ICEH Resources Information Sheet
Pronunciation: Hook-wormOther words: Worms, Ancylostomiasis, Uncinariasis, Necatoriasis
What causes Hookworm?
Hookworm is a common, chronic (long-term) parasitic infection that is caused by the worms Necator americanus (Ne-kay-tor a-mare-e-caan-us) and Ancylostoma duodenale (An-cy-clo-stoma duo-dean-al). Only A. duodenale occurs in Australia.
Humans are the
main reservoir (source) of N. americanus and A. duodenale,
and it is estimated that around 20% of the world population carries
this parasite. Hookworm is not a Nationally Notifiable Disease.
A. duodenale larvae and egg
What does it look like?
Adult females (A. duodenale) are 10-30mm long and 0.6mm wide, and males are 8-11mm long and 0.45mm wide. Eggs are 0.06mm x 0.04mm in size, and can only be seen with a microscope. The same is true with larvae (immature worms).
Hookworm in Australia
Where does it occur?
endemic (constantly occurs) in many tropical and subtropical areas,
especially when human faeces (shit) is not disposed of in a sanitary
Australian / Indigenous Significance
It has been reported that hookworm infections (A. duodenale) are still common in northern Australian communities, particularly amongst Indigenous Australians.
Hookworm infections are a common cause of anaemia and iron deficiency in Aboriginal women and children.
Symptoms: What to look out for?
Symptoms usually vary according to the severity of infection. It is common for people with light infections to be asymptomatic (not feel sick). Heavy infections may cause a person to become anaemic (pale and weak) due to worms feeding on the host’s blood. Other symptoms include fever, abdominal pain, weight loss, constipation (unable to pass faeces), or diarrhoea (runny tummy).
Chronic infections in children may slow growth and thinking ability, and may cause a potbelly appearance.
Occasionally coughing and upper respiratory tract infections may occur from the worms moving through the lungs. Death rarely occurs from infection.
How do you diagnose (confirm) a case?
Cases of hookworm are diagnosed by finding eggs in stool samples (faeces) using a microscope. However, no eggs may be present in the early stages of infection, and other tests like blood examination and endoscopy may need to be done to check for hookworm.
How does it spread?
People can become
infected with hookworm by walking bare foot on soil that contains
infective larvae. Other infection routes include drinking water
or eating food contaminated with larvae. Cases of mother to baby
transfer of the hookworm A. duodenale have also been reported.
How does it reproduce?
Hookworm eggs are deposited on the ground in faeces, and will hatch into non-infective larvae if the right soil type, water quantity, and temperature are present.
The larvae take 7-10 days to become infective, and can then penetrate human skin (usually the foot). Itchy skin or ground itch occurs where the larvae penetrate the skin.
On entry, the larvae make their way to the lungs by the blood and immune systems. Then they are coughed up and swallowed into the digestive system. The larvae attach to the small intestine wall by hooks, and develop into adults (6-7 weeks). Adults produce 15 000 to 20 000 eggs a day which exit in the faeces.
How infectious is it?
Hookworm is not transmitted from person to person. Infected people can contaminate soil for several years if the right conditions are present. Larvae can survive in dirt for several weeks but do not survive in clay, dry or hard packed soils, or in temperatures that are freezing or higher than 45ºC.
How long does it take for symptoms to appear?
take weeks or months to develop depending on the severity of infection,
and the amount of iron in an infected person’s diet. Ancylostoma
duodenale can stay dormant in the body for 8 months.
Who is most at risk?
Anyone can get hookworm. However, agricultural workers in endemic areas have a higher risk of being infected. The illness can be more serious in babies, children, pregnant women and people with poor diets.
How do we prevent it from occurring?
Public education on the dangers associated with dirt contaminated with human, dog or cat faeces can help reduce the number of cases of hookworm infection. Education programs should highlight the importance of:
How can it be controlled?
Cases of hookworm should be reported to the local health clinic or authority. Faeces samples of household members and close contacts should be collected and tested to find out who has been infected. Potential sources of infection like pets should be checked and treated when required.
Medicines are available to get rid of hookworm in humans and in animals. Programs can be conducted in endemic areas to educate residents about hookworm, and to identify and treat infected people.
the Eradication of Hookworm in an Isolated Australian Community
In 1992, a survey was conducted in a remote coastal community (population around 350). The survey found that around 77% of the community was infected with A. duodenale, and around 93% of children aged 5 - 14 years were infected with the parasite. At first the medicine pyrantel and environmental and health strategies were used to try to eradicate hookworm in the community. Unfortunately the campaign was unsuccessful due to A. duodenale resistance to pyrantel.
A second campaign (1993 - 1999) used the drug albendazole to treat infected people, and continued on with health education and environmental management programs (improved housing and sewage systems, rubbish collection etc). This campaign also monitored hookworm infection in the population, which was important because lack of surveillance has been highlighted as a contributing factor to the failure of other hookworm eradication programs.
Firstly the infection status of the whole community was calculated, and then mass treatments were given. Regular checks were carried out to look for the parasites A. duodenale, Giardia and Hymenolepis nana. The original mass treatment (1993) reduced human hookworm infections from 80% to 0% of the population within 30 days. However, over a 3-year period the number of infected people increased to around 40% of the population when no further treatments were given.
Regular treatments were started, and currently hookworm infections occur only in around 2.6% of the population. Presently, hookworm is under control in the community, unless someone reintroduces it. However, any outbreaks could be quickly stopped by regular use of special drugs, although care is needed to ensure the parasite does not become resistant to these drugs.
|Abdomen (abdominal)||Barrang, beli, buurrbiyn, dhulmu, kem, kunto, muhh, munto, tidli, yeek, belly area, tummy, gut, middle, or midriff.|
|Anaemia||When a person is pale and weak from blood being unable to carry enough oxygen to meet body needs. Causes include blood loss from parasites feeding and lack of iron in diet.|
|Asymptomatic||When a person has a disease but does not feel sick.|
|Chronic Infection||When a person is infected with a parasite for a long period of time (years).|
|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.|
|Diarrhoea||Watery or liquid faeces, runny tummy, dysentery, runs or trots.|
|Digestive Tract||Includes stomach and intestines, also called gastrointestinal tract.|
|Endemic||Geographic region 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 that is located in the belly.|
|Larvae||Immature worms that may/may not become adults depending on type of host.|
|Parasite||Plants or animals that may be very small (single cell) or large (1m worm), which rely on another plant or animal to live. Parasites include worms, mites or lice.|
|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.|
|Sanitary||To do something in a healthy way. Also means, clean, safe, hygienic.|
Education Flyer to print out
Chin, J., 2000,
Control of Communicable Disease Manual, 17th edn, American
Public Health Association, Washington DC, pp. 497-499.
D.D., Gwadz, R.W., Hotez, P.J. 1995, Parasitic Diseases,
3rd edn, Springer-Verlag, New York, pp. 151-159.
Parasitic Roundworm Diseases, 2001. NIAID, United States. Available
Hookworm Infection, 1999. CDC, Atlanta. Available at: www.cdc.gov/ncidod/dpd/parasites/hookworm/factsht_hookworm.htm
Fernando, S.E. & Leong, A.S.Y. 2001, Tropical Infectious
Diseases: Epidemiology, Investigation, Diagnosis and Management,
Greenwich Medical Media Ltd, London, pp. 91-94.
& Henderson, H. 1997, Environmental Health for Aboriginal
Communities: A Training Manual for Environmental Health Workers,
Office of Aboriginal Health, East Perth, pp. 16-28.
1993, ‘Worms in Australia’, Medical Journal of Australia,
Vol 159, pp. 464-466.
& Garrow, S.C. 2002, ‘Parasite elimination programs: at
home and away’, Medical Journal of Australia, Vol.
176, pp. 456-457.
Porciv, P. 1998,
‘Zoonotic Hookworm Infections’, in Zoonoses,
eds S.R. Palmer, Lord Soulsby & D.I.H. Simpson, Oxford University
Press, New York.
J.A. et al, 1997, ‘Failure of pyrantel in treatment of human
hookworm infections (Ancylostoma duodenale) in the Kimberly region
of the north west Australia’, Act Tropica, Vol 68,
Issue 3, pp. 301-312.
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.
et al. 2001, ‘Towards the eradication of hookworm in an isolated
Australian community’, The Lancet, Vol 357, pp. 770-771.
WHO, 1994, Report
of the WHO Informal Consultation on Hookworm Infection and Anaemia
in Girls and Women, WHO, Geneva.
may only be reproduced in full and for educational purposes only.