A team of researchers from the University of Melbourne have recently performed a pilot trial on a vaccine that could seriously reduce or eliminate transmission of the parasite that causes neurocyticercosis, Taenia solium.
Taenia solium, or the pork tapeworm is a problem particularly in the developing world where people and pigs live in close proximity and pigs and there isn’t proper sanitation of pig feces. The parasite results in 50 million cases annually with 50,000 deaths from the resulting brain disease.
In the trial, researchers went to Cameroon where almost all pigs are free range and almost half of the pigs do not have adequate latrine.
They initially treated 240 young piglets to eliminate any parasites and then vaccinated half of the piglets to see how effective the vaccine was in preventing reinfection.
The piglets were then distributed in pairs (vaccinated and unvaccinated) to household that keep pigs. After a period of 12-14 months, the piglets were tested for the presence of the tapeworm and live parasites were found in 20 of the control pigs and none of the vaccinated pigs.
Taenia solium is a tapeworm that people get from eating raw or undercooked “measly pork”. The pork meat has cysticerci (the larval stage) which in the human intestine mature to an adult tapeworm. Here the tapeworm attaches to the intestine and produces thousands of eggs.
Most people are asymptomatic and only become aware of the tapeworm by noticing segments of the worm in their feces. Symptoms of infection, if any, are general: nausea, intestinal upset, vague abdominal symptoms such as hunger pains, diarrhea and/or constipation, or chronic indigestion.
Human cysticercosis occurs either by the direct transfer of Taenia solium eggs from the feces of people harboring an adult worm to their own mouth (autoinfection) or to the mouth of another individual, or indirectly by ingestion of food or water contaminated with the eggs.
When the person ingests the eggs, the embryo escape from the shell and penetrates the intestinal wall, gets into the blood vessels, where they spread to muscle, or more seriously, the eyes, heart or brain.
A cysticercus in the eye might lead to blindness, or a cysticercus in the brain (neurocysticercosis) could lead to traumatic neurological damage, epileptic seizures or brain swelling that can kill.
The World Health Organization (WHO) estimates that over half of the world’s population lives in countries where the tapeworm is endemic.