Students Do the Damndest Things

    Late one night, I received a call from one of those students, many years after he had graduated.  He apologized for calling so late, but urgently needed to hear what opinion I might have concerning a problem with his child.  He complained that his daughter had become infected with Ascaris and he wanted to know how that may have occurred.  We small-talked for awhile, during which I ascertained he was a genetics counselor at a local hospital.  He had bought a small farm in the Pittsburgh area and was practicing organic gardening, raising tomatoes, beans, corn etc. and a few pigs.  He had gotten into the practice of fertilizing his plants with pig manure and wondered aloud if somehow the ascarids his pigs were being treated for could possibly have contaminated his produce and ultimately infected his daughter.  At the time, there was considerable doubt that Ascaris lumbricoides (from humans) and Ascaris suum (from pigs) were infective to the pig or human hosts, respectively, so I suggested that it was improbable, but without any other risk factors, may be the source of his daughter’s infection.  Today, the literature states that cross-infection has occurred and that denticles on the oral lips which distinguish the two species wear down and make identification to species difficult. It is hypothesized that one has likely evolved from the other, each occupying hosts which are quite similar metabolically supporting the contention that his daughter was very likely infected by vegetables contaminated with Ascaris-infected pig manure. 

  Another instance involving a parasitology student occurred in my first year of teaching.  My student assistant brought me a couple of  foot-long, slender, tangled worms in a bottle that she claimed her dog “coughed up”.  Ordinarily, I would not have been able to identify the worms, though they resembled nematodes.  However, I had  finished an in-depth invertebrate zoology course in graduate school a couple of years before and had seen that worm and so could identify it.  I asked my student if she had actually seen her dog cough up the worm.  She said she hadn’t but the dog was standing by the worm watching it wriggle and she naturally assumed the dog was the former owner.  I asked her if there were any insects in the vicinity of the worm.  She sheepishly replied yes, but asked me not to repeat it because her mother was embarrassed over the fact they had cockroaches and certainly did not want Herr Professor to suspect she was untidy.  I poked further and found out that her mother’s clothes washer routinely leaked, leaving a puddle on the basement floor and a cockroach was floating in the water.  The roach was not dead but weakened and sort of broken open. She assumed it had been smashed.   What she had mistaken for a dog nematode was a nematomorphan worm.

      The phylum Nematomorpha is a minor phylum, consisting entirely of worms parasitic in insects, mostly beetles and crickets, both orthopterans, the family to which cockroaches also belong.  These worms are often called horsehair worms since legend in the days of spontaneous generation acceptance, suggested they developed from hairs that fell from the mane of horses into watering troughs where they were often seen.  Water does play a major role in the eruption of the adults from the insect host. The juveniles exist in insects and emerge at maturity when insects enter water.  There is some research to suggest that infected insects are more likely to enter small bodies of water than those which are uninfected.  Once in water, the juveniles emerge from their insect host and quickly finish maturation.  They then become entangled in a “Gordian Knot”, so named after King Gordius of Phrygia who tied an untieable knot only to be outdone by Alexander the Great’s sharp knife.  The entanglement or Gordian knot is simply a copulatory position.  The nematomorphans are often referred to as Gordian worms.