Intestinal worms are common parasites that can affect humans, ranging from the well-known threadworm to less common tapeworms and hookworms. These organisms thrive by living within a host, drawing nourishment from them. In Australia, threadworms are the most prevalent, often causing an uncomfortable itchy bottom and visible redness or scratch marks around the anus. Understanding how these infections are contracted, their symptoms, and how they are diagnosed and treated is crucial for maintaining health. While many worm infections are easily managed with medication, some, like hydatid disease, can pose serious health risks if left untreated.
Types of Intestinal Worms and Their Symptoms
Several types of worms can infect humans, each with distinct characteristics and potential symptoms.
Threadworms (Enterobius vermicularis)
The most common worm infection in Australia, threadworms are characterized by intense itching around the anus, particularly at night. This itching occurs as the adult female worms lay eggs in the folds of skin surrounding the anus. These tiny, white, thread-like worms, measuring 2-13 mm in length, may even be visible to the naked eye or with a torch. In children, threadworm infections can also lead to irritability, disrupted sleep, poor appetite, and visible redness and scratch marks around the bottom.
Other Worm Infections
Other intestinal worms, including various species of tapeworms, whipworms, hookworms, and Strongyloides, may not always present with noticeable symptoms. However, when symptoms do occur, they can be varied and include diarrhea, fatigue, abdominal pain, weight loss, and anemia.
Larvae of certain worms, such as dog hookworm (Ancylostoma caninum) or Strongyloides, can migrate beneath the skin after penetrating it. This migration can cause diagnostic pink or red, curving tracks known as larva migrans or larva currens, often accompanied by intense itching and a tingling or prickling sensation.
Transmission and Prevention of Worm Infections
Understanding how worm infections are transmitted is key to effective prevention.
Threadworm Transmission
Threadworms are primarily acquired through ingesting their microscopic eggs. Humans are the exclusive host for threadworms. Adult worms reside in the lower intestine and emerge from the anus at night to lay eggs. Children can inadvertently transfer these eggs to their fingernails when scratching an itchy bottom, leading to the spread of eggs through bed linens, bathroom surfaces, and even food. These eggs can remain viable on surfaces for up to two weeks.
Transmission of Other Worms
Many other worm types enter the human body when their larvae penetrate the skin, often through bare feet. Dog hookworms are commonly contracted this way, particularly in areas where people walk barefoot on soil or sand contaminated with infected dog feces. Strongyloides, a type of roundworm, also infects humans through skin penetration.
Pork tapeworm (Taenia solium) and beef tapeworm (Taenia saginata) are typically acquired by consuming undercooked meat containing tapeworm larvae cysts. These infections are rare in Australia and usually associated with overseas travel. Dog tapeworms (Echinococcus granulosus) can infect humans who accidentally ingest eggs shed in the feces of infected dogs or dingoes. These eggs can contaminate a dog’s coat, living areas, and public spaces, and even casual contact with an infected dog can lead to transmission. Dog tapeworm infection can result in a serious condition known as hydatid disease.
Dwarf tapeworms (Hymenolepis nana) are ingested through their eggs, and transmission can occur between people in areas with poor sanitation. Whipworm (Trichuris trichiura) infection results from ingesting eggs from contaminated soil, often through contact or by consuming food grown in such soil. Dog and cat roundworms can cause toxocariasis, which may manifest as fever, cough, abdominal pain, and eye damage in some individuals. Ascaris infection, more common in tropical regions, can cause abdominal discomfort or pain and is contracted by consuming soil containing Ascaris eggs.
Diagnosis of Intestinal Worms
Diagnosing intestinal worm infections typically involves laboratory examination of samples.
Diagnosing Threadworms
A “sticky tape test” is commonly used to diagnose threadworms. First thing in the morning, special sticky tape is pressed onto the skin around the anus to collect any eggs laid overnight. A doctor or laboratory technician then examines the tape under a microscope for the presence of these eggs.
Diagnosing Other Worms
For other types of intestinal worms, diagnosis usually involves examining a fresh stool sample. This can reveal worm segments, eggs, or larvae. Dog hookworm can sometimes be identified from a gut biopsy specimen, and the characteristic rash of larva migrans on the skin is also indicative of this infection. If the rash migrates rapidly (2-10 cm per hour), it is termed larva currens and suggests Strongyloides infection. Certain parasitic infections, including Strongyloides, can also lead to eosinophilia, an increase in eosinophils, a type of white blood cell.
Visual Identification of Intestinal Worms
Intestinal worms and their larvae vary significantly in appearance and size.
- Threadworms: Small, white, moving threads, typically 2-13 mm long.
- Strongyloides: Microscopic larvae mature into 2-3 mm long worms.
- Dog Hookworm: Adult worms are 12-15 mm long, J-shaped with a large, toothed mouth. Eggs are microscopic.
- Dog Tapeworm: Around 6 mm long with 3-4 segments.
- Pork and Beef Tapeworms: Large, flat, ribbon-like. Adult pork tapeworms can reach 2-7 meters, while beef tapeworms can grow 4-12 meters long. They have a head, neck, and numerous segments containing eggs.
- Dwarf Tapeworms: 2-4 cm long and 1 mm wide.
- Whipworms: Adult worms are approximately 4 cm long, with a broad end and a thin, whip-like end.
Treatment for Worm Infections
Treatment for intestinal worm infections typically involves medication to eliminate the parasites.
Treating Threadworms
Worming tablets, available over-the-counter at pharmacies, are the standard treatment for threadworms. It is essential that all household members are treated simultaneously, even if they show no symptoms, to prevent reinfestation. Strict hygiene practices should also be observed during treatment.
Treating Other Worm Infections
Other intestinal worm infections are treated with specific medications that are effective against the parasite without harming the host. A doctor or gastroenterologist can advise on the most appropriate medication and dosage. In most cases, the dead or expelled worms will pass out of the body naturally.
Hydatid disease, caused by dog tapeworm infection, is a severe and potentially fatal condition. It can lead to the formation of cysts in organs such as the liver, lungs, spleen, kidneys, and occasionally the brain. Surgical removal of these cysts, along with medical treatment, is often required.
Preventing and Managing Worm Infections in Children
Children with treated worm infections can generally attend daycare or school, provided they do not have loose bowel movements.
The most effective way to prevent threadworm infection is through good hand hygiene and keeping fingernails short. For other worm infections, which are more common in rural and remote areas or among travelers returning from overseas, several preventive measures are recommended:
- Thoroughly wash hands after gardening and before eating, drinking, or smoking.
- Always wash fruits and vegetables before consumption.
- Ensure beef and pork are cooked thoroughly.
- Wear shoes when walking on moist, sandy soil or soil that may be contaminated with animal feces.
When caring for dogs, it is important to:
- Wash hands after handling dogs.
- Prevent dogs from feeding on dead animals or wild prey.
- Avoid feeding offal to dogs.
- Ensure dogs are regularly dewormed with appropriate medication.
