Experts are sounding the alarm over the rise of a deadly parasite that, when contracted by humans, can cause fatal liver failure.
Echinococcus multilocularis, also known as the fox tapeworm, mostly lives in wild animals like foxes. However, it can spread if animals or people come into contact with the tapeworm’s eggs, which are present in the feces of those infected.
The parasite enters the body and then multiplies in the liver. In humans, the fox tapeworm can cause an extremely rare liver-related infection known as alveolar echinococcosis (AE) that can lead to liver failure and death.
A group of Swiss scientists have now discovered that cases of the tapeworm caused-infection, though still rare, are increasing by nearly three times.
Additionally, while the parasite was once contained in Europe, China, Japan and Siberia, it is now spreading to regions of Canada and parts of the United States, particularly in the Midwest.
The disease is not reportable in the US, however, which makes it difficult to track and monitor the prevalence. The CDC classifies the infection as a serious public health concern, particularly in areas with high populations of wildlife.
However, data from the University Hospital Zurich shows in 1993, there were about two cases of AE recorded by the institution, while in 2022 – the latest year available – the number jumped to about 14.
Also known as the fox tapeworm, the parasite infects small rodents who unknowingly eat the feces and then multiplies in their livers
Those involved in the study examined medical records of 334 patients who had alveolar echinococcosis were all treated at the University Hospital of Zurich between 1973 and 2022.
Out of the 334 patients, 151 had some type of surgery to remove the parasites while 315 received drug therapy with the medication benzimidazole.
They analyzed patient demographics, symptoms at diagnosis, AE stage, treatment strategy, treatment outcome, survival and causes of death.
Results showed that over the 50-year study period, 90 patients died but mostly from causes other than the parasitic infection.
Only 13 deaths were directly caused by AE.
Survival analyses also showed that those with AE had lower survival rates compared with the general population five years after diagnosis, especially those who were diagnosed with AE later in life.
But, AE did not appear to be the main driver of their shortened life expectancy.
The researchers also found that without benzimidazole therapy, 90 percent of patients died within 10 years of disease onset but with long-term therapy, they were able to prevent a disease from worsening.
They also concluded that removing all of the parasite-damaged tissue in the body through surgery could improve overall survival but could not slow down the disease.
While it remains unclear why, authors of the study speculate that ‘the gradual decline of relative survival five years after diagnosis could reflect a generally sicker population.’
Accidentally ingesting tapeworm eggs often through contaminated food, water or soil, or through direct contact with infected animals can help the parasite enter the human body and begin spreading infection.
AE causes parasitic tumors, primarily in the liver, that can spread to other organs like the lungs and brain in humans
AE causes parasitic tumors, primarily in the liver, that can spread to other organs like the lungs and brain in humans.
While the parasite doesn’t fully mature into cysts, it invades and destroys tissue, leading to liver failure and death.
Symptoms include abdominal pain, jaundice, weight loss and weakness.
According to the CDC, people at high risk include ‘trappers, hunters, veterinarians, or others who have contact with wild foxes, or coyotes, or their stool, or household dogs and cats that have the opportunity to eat wild rodents infected with AE’.
The federal agency also recommends washing and cooking wild-picked foods carefully, keeping pets away from wild animals and their feces as well as maintaining good hand hygiene, especially after contact with animals.