I’ve been doing McMaster egg counts since I got reinfected with hookworms, and I’m always curious how many worms I have.
(image from: http://www.flickr.com/photos/prep4md/2772121447/)
The Nottingham dose-ranging trial has a list of quantitative egg counts per dose. According to that chart, 10 and 25 larvae resulted in an average of 100-300 epg. 50 had a higher egg output, as high as 650 epg. This chart states that 50 worms results in an average of 1600 epg. The World Health Organization defines moderate-intensity infections as those with 2,000–3,999 eggs per gram of feces, and heavy-intensity infections as those with 4,000 or more eggs per gram.
This book says one can estimate worm burden roughly by 500 epg per worm, but that doesn’t seem to correspond to these other charts. This study followed a male infected with only 5 hookworms for 18 years! His epg was between 1000-1500 epg.
This study estimates necator by 25 eggs per gram of feces per adult. (www.ajph.org/cgi/reprint/50/6_Pt_1/837.pdf)
I am counting 1050-1200 epg from my recent dose of 10. So I suppose from all of this information, I could estimate that I have at least 5 females. The above information seems very contradictory.
Any parisitologists reading this, could you clarify why there are so many variations in estimates of egg output and population density?
4 Comments
You should consider writing and self-publishing a “how to” book on helminthic therapy. Your personal experience, combined with seemingly extensive knowledge and large amounts of research that you’ve done would be so useful for people who are interesting in experimenting with therapy–and you certainly have an ability to write well. Just this issue of doing worm egg counts from an amateur (assumed non science trained) would be valuable on its own!
The Puerto Rican hookworm study said their count was “low,” and it is a study that is almost 50 years old (since publication). I think that an estimate that is safely conservative is in the low three digits (epg). If it were much lower, then the worm count would be higher, implying a much greater blood loss to the host.
Could you post a link to the Puerto Rican study?
Embryo output varies by diet, drug use, age of worm population and I am certain other factors as yet undetermined. Without having any of the sites or studies you link to, recently, I can say that unless they controlled for each of these factors (which would mean other studies to provide the data to do such controls) they are largely meaningless for someone trying to estimate their small worm population.
With science one has to read critically and consider the problem they were trying to solve and the bias they bring to their research. Most of the research into hookworm has been with their eradication in mind, or on controlling the harm they do in areas where people cannot afford the $2 pill required to clear an infection. As such the studies do not have to provide the precision you seek. They just need to identify the most at-risk individuals so they can focus health and infrastructure resources. Crude measures are all that are required.
You will see a sharp drop off in embryo production around month 12-18 after your initial infection, if the literature I have read is correct. Obviously when studying people in the third world one has no way of determining the age of each individual worm they host, this is just one example of the confounding variables that render this research meaningless for your purposes.
But, you could provide a data set by tracking your embryo out put over the next two years, and by recording your dietary intake and use of OTC and prescription drugs. That would be a very valuable data set, even though based on one individual, for it would identify (possibly) the impact of various drugs and foods on worm health, embryo output. You might also disprove the “truth” that embryo output declines by approximately 50% between 12-18 months post infection. I doubt that such an effect is universal for instance, as we have observed so much variation in every other factor associated with hookworm infection in the 100+ people we have treated so far. No mention is made in any parasitology text I have read, or in any of the studies, either. Which, generally, examine the reactions of at most a few dozen individuals and more commonly just one or two.
Your Crohn’s disease is an adaptation to helminths, so any data you gather will likely only apply to that subset of people with Crohn’s who share your genotype and phenotype, as well as, possibly, various environmental factors. Diet as just one example.
Keep it up, it is energy and determination like yours that changes the world.
Jasper
Post a Comment