Cryptosporidium and Bile Duct Injury
Gianfranco Alpini, Domenico Alvaro, Marco Marzioni, Gene LeSage, Nicholas LaRusso in The Pathophysiology of Biliary Epithelia, 2020
Cryptosporidium is now an established cause of acute and chronic diarrhea in humans. However, the duration and severity of clinical symptoms depends largely upon the immune status of the infected individual (Table 2).2 Cryptosporidiosis in the otherwise healthy individuals is usually a self-limited illness of 9–15 days.27 The most common clinical manifestation is profuse watery diarrhea, containing mucus, but rarely blood or leukocytes. Watery diarrhea is commonly associated with a variety of other symptoms including nausea, vomiting, cramp-like abdominal pain and mild fever. Three major presentations of cryptosporidiosis in immunocompetent individuals have been identified: asymptomatic carriage;acute diarrhea; andpersistent diarrhea.27
An Outbreak of Cryptosporidium sp. Associated with a Public Swimming Pool
Meera Chand, John Holton in Case Studies in Infection Control, 2018
Cryptosporidium is transmitted by the faecal–oral route either by direct contact with an infected human or animal or their faeces, or indirectly through contaminated food or water. Contamination of food crops and source water with faeces from livestock is an important mechanism of zoonotic transmission for C. parvum, as well as children’s farm visits or exposure to animal dung during outdoor recreation. Sporadic infections occur as well as outbreaks of disease. Cryptosporidium spreads proficiently in settings without adequate sanitation and hygiene. The epidemiology of the parasite can be explained by a number of key intrinsic characteristics. Oocysts are immediately infectious on excretion in the faeces, are shed in high numbers (up to 109 per stool), and can be passed for as long as two months after diarrhoea has stopped. The infectious dose is low (as few as 10 oocysts for some C. hominis and C. parvum strains) and oocysts can remain infectious in the environment for ≥6 months if kept moist (for example, in damp soil) and resist disinfection (including normal chlorine-based disinfection). Oocysts can survive in properly chlorinated recreational water for ≥10 days. In addition, the extended incubation period (mean: 7 days; normal range: 3–12 days) allows transmission to continue for days before public health officials detect an outbreak.
Cryptosporidium
Dongyou Liu in Laboratory Models for Foodborne Infections, 2017
During asexual reproduction, sporozoites multiply several times; and in subsequent sexual reproduction, sporozoites form oocysts (via trophozoites and merozoites) at the luminal apex of the enterocytes. The newly formed oocysts gather in an extracytoplasmatic parasitophorous vacuole whose membrane is made from the enteric epithelium. It is notable that while about 80% of oocysts have a thicker, strong wall and are shed in the feces and become immediately infective, the remainder 20% of oocysts have a thin, incomplete wall, rupture in the intestine, and release four infectious sporozoites, resulting in a new cycle of infection (endogenous autoinfection). The autoinfection allows Cryptosporidium to sporulate and persist within the same host indefinitely, accounting for the severe chronic forms of cryptosporidiosis in immunocompromised persons in the absence of exogenous reinfection. In respiratory cryptosporidiosis, as seen in immune-deficient patients, the infective oocysts spread via nasal secretions into the environment [1,2].
Novel treatment strategies and drugs in development for cryptosporidiosis
Published in Expert Review of Anti-infective Therapy, 2018
Miguel A Chavez, A Clinton White
Cryptosporidium is a known pathogen with worldwide distribution that can cause diarrheal disease in healthy and immunosuppressed individuals, with considerable impact on children. Nitazoxanide is approved by the FDA for treatment of cryptosporidiosis but was not significantly effective in AIDS patients. There is a clear need for potent novel drugs that hopefully will become new alternatives against the treatment of cryptosporidiosis. Promising novel compounds, improvements of existing regimens, and identification of anticryptosporidial activity of existing FDA-approved drugs are all encouraging for the near future. In addition, genetically manipulation of Cryptosporidium is likely to reveal new molecular targets [59]. Overall, most of the new compounds were able to show some efficacy in vitro, in vivo, or both. Some compounds have already proven effective in large animal models. The challenge now is to obtain the best candidates for clinical studies. We have found, however, heterogeneity among studies in in vitro and in vivo models, making comparison difficult. Thus, standardization is a necessity as part of the efforts to obtain new alternatives for treatment of cryptosporidiosis.
Novel drug targets for treatment of cryptosporidiosis
Published in Expert Opinion on Therapeutic Targets, 2020
Beilin Wang, Alejandro Castellanos-Gonzalez, A. Clinton White Jr
Cryptosporidium species have been long recognized as important causes of diarrheal disease in compromised hosts and water-born epidemics for over 35 years. Nitazoxanide was approved treatment for cryptosporidiosis in 2003, but it has performed poorly in compromised hosts (including HIV and transplant patients) as well as malnourished children. Recent epidemiologic studies have highlighted the important role of endemic cryptosporidiosis as a cause of morbidity and mortality in young children in resource-limited areas. These studies have finally stimulated interest in drug development for human cryptosporidiosis, including the development of a target product profile. Two distinct approaches have been used in drug development. Some groups have identified targets for chemotherapy and attempted to develop small molecule to address those targets. Other groups have focused on phenotypic screening of libraries of compounds, including repurposing of compounds developed for other indications. Both approaches have progressed rapidly from hits to lead compounds, to studies in rodent and large animal models.
Cryptosporidium infection among people living with HIV/AIDS in Ethiopia: a systematic review and meta-analysis
Published in Pathogens and Global Health, 2020
Mehdi Mohebali, Yonas Yimam, Ambachew Woreta
Cryptosporidium is a ubiquitous protozoan parasite of humans and a wide range of animals [7]. Globally, the majority of human Cryptosporidium infections are caused by Cryptosporidium hominis and Cryptosporidium parvum: however, Cryptosporidium meleagridis, Cryptosporidium felis, Cryptosporidium canis, Cryptosporidium muris, Cryptosporidium suis, and Cryptosporidium andersoni were also infrequently isolated from humans [8–10]. Cryptosporidium is transmitted mainly by the fecal-oral route. Human to human (anthroponotic) as well as animal to human (zoonotic) transmissions have also been documented. Though cryptosporidiosis has a worldwide distribution, its occurrence is higher in low-income countries with limited access to the necessary infrastructure and potable water. Consequently, people are left struggling with the necessary facilities to prevent food and water contaminated by infective oocysts [11]. Cryptosporidium usually causes asymptomatic or self-limiting diarrhea in healthy immunocompetent persons; however, it can progress to chronic diarrhea in immunocompromised individuals, including PLWHA [7]. This may results in significant morbidity and mortality if appropriate measures are not promptly instituted [12].
Related Knowledge Centers
- Cryptosporidiosis
- Cyclospora Cayetanensis
- Loperamide
- Malaria
- Nitazoxanide
- Parasitism
- Plasmodium
- Diarrhea
- Zinc Deficiency
- Acid-Fastness