Protozoan Diseases - CRYPTOSPORIDIOSIS
Extracellular protozoal organisms - similar to coccidia. Genus: Cryptosporidium, it remains unsettled whether more than one species exists. Taxonomy of species somewhat controversial but considered to be infective across species lines.
RESERVOIR AND INCIDENCE:
Rodents, birds (particularly turkeys and chickens), ruminants, fish, reptiles, cats, dogs, rabbits, NHP's. Children over 2 years of age, animal handlers, travelers, homosexual men, and close personal contacts of infected individuals (families, health care and day-care workers) may be particularly likely to be infected. More than a dozen outbreaks have been reported in day-care centers around the world. Two major waterborne outbreaks have been documented. Cryptosporidium antibodies were detected in the serum of 20 of 23 cats (87%) suggesting that the exposure rate may be high.
Fecal-oral transmission is from animals to humans or humans to humans; waterborne transmission is also important. Oocysts passed in stool are fully sporulated and infectious; infection occurs as a result of their ingestion. In humans and animals, the full life cycle occurs within a single host. The organisms attach to the microvillous borders of enterocytes of the small bowel and also are found free in mucosal crypts. The host cell membrane deteriorates, leaving the parasitic membrane in direct contact with epithelial cell cytoplasm. The organisms do not, however, invade the tissues.
DISEASE IN ANIMALS:
Severe watery diarrhea in neonatal calves and lambs. In turkeys and chickens, the parasites are reported to occur in the sinuses, trachea, bronchi, cloaca, and bursa of Fabricius. The respiratory disease causes coughing, gasping, and airsacculitis. In reptiles, cryptosporidiosis is frequently reported in association with postprandial regurgitation. The organism affects the GI mucosa, resulting in marked thickening of the rugae and loss of segmented motility.
DISEASE IN MAN:
In immunocompetent persons, infection varies from no symptoms to mild enteritis to marked watery diarrhea (up to 10 stools daily) without mucus or gross or microscopic blood. Low-grade fever, malaise, nausea, vomiting, abdominal cramps, anorexia and weight loss may occur. The infection is generally self-limited and lasts a few days to about 2 weeks. In immunologically deficient patients, the illness is characterized by profuse (up to 15L daily), cholera-like diarrhea and by fever, severe malabsorption, marked weight loss, and lymphadenopathy. In AIDS, infection may involve any part of the GI tract, and multisystemic involvement has been described, especially involving the respiratory tract.
Diagnosis is by detection of oocysts in stool by a variety of flotation or concentration methods or by mucosal biopsy, followed by special staining methods that use modifications of an acid-fast stain (routine fecal staining methods do not detect the organisms). Three stools should be examined over 5 days. A fluorescein-labeled IgG monoclonal antibody test has recently become available to detect oocysts.
No successful treatment has been developed so far. Generally, no treatment other than supportive is needed in immunocompetent persons since it is self-limiting. In immunoincompetent persons, spiramycin, zidovudine (AZT), paromomycin, octreotide, and eflornithine have been reported of value.PHSourceWaterborne outbreaks of cryptosporidiosis.
Cryptosporidium Reference Unit, Public Health Wales, Singleton Hospital, Swansea, UK. E- mail: firstname.lastname@example.org
Water is the most commonly reported vehicle of transmission in Cryptosporidium outbreaks. While mains drinking water quality is highly regulated in industrialised countries, treated recreational water venues remain highly variable and these have emerged as important settings in the transmission of cryptosporidiosis. Epidemiological investigations of outbreaks benefit from supplementary microbiological evidence and, more recently, the application of molecular typing data to link isolates from cases to each other and to suspected sources. This article documents how waterborne Cryptosporidium outbreaks are identified and reported, how such outbreaks have acted as drivers of regulatory change, and some of the recent developments in the detection and investigation of these outbreaks and their spread, especially the application of molecular typing assays.PubMed
Clinical and subclinical infections with Cryptosporidium in animals.
Cryptosporidium spp. are frequent parasites of livestock and companion animals, raising questions about the clinical significance of such infections. Cryptosporidium infections have a wide spectrum of clinical signs that can vary from asymptomatic to serious infection to death. In neonatal ruminants, cryptosporidiosis is considered an important disease characterised by diarrhoea and mortality. In companion animals most infections are asymptomatic but severe clinical illness has also been reported in dogs, cats and horses. In birds, three main clinical forms of cryptosporidiosis are primarily seen in naturally occurring infections, i.e. respiratory, intestinal, and renal. In reptiles, cryptosporidiosis is an emerging problem given that infections are frequently chronic and lethal. Molecular tools have been developed to detect and differentiate Cryptosporidium at the species/genotype and subtype levels. The use of those tools has led to a more in-depth understanding of the genetic diversity of Cryptosporidium which plays an important role in the diverse clinical presentations of cryptosporidiosis. This review presents an overview of the current knowledge on clinical cryptosporidiosis in livestock, pets, and other animals.
Full Text:Taylor, Francis OnlineCryptosporidiosis: prevalence and water-related outbreaks of infection.
[Article in Russian]
The data available in the literature show that 1.5-3% of Russia's population is carriers of cryptosporidium oocysts. Cryptosporidia are ascertained to be able to cause diarrhea of varying severity in preschool children. However, cryptosporidiosis in the latter is not frequently diagnosed. The urgency of the problem of cryptosporidiosis is also due to the practically ubiquitous prevalence of the causative agent in nature and to the role of this infection in the development of perinatal diseases, as well as complications in immunocompetent patients (infected and uninfected with AIDS virus). Cryptosporidiasis is an HIV-associated infection and of great importance for the diagnosis of AIDS.PubMedEvaluation of garlic plant and indinavir drug efficacy in the treatment of cryptosporidiosis in experimentally immumosuppressed rats.PubMedPotential effects of global environmental changes on cryptosporidiosis and giardiasis transmission.Trends in ParasitologyOutbreak of cryptosporidiosis associated with a man-made chlorinated lake--Tarrant County, Texas, 2008.
PubMedInnate immune responses against Cryptosporidium parvum infection.
McDonald V, Korbel DS, Barakat FM, Choudhry N, Petry F.
Centre for Digestive Diseases, Barts and the London School of Medicine, Queen Mary College University of London, UK.
Cryptosporidium parvum infects intestinal epithelial cells and is commonly the parasite species involved in mammalian cryptosporidiosis, a major health problem for humans and neonatal livestock. In mice, immunologically mediated elimination of C. parvum requires CD4(+) T cells and IFN-γ. However, innate immune responses also have a significant protective role in both adult and neonatal mice. NK cells and IFN-γ have been shown to be important components in immunity in T and B cell-deficient mice but IFN-γ-dependent resistance has also been demonstrated in alymphocytic mice. Epithelial cells may play a vital role in immunity since once infected these cells have increased expression of inflammatory chemokines and cytokines and demonstrate antimicrobial killing mechanisms, including production of NO and antimicrobial peptides. TLRs facilitate the establishment of immunity in mice and are involved in the development of inflammatory responses of infected epithelial cells and also dendritic cells.NIH