Trichostrongylus species are considered incidental parasites of humans. Trichostrongylus orientalis however is found in humans more often then in other mammals in some countries.

Disease / Pathology

Trichostrongylus species can cause gastrointestinal disturbances when infections are heavy and can be asymptomatic in light infections. Eosinophilia can be present as well as diarrhea that can be severe.

Location in the Host

Trichostrongylus species is found in the small intestine of the host.

Geographic Distribution

Trichostrongylus species are found worldwide but especially in areas where herbivorous animals are raised. They are thought of as being incidental parasites of humans. Unlike Necator and Ancylostoma the infective filariform cannot penetrate the skin but instead they are ingested with grass and will burrow into the intestinal wall.

Life Cycle

Unlike Necator and Ancylostoma the infective filariform of Trichostrongylus species cannot penetrate the skin but instead they are ingested with grass and will burrow into the intestinal wall. Approximately 4 days later they emerge without the migration to the lungs as seen in Necator or Ancylostoma. When it emerges the it inserts its anterior end into the intestinal wall deeply and develops into an adult.

Morphology & Diagnosis

Trichostrongylus species eggs are similar to Necator and Ancylostoma species eggs in that they are thin shelled and clear. However the eggs tend to be more elongated and larger. Eggs are oval-elliptical and measure 87-92 µm by 50-55 µm. Necator and Ancylostoma are more oval/round in shape.

Images

The image above is the of a Trichostrongylus species egg stained with Lugol’s Iodine. These eggs are considerably large and have the dimensions of 87-92 µm in length by 50-55 µm in width. The image is courtesy of the Leiden University Medical Center, The Netherlands.