Trichuriasis (whipworm infection): symptoms, diagnosis and treatment

Whipworm is a parasitic roundworm that lives in the large intestine. The MSD Manual consumer version explains that the eggs hatch in the small intestine and release larvae, which travel to the large intestine, mature and embed in the lining. Adult worms are about 4 centimetres long, and each is estimated to live about a year, though some live longer.

The NHS page on worms in humans describes the wider group: some worms can be caught in the UK and others are only caught abroad. It names threadworms as the common UK infection, and roundworm, hookworm and tapeworm as infections usually caught while travelling. Whipworm is another roundworm that belongs with those travel-related infections.

No UK public-health page specific to whipworm was available when this guide was written, so the detail on whipworm comes from the MSD Manual, a US-originated reference, with the NHS page used for UK advice on worms generally.

The MSD Manual says infected people pass whipworm eggs in their stool; in warm, moist soil the eggs mature, and they become infectious after 15 to 30 days. People are infected by swallowing food contaminated with that soil, or by swallowing eggs after contact with soil. Young children, who may put soil in their mouths, are particularly exposed.

The NHS lists general ways of catching worms: touching surfaces with worm eggs on them, touching soil or swallowing water or food with worm eggs in it, which it describes as mainly a risk in parts of the world without modern toilets or sewage systems, and walking barefoot on soil containing worms. For most people living in the UK, the realistic route is exposure during travel or residence abroad.

The MSD Manual says mild infections often cause no symptoms. Severe infections may cause abdominal pain, loss of appetite and diarrhoea, and weight loss, anaemia and protrusion of the rectum through the anus (rectal prolapse) may occur, especially in children.

The NHS says to see a GP if you find a large worm, a piece of worm or worm eggs in your poo, or if you have sickness, diarrhoea or a stomach ache for longer than 2 weeks or are losing weight for no reason. It adds that these infections can take a long time to cause symptoms, so you should tell the GP if you have been abroad in the last 2 years.

• No symptoms at all in light infections.

• Abdominal pain, reduced appetite and diarrhoea in heavier infections.

• Weight loss and tiredness from anaemia in severe cases.

• In children, rectal prolapse can occur with heavy infection.

Diagnosis depends on finding eggs. The MSD Manual says doctors identify them in stool samples examined under a microscope, and occasionally see adult worms during an endoscopic examination of the large intestine, rectum and anus. Blood tests are done to check for anaemia.

The NHS says you might be asked to provide a sample of poo so it can be tested for worm eggs. Mention your travel history so the laboratory and clinician look for the right parasites.

The MSD Manual says whipworm infection is treated with mebendazole, albendazole or ivermectin, taken by mouth. Doctors do not usually prescribe these medicines to pregnant women because they can harm the fetus. People who have been in parts of central Africa where another roundworm, Loa loa, occurs are checked for that infection before ivermectin is given, because ivermectin can cause serious brain inflammation in people with a heavy Loa loa infection.

The NHS general advice for worm infections is that treatment takes 1 to 3 days, people you live with may also need treatment, and that during the weeks after starting treatment you should wash your hands after going to the toilet, before eating or preparing food and regularly during the day. Go back to the GP if symptoms do not improve in 2 weeks or you keep passing live worms.

The MSD Manual says prevention depends on adequate sanitation, particularly sanitary toilet facilities, and good personal hygiene, including washing hands before handling food and avoiding unwashed fruit and vegetables and potentially contaminated water. The NHS advice for high-risk areas is to drink only bottled or boiled water, wash garden-grown fruit and vegetables thoroughly, avoid eating raw fruit and vegetables there and avoid walking barefoot.

A GP can arrange stool testing and prescribe treatment on the NHS. If you have been in a tropical area and have persistent symptoms, a referral to a tropical medicine or infectious diseases clinic is available through NHS services, and private travel clinics offer similar testing; the medicines used are inexpensive, so the main value of specialist input is correct diagnosis.