Background. Cryptosporidiosis is an intestinal disease caused by a protozoan parasite called Cryptosporidium. It is also known as “Crypto”. Although Crypto can affect all people, some groups are likely to develop more serious illness. For people with weakened immune systems, symptoms can be severe and could lead to severe or life-threatening illness. Genus Cryptosporidium has two species that mostly cause human infection such as Cryptosporidium parvum (which also infects bovines) and C. hominis. C. parvum inhabits the small intestine. It may also be found in stomach, appendix, colon, rectum and pulmonary tree.
Morphology. The infective form of the parasite is oocyst. The oocyst is spherical or oval and measures about 5 μm in diameter. Oocyst does not stain with iodine and is acid-fast. The wall of the oocysts is thick, but in 20% cases, the wall may be thin. These thin-walled oocysts are responsible for autoinfection.
Epidemiology. It is worldwide in distribution. Prevalence rates reported in large-scale surveys of fecal oocyst excretion generally range from 1-3% in developed countries in Europe and North America. There, most infections are caused by C.hominis, while C.parvum is associated with rural areas and animal contact.
Laboratory Diagnosis. Diagnosis is made by demonstration of the oocysts in feces with stool examination. Modified ZN staining is the method of choice for demonstration of C. parvum in the stool specimen. Indirect fluorescent antibody and ELISA using purified oocysts as antigens have been used to detect circulating antibodies specific to C. parvum.
Pathophysiology. Cryptosporidiosis typically presents with watery diarrhea, includes a combination of increased intestinal permeability, chloride secretion, and malabsorption, which are all thought to be caused by the host response to infection. The symptoms from this disease include watery diarrhea, stomach cramps or pain, dehydration, nausea, vomiting, fever, and weight loss.
References:
Cabada, M.M. Cryptosporidiosis. [Updated: August 24, 2018]. Available from:https://emedicine.medscape.com/article/215490-overview
Centers for Disease Control and Prevention. Parasites – Cryptosporidium (also known as “Crypto”). [Updated: January 23, 2015]Available from: https://www.cdc.gov/parasites/crypto/audience.html
Paniker, C.K.J. Paniker’s Textbook of Medical Parasitology 8thedition. [Revised and Edited by Ghosh, S]. Jaypee Brothers Medical Publisher (P) Ltd., India: 2018.
