61. Class Nematoda. Enterobius vermicularis. Trichuris trichiura. Trichinella spiralis. Phylum Nemathelminthes. Class Nematoda. Strongiloides stercorolis. Ancylostoma duodenole. Wuchereria bancrofti. Dracunculus medinensis.

Enterobius vermicularis (Pinworm)

Overview and Characteristics

• Known commonly as the pinworm
• Not considered a typical soil-transmitted helminth because its eggs mature on the skin around the anus, not in soil
• Adult females measure about eight to thirteen millimeters in length
• Adult males are smaller, ranging from two to five millimeters

Eggs and Development

• Eggs are transparent and have a slightly asymmetrical shape
• These eggs are both the infective and diagnostic form of the parasite
• After being laid, the larvae inside the eggs become fully developed in about four to six hours

Geographic Distribution and Prevalence

• Found worldwide, especially common in temperate climates
• Infection is more frequent among children in school or preschool settings
• Spread is more likely in crowded environments such as daycare centers or institutions
• Interestingly, it is the most common helminthic infection in places with good sanitation

Life Cycle and Transmission

• Gravid females migrate at night to the area around the anus to lay their eggs directly on the skin
• Self-infection often occurs when contaminated fingers are used to scratch the anal area and then touch the mouth
• Eggs can be transferred from person to person through direct contact or shared surfaces like bedding or clothing
• Eggs can also become airborne and inhaled; once swallowed, they follow the same developmental path as ingested eggs
• After ingestion, the eggs hatch in the small intestine, and the worms mature in the colon
• From ingestion to egg production takes about one month
• Adult worms typically live for two months