Six parasites you need to be aware of in Australia

After the horrifying story of the woman who had a live and wriggling roundworm removed from her brain came to light last month, you may be wondering what other parasites you have to worry about here in Australia.

The Ophidascaris robertsi roundworms are common in carpet pythons. Typically living in the animal’s oesophagus and stomach, their eggs are shed in the python’s faeces.

The 64-year-old woman from southeast New South Wales is believed to have become infected when she collected and cooked a type of native groundcover called Warrigal greens. The greens were likely laced with the parasite shed by a python. Researchers suspected the woman’s other organs, including her lungs and liver, also had larvae in them.

“This is the first-ever human case of Ophidascaris to be described in the world,” infectious diseases expert Dr Sanjaya Senanayake said.

“To our knowledge, this is also the first case to involve the brain of any mammalian species, human or otherwise.

“Normally the larvae are found in small mammals and marsupials, which are eaten by the python, allowing the life cycle to complete itself in the snake.”

Unfortunately, parasitic infections are not uncommon and once parasites establish themselves in the body, they can be notoriously difficult to eliminate. People can become infected with a parasite by eating contaminated food or drinking contaminated water. 

When most people think of food-borne illnesses, their minds often go to harmful bacterial pathogens such as Listeria monocytogenes, which can result in outbreaks of Listeria. This association often brings to mind grocery store recalls of staple items such as packaged salads, herbs, soft cheeses, ice cream and other frozen goods. Bacterial food contamination is the most prevalent cause of foodborne illness outbreaks across the world. However, parasites can do just as much damage.

Parasites can live inside a human digestive tract completely undetected but they can make you very sick too.

Parasites that can affect humans

Giardia

This is one of the most common intestinal parasites in Australia and drinking untreated water is a common route of infection. 

Giardia causes giardiasis, symptoms can vary but often include diarrhoea, abdominal cramps, bloating, gas and nausea. Some individuals may not show any symptoms, while others can experience severe symptoms. Giardiasis is usually a self-limiting illness, meaning it can resolve on its own without treatment in some cases. However, in severe or persistent cases, a healthcare professional may prescribe medication to help eliminate the parasite.

Practise good hygiene and ensure the safety of drinking water and food sources, especially when travelling or in areas with a higher risk of contamination. Boiling or filtering water, washing your hands properly and not drinking untreated water from lakes, rivers or streams are preventative measures.

Cyclospora cayetanensis

This microscopic parasite can cause an intestinal infection (cyclosporiasis) in humans. Contaminated food or water is a common source of transmission

This parasite is unique in that it requires time outside the host (in the environment) to mature before it becomes infectious. Fresh produce is a common source of cyclospora infection when washed or contaiminated with water containing the parasite.

Symptoms of cyclosporiasis include watery diarrhoea, frequent bowel movements, abdominal cramps, bloating, fatigue, and sometimes fever. These symptoms typically begin about a week after exposure to the parasite. Cyclospora infections may last for several weeks, but they are not usually life-threatening.

Pinworms

Pinworms are small, white, thread-like worms that commonly infect the intestines of humans. They cause a condition known as pinworm infection or enterobiasis. 

Pinworm infections are highly contagious and are typically spread through the faecal-oral route. Food handlers who haven’t adequately washed their hands after using the toilet can pass on the infection to customers.

Tapeworms

These usually affect humans who ingest undercooked beef, pork or fish containing the larvae that later grow into full tapeworms inside the host’s intestines. Some common types of tapeworms include the beef tapeworm (Taenia saginata), the pork tapeworm (Taenia solium), and the fish tapeworm (Diphyllobothrium spp.). Each of these tapeworms has a different life cycle and can infect humans who consume undercooked or raw contaminated meat.

Ensure all meat is properly cooked, deworm pets and practise good hand hygiene to prevent tapeworm infections.

Toxoplasma gondii

The parasite Toxoplasma gondii is responsible for the infection toxoplasmosis. People often get the infection from eating undercooked meat. You can also get it from contact with cat faeces. 

Many infected people do not experience noticeable symptoms, especially if their immune system is healthy. When symptoms do occur, they can resemble those of the flu, such as mild fever, muscle aches and fatigue.

Anisakis

This worm can live in poorly prepared sushi or sashimi and be transmitted to a human after eating. Squid and undercooked marine fish such as cod, flounder, haddock and Pacific salmon are also common culprits.

Anisakis can cause a range of symptoms, which typically appear within hours of consuming the infected seafood. Common symptoms include severe abdominal pain, nausea, vomiting and diarrhoea. 

When consuming raw or lightly cooked seafood, such as sushi, be aware of the potential risk of anisakis and choose reputable restaurants and suppliers that follow food safety guidelines.

Common food sources of parasites

Here are some of the most common food sources of parasites:

• undercooked pork
• raw fruits and vegetables
• raw or undercooked freshwater or marine fish
• raw or undercooked crustaceans or mollusks
• raw aquatic plants such as watercress
• unpasteurised cider and milk
• other undercooked or raw meats, such as beef.

A thorough cooking process will kill most parasites. As a general rule, food must reach an internal temperature of 75°C or higher during cooking, though different foods may have different temperature requirements. 

Remember to follow the safe food cooking temperatures of potentially hazardous foods and choose reputable spots to eat. When it comes to sushi or sashimi, meeting the strict time and temperature controls will ensure safety.

How many of these parasites have you heard of? Have you had a run-in with a parasite? Was your health professional able to identify it? Let us know in the comments section below.

Also read: How parasites make us sick

Disclaimer: This article contains general information about health issues and is not advice. For health advice, consult your medical practitioner.