- Abdominal pain and discomfort
- Appetite loss
- Bloody stool
- Bloody sputum
- Delayed puberty
- Impaired mental development
- Itchy rash
- Stunted growth
- Weight loss
Infection is often accompanied by no symptoms, particularly during early stages of infection.
What is a hookworm?
Hookworms are roundworms (Necator americanus, Ancylostoma duodenale, Ancylostoma ceylanicum, Ancylostoma braziliense) that infest the small intestine and lungs in humans.
Ranging in size from 5 to 13mm (0.5 inch) long, the four most common hookworm species can all infect humans, with N americanus accounting for about 90% of all infections worldwide. N americanus is most prevalent in tropical and subtropical regions, while A duodenale is found on all continents. A ceylanicum and A braziliense can also infect dogs and cats.
Hookworms are characterized by their cutting plates or teeth from which they attach to the inside of the small intestine to suck blood. Depending on the species, individual worms may consume up to 0.15ml (0.005oz) of blood from their host per day, resulting in severe anemia in cases of serious infection.
They are also prolific breeders, with A duodenale females producing up to 20,000 eggs per day, and N americanus up to 9,000 daily.
How did I get infected?
Infection is mainly spread by walking on soil or grass barefoot, but hookworms can also be transmitted through swallowing larvae. Mothers may also cross-infect their infants during pregnancy and birth.
Hookworms have a complex lifecycle that begins and ends in the small intestine. When a carrier animal defecates hookworm eggs are released onto the ground. Eggs tend not to be infective in themselves, however once in soil they hatch into larvae that extend their bodies into the air, waving to and fro, until they come into contact with human skin.
The barely visible larvae penetrate the skin into the bloodstream where they are carried to the lungs. From here they travel up the respiratory tract (often through coughing) into the mouth where they are swallowed and eventually reach the small intestine. Here they mature into adult worms. This journey commonly takes about one week to complete.
Sometimes an allergic reaction takes place on the skin at the point of penetration, often manifested as an itchy rash. Sweat glands and hair follicles often present a convenient opportunity for larvae to penetrate.
Larvae can survive up to 4 weeks outside of the body under the right conditions (moist, sandy or loamy soil in temperature ranges of 24-32°C (75-90°F). Adult hookworms can live up to 10 years inside a host.
Children are highly susceptible to hookworm infestation as they play in dirt and often go barefoot. Also at risk are people who work with soil. Direct person to person contact is not thought to play a significant factor in spreading infection as larvae need to develop in soil.
In 2002 the estimated number of people worldwide infected with hookworm was 1.3 billion, with an accepted universal susceptibility in all lands.
Incidence is higher in tropical and subtropical regions as warm, moist climates suit the development of larvae in soil. However hookworm species are found on every continent.
Widespread incidence includes lands in South East Asia, South Pacific, East Africa and South America.
In developing nations hookworms remain a scourge. The prevalence of infection in endemic countries continues to rise amongst young adults. Hookworms increase the susceptibility to other infections in many children causing death.
Sporadic outbreaks occur in southeastern USA, and have been documented in rural areas in Australia and Taiwan.
Is hookworm infestation dangerous?
Hookworm infection can be dangerous. Serious results of infestation include anemia and protein deficiency caused by blood loss. When combined with poor nutrition, pregnancy or malaria, the anemia can be severe.
Complications of hookworm infestation can include tiredness, breathing difficulties, fluid build-up in the abdomen, and (in severe cases) congestive heart failure.
Continuous infection can retard growth and mental development in children, sometimes irreversibly.
People most at risk of serious complications from hookworm infection include newborn infants, children, pregnant women and people who are malnourished.
Can I prevent hookworm infestation?
It is difficult to avoid hookworm infestation altogether as otherwise healthy activity (e.g. barefoot walking on grass or bare ground) results in infection. Totally avoiding other high-risk activities (e.g. skin contact with soil) may be impracticable.
Also hookworm larvae are extremely hardy and may survive periods of up to 4 weeks in soil under the right conditions.
Nevertheless simple precautions, particularly in regions where hookworm is common or poor sanitation is practiced, can limit the likelihood of infection.
Avoid walking barefoot and direct contact with soil. Improve sanitation practices, avoiding fecal contamination of soil by humans or animals wherever possible.
Can I be safely treated for hookworms?
As prevention of infection is difficult, treatment options take on greater importance.
In cases of severe infestation, treating hookworms involves factors beyond just killing off the parasitic eggs, larvae and worms. Other treatment goals may need to include improving nutrition and treating complications of anemia.
As with other parasitic worms, hookworms often require an ongoing course of anti-parasitic compounds to eradicate each of the lifecycle stages. Treatment may involve ongoing administration for between 30 and 60 days continuously depending on the type, severity and length of the infection.
Herbal treatments are well suited to this ongoing administration due to their relative safety and long documented history.
For example, The World Health Organization “Monographs on Selected Medicinal Plants” reports garlic has having been used to treat hookworm infestations, listing allicin (a natural chemical in garlic,) as the active constituent. Also Thymol, a key constituent of Thyme, is traditionally considered to be particularly effective against hookworm.
Also as herbal medicines are based on the philosophy of weed, seed and feed, nutrition inherent in natural treatments can be successfully employed to combat anemia and nutritional deficiencies.
Modern science is often used to refine the harvesting and processing of medicinal herbs, and herbal medicines are now being manufactured to pharmaceutical grade in countries like Australia and Germany. The scientific advances in herbal medicine demonstrate that ancient traditions and science can combine to produce effective treatments of the highest quality and safety standards.
Alternative: Parasite killing drugs such as albendazole, mebendazole or, pyrantel pamoate are usually prescribed, although some mebendazola resistant strains have been reported. Symptoms and complications of anemia are separately treated as the need arises. Iron supplements are commonly prescribed as an adjunct to anti-parasite drugs in treating hookworm.
Tetrachlorethylene has been used during the early part of the 20th Century as the most effective available drug for eliminating hookworm (identified at 90% success), but it has now been classified as a Group 2A carcinogen (promotes cancer). Tetrachlorethylene is widely used as a solvent in the dry cleaning industry (nick named “perc”), and in the production of refrigerants.
Bephenium hydroxynaphthoate shows better effectiveness against some types of hookworm (e.g. Ancylostoma duodenale) than Tetrachlorethylene in some studies, but to date is not approved by the FDA and is not available in the United States.
Center for Disease Control, Division of Parasitic Diseases: Hookworm Infection
National Library of Medicine: Medical Encyclopedia – Hookworm
National Institute of Allergy and Infectious Diseases – Hookworm Disease
Encyclopedia Britannica Online Edition Hookworm disease http://www.britannica.com/EBchecked/topic/271350/hookworm-disease#ref=ref267498
Public Health Agency of Canada Necator americanus Material Safety Data Sheets May 23, 2001
Thompson R., Reynoldson J., GarrowS., McCarthyJ., Behnke J. Towards the eradication of hookworm in an isolated Australian community The Lancet, Volume 357, Issue 9258, Pages 770-771
Bergner J.F., Jr. Intestinal Parasites in an Aborigine Village in Southeast Taiwan Am. J. Trop. Med. Hyg., 13(1), 1964, pp. 78-81
World Health Organization (WHO) (1999). Monographs on Selected Medicinal Plants. Volume 1. WHO, Geneva.
Jellin JM, Batz F, Hitchens K. Natural Medicines Comprehensive Database. Third Edition. Stockton, California: Therapeutic Research Faculty, 2000.
Lueng AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. Second Edition. New York, NY: Wiley & Sons, 1996.
Barnes J, Anderson LA, Phillipson JD, Herbal Medicines: A Guide for Healthcare Professionals. Second Edition. London: Pharmaceutical Press, 2002.
http://prod.hopkins-abxguide.org/antibiotics/antiparasitic/bephenium_hydroxynaphthoate.html?contentInstanceId=468569 Young M.D., Jeffery G.M., Morehouse W.G., Freed J.E., Johnson R.S. The Comparative Efficacy of Bephenium Hydroxynaphthoate and Tetrachloroethylene against Hookworm and other Parasites of Man Am. J. Trop. Med. Hyg., 9(5), 1960, pp. 488-491
This page is for information only and is not meant to be used for self-diagnosis or as a substitute for consultation with a health care professional. If you have any questions about the disease described above or think that you may have a parasitic infection, consult a health care professional.