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Candida and parasitic infection: Helminths, trichomoniasis, lice, scabies, and malaria
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
Strongyloidiasis has a worldwide distribution, but is most common in warm climates with a high water table. Adult worms are all females. They measure 2 to 3mm in length and live in the small intestine. Strongyloides eggs are thin shelled (32). Female worms deposit eggs in the intestinal mucosa, where they hatch, releasing larvae. The larvae migrate into the lumen and pass in the feces into soil. Following maturation in the soil, infective larvae infect humans through direct skin penetration. The larvae then migrate, via the venous system and lungs, to the intestine, where they mature to adulthood and lay eggs. The entire life cycle may occur outside the body (in soil) or inside the body (internal autoinfection) (32). Strongyloidiasis is difficult to diagnose. Fecal concentration techniques are required to find larvae in feces, owing to the low number present.
Strongyloidiasis
Published in Peter D. Walzer, Robert M. Genta, Parasitic Infections in the Compromised Host, 2020
Robert M. Genta, Peter D. Walzer
Cutaneous penetration of filariform larvae found in contaminated soil is the most common way by which human strongyloidiasis is acquired. The ingestion of infective larvae is not believed to be a common mode of transmission in humans, although coprophagia may play an important role in dogs. In some reported cases, S. stercoralis has been transmitted in unusual manners, such as through renal transplantation (105) or apparently from immersion in a swimming pool (106), but these events represent little more than medical curiosities. Transmammary transmission during breast feeding, a well-documented mode of infection for S. ratti in rodents (107), appears to occur occasionally in human S. fulleborni infections (108) but has not been observed for S. stercoralis.
Infections
Published in C. Simon Herrington, Muir's Textbook of Pathology, 2020
Strongyloidiasis is caused by the nematode Strongyloides stercoralis. This worm is endemic in the tropics and subtropics and, because of its lifecycle, it can be a lifelong infection and is potentially fatal. Importantly, people infected previously (e.g. soldiers in the Far East during the Second World War) can present decades later with acute illness for the first time. Humans are infected by larvae in the soil, deposited from human faeces. The larvae penetrate the skin and migrate to the small intestine and lodge in mucosal crypts. The female lays eggs, which immediately hatch into larvae in the bowel lumen. These are able to re-invade the bowel or perianal skin, so keeping an autoinfection cycle going. Should the patient become immunosuppressed (Box 20.25), this autoinfection cycle can rapidly generate massive infection (hyperinfection) with millions of parasites throughout the whole intestine, and haematogenous dissemination of larvae to all organs including the liver, lungs, and meninges.
Parasitic necrotizing pneumonia in an immunocompetent patient in United States
Published in Journal of Community Hospital Internal Medicine Perspectives, 2021
Harish Gopalakrishna, Gayatri B. Nair, Ricardo Conti
Among parasites, Toxoplasma gondii pneumonia is the most common in the USA but observed most frequently in acquired-immunodeficiency-syndrome patients [5]. Strongyloidiasis is generally a benign parasitic infection, more common in tropical and subtropical countries [6]. There have been cases of strongyloides pneumonia seen in immunocompromised patients, like HTLV-I, HIV, malignancy, congenital immunodeficiency or those on long-term corticosteroids or other immunosuppressive agents [7,8]. Although the exact dose of corticosteroids is not known, doses as low as 20 mg daily for 5 weeks have been shown to be sufficient to cause immunosuppression causing strongyloides necrotizing pneumonia [9]. Steroids are known to cause the transformation of rhabditiform larvae to invasive and infective form, filariform larvae [10].
Strongyloides stercoralis colitis in a patient positive for human T-cell leukaemia virus with rheumatoid arthritis during an anti-rheumatic therapy: a case report
Published in Modern Rheumatology Case Reports, 2021
Yayoi Hashiba, Kunihiko Umekita, Hiroyuki Minami, Atsuko Kawano, Eiji Nagayasu, Haruhiko Maruyama, Toshihiko Hidaka, Akihiko Okayama
Strongyloides stercoralis is an intestinal nematode that is the etiologic agent of strongyloidiasis; chronic infection affects ∼30–100 million people worldwide [1]. Strongyloidiasis is an endemic disease in tropical and subtropical regions with a prevalence of 20% in some regions; this infection is endemic to the southern regions of Japan, including Kyushu and Okinawa. The disease may be asymptomatic in immunocompetent patients or may manifest with occasional stomachaches, intermittent diarrhoea and constipation, bloating, nausea and loss of appetite. Infection with human T-cell leukaemia virus type 1 (HTLV-1) is also a known risk factor associated with strongyloidiasis [1]; the prevalence of strongyloidiasis is reported to be high among HTLV-1 carriers [2]. Among the potential mechanisms, HTLV-1 infection may modify the immune response against S. stercoralis infection [3,4]. As such, immunocompromised patients, including those experiencing malnutrition and those undergoing bone marrow transplantation and/or immunosuppressive therapies including corticosteroids, chemotherapy and biologics, are at increased risk for strongyloidiasis [1]. Several published case reports describe exacerbations of S. stercoralis infection in patients with rheumatoid arthritis (RA) who were undergoing treatment with anti-rheumatic therapies, including methotrexate, corticosteroids and anti-TNF biologics [5–8].
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
Strongyloides stercoralis (and S. fülleborni) belongs to the group of soil-transmitted helminthiases that may cause chronic infection in humans. Transmission occurs mainly in tropical and subtropical regions and an estimated 30–100 million people could be infected worldwide. Strongyloidiasis may affect migrants from all geographical areas. A recent systematic review and meta-analysis found a pooled strongyloidiasis seroprevalence of 12.2% in migrants and a stool-based prevalence of 1.8% [103]. The highest seroprevalences were found in migrants from East Asia and the Pacific region (17.3%), sub-Saharan Africa (14.6%) and Latin America and the Caribbean (11.4%). Data from the GeoSentinel network also found strongyloidiasis to be a frequent infection in migrants, accounting for 5% of the diagnoses in this group during the period 1997 to 2009 [104]. In a recent study of imported infections in Spain during the period 2009 to 2017, over 1200 cases of strongyloidiasis were reported, mostly in immigrants, accounting for nearly 10% of all cases registered [105].