Enterobiasis (pinworm) and trichuriasis (whipworm)
- Karin Leder, MBBS, FRACP, PhD, MPH, DTMH
Karin Leder, MBBS, FRACP
Enterobiasis (pinworm) and trichuriasis (whipworm)
- Karin Leder, MBBS, FRACP, PhD, MPH, DTMH
Karin Leder, MBBS, FRACP, PhD, MPH, DTMH
- Section Editor — Travel Medicine
- Head of Infectious Diseases Unit
- Monash University, Australia
- Peter F Weller, MD, MACP
Peter F Weller, MD, MACP
- Editor-in-Chief — Infectious Diseases
- Section Editor — Tropical Medicine
- William Bosworth Castle Professor of Medicine
- Harvard Medical School
- Professor of Immunology and Infectious Diseases
- Harvard T. H. Chan School of Public Health
Enterobius vermicularis (pinworm) and Trichuris trichiura (whipworm) are two of the most common nematode infections worldwide.
Enterobiasis occurs in both temperate and tropical climates; it is the most common helminthic infection in the United States and Western Europe. Prevalence estimates suggest there are 40 million infected persons in the United States.
Humans are the only natural host. Infection occurs in all socioeconomic groups; transmission is most efficient when people are living in closed, crowded conditions and is common within families. Enterobiasis is observed most frequently among school children aged 5 to 10 years; it is relatively uncommon in children <2 years old.
Life cycle and transmission — E. vermicularis has a simple life cycle (figure 1). The cycle begins with egg deposition by gravid adult female worms on the perianal folds. Autoinfection occurs by scratching the perianal area and transferring infective eggs to the mouth with contaminated hands. Person-to-person transmission can occur by eating food touched by contaminated hands or by handling contaminated clothes or bed linens. Infection may also be acquired via contact with environmental surfaces (curtains, carpeting) that are contaminated with eggs. In addition, eggs may become airborne, inhaled, and swallowed.
Following ingestion, eggs hatch and release larvae in the small intestine. The adult worms establish themselves in the gastrointestinal tract, mainly in the cecum and appendix. The time interval from ingestion of infective eggs to oviposition by the adult females is about one month. Each female worm can produce 10,000 or more eggs. The life span of the adults is two to three months. Most infected individuals have a few to several hundred adult worms. The worm burden is not distributed evenly among individuals; the one-quarter of the population that is most heavily infected has more than 90 percent of the total worm burden.
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