Worm infections

Overview

Worms can infect human organs and trigger various diseases. There are often no or weak symptoms, with gastrointestinal complaints taking centre stage. Good hygiene and careful handling of food reduce the risk of an infection.

Symptoms

The symptoms of a worm infection depend on the type of worm involved, and differ greatly. Symptoms can be very weak or totally absent, and sometimes they only appear after many years.

Main symptoms

• Stomach ache
• Nausea, vomiting, diarrhoea
• Flu-like symptoms such as fever and fatigue
• Weight loss
  

Other symptoms (depending on the parasite)

• Pinworm infection (oxyuriasis): in community facilities, many people can be infected
  • Anal itching at night, scratch marks and redness at the anus
  • Whitish parasites can be seen in the stool
  • For girls, the vulva and vagina can also be infected (red, itchy)
• Roundworm infection (ascariasis): often there are no symptoms
  • Anal itching
  • Possibly yellowish discolouration of eyes and/or skin
• Trichinella infection (trichinosis)
  • Sore muscles
  • Rarely, fluid retention (oedema) in the face (in particular around the mouth)
• Hookworm infection (ancylostomatidosis)
  • The worms enter the body through the skin (mostly the feet): redness and itching
• Tapeworm infection (taeniasis): often there are no symptoms
  • Whitish worm particles can be seen in the stool
• Pork tapeworm infection:
  • Taeniasis: Infection by tapeworm larvae: often there are no symptoms
  • Cysticercosis: Infection caused by swallowing tapeworm eggs: sore muscles, headaches
• Dog tapeworm infection (cystic echinococcosis): symptoms often only appear after weeks or years
  • Dry coughing, slight shortness of breath
• Fox tapeworm infection (alveolar echinococcosis): symptoms often only appear after months or years
  • Yellowish discolouration of eyes and/or skin
• Fish tapeworm infection (diphyllobothriasis): often there are no symptoms
  • Over time, symptoms of a vitamin B12 deficiency occur because the fish tapeworm absorbs this vitamin from the gut (e.g. fatigue, pale skin due to anaemia)
• Snail worm infection (schistosomiasis or bilharzia): symptoms often only appear after weeks or months
  • Red and itchy skin at the site of entry
  • Sore muscles
  • Water-logged stomach, vomiting of blood
  • Blood in urine, pain when urinating
• Cercaria infection: (cercarial dermatitis, “swimmer’s itch”)
  • Red and itchy skin at the site of entry
  • Mostly noticed after swimming
    

Causes and treatment

Causes

Infections occur according to the type of worm:

• Ingestion of contaminated food
• Use of dirty toilets
• Stroking of infected dogs/foxes
• Swimming in dirty water
  

Further treatment by your doctor / in hospital

Examination and treatment of worm infections depend on the type of infectious agent. Sometimes, worms can't immediately be shown to be the cause of the symptoms. If a child is affected, it’s a good idea to examine the rest of the family too.

Possible tests

• Stool and/or urine test
• Scotch tape test of anal area (in particular for pinworms)
• Blood tests: inflammatory markers, identification of blood components, search for antibodies)
• Removal of small tissue samples (e.g. of muscles, liver) to examine under a microscope
• Ultrasound (sonography)
• X-ray
• CT scan (computed tomography)
• MRI (magnetic resonance imaging)

Possible therapies

• Medication (vermifuges = anthelmintics)
• Strict hygiene measures
• Operation to remove worm cysts (for dog tapeworm, fox tapeworm and the cysticercosis form of the pork tapeworm)
  

What can I do myself?

Before treatment, humans excrete worms, worm particles and eggs. When a worm infection is diagnosed, strict hygiene is therefore very important:

• Carefully wash and disinfect hands after going to the toilet
• Cut long finger nails, or clean nails with a nail brush after going to the toilet
• Regularly clean and disinfect the toilet
• Don't share hand and bath towels with others
• Wash bed linen, hand towels, bath towels and underwear at 95° (boil wash)
  

Prevention

Many worm infections can be prevented with proper hygiene measures and care. A good motto (particularly while travelling), is: “Cook it, boil it, peel it or leave it!” But some everyday tips can also help prevent an infection:

• Make sure that you cook meat and fish of unknown origin very well or freeze it for a long time
• Carefully wash raw vegetables, fruit and berries before eating them
• Wash and disinfect hands after going to the toilet
• Regularly have your pets (in particular cats and dogs) examined for worms, prevent dogs from eating faeces or mice
• Don’t pet or fondle strange animals
• Don't share towels with others
• Find out about the risks of travelling in foreign countries, in particular in the tropics and sub-tropics
  • Take care when eating raw food (cook it, boil it, peel it or leave it!)
  • Buy water in sealed bottles
  • Don’t swim in standing water
    

When to see a doctor?

In particular travellers returning home should have the following symptoms checked by a doctor:

• Weight loss in spite of an unchanged diet
• Whitish coating on stools
• Persistent nausea, vomiting, diarrhoea
• Yellowish discolouration of eyes and/or skin
  

Further information

safetravel - medical advice for travellers
www.safetravel.ch

Synonyms

worm diseases, worm infections, helminthiasis, pinworms, roundworms, tapeworms, trematodes, trichinella, oxyuriasis, ascariasis, ancylostomatidosis, trichinosis, teaniasis, echinococcosis, diphyllobothriasis, schistosomiasis, bilharzia, cercarial dermatitis, swimmer's itch, cercaria