In 1923, the son of a German coffee-grower that resided in Chiapas developed a mysterious skin disease. He was taken to Germany, to the Institute of Tropical and Naval Research in Hamburg, where he was diagnosed with onchocerciasis. This was the first news on the existence of the disease in Mexico, an infection caused by millions of microscopic worms (microfilariae) that migrate through the skin and produce reddening and inflammation of the face, reason for which the disease was known as the “mal morado” (purple disease) in Chiapas and Oaxaca. The terrible part of this disease is that the small worms reach the eyes and produce vision disorders that ultimately lead to irreversible blindness and, thereby, misery.
Onchocerca volvulus, the nematode that causes onchocerciasis.
The small worms reach the eyes and produce vision disorders that ultimately lead to irreversible blindness and, thereby, miseryMexico had three endemic areas of the disease: two in Chiapas and one in Oaxaca. All three are mountainous regions with warm weather exuberant vegetation, heavy rains, and narrow rivers - conditions that favor the cultivation of coffee but also the breeding of the fly that transmits the parasitic disease. That is why in Africa, where it mostly affects the impoverished regions of 31 countries, it is known as “river blindness”.
Onchocerciasis is caused by the bite of flies infected with onchocerca microfilariae, that several months later transform into adult worms and form sub-cutaneous painless nodules, mostly in the head, called “balls” by local people.
One of the first doctors that visited an endemic area in Chiapas in 1927, described its inhabitants:
Once the extension and severity of onchocerciasis was known, Mexico initiated an exemplary mobilization to minimize the devastating effects of the infection “Here, the women don’t even cry when they are sad… we find pale, listless people, many of them with goiter, dry skin, flaccid muscles, broken nails, swollen faces… a height of 1 meter 30 centimeters can be considered as acceptable”
Around the same time, another onchocerciasis area was found in Oaxaca “inhabited by people living in wooden huts in the most extreme poverty, with almost no food or domestic animals, almost naked, many of them sick, some bleeding due to vampire bites”.
On September 29 of 2015, the much longed-for announcement was made: onchocerciasis was officially eradicated from Chiapas and OaxacaOnce the extension and severity of onchocerciasis was known, Mexico initiated an exemplary mobilization of medical doctors, biologists, entomologists, epidemiologists and social workers, determined, during several decades, to minimize the devastating effects of the infection. New control measures were adopted and for the first time in the history of tropical diseases, an effective drug named diethylcarbamizine was used. Thousands of onchocerca nodules were eliminated in attempts to reduce parasite transmission; a simple diagnosis test was found; the mechanisms by which the parasites affect the skin and eyes were investigated; with all this, the impact of the disease was greatly reduced and Mexico contributed, as with no other illness, to the control of one of humanity’s “neglected diseases”. Despite these achievements, some years ago there were still an estimated 20,000 cases of onchocerciasis in Mexico and more than half a million of inhabitants in Chiapas and Oaxaca that were at risk of getting infected.
Finally, on September 29 of 2015, after almost 90 years of fighting against the infection, the Ministry of Health and the Panamerican Health Organization made the much longed-for announcement: onchocerciasis was officially eradicated from Chiapas and Oaxaca.
The pharmaceutical industry developed this drug to control worm infections in cattle, because the human market was not attractive enough!Coincidentally, only one week later, the 2015 Nobel Prize in Medicine was awarded to the scientists that discovered ivermectin, the most efficient drug for the control of oncherciasis, and used successfully in Mexico over recent years.
The pharmaceutical industry developed this drug to control worm infections in cattle, because the human market was not attractive enough! In fact, ivermectin has been one of the most successful products in veterinary medicine.
The history of ivermectin starts in 1974 when Satoshi Omura, researcher at the Kitasato Institute in Japan, sent soil samples from a Japanese golf club to Merck, Sharp and Dome laboratories in the USA. There, William C. Campbell found several actinomycetes with potent activity when tested in experimental infections by worms. On top of its potent activity, based on its capacity to kill worms by blocking their chlorine channels, the isolated compound had no toxic effects. It was soon used successfully to clear worms from tens of millions of horses, pigs, sheep and cattle.
In Africa, the onchocerciasis programme of the WHO has managed to control the infection in 40 million people, prevent blindness in 60,000 patients and ensure that 18 million newborns are free from the disease Upon subsequent demonstration of its efficacy in the treatment of human onchocerciasis, Merck laboratories took the unprecedented decision to offer ivermectin for free to all those countries who would require it. Thanks to this, the disease is considered eradicated not only in Mexico but also in Colombia, Ecuador, and soon in Guatemala.
In Africa, the onchocerciasis programme of the WHO has managed to control the infection in 40 million people, prevent blindness in 60,000 patients and ensure that 18 million newborns are free from the disease. In addition, 25 million hectares of abandoned land has been reutilized for agriculture and livestock, producing food for 17 million inhabitants.
For the pharmaceutical industry, most particularly for the veterinary industry, ivermectin has represented profits of over 1000 million dollars a year; for public health, one of last century´s greatest medical accomplishments; and for Satoshi Omura and William C. Campbell, the 2015 Nobel Prize for Medicine!
A happy ending to a 40 year-old story on how to combat a disease that affects the poorest and deprives them of their most precious treasure: their sight.