Strongyloidiasis
Encyclopedia
Strongyloidiasis is a human parasitic disease caused by the nematode
(roundworm) Strongyloides stercoralis
, or sometimes S. fülleborni. It can cause a number of symptoms in people, principally skin symptoms, abdominal pain
, diarrhea
and weight loss. In some people, particularly those who require corticosteroid
s or other immunosuppressive medication, Strongyloides can cause a hyperinfection syndrome that can lead to death if untreated. The diagnosis is made by blood and stool tests. The drug ivermectin is widely used in the treatment of strongyloidiasis.
It is thought to affect 30–100 million people worldwide, mainly in tropical and subtropical countries. Worldwide efforts are aimed at eradicating the infection in high-risk groups. Strongyloidiasis was first described in France in 1876.
). The infection may then become chronic with mainly digestive symptoms. On reinfection (when larvae migrate through the body), there may be respiratory, skin and digestive symptoms. Finally, the hyperinfection syndrome causes symptoms in many organ systems, including the central nervous system
.
. Gastrointestinal system symptom
s include abdominal pain
and diarrhea
. Pulmonary symptoms (including Löffler's syndrome
) can occur during pulmonary migration of the filariform larvae. Dermatologic
manifestations include urticaria
l rash
es in the buttocks and waist areas. Blood
eosinophilia
is generally present.
Strongyloidiasis can become chronic and then become completely asymptomatic.
ed. It presents with abdominal pain, distension, shock, pulmonary and neurologic complications
and septicemia, and is potentially fatal. The worms enter the bloodstream from the bowel wall, simultaneously allowing entry of bowel bacteria such as Escherichia coli
. This may cause symptoms such as sepsis
(bloodstream infecion), and the bacteria may spread to other organs where they may cause localized infection such as meningitis
.
Dissemination can occur many decades after the initial infection and has been associated with high dose corticosteroids, organ transplant
, HIV
, lepromatous leprosy
, tertiary syphilis
, aplastic anemia
, malnutrition, advanced tuberculosis
and radiation poisoning
. It is often recommended that patients being started on immunosuppression be screened for chronic strongyloidiasis; however, this is often impractical (screen tests are often unavailable) and in developed countries, the prevalence of chronic strongyloidiasis is very small, so screening is usually not cost-effective, except in endemic areas.
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 direct stool examination is relatively insensitive.
The stool can be examined in wet mount
s:
Culture techniques are the most sensitive, but are not routinely available in the West. In the UK, culture is available at either of the Schools of Tropical Medicine in Liverpool or London. Direct examination must be done on stool that is freshly collected and not allowed to cool down, because hookworm
eggs hatch on cooling and the larvae are very difficult to distinguish from strongyloides.
Finding strongyloides in the stool is negative in up to 70% of tests. It is important to undergo frequent stool sampling as well as duodenal biopsy if a bad infection is suspected. 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.
and thiabendazole
(25 mg/kg twice daily for 5 days—400 mg maximum (generally)). All patients who are at risk of disseminated strongyloidiasis should be treated. It is not clear what the optimal duration of treatment for patients with disseminated infectious should be.
Treatment of strongyloides can be difficult and has been known to live in individuals for upwards of 1–2 years after treatment. Continued treatment may be necessary if symptoms persist. Treatment should be continued until symptoms resolve themselves.
physician Louis Alexis Normand, working in the naval hospital in Toulon
; he identified the adult worms, and sent them to Arthur Réné Jean Baptiste Bavay, chief inspector for health, who observed that these were the adult forms of the larvae found in the stool. In 1883 the German
parasitologist Rudolf Leuckart
made initial observations on the life cycle of the parasite, and Belgian physician Paul Van Durme (building on observations by the German parasitologist Arthur Looss
) described the mode of infection through the skin. The German parasitologist Friedrich Fülleborn
described autoinfection and the way by which strongyloidiasis involves the intestine. Interest in the condition increased in the 1940s when it was discovered that those who had acquired the infection abroad and then received immunosuppression developed hyperinfestation syndrome.
Nematode
The nematodes or roundworms are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 28,000 have been described, of which over 16,000 are parasitic. It has been estimated that the total number of nematode...
(roundworm) Strongyloides stercoralis
Strongyloides stercoralis
Strongyloides stercoralis, also known as the threadworm, is the scientific name of a human parasitic roundworm causing the disease of strongyloidiasis....
, or sometimes S. fülleborni. It can cause a number of symptoms in people, principally skin symptoms, abdominal pain
Abdominal pain
Abdominal pain can be one of the symptoms associated with transient disorders or serious disease. Making a definitive diagnosis of the cause of abdominal pain can be difficult, because many diseases can result in this symptom. Abdominal pain is a common problem...
, diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
and weight loss. In some people, particularly those who require corticosteroid
Corticosteroid
Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiologic systems such as stress response, immune response and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte...
s or other immunosuppressive medication, Strongyloides can cause a hyperinfection syndrome that can lead to death if untreated. The diagnosis is made by blood and stool tests. The drug ivermectin is widely used in the treatment of strongyloidiasis.
It is thought to affect 30–100 million people worldwide, mainly in tropical and subtropical countries. Worldwide efforts are aimed at eradicating the infection in high-risk groups. Strongyloidiasis was first described in France in 1876.
Signs and symptoms
Strongyloides infection occurs in five forms. On acquiring the infection, there may be respiratory symptoms (Löffler's syndromeLöffler's syndrome
Löffler's syndrome or Loeffler's syndrome is a disease in which eosinophils accumulates in the lung in response to a parasitic infection....
). The infection may then become chronic with mainly digestive symptoms. On reinfection (when larvae migrate through the body), there may be respiratory, skin and digestive symptoms. Finally, the hyperinfection syndrome causes symptoms in many organ systems, including the central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
.
Uncomplicated disease
Frequently asymptomaticAsymptomatic
In medicine, a disease is considered asymptomatic if a patient is a carrier for a disease or infection but experiences no symptoms. A condition might be asymptomatic if it fails to show the noticeable symptoms with which it is usually associated. Asymptomatic infections are also called subclinical...
. Gastrointestinal system symptom
Symptom
A symptom is a departure from normal function or feeling which is noticed by a patient, indicating the presence of disease or abnormality...
s include abdominal pain
Pain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...
and diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
. Pulmonary symptoms (including Löffler's syndrome
Löffler's syndrome
Löffler's syndrome or Loeffler's syndrome is a disease in which eosinophils accumulates in the lung in response to a parasitic infection....
) can occur during pulmonary migration of the filariform larvae. Dermatologic
Dermatology
Dermatology is the branch of medicine dealing with the skin and its diseases, a unique specialty with both medical and surgical aspects. A dermatologist takes care of diseases, in the widest sense, and some cosmetic problems of the skin, scalp, hair, and nails....
manifestations include urticaria
Urticaria
Urticaria is a kind of skin rash notable for pale red, raised, itchy bumps. Hives is frequently caused by allergic reactions; however, there are many non-allergic causes...
l rash
Rash
A rash is a change of the skin which affects its color, appearance or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, cracked or blistered, swell and may be painful. The causes, and...
es in the buttocks and waist areas. Blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
eosinophilia
Eosinophilia
Eosinophilia is a condition in which the eosinophil count in the peripheral blood exceeds 0.45×109/L . A marked increase in non-blood tissue eosinophil count noticed upon histopathologic examination is diagnostic for tissue eosinophilia. Several causes are known, with the most common being...
is generally present.
Strongyloidiasis can become chronic and then become completely asymptomatic.
Disseminated disease
Disseminated strongyloidiasis occurs when patients with chronic strongyloidiasis become immunosuppressImmunosuppression
Immunosuppression involves an act that reduces the activation or efficacy of the immune system. Some portions of the immune system itself have immuno-suppressive effects on other parts of the immune system, and immunosuppression may occur as an adverse reaction to treatment of other...
ed. It presents with abdominal pain, distension, shock, pulmonary and neurologic complications
Complication (medicine)
Complication, in medicine, is an unfavorable evolution of a disease, a health condition or a medical treatment. The disease can become worse in its severity or show a higher number of signs, symptoms or new pathological changes, become widespread throughout the body or affect other organ systems. A...
and septicemia, and is potentially fatal. The worms enter the bloodstream from the bowel wall, simultaneously allowing entry of bowel bacteria such as Escherichia coli
Escherichia coli
Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...
. This may cause symptoms such as sepsis
Sepsis
Sepsis is a potentially deadly medical condition that is characterized by a whole-body inflammatory state and the presence of a known or suspected infection. The body may develop this inflammatory response by the immune system to microbes in the blood, urine, lungs, skin, or other tissues...
(bloodstream infecion), and the bacteria may spread to other organs where they may cause localized infection such as meningitis
Meningitis
Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...
.
Dissemination can occur many decades after the initial infection and has been associated with high dose corticosteroids, organ transplant
Organ transplant
Organ transplantation is the moving of an organ from one body to another or from a donor site on the patient's own body, for the purpose of replacing the recipient's damaged or absent organ. The emerging field of regenerative medicine is allowing scientists and engineers to create organs to be...
, HIV
HIV
Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...
, lepromatous leprosy
Leprosy
Leprosy or Hansen's disease is a chronic disease caused by the bacteria Mycobacterium leprae and Mycobacterium lepromatosis. Named after physician Gerhard Armauer Hansen, leprosy is primarily a granulomatous disease of the peripheral nerves and mucosa of the upper respiratory tract; skin lesions...
, tertiary syphilis
Syphilis
Syphilis is a sexually transmitted infection caused by the spirochete bacterium Treponema pallidum subspecies pallidum. The primary route of transmission is through sexual contact; however, it may also be transmitted from mother to fetus during pregnancy or at birth, resulting in congenital syphilis...
, aplastic anemia
Aplastic anemia
Aplastic anemia is a condition where bone marrow does not produce sufficient new cells to replenish blood cells. The condition, per its name, involves both aplasia and anemia...
, malnutrition, advanced tuberculosis
Tuberculosis
Tuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...
and radiation poisoning
Radiation poisoning
Acute radiation syndrome also known as radiation poisoning, radiation sickness or radiation toxicity, is a constellation of health effects which occur within several months of exposure to high amounts of ionizing radiation...
. It is often recommended that patients being started on immunosuppression be screened for chronic strongyloidiasis; however, this is often impractical (screen tests are often unavailable) and in developed countries, the prevalence of chronic strongyloidiasis is very small, so screening is usually not cost-effective, except in endemic areas.
Laboratory diagnosis
DiagnosisDiagnosis
Diagnosis is the identification of the nature and cause of anything. Diagnosis is used in many different disciplines with variations in the use of logics, analytics, and experience to determine the cause and effect relationships...
rests on the microscopic
Microscope
A microscope is an instrument used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy...
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 direct stool examination is relatively insensitive.
The stool can be examined in wet mount
Microscope slide
A microscope slide is a thin flat piece of glass, typically 75 by 25 mm and about 1 mm thick, used to hold objects for examination under a microscope. Typically the object is placed or secured on the slide, and then both are inserted together in the microscope for viewing...
s:
- 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 plateAgar plateAn agar plate is a Petri dish that contains a growth medium used to culture microorganisms or small plants like the moss Physcomitrella patens.Selective growth compounds may also be added to the media, such as antibiotics....
s
Culture techniques are the most sensitive, but are not routinely available in the West. In the UK, culture is available at either of the Schools of Tropical Medicine in Liverpool or London. Direct examination must be done on stool that is freshly collected and not allowed to cool down, because hookworm
Hookworm
The hookworm is a parasitic nematode that lives in the small intestine of its host, which may be a mammal such as a dog, cat, or human. Two species of hookworms commonly infect humans, Ancylostoma duodenale and Necator americanus. A. duodenale predominates in the Middle East, North Africa, India...
eggs hatch on cooling and the larvae are very difficult to distinguish from strongyloides.
Finding strongyloides in the stool is negative in up to 70% of tests. It is important to undergo frequent stool sampling as well as duodenal biopsy if a bad infection is suspected. The duodenal fluid can be examined using techniques such as the Enterotest string or duodenal aspiration. Larvae may be detected in sputum
Sputum
Sputum is mucus that is coughed up from the lower airways. It is usually used for microbiological investigations of respiratory infections....
from patients with disseminated strongyloidiasis.
Treatment
The drug of choice for the treatment of uncomplicated strongyloidiasis is ivermectin. Ivermectin does not kill the strongyloides larvae only the adult worms therefore repeat dosaging may be necessary to properly eradicate the infection. There is an auto-infective cycle of roughly two weeks in which Ivermectin should be re-administered however additional dosaging may still be necessary as it will not kill strongyloides in the blood or larvae deep within the bowels or diverticuli. Other drugs that are effective are albendazoleAlbendazole
Albendazole, marketed as Albenza, Eskazole, Zentel and Andazol, is a member of the benzimidazole compounds used as a drug indicated for the treatment of a variety of worm infestations. Although this use is widespread in the United States, the U.S. Food and Drug Administration has not approved...
and thiabendazole
Thiabendazole
Tiabendazole is a fungicide and parasiticide.-Fungicide:...
(25 mg/kg twice daily for 5 days—400 mg maximum (generally)). All patients who are at risk of disseminated strongyloidiasis should be treated. It is not clear what the optimal duration of treatment for patients with disseminated infectious should be.
Treatment of strongyloides can be difficult and has been known to live in individuals for upwards of 1–2 years after treatment. Continued treatment may be necessary if symptoms persist. Treatment should be continued until symptoms resolve themselves.
History
The disease was first recognized in 1876 by the FrenchFrance
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
physician Louis Alexis Normand, working in the naval hospital in Toulon
Toulon
Toulon is a town in southern France and a large military harbor on the Mediterranean coast, with a major French naval base. Located in the Provence-Alpes-Côte-d'Azur region, Toulon is the capital of the Var department in the former province of Provence....
; he identified the adult worms, and sent them to Arthur Réné Jean Baptiste Bavay, chief inspector for health, who observed that these were the adult forms of the larvae found in the stool. In 1883 the German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
parasitologist Rudolf Leuckart
Rudolf Leuckart
Karl Georg Friedrich Rudolf Leuckart was a German zoologist who was born in Helmstedt. He was a nephew to naturalist Friedrich Sigismund Leuckart ....
made initial observations on the life cycle of the parasite, and Belgian physician Paul Van Durme (building on observations by the German parasitologist Arthur Looss
Arthur Looss
Arthur Looss was a German zoologist and parasitologist. Looss was born in 1861 in Chemnitz, and was educated both there and in Łódź, Poland ...
) described the mode of infection through the skin. The German parasitologist Friedrich Fülleborn
Friedrich Fülleborn
Friedrich Fülleborn was a physician who specialized in tropical medicine and parasitology. He was a native of Kulm, West Prussia, which today is known as Chełmno, Poland. He studied medicine and natural sciences in Berlin, where one of his instructors was Heinrich Wilhelm Waldeyer...
described autoinfection and the way by which strongyloidiasis involves the intestine. Interest in the condition increased in the 1940s when it was discovered that those who had acquired the infection abroad and then received immunosuppression developed hyperinfestation syndrome.
External links
- Strongyloidiasis. U.S. Centers for Disease Control and PreventionCenters for Disease Control and PreventionThe Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...
(CDC)