Cryptosporidium hominis: Difference between revisions

Latest revision as of 14:17, 30 August 2023

A member of the Cryptosporidium which causes diarrheal disease in humans
Similar to Cryptosporidium parvum which typically infects cows, but can also infect humans

Background

Microbiology

Protozoan parasite in the genus Cryptosporidium

Epidemiology

Infects humans, but can also infect cows, mice, gnotobiotic pigs, and rarely other species
Transmitted fecal-oral via environmental contamination (such as recreational water), and can be spread person-to-person
- Outbreaks are most commonly associated with drinking water, even when properly treated
- Daycares (more common than Giardia)
- Also seen with petting zoos and cider
- Higher rates of transmission in MSM
Resistant to chlorination and can survive in the environment up to 6 months
In developing countries, primarily affects children less than 5 years
In developed countries, primarily affects adults, related to travel
- Causes 2-6% of traveller's diarrhea

Life Cycle

Host ingests an oocyst (needing as few as 10 to cause disease)
The oocyst excyst in the stomach and proximal small bowel, releasing four sporozoites
Sporozoites bind to the intestinal epithelial cells and becomes vacuolized by the host cell membrane
In the parasitophorous vacuole, they reproduce asexually into further sporozoites, which divide into type I meronts
The type I meronts mature and release motile merozoites
The merozoites again attach to the intestinal epithelial cells
Merozoites then either reproduce asexually, as above, or sexually
- Sexual reproduction involves a macrogamont and microgamont, which form a zygote
- The zygote develops into an oocyst which contains four sporozoites
Oocysts may be involved in auto-inoculation (if thin-walled) or environmental contamination (if thick-walled)

Pathophysiology

Infection activates nuclear factor kappa B (NF-κB), which activates a large response
Infection results in increased permeability of the intestinal mucosa
T-cells are involved, with chronic infection in patients who are CD4-deplete

Clinical Manifestations

Incubation period 7 days (range 1 to 30 days)

Immunocompetent adults

Associated with waterborne outbreaks, travel, animal contacts, or child contacts
Watery (to mucoid) diarrhea and malabsorption, more lower bowel symptoms
May also have abdominal cramping, nausea or vomiting, and fever
Lasts 5 to 14 days, but up to 100
However, recurs in about 40% and can become an intermittent or chronic diarrhea similar to irritable bowel syndrome

Childhood diarrhea

Causes about 10-15% of acute childhood diarrhea in developing countries
Presents with watery diarrhea, cramps, and nausea and vomiting
May also have fever, cough, dyspnea, and foul-smelling stool
Can turn into chronic diarrhea and malabsorption

People living with HIV

Most cases are asymptomatic or mild and self-limited
Chronic infection more common in HIV with CD4 <150, lasting up to 6 months
May also involve extraintestinal cryptosporidiosis, such as biliary or respiratory disease

Other immunocompromised patients

May present similarly to HIV
Includes solid organ transplant, hematopoietic stem cell transplant, and hyper-IgM syndrome

Diagnosis

Stool microscopy
- Seen on modified acid-fast staining (70% sensitive)
- Can do immunofluorescence as well (more sensitive)
Stool antigen
PCR

Management

For immunocompetent hosts, supportive care, including fluids and antimotility agents like loperamide, is generally adequate
In immunocompetent hosts: nitazoxanide 500 mg p.o. twice daily for 3 days
- Not approved in Canada, needs SAP
In severely immunocompromised patients, may not be curable without reversing immunosuppression
- Can treat with nitazoxanide 500 to 1000 mg p.o. twice daily for 14+ days
Other medications
- Paromomycin likely inferior to nitazoxanide
  - Dose is 500 mg p.o. three to four times daily for 14 days
- Macrolides likely ineffective
- Rifaximin and albendazole need more study

@@ Line 1: / Line 1: @@
-* A member of the [[Cryptosporidium species]] which causes diarrheal disease in humans
+*A member of the [[Cryptosporidium]] which causes diarrheal disease in humans
-* Similar to [[Cryptosporidium parvum]] which typically infects cows, but can also infect humans
+*Similar to [[Cryptosporidium parvum]] which typically infects cows, but can also infect humans
-== Background ==
+==Background==
-=== Microbiology ===
+===Microbiology===
-* Protozoan parasite in the genus [[Cryptosporidium species|''Cryptosporidium'']]
+*Protozoan parasite in the genus [[Cryptosporidium species|''Cryptosporidium'']]
-=== Epidemiology ===
+===Epidemiology===
-* Infects humans, but can also infect cows, mice, gnotobiotic pigs, and rarely other species
+*Infects humans, but can also infect cows, mice, gnotobiotic pigs, and rarely other species
-* Transmitted fecal-oral via environmental contamination (such as recreational water), and can be spread person-to-person
+*Transmitted fecal-oral via environmental contamination (such as recreational water), and can be spread person-to-person
-** Outbreaks are most commonly associated with drinking water, even when properly treated
+**Outbreaks are most commonly associated with drinking water, even when properly treated
-** Daycares (more common than [[Giardia]]
+**Daycares (more common than [[Giardia]])
-** Also seen with petting zoos and cider
+**Also seen with petting zoos and cider
-** Higher rates of transmission in MSM
+**Higher rates of transmission in MSM
-* Resistant to chlorination and can survive in the environment up to 6 months
+*Resistant to chlorination and can survive in the environment up to 6 months
-* In developing countries, primarily affects children less than 5 years
+*In developing countries, primarily affects children less than 5 years
-* In developed countries, primarily affects adults, related to travel
+*In developed countries, primarily affects adults, related to travel
-** Causes 2-6% of traveller's diarrhea
+**Causes 2-6% of traveller's diarrhea
-=== Life Cycle ===
+===Life Cycle===
-* Host ingests an '''oocyst''' (needing as few as 10 to cause disease)
+*Host ingests an '''oocyst''' (needing as few as 10 to cause disease)
-* The oocyst excyst in the stomach and proximal small bowel, releasing four '''sporozoites'''
+*The oocyst excyst in the stomach and proximal small bowel, releasing four '''sporozoites'''
-* Sporozoites bind to the intestinal epithelial cells and becomes vacuolized by the host cell membrane
+*Sporozoites bind to the intestinal epithelial cells and becomes vacuolized by the host cell membrane
-* In the '''parasitophorous vacuole''', they reproduce asexually into further sporozoites, which divide into '''type I meronts'''
+*In the '''parasitophorous vacuole''', they reproduce asexually into further sporozoites, which divide into '''type I meronts'''
-* The type I meronts mature and release motile '''merozoites'''
+*The type I meronts mature and release motile '''merozoites'''
-* The merozoites again attach to the intestinal epithelial cells
+*The merozoites again attach to the intestinal epithelial cells
-* Merozoites then either reproduce asexually, as above, or sexually
+*Merozoites then either reproduce asexually, as above, or sexually
-** Sexual reproduction involves a '''macrogamont''' and '''microgamont''', which form a '''zygote'''
+**Sexual reproduction involves a '''macrogamont''' and '''microgamont''', which form a '''zygote'''
-** The zygote develops into an oocyst which contains four sporozoites
+**The zygote develops into an oocyst which contains four sporozoites
-* Oocysts may be involved in auto-inoculation (if thin-walled) or environmental contamination (if thick-walled)
+*Oocysts may be involved in auto-inoculation (if thin-walled) or environmental contamination (if thick-walled)
-=== Pathophysiology ===
+===Pathophysiology===
-* Infection activates nuclear factor kappa B (NF-κB), which activates a large response
+*Infection activates nuclear factor kappa B (NF-κB), which activates a large response
-* Infection results in increased permeability of the intestinal mucosa
+*Infection results in increased permeability of the intestinal mucosa
-* T-cells are involved, with chronic infection in patients who are CD4-deplete
+*T-cells are involved, with chronic infection in patients who are CD4-deplete
-== Clinical Presentation ==
+==Clinical Manifestations==
-* Incubation period 7 days (range 1 to 30 days)
+*Incubation period [[Usual incubation period::7 days]] (range [[Incubation period range::1 to 30 days]])
-=== Immunocompetent adults ===
+===Immunocompetent adults===
-* Associated with waterborne outbreaks, travel, animal contacts, or child contacts
+*Associated with waterborne outbreaks, travel, animal contacts, or child contacts
-* Watery (to mucoid) diarrhea and malabsorption, more lower bowel symptoms
+*Watery (to mucoid) diarrhea and malabsorption, more lower bowel symptoms
-* May also have abdominal cramping, nausea or vomiting, and fever
+*May also have abdominal cramping, nausea or vomiting, and fever
-* Lasts 5 to 14 days, but up to 100
+*Lasts 5 to 14 days, but up to 100
-* However, recurs in about 40% and can become an intermittent or chronic diarrhea similar to irritable bowel syndrome
+*However, recurs in about 40% and can become an intermittent or chronic diarrhea similar to irritable bowel syndrome
-=== Childhood diarrhea ===
+===Childhood diarrhea===
-* Causes about 10-15% of acute childhood diarrhea in developing countries
+*Causes about 10-15% of acute childhood diarrhea in developing countries
-* Presents with watery diarrhea, cramps, and nausea and vomiting
+*Presents with watery diarrhea, cramps, and nausea and vomiting
-* May also have fever, cough, dyspnea, and foul-smelling stool
+*May also have fever, cough, dyspnea, and foul-smelling stool
-* Can turn into chronic diarrhea and malabsorption
+*Can turn into chronic diarrhea and malabsorption
-=== People living with HIV ===
+===People living with HIV===
-* Most cases are asymptomatic or mild and self-limited
+*Most cases are asymptomatic or mild and self-limited
-* Chronic infection more common in HIV with CD4 <150, lasting up to 6 months
+*Chronic infection more common in HIV with CD4 <150, lasting up to 6 months
-* May also involve extraintestinal cryptosporidiosis, such as biliary or respiratory disease
+*May also involve extraintestinal cryptosporidiosis, such as biliary or respiratory disease
-=== Other immunocompromised patients ===
+===Other immunocompromised patients===
-* May present similarly to HIV
+*May present similarly to HIV
-* Includes solid organ transplant, hematopoietic stem cell transplant, and hyper-IgM syndrome
+*Includes solid organ transplant, hematopoietic stem cell transplant, and hyper-IgM syndrome
-== Diagnosis ==
+==Diagnosis==
-* Stool microscopy
+*Stool microscopy
-** Seen on modified acid-fast staining (70% sensitive)
+**Seen on modified acid-fast staining (70% sensitive)
-** Can do immunofluorescence as well (more sensitive)
+**Can do immunofluorescence as well (more sensitive)
-* Stool antigen
+*Stool antigen
-* PCR
+*PCR
-== Management ==
+==Management==
-* Supportive care, including fluids and antimotility agents like loperamide
+*For immunocompetent hosts, supportive care, including fluids and antimotility agents like loperamide, is generally adequate
-* In immunocompetent hosts: [[Is treated by::nitazoxanide]] 500 mg po tid for 3 days
+*In immunocompetent hosts: [[Is treated by::nitazoxanide]] 500 mg p.o. twice daily for 3 days
+**Not approved in Canada, needs SAP
-* In severely immunocompromised patients, may not be curable without reversing immunosuppression
+*In severely immunocompromised patients, may not be curable without reversing immunosuppression
+**Can treat with [[nitazoxanide]] 500 to 1000 mg p.o. twice daily for 14+ days
+*Other medications
+**[[Paromomycin]] likely inferior to nitazoxanide
+***Dose is 500 mg p.o. three to four times daily for 14 days
+**[[Macrolides]] likely ineffective
+**[[Rifaximin]] and [[albendazole]] need more study
+== Further Reading ==
-{{DISPLAYTITLE:''Cryptosporidium hominis''}}
+* Treatment of human intestinal cryptosporidiosis: A review of published clinical trials. Int J Parasitol. 2021;17:128-138: doi:[https://doi.org/10.1016/j.ijpddr.2021.09.001 10.1016/j.ijpddr.2021.09.001]{{DISPLAYTITLE:''Cryptosporidium hominis''}}
 [[Category:Protozoa]]
 [[Category:Gastrointestinal infections]]