Strongyloides stercoralis. Source: CDC

Strongyloidiasis is a human parasitic disease caused by the nematode (roundworm) Strongyloides stercoralis. Other Strongyloides include S. fülleborni, which infects chimpanzees and baboons and may produce limited infections in humans. Image File history File links Strongyloides_stercoraliz_larva. ... Image File history File links Strongyloides_stercoraliz_larva. ... Classes Adenophora    Subclass Enoplia    Subclass Chromadoria Secernentea    Subclass Rhabditia    Subclass Spiruria    Subclass Diplogasteria The roundworms (Phylum Nematoda) are one of the most common phyla of animals, with over 20,000 different described species. ... Classes Adenophorea    Subclass Enoplia    Subclass Chromadoria Secernentea    Subclass Rhabditia    Subclass Spiruria    Subclass Diplogasteria The roundworms (Phylum Nematoda from Gr. ... Strongiloides stercoralis. ... Type species Simia troglodytes Blumenbach, 1775 Species Pan troglodytes Pan paniscus Chimpanzee, often abbreviated to chimp, is the common name for two species in the genus Pan. ... Type Species Simia hamadryas Linnaeus, 1758 Species Papio hamadryas Papio papio Papio anubis Papio cynocephalus Papio ursinus The baboons are some of the largest non-hominid members of the primate order; only the Mandrill and the Drill are larger. ...

Life Cycle

The Strongyloides life cycle is more complex than that of most nematodes with its alternation between free-living and parasitic cycles, and its potential for autoinfection and multiplication within the host. Two types of cycles exist:

• Free-living cycle: The rhabditiform larvae passed in the stool can either molt twice and become infective filariform larvae (direct development) or molt four times and become free living adult males and females that mate and produce eggs from which rhabditiform larvae hatch. The latter in turn can either develop into a new generation of free-living adults, or into infective filariform larvae. The filariform larvae penetrate the human host skin to initiate the parasitic cycle.
• Parasitic cycle: Filariform larvae in contaminated soil penetrate the human skin , and are transported to the lungs where they penetrate the alveolar spaces; they are carried through the bronchial tree to the pharynx, are swallowed and then reach the small intestine. In the small intestine they molt twice and become adult female worms. The females live threaded in the epithelium of the small intestine and by parthenogenesis produce eggs, which yield rhabditiform larvae. The rhabditiform larvae can either be passed in the stool (see "Free-living cycle" above), or can cause autoinfection. In autoinfection, the rhabditiform larvae become infective filariform larvae, which can penetrate either the intestinal mucosa (internal autoinfection) or the skin of the perianal area (external autoinfection); in either case, the filariform larvae may follow the previously described route, being carried successively to the lungs, the bronchial tree, the pharynx, and the small intestine where they mature into adults; or they may disseminate widely in the body. To date, occurrence of autoinfection in humans with helminthic infections is recognized only in Strongyloides stercoralis and Capillaria philippinensis infections. In the case of Strongyloides, autoinfection may explain the possibility of persistent infections for many years in persons who have not been in an endemic area and of hyperinfections in immunodepressed individuals.

A larva (Latin; plural larvae) is a juvenile form of animal with indirect development, undergoing metamorphosis (for example, insects or amphibians). ... Look up stool in Wiktionary, the free dictionary. ... An average Whooping Crane egg is 102 mm long, and weighs 208 grams A baby tortoise emerges from a reptile egg. ... Diagram of the layers of human skin In zootomy and dermatology, skin is an organ of the integumentary system composed of a layer of tissues that protect underlying muscles and organs. ... Soil is material capable of supporting plant life. ... The heart and lungs (from an older edition of Grays Anatomy) The lung is an organ belonging to the respiratory system and interfacing to the circulatory system of air-breathing vertebrates. ... Detailed drawing of the alveoli from Grays Anatomy, 1918 - Schematic longitudinal section of a primary lobule of the lung (anatomical unit); r. ... The pharynx is the part of the digestive system and respiratory system of many animals immediately behind the mouth and in front of the esophagus. ... Diagram showing the small intestine In biology the small intestine is the part of the gastrointestinal tract between the stomach and the large intestine (colon). ... A worm is an elongated soft-bodied invertebrate animal. ... In zootomy, epithelium is a tissue composed of a layer of cells. ... Kaguya is one success from 460 attempts at growing embryos. ...

Geographic distribution

Tropical and subtropical areas, but cases also occur in temperate areas (including the South of the United States). More frequently found in rural areas, institutional settings, and lower socio-economic groups.

Clinical features

Frequently asymptomatic. Gastrointestinal system symptoms include abdominal pain and diarrhea. Pulmonary symptoms (including Loeffler’s syndrome) can occur during pulmonary migration of the filariform larvae. Dermatologic manifestations include urticarial rashes in the buttocks and waist areas. Disseminated strongyloidiasis occurs in immunosuppressed patients, can present with abdominal pain, distension, shock, pulmonary and neurologic complications and septicemia, and is potentially fatal. Blood eosinophilia is generally present during the acute and chronic stages, but may be absent with dissemination. In medicine, a disease is asymptomatic when it is at a stage where the patient does not experience symptoms. ... For the Physics term GUT, please refer to Grand unification theory The gastrointestinal or digestive tract, also referred to as the GI tract or the alimentary canal or the gut, is the system of organs within multicellular animals which takes in food, digests it to extract energy and nutrients, and... The term symptom (from the Greek syn = con/plus and pipto = fall, together meaning co-exist) has two similar meanings in the context of physical and mental health: A symptom may loosely be said to be a physical condition which shows that one has a particular illness or disorder (see... Pain is an unpleasant sensation which may be associated with actual or potential tissue damage and which may have physical and emotional components. ... Diarrhea (American English) or diarrhoea (Commonwealth English) is a condition in which the sufferer has frequent and watery, chunky, or loose bowel movements (from the ancient Greek word διαρροή = leakage; lit. ... The heart and lungs (from an older edition of Grays Anatomy) The lung is an organ belonging to the respiratory system and interfacing to the circulatory system of air-breathing vertebrates. ... Dermatology (from Greek derma, skin) is a branch of medicine dealing with the skin and its appendages (hair, nails, sweat glands etc). ... For the garage rock band from Sweden, please see The Hives. ... RASH (Red and Anarchist Skinheads) is a left-wing anti-racist, anti-fascist skinhead group. ... Immunosuppression is the medical suppression of the immune system. ... In medicine, shock (hypoperfusion) is a life-threatening medical emergency characterized by inability of the circulatory system to supply enough oxygen to meet tissue requirements. ... Sepsis (in Greek Σήψις) is a serious medical condition caused by a severe systemic infection leading to a systemic inflammatory response. ... Red blood cells (erythrocytes) are present in the blood and help carry oxygen to the rest of the cells in the body Blood is a circulating tissue composed of fluid plasma and cells (red blood cells, white blood cells, platelets). ... Eosinophilia is the state of having high eosinophil granulocytes in the blood. ... Acute may refer to: An acute accent is a diacritic character. ... The word chronic comes from Chronos, the ancient Greek god of time. ...

Laboratory diagnosis

Diagnosis rests on the microscopic identification of larvae (rhabditiform and occasionally filariform) in the stool or duodenal fluid. Examination of serial samples may be necessary, and not always sufficient, because stool examination is relatively insensitive. Diagnosis (from the Greek words dia = by and gnosis = knowledge) is the process of identifying a disease by its signs, symptoms and results of various diagnostic procedures. ... It has been suggested that microscopy be merged into this article or section. ... In anatomy of the digestive system, the duodenum is a hollow jointed tube that connects the stomach to the jejunum. ...

The stool can be examined in wet mounts:

• directly
• after concentration (formalin-ethyl acetate)
• after recovery of the larvae by the Baermann funnel technique
• after culture by the Harada-Mori filter paper technique
• after culture in agar plates

The duodenal fluid can be examined using techniques such as the Enterotest string or duodenal aspiration. Larvae may be detected in sputum from patients with disseminated strongyloidiasis. Agar is a galactose polymer (or agarose) obtained from the cell walls of some species of red algae or seaweed (Sphaerococcus euchema) and species of Gelidium, chiefly from eastern Asia and California. ... Sputum is matter that is coughed up from the respiratory tract, such as mucus or phlegm, mixed with saliva and then expectorated from the mouth. ...

Treatment

The drug of choice for the treatment of uncomplicated strongyloidiasis is ivermectin with albendazole as the alternative. All patients who are at risk of disseminated strongyloidiasis should be treated. Ivermectin sold under brand names Stromectol® in the US and Mectizan® in Canada. ... Albendazole marketed as Albenza or Zentel, is indicated for the treatment of a variety of work infestations. ...

Source

• Strongyloidiasis. US Centers for Disease Control and Prevention (CDC)