Tag Archives: africa

Meet the Guinea Worm

Screen Shot 2016-03-14 at 10.48.20 PM.pngGuinea worm disease is caused by a parasitic worm found in stagnant waters of Africa. It has been known since early recorded history with possible mentions in the Bible and a definite reference (along with a treatment method for removing the worm that is still used today) in the Ebers Papyrus, an ancient scroll written around 1500B.C.
Presently, only four countries, Chad, Ethiopia, Mali and South Sudan have reported cases of the disease. The worm, Dracunculus medinesis infects its (human) host through the drinking of unfiltered water inhabited by the larval forms that have been eaten by “water fleas.” When a person drinks water containing these water fleas, the larva are released from their insect host while in the stomach and burrow through the digestive tract into the body cavity where they grow into adult worms. After fertilization, male worms die in the host, but female worms can grow up to 2-3 feet long.

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A section of the Ebers Papyrus

The insidious nature of the beast is the way that it manipulates the host (human) when it is ready to release larvae. At this time, the worm will burrow to the surface of the skin (usually on the foot) where it will cause a blister. When the blister erupts, it causes a painful burning sensation that is somewhat alleviated when immersed in water.

Whenever the blistered area is immersed, the worm will eject a milky liquid containing millions of larvae into the water to repeat the life cycle. During this time, the pain can be disabling and the blisters are easily infected with bacteria.
As the worm emerges, it can be captured and wound around a twig, etc. Pulling the worm will result in a break that worsens the condition, but if attended to, the worm can be removed a bit at a time as it emerges from the blister over the course of days to weeks.
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Since the 1980s eradication of the Guinea Worm has been aggressively pursued by a number of organizations, most notably the Carter Center, founded by President Jimmy Carter. The Carter Center has coordinated the efforts of the Nation Ministries of Health in affected countries, with the World Health Organization, The US Centers for Disease Control and Prevention, and UNICEF. Together, these organizations provide education to at risk populations, water filters, and pumps to obtain uninfected groundwater.
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These efforts have reduced the number of Guinea Worm Disease cases from 3.5 million in 17 countries in1986 to just 22 in four countries in 2015 (provisional total). Importantly, humans are the principal host of Guinea Worms, therefore, if all cases of infection can be eliminated for just one year, this should lead to complete eradication of the organism.

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Posted by on March 14, 2016 in Uncategorized


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An Ebola Question

Olytico-Question-Mark-1024x576I’ve had a question about Ebola posted on the StackExchange Biology page for some time without getting any answers. Basically, I was wondering about how antibody responses to Ebola can drive either sterilizing immunity (the goal) or actually improve the virus’s entry into host cells (a big problem). The idea that Ebola antibodies may be detrimental to the host was first raised by Baize et al, and my question is how this has impacted efforts to develop an effective vaccine. For background, I’ve written about this topic previously.

If anyone knows what the current thinking is in this area, please point them my way.

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Posted by on September 4, 2015 in Uncategorized


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Working Overtime to Prevent Sudden Death

Do you have Ebola? If you're reading this, then probably not.

Do you have Ebola?
If you’re reading this, then probably not.

My cousin, in Philadelphia, tipped me off that I should write a blog article about the current Ebola outbreak that has occurred this year in Western Africa. One of the reasons that this interested him was that the story of the outbreak was being shadowed by another story of a ‘secret’ serum that was being used to treat some of the American victims of the disease. I think ‘Secret’ was the operative word. I had definitely heard about the outbreak, but this was actually the first time that I heard about this serum – and it immediately tipped of my BS / Conspiracy theory detector because of the suggestion that America actually had a secret ‘cure’ for Ebola. It almost begs for allegations by people wearing tinfoil anti-alien hats that America was engineering some Apocalypse Bringing Disease a la I am Legend or Dawn of the Planet of the Apes.

So, I was interested to hear that there actually is a serum to treat Ebola – it’s just not secret, and it’s not an approved treatment, but an experimental one. Ebola VirusFirst, something about the virus…

There is currently no vaccine available for Ebola virus infection and the standard of care remains supportive therapy aimed at maintaining the body’s electrolytes, blood pressure and to prevent / treat additional infections that may otherwise complicate care(1). Coupled with an extraordinarily high fatality rate (up to 90%) and horrifying symptoms including internal and external bleeding, fever and

Western Africa

Western Africa

intense weakness, it remains one of the most feared diseases in the world (2). Ebola is so debilitating and deadly, in fact, that its severity has actually functioned to keep it contained within a relatively small area of western Africa. Most cases tend to occur in and around poor, unsanitary hospitals where virus spreads from a contaminated individual or cadaver to a person (often serving as a healthcare worker). Often cases present with symptoms similar to more common, less lethal diseases and are not quarantined away from other patients leading to a rapid accumulation of nosocomial infections (3). One reason for the high mortality rate associated with Ebola infections may be due to a curious condition in which antibodies against the virus may, ironically, worsen the infection. The mechanism of this behavior appears to operate through the binding of antibody to viral glycoproteins, followed by antibody-mediated phagocytosis of virus by immune cells. This is confounding because it is this process that is utilized by immune cells to destroy viruses and may further impair the ability of researchers to develop an effective vaccine as most vaccines work by promoting antibody development (4). With Ebola, the interaction of a protein on the virus’ surface is bound by antibody, which is then bound by an immune cell that internalizes the virus, but instead of destroying the virus, it manages to escape destruction and infect the cell.

Rather than making you better, antibodies against Ebola may make you worse off.

Rather than making you better, antibodies against Ebola may make you worse off.

To make matters worse, this time around many more people are contracting the disease, so concern is elevated around the world, even some US Congressmen have been making hay about the possibility that undocumented immigrants from Central America may introduce Ebola into the US. Which brings me back to the conspiracy angle. What’s this about a secret serum again?

The serum is actually just an experimental treatment – one that is extremely early in the development process, called ZMapp. This is a product produced by Mapp Biopharmaceutical Inc. that is a combination of three monoclonal antibodies made in tobacco plants (this is a more common method than you might think). The idea being that these antibodies will provide passive protection against Ebola, much like the antibodies produced by a typical vaccine, but -hopefully – without the adverse effects associated with the antibodies that enhance infectivity. Reading the article describing the manufacture of these antibodies does not provide an explanation of how the antibody-mediated enhancement of infection will be evaded, but one may imagine the construction of neutralizing antibodies that lack the constant regions associated with FcR or C1q binding as the binding of these two proteins have been proposed as causing the adverse effect. As this drug lends passive immunity, it may (if effective) prevent infection of an exposed person – or at least lesson the severity of the infection, however it will NOT lead to the accumulation of antibodies by the patient as would a vaccine. Rather, this form of immunity is more akin to treatment with an anti-serum following a snake bite. With luck, a silver lining to this major outbreak may be the opportunity to test an early-stage treatment, possibly resulting in the first ray of hope in improving Ebola survival.

Can I catch this?

Can I catch this?



Posted by on August 7, 2014 in Uncategorized


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Agriculture, emigration, deforestation and Malaria

ImageWhen malaria first began to infect humans is something of a mystery. It was a mystery that I hadn’t thought about much before now because … well, I don’t know, it just never occurred to me.

However, recently a colleague mentioned that there was a connection between it and the beginnings of agriculture. Despite the fact that I should know better, I dismissed the idea out of hand. That’s too recent, I thought. There’s no way that could be the case.

The idea of a connection was originally suggested by Frank Livingstone, who “suggested that Plasmodium falciparum (which is by far the deadliest of the several parasites that cause human malaria) had jumped into Homo sapiens from chimpanzees. He speculated that the rise of agriculture had led to human encroachment on wild forests, giving the chimp version of the bug, P. reichenowi, the chance to find a new host.” 1 

Despite my dismissal, the idea did come back to me late last night and I started to look into what was published on the subject. The first thing I found was one of Scientific American’s 60 second science podcasts on the possible connection between recent deforestation in South America and a resurgence in Malaria.  “Researchers looked at stats for 2006 …[and] compared those cases to deforestation in the same health districts over the previous 10 years. They found that a loss of just four percent of forest cover was associated with nearly 50 percent more malaria cases.”2

As always, correlation isn’t causation, but something is happening, and because Malaria is more common in open areas than forests, causation isn’t much of a stretch. And, if malaria does increase when land is cleared of forest, the connection to the advent of agriculture may not be far fetched at all.

Humans started domesticating animals and farming the land about 10,000 years ago , so we do have a date to shoot for in our estimate. The question is, ‘was malaria widespread prior to ~8000 B.C.E.?”

One way to ask this question was to question whether Malaria was with us before we (humans) left Africa, or more recently. This moves the timeframe back to about 50,000 years ago (a reasonable landmark prior to agriculture). One way to ask this question is to look at diversity of the parasite’s genes. Just as the greatest diversity among humans occurs in Africa with less diverse groups coming out from this population, the same should be true of the microbe.

“The researchers found that genetic diversity did indeed decrease at greater distances from Africa. The correlation is very strong, says lead author Francois Balloux of the MRC Centre for Outbreak Analysis and Modelling in London, and the pattern matches human migration out of Africa, which scientists believe started some 50,000 to 60,000 years ago.”3 ( See here and here

For a visual representation of the genetic argument for the origin of malaria, see the map below:


                                         Genetic Variation of Malaria                                                     (grey dots represent possible sites of origin)

Whether Livingstone’s idea may be correct or not probably has no bearing on the idea that human disease originated in chimps and does nothing to undermine the possibility of a connection between recent outbreaks of disease and clearing land for farms.



1. “The source of malaria” The Economist. Aug 4th 2009.

 2. “Plasmodium falciparum Accompanied the Human Expansion out of Africa “Kazuyuki Tanabe  et al. Current Biology, Volume 20, Issue 14, 1283-1289, 17 June 2010

 3. “When Humans Left Africa, Malaria Came Along” MARTIN ENSERINK. Science Now. 18 June 2010.


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Posted by on January 30, 2014 in Uncategorized


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