Cryptosporidium hominis: Difference between revisions
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Cryptosporidium hominis
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+ | *A member of the [[Cryptosporidium species]] which causes diarrheal disease in humans |
â | * |
+ | *Similar to [[Cryptosporidium parvum]] which typically infects cows, but can also infect humans |
â | == |
+ | ==Background== |
â | === |
+ | ===Microbiology=== |
â | * |
+ | *Protozoan parasite in the genus [[Cryptosporidium species|''Cryptosporidium'']] |
â | === |
+ | ===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 | ** |
+ | **Daycares (more common than [[Giardia]]) |
â | ** |
+ | **Also seen with petting zoos and cider |
â | ** |
+ | **Higher rates of transmission in MSM |
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 |
â | === |
+ | ===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) |
â | === |
+ | ===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 |
â | == |
+ | ==Clinical Manifestations== |
â | * |
+ | *Incubation period [[Usual incubation period::7 days]] (range [[Incubation period range::1 to 30 days]]) |
â | === |
+ | ===Immunocompetent adults=== |
â | * |
+ | *Associated with waterborne outbreaks, travel, animal contacts, or child contacts |
â | * |
+ | *Watery (to mucoid) diarrhea and malabsorption, more lower bowel symptoms |
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 |
â | === |
+ | ===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 |
â | === |
+ | ===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 |
â | === |
+ | ===Other immunocompromised patients=== |
â | * |
+ | *May present similarly to HIV |
â | * |
+ | *Includes solid organ transplant, hematopoietic stem cell transplant, and hyper-IgM syndrome |
â | == |
+ | ==Diagnosis== |
â | * |
+ | *Stool microscopy |
â | ** |
+ | **Seen on modified acid-fast staining (70% sensitive) |
â | ** |
+ | **Can do immunofluorescence as well (more sensitive) |
â | * |
+ | *Stool antigen |
â | * |
+ | *PCR |
â | == |
+ | ==Management== |
â | * |
+ | *Supportive care, including fluids and antimotility agents like loperamide |
â | * |
+ | *In immunocompetent hosts: [[Is treated by::nitazoxanide]] 500 mg po tid for 3 days |
â | * |
+ | *In severely immunocompromised patients, may not be curable without reversing immunosuppression |
{{DISPLAYTITLE:''Cryptosporidium hominis''}} |
{{DISPLAYTITLE:''Cryptosporidium hominis''}} |
Revision as of 09:57, 5 August 2020
- A member of the Cryptosporidium species 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
- Supportive care, including fluids and antimotility agents like loperamide
- In immunocompetent hosts: nitazoxanide 500 mg po tid for 3 days
- In severely immunocompromised patients, may not be curable without reversing immunosuppression