Parasitic worms are organisms that can live and replicate in the gastrointestinal system. These soil-transmitted helminths (hookworms, roundworms, whipworms) are transmitted through the fecal-oral route as a result of poor sanitary practices. The most common infections that can affect travellers are Ascariasis, Hookworm, and Trichuriasis which are Neglected Tropical Diseases (NTDs)*.
* Neglected Tropical Diseases are chronic infections that are typically endemic in low income countries. They prevent affected adults and children from going to school, working, or fully participating in community life, contributing to stigma and the cycle of poverty.
Travellers can get ill when worm eggs are ingested by:
Ascariasis: The infection is caused by Ascaris lumbricoides roundworms and is typically found in tropical and sub-tropical areas. Persons with light infections may not exhibit any symptoms. Those who develop symptoms start with a persistent cough, wheezing, shortness within 1 week of exposure as a result of larvae migrating to the lungs and throat. The second set of symptoms, including abdominal pain, nausea, vomiting, diarrhea, bloody or worm in stools, fatigue, weight loss appear a few weeks (up to 2 or 3 months) later as the roundworms become adults and the females lay eggs which are shed through feces. The parasite can live in humans for up to 2 years. Children are particularly affected by this illness because they tend to play in and eat dirt. Treatment includes taking anthelmintic drugs.
Hookworm | Ancyclostomiasis: This intestinal infection is primarily caused by Necator americanus, followed by Ancylostoma duodenale, and to a lesser extent by Ancylostoma ceylanicum nematodes typically found in tropical and sub-tropical areas. Persons with light infections may not exhibit any symptoms. Those who develop symptoms first get a skin rash where the larvae penetrate the skin. Abdominal pain, diarrhea, loss of appetite, weight loss, and fatigue occur as the migrated larvae grow into adults and mate in the gastrointestinal system. The eggs produced by the females are shed through feces. Note that the Ancylostoma duodenale hookworm can also be acquired by ingesting soil or sand through dirty hands or unwashed fruits and vegetables. A typical sign of this infection is anemia (iron deficiency). Treatment includes taking anthelmintic drugs.
Trichuriasis: The infection in humans is caused by the Trichuris trichuria whipworm and occurs worldwide, especially in areas with lack of proper sewage disposal. Persons with light infections may not exhibit any symptoms. Those who exhibit symptoms have diarrhea, containing blood, mucous, and water as a result of the swallowed eggs hatching in the caecum (the pouch-like area of the large intestine) followed by the larvae migrating to the lining the colon to grow into adulthood and mate. The eggs produced by the females are shed through feces. Severe cases include abdominal pain, chronic diarrhea, and rectal prolapse. Whipworms can live in humans for years. Children are particularly affected by this illness because they tend to play in and eat dirt. Treatment includes taking anthelmintic drugs.
Information last updated: February 23, 2021.