Young men often do dangerous things, extreme sports for example. It’s less common for eating something to be the concern. Paragonimus kellicotti was first named as a species in 1908. However, P. kellicotti wasn’t known in most corners until it gained some notoriety in the 2000s when paragonimiasis cases began to be more commonly described among intoxicated young men who ate raw crayfish during ‘float trips’ down creeks or rivers in Missouri, USA. The unique risk factors attracted some brief attention, but case reports are still relatively rare. Yet, the disease appears to be more common than the lack of case descriptions would indicate.

Unfortunately, there haven’t been large scale serosurveys in humans or animals to date – we don’t really have a good idea of what areas are most at risk aside from the areas where cases have been reported. In addition, the true spectrum of clinical disease isn’t clear. We know that patients have been reported to have severe lung disease and even meningitis due to P. kellicotti. But can infections be asymptomatic or mildly symptomatic? It’s likely that this could occur but this entity hasn’t been extensively documented. We need more information on the true distribution and incidence of human (and/or veterinary) disease due to P. kellicotti. That lack of information serves to limit suspicion among clinicians in many areas and may cause missed diagnoses and further hampers both our understanding of the disease, and the care of patients that might have been infected with P. kellicotti.

Scientific knowledge about the parasite however has improved in recent years in some ways. Currently, there are no commercial diagnostic tests available for P. kellicotti though one is being developed. Thus, if a clinician suspects P. kellicotti, they either contact the CDC or a research lab at Washington University in St. Louis to inquire about diagnostic testing– or just treat the patient, assuming it is P. kellicotti that is harming their patient. This limits our understanding of what P. kellicotti does to humans and also exposes patients to potential side effects of treatments that may not have truly been needed. Researchers have worked diligently to match genetic information to proteins that have potential for use as targets for diagnostic tests. These exciting advances could eventually lead to a rapid and accurate test for paragonimiasis in North America. In the meantime, diagnosis of this condition in North America relies on high clinician suspicion and rapid communication with the laboratories that can do testing if indicated.

The paper “A clinical review of human disease due to Paragonimus kellicotti in North America“, by Brianna Coogle, Samuel Sosland and Nathan C. Bahr, published in Parasitology, is available free for a month.