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STRONGYLOIDIASIS

Pronunciation: Strong-e-loyd-e-asis

Other words: worms, Strongyloides stercoralis

What causes Strongyloidiasis?

In Australia, strongyloidiasis is an infection caused by the nematode (parasitic worm) Strongyloides stercoralis (strong-e-loyd-eez stare-coral-is) invading the small intestine.

Humans are the main reservoir (home) of S. stercoralis. However cats and dogs can also carry the parasite.

Strongyloidiasis was first described in 1876, and is not a Nationally Notifiable Disease.

What does it look like?

Adult worms are 2-3 mm long and around 0.04 mm wide. The larvae (immature adults) are very small, measuring 0.4mm long and 0.02mm wide. The eggs have an extremely sticky outer coat that allows them to be transported on objects. They can survive for 2-4 years in cool, moist areas.

 

Strongloides stercoralis

Strongyloides stercoralis

Australia map

Strongyloidiasis in Australia

Where does it occur?

Strongyloidiasis occurs in all tropical and temperate areas, but is more common in warm wet regions. The disease is also often present in mental institutions where there is poor personal hygiene. The number of cases increases during the wet season.

Australian / Indigenous Significance

This disease is present in Indigenous communities. A survey of 122 Torres Strait Islander and Aboriginal communities found that 52 of the communities were infected with strongyloides.

Treatment programs have been successful in reducing the occurrence of strongyloidiasis in some areas. One example is Mornington Island where infection rates among residents dropped from 26.2% to less than 7% after a treatment program.

Symptoms: What to look out for?

It is common for people to have asymptomatic infections where they do not feel sick.

The infective larvae may cause itchy and flaky skin in areas where they enter the body. As the larvae move through the lungs, coughing or pneumonia may occur.

Chronic infection symptoms may be mild or strong, depending on how heavy the infection is. People may have abdominal pain, diarrhoea, rashes, nausea, vomiting, weakness or constipation (cannot pass faeces).

People with poor immune systems may get liver disease, which can cause jaundice (yellowing of the skin). This is a severe form of strongyloidiasis that is often fatal, and patients may also have severe abdominal pain, diarrhoea (runny tummy), dehydration (excessive water loss from body), fever and shock.

How do you diagnose (confirm) a case?

Strongyloides is diagnosed by finding larvae in stool samples (faeces) using a microscope.

How does it spread?

Human strongyloidiasis infections are most often caused by larvae in contaminated soil burrowing through the skin, and then spreading by the blood system through the body. However, there have been cases of mother to baby transmission through breast milk and medical instruments.

How does it reproduce?

Strongyloides stercoralis has a complex lifecycle. Infective larvae in contaminated soil penetrate a person’s skin, and spread by the blood system through the body, ending up in the lungs.

Larvae then go up the windpipe, enter the gastrointestinal tract, and then stop in the small intestine. Here the larvae become adult females and produce eggs that hatch into non-infective larvae.

Non-infective larvae may then exit the host in faeces (shit) and develop into more infective larvae, or free-living male and female worms in the soil.

Life cycle

Lifecycle of Strongyloides stercoralis

Free-living worms in the soil produce eggs, which hatch into non-infective larvae that later develop into infective larvae (24-36 hours). The infective larvae then infect new hosts.

Sometimes non-infective larvae develop into infective larvae without leaving the host's intestine. The infective larvae may then cause autoinfection by going through the intestinal wall and entering the blood system. This is how long term (chronic) infections occur. Germs that the larvae often carry may cause other infections when the larvae go through the intestine wall.

How infectious is it?

Strongyloidiasis can spread from human to human, and people are infectious as long as worms are in their intestine. People with autoinfections can stay infectious for up to 35 years.

How long does it take for symptoms to appear?

Symptoms can take days, weeks, months or years to appear. It takes 2-4 weeks for non-infective larvae to appear in stool samples.

Who is most at risk?

Anyone can get strongyloidiasis. However, people are more at risk of having severe infections if they have AIDS or other serious illnesses, or if they are on medications that suppress their body’s natural defences.

washing hands

covered footwear

no faeces in water

 

 

How do we prevent it from occurring?

Community education on good personal hygiene practices is essential for reducing the occurrence of strongyloidiasis. Emphasis should be placed on the importance of:

  • Washing hands after going to the toilet, and before handling or eating food
  • Disposing of human faeces in a sanitary way
  • Wearing covered footwear when outside in areas where the disease is endemic (constantly present)
  • Using safe food handling practices
  • Keeping dogs and cats out of areas used for sleeping and eating.

Medical staff should be aware of this condition and always check that a person does not have strongyloides before giving patients medications that will reduce the ability of their body to fight off diseases.

Dogs and cats that are in contact with people should be examined regularly for worms and treated when necessary. Stray animals should be culled after consultation with communities.

Animal living areas should be regularly cleaned, and faeces hygienically collected and disposed of so that it does not contaminate soil.

How can it be controlled?

Faeces samples of household members and close contacts should be collected and tested to find out who else has been infected. Sources of infection like pets should be checked and treated when required.

All cases should be treated with suitable medicines to prevent autoinfection, and treatments may need to be repeated.

Case Study

Observations of Strongyloidiasis in Queensland Aboriginal communities
(Prociv & Luke, 1993)

A study was conducted in the early 1990s to identify where and how often strongyloides infections were occurring in Queensland. The study findings were based on 20 years worth of data that was obtained from the former Aboriginal Health Program (AHP), which was run by the State Health Department of Queensland.

The study was based on children 15 years or younger from 122 Aboriginal and Torres Strait Islander communities. Between 1972 and 1991, 32 145 faecal samples were collected from the study group and examined. Around 1.97% of people were infected with Strongyloides stercoralis, and its larvae were found in 52 of the 122 communities that participated in the program. The parasite did not appear to be present in many of the small southern inland communities. It was noted that the number of infections increased during the summer wet seasons in the northern areas.

Some people with strongyloides infections recovered without the need for treatment. However, others remained infected for more than 4 years. In some areas special medicines were given to treat infections. On Gununa (Mornington Island) this reduced the number of people infected with S. stercoralis from 26.2% to less than 7% of the population.

The study identified that strongyloidiasis is well established in many Aboriginal communities in northeastern Australia, but that the occurrence of this disease could be reduced by the treating children with medications that kill the parasite. This is because children are thought to be the major reservoir of strongyloides infections. Improved community sanitation and hygiene would also assist in reducing the number of infections.

Glossary

Abdomen (abdominal) Barrang, beli, buurrbiyn, dhulmu, kem, kunto, muhh, munto, tidli, yeek, belly area, tummy, gut, middle, or midriff.
Asymptomatic When a person has a disease, but doesn’t feel sick.
Autoinfection When larvae reinfect a person without leaving the body to develop into adults.
Communicable Disease Diseases caused by the transfer of a germ or its toxin (poison) from an infected person, animal or object to a new host.
Constipation When a person cannot pass faeces (birlkthun, gunayi-gu, kudna-rna, kudnatendi, kuma, kun nyiinan, thek, thirraj, or ulheme).
Diarrhoea Watery or liquid faeces, runny tummy, dysentery, runs or trots.
Endemic An area where a particular germ or parasite is constantly present.
Faeces Guna, guni, gunah, gurla, guunang, kuma, kun, kuna, kuuenyuk, ngukin, roo, thaka, excretement, shit or stools.
Host A person or animal that can become infected with a germ or parasite.
Infection When germs or parasites enter the body of a host and start multiplying.
Intestine Gut, organ located in the tummy.
Jaundice Yellowing of the skin caused by a disease, also called sallowness or yellows.
Larvae Immature worms that may or may not develop into adults, depends on host type.
Nausea When a person feels like they are going to throw up, anteweke-antewe-irreme.
Nematodes Worms of a particular group, some which may be parasitic and cause disease.
Parasite Plants or animals that may be extremely small (single cell) or very large (1m worms), which need another plant or animal to live. Animal parasites include protozoa, worms, mites and lice.
Pneumonia Swelling of the lungs.
Reservoir The main source of a germ in the environment where it lives and multiplies. May be soil, water, plants, animals or combination of these.
Stool Sample A sample of faeces that is taken to check for signs of disease.

 

Resources

For more information
click on these websites

Community Education Flyer to print out
Available at: iceh.uws.edu.au/fact_sheets/strong_flyer.pdf
[1 page sheet for community information, 102KB PDF file]

Chin, J. (ed) 2000, Control of Communicable Disease Manual, 17th edn, American Public Health Association, Washington DC, pp. 39-43.
[Book on infectious diseases that is often referred to by health departments (technical language)]

Despommier, D.D., Gwadz, R.W., Hotez, P.J. 1995, Parasitic Diseases, 3rd edn, Springer-Verlag, New York, pp. 151-159.
[Book on diseases caused by parasites (technical language)]

Fact Sheet: Parasitic Roundworm Diseases, 2001. NIAID, United States. Available at: www.niaid.nih.gov/factsheets/roundwor.htm
[American fact sheet on worm diseases, good for community members]

Fernando, R.L., Fernando, S.E. & Leong, A.S.Y. 2001, Tropical Infectious Diseases: Epidemiology, Investigation, Diagnosis and Management, Greenwich Medical Media Ltd, London, pp. 279-289.
[Book that focuses on infectious diseases in Australia (technical language)]

Fisher, D. McCarry, F & Currie, B. 1993, ‘Strongyloidiasis in the Northern Territory. Under-recognised and under-treated?’, Medical Journal of Australia, Vol 159, pp. 636-637.
[Journal article on strongyloidiasis in Northern Territory (technical language)]

Griffiths, O. & Henderson, H. 1997, Environmental Health for Aboriginal Communities: A Training Manual for Environmental Health Workers, Office of Aboriginal Health, East Perth, pp. 16-28.
[Training manual for Environmental Health Workers in Western Australia]

Grove, D.I. 1993, ‘Worms in Australia’, Medical Journal of Australia, Vol 159, pp. 464-466.
[Article on various worm related diseases that occur in Australia (technical)]

Lloyd, S. 1998, ‘Strongyloidiasis’, in Zoonoses, eds S.R. Palmer, Lord Souls by & D.I.H. Simpson, Oxford University Press, New York.
[Book on diseases that spread from animals to humans (technical language)]

McCarthy, J.A. & Garrow, S.C. 2002, ‘Parasite elimination programs: at home and away’, Medical Journal of Australia, Vol. 176, pp. 456-457.
[Journal article on parasite control programs in Australia (technical language)]

Porciv, P. & Luke, R. 1993, ‘Observations on strongyloidiasis in Queensland Aboriginal communities’, Medical Journal of Australia, Vol 158, pp. 160-163.
[Journal article on strongyloidiasis in Queensland (contains technical language)].

Thielberger, N. & McGregor, W. 1994, Macquarie Aboriginal Words: a dictionary of words from Australian Aboriginal and Torres Strait Islander languages, Macquarie Library Pty Ltd, NSW.

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Created October 2003
by Margaret Davidson

copyright UWS 2003
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