Sarcocystosis is an uncommonly reported parasitic infection which has not been listed as an opportunistic infection as infections caused by other coccidia (Cryptosporidium, Cystoisospora). Epidemiology and clinical impact of human infections by Sarcocystis are largely unknown and reports continue to be rare.
Unlike other coccidia, sarcocystosis is not considered an opportunistic infection and evidence linking sarcocystosis with AIDS is limited with only three cases published globally:
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I am interested in knowing of other reports (even not officially published resources) of Sarcocystis infections in immunocompromised patients. Thanks
Hi!
I had downloaded that review article but missed checking the case of sarcocystosis in an HIV-infected person reported in there.
Thanks!
This comment is about the significance of the presence of Sarcocystis in someone who is immunocompromised. The reported occurrence of Sarcocystis in the gut (a finding in one of the 3 publications referenced in previous postings related to this question) is not evidence that it was opportunistic. In another of the 3 papers, Fig. 1 looks like an Isospora belli oocyst. It is not an oocyst of Sarcocystis. Likewise, Fig. 2 (whatever it might be) is not a Sarcocystis sporocyst. As regards the 3rd article, some things (despite the molecular results) do not fit in with current understanding of aspects of the life cycle of Sarcocystis. These are the suggested replication of Sarcocystis in gallbladder epithelium (epithelial cells not being the organism’s historically known, classical site of occurrence) and the apparent absence, microscopically, of parasites in the lamina propria. I am not saying that Sarcocystis cannot be an opportunistic pathogen in HIV/AIDS (it is not an obvious one, though), but none of these 3 publications have shown that it is. Furthermore, it should be noted that isosporiasis was diagnosed in the patients who were the subjects of the 2nd and 3rd publications. This complicates the issue parasitologically. However, "intestinal" stages of Sarcocystis have, indeed, been found outside the gut in primates. This was first recognized in the 1970s (Markus 1974; 1978), which fact has been lost sight of subsequently. To understand the situation, the detailed story in Markus (1978) should be read. It appears between the bottom of p. 172 and p. 174. The last paragraph, on p. 174, of the section concerned is particularly important. REFERENCES: Markus, M.B. et al. 1974. The coccidial nature and life-cycle of Sarcocystis. Journal of Tropical Medicine and Hygiene 77: 248-259; Markus, M.B. 1978. Sarcocystis and sarcocystosis in domestic animals and man. Advances in Veterinary Science and Comparative Medicine 22: 159-193.
Thanks for the input, Miles. I definitely agree with you. The presence of Sarcocystis is not indicative of being opportunistic just because the host is immunocompromised. As you said, Sarcocystis might be another coccidian parasite with an opportunistic pattern but not an obvious one, though. Unfortunately, this issue could not be clarified until a epidemiological or population-based study with several more cases of sarcocystosis is conducted (which is not the case for this coccidia).
Could you share a pdf of your articles because I could not find them in the databases to which I have access.
Thanks
Thanks, Kevin. I can't find them online either. However, I have hard copies of both and will be able to produce scanned copies late this week or next week.
Sarcocystis species are intracellular protozoan parasites with an intermediate-definitive host life cycle based on a prey-predator relationship. Asexual stages develop in intermediate hosts after they ingest the oocyst stage from definitive-host feces and terminate with the formation of intramuscular cysts (sarcocysts). Sarcocysts in meat eaten by a definitive host initiate sexual stages in the intestine that terminate in oocysts excreted in the feces. Most Sarcocystis species infect specific hosts or closely related host species. For example, humans and some primates are definitive hosts for Sarcocystis hominis and S. suihominis after eating raw meat from cattle and pigs, respectively. The prevalence of intestinal sarcocystosis in humans is low and is only rarely associated with illness, except in volunteers who ingest large numbers of sarcocysts. Cases of infection of humans as intermediate hosts, with intramuscular cysts, number less than 100 and are of unknown origin. The asexual stages, including sarcocysts, can stimulate a strong inflammatory response. Livestock have suffered acute debilitating infections, resulting in abortion and death or chronic infections with failure to grow or thrive. This review provides a summary of Sarcocystis biology, including its morphology, life cycle, host specificity, prevalence, diagnosis, treatment, and prevention strategies, for human and food animal infections.
Well, the text you wrote is an exact extract from a Sarcocystis review by Ronald Fayer in 2004. The epidemilogy panorama has changed a little bit, there are newer reviews (even an update by the same author in 2015), and cases seem to be not so infrequent as one decade ago.
The attached link below is a study regarding the prevalence and genetic characterization of Cryptosporidium spp. and Cystoisospora belli in HIV-infected patients. It includes information how sarcocystis human infections affects in immunocompromised individuals. I hope this may help you.
Article Prevalence and genetic characterization of Cryptosporidium s...
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