Cryptosporidium hominis: Difference between revisions
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Cryptosporidium hominis
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â | * |
+ | *A member of the [[Cryptosporidium]] which causes diarrheal disease in humans |
â | * |
+ | *Similar to [[Cryptosporidium parvum]] which typically infects cows, but can also infect humans |
â | == |
+ | ==Background== |
+ | ===Microbiology=== |
||
â | * Protozoan parasite in the genus [[Cryptosporidium species|''Cryptosporidium'']] |
||
+ | *Protozoan parasite in the genus [[Cryptosporidium species|''Cryptosporidium'']] |
||
â | == Epidemiology == |
||
+ | ===Epidemiology=== |
||
â | * Infects humans, but can also infect cows, mice, gnotobiotic pigs, and rarely other species |
||
â | * Transmitted fecal-oral via environmental contamination (such as recreational water), and can be spread person-to-person |
||
â | ** Outbreaks are most commonly associated with drinking water, even when properly treated |
||
â | * Resistant to chlorination and can survive in the environment up to 6 months |
||
â | * In developing countries, primarily affects children less than 5 years |
||
â | * In developed countries, primarily affects adults, related to travel |
||
â | ** Causes 2-6% of traveller's diarrhea |
||
+ | *Infects humans, but can also infect cows, mice, gnotobiotic pigs, and rarely other species |
||
â | == Life Cycle == |
||
+ | *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=== |
||
â | * Host ingests an '''oocyst''' (needing as few as 10 to cause disease) |
||
â | * The oocyst excyst in the stomach and proximal small bowel, releasing four '''sporozoites''' |
||
â | * Sporozoites bind to the intestinal epithelial cells and becomes vacuolized by the host cell membrane |
||
â | * In the '''parasitophorous vacuole''', they reproduce asexually into further sporozoites, which divide into '''type I meronts''' |
||
â | * The type I meronts mature and release motile '''merozoites''' |
||
â | * The merozoites again attach to the intestinal epithelial cells |
||
â | * Merozoites then either reproduce asexually, as above, or sexually |
||
â | ** Sexual reproduction involves a '''macrogamont''' and '''microgamont''', which form a '''zygote''' |
||
â | ** The zygote develops into an oocyst which contains four sporozoites |
||
â | * Oocysts may be involved in auto-inoculation (if thin-walled) or environmental contamination (if thick-walled) |
||
+ | *Host ingests an '''oocyst''' (needing as few as 10 to cause disease) |
||
â | == Pathophysiology == |
||
+ | *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=== |
||
â | * Infection activates nuclear factor kappa B (NF-ÎşB), which activates a large response |
||
â | * Infection results in increased permeability of the intestinal mucosa |
||
â | * T-cells are involved, with chronic infection in patients who are CD4-deplete |
||
+ | *Infection activates nuclear factor kappa B (NF-ÎşB), which activates a large response |
||
â | == Clinical Presentation == |
||
+ | *Infection results in increased permeability of the intestinal mucosa |
||
+ | *T-cells are involved, with chronic infection in patients who are CD4-deplete |
||
+ | ==Clinical Manifestations== |
||
â | * Incubation period 7 days (range 1 to 30 days) |
||
+ | *Incubation period [[Usual incubation period::7 days]] (range [[Incubation period range::1 to 30 days]]) |
||
â | === Immunocompetent adults === |
||
+ | ===Immunocompetent adults=== |
||
â | * Associated with waterborne outbreaks, travel, animal contacts, or child contacts |
||
â | * Watery (to mucoid) diarrhea and malabsorption |
||
â | * May also have abdominal cramping, nausea or vomiting, and fever |
||
â | * Lasts 5 to 14 days, but up to 100 |
||
â | * However, recurs in about 40% and can become an intermittent or chronic diarrhea similar to irritable bowel syndrome |
||
+ | *Associated with waterborne outbreaks, travel, animal contacts, or child contacts |
||
â | === Childhood diarrhea === |
||
+ | *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=== |
||
â | * Causes about 10-15% of acute childhood diarrhea in developing countries |
||
â | * Presents with watery diarrhea, cramps, and nausea and vomiting |
||
â | * May also have fever, cough, dyspnea, and foul-smelling stool |
||
â | * Can turn into chronic diarrhea and malabsorption |
||
+ | *Causes about 10-15% of acute childhood diarrhea in developing countries |
||
â | === People living with HIV === |
||
+ | *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=== |
||
â | * Most cases are asymptomatic or mild and self-limited |
||
â | * Chronic infection more common in HIV with CD4 <150, lasting up to 6 months |
||
â | * May also involve extraintestinal cryptosporidiosis, such as biliary or respiratory disease |
||
+ | *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=== |
||
â | {{DISPLAYTITLE:''Cryptosporidium hominis''}} |
||
+ | |||
+ | *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: [[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 |
||
+ | **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 == |
||
+ | |||
+ | * 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:Protozoa]] |
||
[[Category:Gastrointestinal infections]] |
[[Category:Gastrointestinal infections]] |
Latest revision as of 10:17, 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-ÎşB), 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
- Paromomycin likely inferior to nitazoxanide
Further Reading
- Treatment of human intestinal cryptosporidiosis: A review of published clinical trials. Int J Parasitol. 2021;17:128-138: doi:10.1016/j.ijpddr.2021.09.001