Researchers have uncovered a parasite that has been infecting San Miguel Island foxes (Urocyon littoralis), one of smallest fox species in the world. This causes the fox to almost go extinct.
The parasite is newly detected and described. It is a acanthocephalan parasite, thought to have become exacerbated by a prolonged drought occurring in 2018.
The investigation, run by scientists based at Florida Atlantic University, employed morphological and molecular methods, alongside necropsy records, to identify the parasite and assess its health impacts on the foxes.
The parasite has been named as Pachysentis canicola, a type of acanthocephalan (spiny-headed worms) that infects multiple carnivore species in mainland North America. The parasite was detected in 69 percent of the necropsied foxes from San Miguel Island although it was not found in any of the other five Channel Island fox subspecies.
The parasite causes intestinal damage and inflammation, as seen in 47 percent of the infected foxes.
The reason for focusing on P. canicola is because other parasites did not significantly impact the health or survival rates of San Miguel Island foxes.
A study of rainfall enabled the researchers to draw a connection between the acanthocephalan outbreak and environmental factors upon fox populations.
According to Ale Aleuy, assistant professor in the FAU Department of Biological Sciences within the Charles E. Schmidt College of Science: “We suspect that this parasite likely arrived on the island through infected arthropods such as insects inadvertently transported by humans.”
Aleuy adds: “This discovery raises concerns about the impact of human activity on isolated ecosystems and underscores the importance of monitoring parasitic infections in vulnerable wildlife populations.”
The scientists used detailed fox capture-recapture data from 4,269 captures of 846 foxes to investigate population health and demographic trends of foxes before and after the parasite was detected.
After this, they analysed and monitored changes in body condition and weight from 2006 to 2022. Before the acanthocephalan arrived, the foxes had good health and low mortality despite other parasites.
Aleuy steps back in: “This parasite attaches to the intestinal wall of its host, which is particularly problematic for heavily infected foxes that exhibited more significant health issues such as emaciation, enteritis, and in some cases, death.”
Going forwards, implementing appropriate management strategies is crucial to ensuring the health and longevity of this species of fox.
The study appears in the journal International Journal for Parasitology, titled “The invasive acanthocephalan parasite Pachysentis canicola is associated with a declining endemic island fox population on San Miguel Island.”
