Pinworm vs Hookworm: What’s The Difference?

pinworms vs hookworms featured image

Pinworm and hookworm are two types of worms that can infect humans and animals. You’ll want to avoid both but, what are the differences between pinworms vs hookworms?

In this article, we’ll explain in depth the similarities and the key differences about these animal and human parasites.

Key Takeaways:

  • Pinworms are a type of roundworm that live in the digestive tract and lay their eggs on the skin around the anus.
  • When the infected person scratches this area of itchy skin, the eggs can be transferred via their nails to other surfaces, leading to further infection.
  • Hookworms live in soil and enter the body through the skin, attaching themselves to the intestinal wall. This type of worm can cause serious infections if left untreated.

To prevent infections from both the pinworm and hookworm parasites, proper hygiene and sanitation practices should be followed, including washing your hands regularly and avoiding contact with contaminated soil. 

What’s the Difference Between Pinworms (Roundworms) and Hookworms?

There are a number of differences between pinworms and hookworms including:

  • Pinworms, can move freely within their host’s intestines, while hookworms stay “hooked” on to the host’s intestinal wall.
  • Pinworms are the most common worm infection in the United States and affect over 1 billion people worldwide, while the CDC estimates 576-740 million people globally are infected by hookworm.
  • Symptoms may vary between both worms. Itching and a localized, raised and red rash is a symptom when hookworm larvae penetrate the skin. In pinworms or roundworms, the itching is usually limited to the anus.
  • Hookworms can range anywhere from 5-15mm in length. Pinworms can be anywhere from 6-13mm.
  • The route of entry varies: Hookworms burrow and penetrate the skin, while roundworms can only enter through the mouth
  • Hookworms can be a more serious infection than pinworms as they feed on hosts blood and fatalities from hookworm infection is much higher than that of pinworms.

Similarities Between Pinworms and Hookworms

  • Pinworms and Hookworms are species of “roundworm”
  • Both types of worm infections can use a human host and infect pets like cats and dogs.
  • Both are parasites and the cause of common parasitic infection in their hosts.
  • Both live in the intestines of animals and humans. (hookworms attach to the walls)
  • Both are nematode species
  • Both types of worms in humans can be treated by over-the-counter medication like Mebendazole (brand names: Vermox/Ovex) [1] 
  • Both hookworm infection and roundworm infections (pinworms) in animals can be treated with medication such as Pyrantel Pamoate (brand names: Nemex or Nemex 2) with at least a 99.5% success rate [2]
  • Both worms look similar to the naked eye
  • Both worms lay eggs which come out of the host in their feces

What are Pinworms?

Pinworms are a type of roundworm infection that affects the intestines.

They are small, white, and threadlike parasites that live in the colon and rectum.

Pinworm infections are most common in children, but can affect people of all ages.

The female pinworm lays her eggs around the anus – which causes intense itching.

Their eggs are usually transmitted through:

  • contaminated surfaces
  • clothing
  • bedding 

There may even be an unlikely possibility that water contaminated by pinworm eggs may also spread infection, but this would be very rare. 

pinworm very close up microscope

What Is a Pinworm Infection?

A pinworm infection, also known as a threadworm infection in the United Kingdom, Australia and New Zealand, is a common parasitic infection that affects the intestinal tract. 

It is caused by pinworms, which are small, thread-like worms that reside in the intestines and lay eggs around the anus.

The infection is commonly transmitted through contact with contaminated surfaces or accidental ingestion of eggs through the mouth. 

Symptoms include:

  • itching
  • discomfort
  • occasional disturbed sleep due to discomfort and itchiness 

Treatment for Pinworm Infection

Proper hygiene and medication can effectively treat and prevent pinworm infections. 

Roundworms (including Pinworms) in humans can be treated by over-the-counter medication like Mebendazole (brand names: Vermox/Ovex).

In animals, the infection can be treated successfully with medication such as Pyrantel Pamoate (brand names: Nemex or Nemex 2).

Are Pinworms the Same as Threadworms?

Pinworms and threadworms are referencing the same parasitic worm.

The name used for the worm will depends on the different part of the world the worms are being referenced.

In the United States, the worm is known as a pinworm.

In the United Kingdom, New Zealand and Australia, they’re generally called threadworms.

They mean the same thing and both are considered roundworms (or nematodes). 

What is a Hookworm?

A hookworm is a parasitic worm that infects humans and animals, like dogs and cats. 

They are most common in warm, tropical and humid regions where they are able to contaminate soil with their hookworm eggs.

The life-cycle of a hookworm starts in the egg stage, hatching into the larvae stage which latches onto human or an animal’s skin when they come into contact with any contaminated soil. 

Once the hookworm larva has attached itself, it can penetrate the skin where the larva enters, at which point they’ll make their way into their host’s bloodstream. 

From there, the larvae will travel to the lungs and eventually, they’re coughed up and swallowed by the host, which helps the hookworm continue its journey to the hosts’s small intestine where it can attach itself to the intestinal wall and feed. 

This is where they grow and mature into adult worms. 

hookworm lifecycle diagram

Hookworm larvae can also enter a host if they accidentally ingest contaminated soil (pet owners should be especially careful and keep an eye on what their pets are up to), or if your hands which are  contaminated with hookworm eggs are unwittingly put near your mouth.

Washing hands thoroughly will help prevent the transmit of hookworm larvae into humans and eventually, human intestines.   

A person with a light hookworm infection might not present any symptoms. 

But, despite being small in size, hookworms can cause a range of symptoms and health problems (sometimes serious) in infected individuals like:

  • Itching and localized rash when the larvae initially penetrate the skin. 
  • A person with a heavy infection may experience:
  • abdominal pain
  • diarrhea or loose stool
  • weight loss
  • fatigue
  • loss of appetite
  • anemia (serious infections)

As mentioned earlier in our article, infection is curable and there is effective treatment available that your doctor can prescribe (or even over the counter), but prevention is always the best cure!

What Do Hookworms Look Like Compared to Pinworms?

Both the pinworms and hookworms can look very similar, even under a microscope. 

Their ranges in length crosses over in both species, depending on the gender of the worm (males being around half the length in both worms). 

Hookworm Image Under the Microscope

It’s rare you’ll ever see an adult hookworm, as they rarely come out in a stool sample because of their life cycle.

So, if you do find worm-like segments in your feces, then it’s unlikely to be hookworms. 

Here’s what they look like under a microscope:

Hookworm under a microscope

Pinworm Image Under the Microscope

The pinworm will have a thinner, more delicate appearance and is usually white and small. 

pinworm under a microscope

What Do Pinworms Look Like to the Eye?

One difference is that pinworms are normally visible to the naked eye as they can be seen near the anus or in stools. 

pinworms in stool

Pinworms can look very similar to beansprouts.

In fact, there was a fairly amusing study done where a patient presented with what they thought was a pinworm infection.

Only for it to turn out that it was partially digested beansprouts they were seeing in their stool. [3]

If you want a video representation of what they look like alive and inside their host, this video will do the trick if you have a strong stomach: 

What is the Difference Between a Roundworm and a Pinworm?

A pinworm (or threadworms) are species of roundworm.

Roundworms are a group of worms which are known as “ascarids”.

They include different worm types that also include hookworms, and whipworm species.

Roundworms do not include tapeworm species – we’ve posted about the differences between tapeworms and pinworms – which are much longer and belong the phylum “Platyhelminthes” (flatworms). 

Our resident vet has also discussed flatworms and whether they are harmful to dogs at length for any curious pet owners.

What are the Similarities Between Roundworm and Hookworm?

The hookworm is a species of roundworm. 

While the hookworm is considered a roundworm, there are many sub-species of roundworms, including the pinworm (however, roundworms are different to earthworms)

Roundworm eggs live in infected soil and usually get their from animal feces. The eggs contain roundworm parasites that must live inside the body of their host.

You can learn more about how long roundworms live outside the body if you’re curious.



[2] Ridley RK, Terhune KS, Granstrom DE. The efficacy of pyrantel pamoate against ascarids and hookworms in cats. Vet Res Commun. 1991;15(1):37-44. doi: 10.1007/BF00497788. PMID: 2048286.

[3] Leung FH, Watson W. The parasite that wasn’t: a case of mistaken identity. Can Fam Physician. 2011 Oct;57(10):1145-7. PMID: 21998230; PMCID: PMC3192079.