The Helminths
Donald L. Price in Procedure Manual for the Diagnosis of Intestinal Parasites, 2017
In addition to eggs of helminths, juvenile worms (larvae) may be found in fecal specimens. Infection with Strongyloides stercoralis occurs throughout tropical and temperate areas of the world but is more prevalent in the warm, wet regions of the tropics. Man is considered to be the typical, definitive host of S. stercoralis, but dogs and cats may also be infected and act as reservoir hosts for man (Georgi and Sprinkle, 1974). The female worms of S. stercoralis inhabit the crypts of the duodenum or the first section of the jejunum where they lay partially embryonated eggs. The juvenile develops rapidly, emerges from the egg, and usually migrates to the intestinal lumen. Juveniles pass down the intestinal tract and are evacuated with the feces.
Mebendazole
M. Lindsay Grayson, Sara E. Cosgrove, Suzanne M. Crowe, M. Lindsay Grayson, William Hope, James S. McCarthy, John Mills, Johan W. Mouton, David L. Paterson in Kucers’ The Use of Antibiotics, 2017
Infection with Strongyloides stercoralis occurs mostly in wet tropical regions, but can also be found in returning travelers. A small number of veterans of conflicts in endemic areas develop chronic infections that can be difficult to treat. Benzimidazole anthelmintics have been used for many years and have been reported to be effective and well tolerated. The usual dose of mebendazole is 100 mg twice daily for 3 days, which is sufficient to kill the adult worms. However, it does not kill the auto-infecting larvae, and more prolonged dosing is necessary to effect a complete cure. In one study (Shikiya et al., 1991), a regimen of 100 mg twice daily for 28 days led to a 74% cure rate at 6 months (immediate cure rates being over 95%). However, a significant incidence of liver function abnormalities was observed. Interestingly, this same group showed 100% efficacy with a sequential treatment of thiabendazole followed by mebendazole. Currently, single-dose ivermectin (see Chapter 204, Ivermectin and moxidectin) is considered the treatment of choice for strongyloidiasis.
Host Defense and Parasite Evasion
Eric S. Loker, Bruce V. Hofkin in Parasitology, 2015
A final example is provided by Strongyloides stercoralis. Infection with this nematode is often asymptomatic in immunocompetent individuals. Eggs usually hatch in the intestine and L1 larvae are passed in the feces. In some cases, the larvae manage to molt twice before they are shed. As L3 larvae, they have reached the infective stage for their mammalian host, whereupon they can penetrate the gut wall. They then retrace their larval migration through the body, ultimately either returning to the intestine where they mature into adults or disseminating widely through the body. This process, called autoin-fection, occurs only very early in a primary infection in immunocompetent hosts, before the onset of an adaptive response. In severely immunocom-promised individuals, autoinfection can occur indefinitely, resulting in an overwhelming and potentially lethal hyperinfection.
Identifying the response process validity of clinical vignette-type multiple choice questions: An eye-tracking study
Published in Medical Teacher, 2023
Francisco Carlos Specian Junior, Thiago Martins Santos, John Sandars, Eliana Martorano Amaral, Dario Cecilio-Fernandes
Boy, 4 years old, complaining of perianal itching, exacerbated at night with restless sleep and irritability. The older brother has had similar symptoms for about a month. Physical examination: no changes. The cause is infection with:Trichuris Trichiura.Enterobius vermicularis.Ancylostoma duodenalis.Strongyloides stercoralis.Typical HCQ
Overcoming challenges in the diagnosis and treatment of parasitic infectious diseases in migrants
Published in Expert Review of Anti-infective Therapy, 2020
Francesca F. Norman, Belen Comeche, Sandra Chamorro, Rogelio López-Vélez
Infection is acquired through direct penetration of human skin by infective larvae when in contact with contaminated soil during domestic, agricultural, and recreational activities. Strongyloides spp. has a free-living life cycle in soil and a parasitic cycle, which may be maintained for years in the host through repeated replication and auto-infection. Rarely, infections through solid organ transplantation from an infected donor have been reported [106,107]. Infections may range from asymptomatic or mild infections with cutaneous and gastrointestinal symptoms, to severe life-threatening disease due to increased replication and dissemination of larvae. Underlying conditions such as HTLV-1 co-infection and alcoholism have been identified as possible risks for acquisition of Strongyloides stercoralis infection and dissemination [108].
Multiple lung nodules, eosinophilia and severe asthma
Published in Canadian Journal of Respiratory, Critical Care, and Sleep Medicine, 2022
Anurag Bhalla, Jean-Claude Cutz, Ehsan A. Haider, Michael Trus, Parameswaran Nair
Spirometry demonstrated FEV1 0.95 L (40%), VC 2.1 L (70%), FEV1/VC 0.45. She had persistent blood eosinophilia since 2007 (peak of 2.0 × 109 cells/L). Investigations demonstrated high sputum eosinophils (peak of 54%), elevated IgE (967 IU/mL), positive antinuclear antibodies (ANA) (1:40 titer with a homogenous pattern), positive rheumatoid factor (51.2 IU/mL) and negative anti-neutrophil cytoplasmic autoantibody (ANCA). Flow cytometry of bone marrow aspirate and peripheral blood did not show any aberrant T-cells or clonal B-cell population. Molecular testing was negative for c-KIT, Janus Kinase 2 (JAK2) (V617F) and Fip1-like 1 and platelet-derived growth factor receptor alpha (FIP1L1/PDGFRA) mutations, T-cell gene rearrangement and BCR-ABL1 fusion gene transcript. Bone marrow biopsy showed a large lymphoid nodule with a mix of B- and T-cells. Echocardiogram was normal. Stool examination for ova and parasites was negative and serology for strongyloides stercoralis was negative.
Related Knowledge Centers
- Gastrointestinal Tract
- Mucous Membrane
- Parasitism
- Strongyloides
- Pathogen
- Feces
- Strongyloidiasis
- Pinworm
- Host
- Urocanic Acid