 AM

There are quite a few of them. Malaria for one. It completes part of its life cycle in the mosquito, but doesn't harm it. It can be lethal in humans. I am not aware of it affecting any other species.

Oolon Colluphid · 02-20-2002, 08:03 AM

Ah, that's probably me. It’s one of hundreds of possible examples, of course, but especially nice because of both the agents being specific to us humans.

The organisms in question are the bacterium Rickettsia prowazekii and the human body louse Pediculus humanus. Between them, they cause epidemic typhus.

Here’s the louse:

As <a href="http://entomology.unl.edu/history_bug/typhus.htm" target="_blank">this site</a> says:

Quote:

A louse becomes infected with typhus by taking a blood meal from a fever-ridden human. Once in the louse's gut, the rickettsiae reproduce to such enormous numbers that they cause cells in the insect's gut to rupture. The rickettsiae then are present in the feces of the louse. Humans become infected by rubbing or scratching the lice feces into their skin or into their mucous membranes. It is an interesting disease because even though lice imbibe human blood, the parasite is not transmitted to humans during this process. Most of the other diseases carried by insects are transmitted through the bite.

Once infected, humans experience a high fever that continues for approximately two weeks. Simultaneous symptoms may include severe headaches, bronchial disturbances, and mental confusion. Indeed, typhus is from the Greek word typhos meaning stupor. After approximately six days, red eruptions appear on the torso, hands, feet, and face. Mortality is incredibly high under epidemic conditions, nearing 100%.

According to the US Centres for Disease Control, “throughout history, epidemics of louse-borne typhus have caused more deaths than all the wars combined”.

Being our own louse species, they naturally live only on humans. Infected lice die about two weeks after an infected blood meal, and the disease is not transmitted to their eggs, so the mammalian host -- us -- is essential for the long-term propagation of R prowazeki. In the lingo, we are its only reservoir. They both need us to survive. I’m inclined to use this as an ‘irreducibly complex’ system to throw at IDiots

<a href="http://www.who.int/inf-fs/en/fact162.html" target="_blank">Here</a> is a WHO factsheet on epidemic typhus.

As an intriguing aside, it seems that R prowazekii is related to our mitochondria. See <a href="http://www.nature.com/genomics/papers/r_prowazekii.html" target="_blank">http://www.nature.com/genomics/papers/r_prowazekii.html</a>

Hope that helps. There’s plenty more on the web.

Cheers, Oolon

nogods4me · 02-20-2002, 12:22 PM

thanks Oolon, that was the one I was trying to recall.

02-20-2002, 07:22 AM	#1
nogods4me Contributor Join Date: Jun 2001 Location: Baltimore, MD USA Posts: 17,432	A little help please? I have seen posted here on a couple of occaisions the name of a particular disease, carried by a particular insect, that affects only humans. It was being used as an example of the cruelty inherent in a god who would create such a thing. I cannot figure out a quick way to do a search, and was hoping someone here might have the info.

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02-20-2002, 07:28 AM	#2
liquid Veteran Member Join Date: Jan 2001 Location: UK Posts: 1,440	There are quite a few of them. Malaria for one. It completes part of its life cycle in the mosquito, but doesn't harm it. It can be lethal in humans. I am not aware of it affecting any other species.

02-20-2002, 12:22 PM	#4
nogods4me Contributor Join Date: Jun 2001 Location: Baltimore, MD USA Posts: 17,432	thanks Oolon, that was the one I was trying to recall.

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