Volunteers Had 20 Deadly Tropical Parasitic Worms Implanted In Their Arms For Vaccine Trial

Seventeen volunteers in the Netherlands agreed to be purposely infected with deadly tropical parasitic worms. The trial is meant to show that safely infecting volunteers is a far more effective way to test potential vaccines for neglected diseases than finding already infected patients in affected areas.

In September 2016, said volunteers at Leiden University Medical Center in The Netherlands had up to 20 schistosoma mansoni worms implanted into their arms. These parasites can cause the serious condition schistosomiasis, also known as bilharzia or snail fever. The disease can damage the liver, intestine, lungs and bladder.

However, only male worms were used in the study, meaning that the parasites cannot reproduce, lay eggs or cause serious symptoms in volunteers, The Independent reported. In addition, volunteers will be paid the equivalent of $1,200 for their troubles.  

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All of the 17 volunteers went on to show detectable signs of schistosomiasis soon after being exposed to the parasites, such as rash and fever. The volunteers will be constantly monitored until the end of the trial to ensure that the disease does not progress further. At the end of the 12-week trial, all volunteers will be given Praziquantel, a drug that is meant to completely expel the parasite from the human body, Live Science reported.

03_06_worm Individuals in Sub-Saharan African who wade in rivers are at-risk for this parasite. TONY KARUMBA/AFP/Getty Images

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There are two potential vaccines for schistosomiasis that have been approved for human trials, The New York Times reported. However, the 17 volunteers in this study were not given the vaccine prototypes prior to being infected, because this specific trial was not designed to test the vaccine’s effectiveness. Instead, the trial is meant to show that safely infecting healthy volunteers with a parasitic worm may be a cheap and quick way to test vaccines for rare or neglected diseases.

Today, doctors who wish to test out potential vaccines for neglected diseases—illneses that are only found in tropical and subtropical regions—must travel to affiliated areas. Researchers must then search out already infected individuals to gain volunteers for vaccine trials. This method is costly and can take a long time to get accurate results.

Lead researcher of the current study, Meta Roestenberg, an infectious disease physician at Leiden University Medical Center, told The New York Times that she hopes that this trial will prove that purposely infecting volunteers with a parasite is less expensive than traditional methods, and produces results far sooner. This may perhaps usher in a new age of vaccine clinical trials.

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