Submitted to: Transactions of the Royal Society of Tropical Medicine and Hygiene
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/13/2007
Publication Date: 4/1/2007
Citation: Bushen, O.Y., Kohli, A., Pinkerton, R.C., Newman, R.D., Fayer, R., Lima, A.A., Guerrant, M.D. 2006. Heavy Cryptosporidial infections in children in Northeast Brazil: Comparison of C. hominis and C.parvum. Transactions of the Royal Society of Tropical Medicine and Hygiene. 101(4):378-384. Interpretive Summary: Cryptosporidiosis, caused by various species of the protozoan parasite Cryptosporidium, is an important infectious diarrheal disease in humans and animals worldwide. However, little is known of the severity of illness or long term health effects caused by different species of Cryptosporidium. A study of 157 children living in a favela in Fortaleza, Brazil was conducted over a period of 5 years to determine if differences in the severity of illness were related to infection with different species of the parasite. It was found that more children were infected, greater numbers of parasites were excreted, and growth was more retarded from Cryptosporidium hominis infections than from Cryptosporidium parvum, even in asymptomatic children. The underlying reason for these differences was not determined.
Technical Abstract: Cryptosporidium is an important cause of infectious diarrhea worldwide, but little is known about the course of illness when infected with different species. Over 5 years Cryptosporidium was identified in stools of 58 of 157 children, 40 and 42 were available for quantification and speciation respectively. Oocyst counts were higher among symptomatic children (p =0.002). Although neither symptoms nor length of diarrhea differed between species, those with C. hominis shed significantly more oocysts, 3.7 vs. 1.7 x 106 (p = 0.001). However, heavier C. parvum shedding was significantly associated with symptoms (p=0.004), and symptomatic C. parvum infected children were significantly more likely than asymptomatic children to be lactoferrin positive (p=0.004). HAZ scores showed significant declines within 3 months of infection for both C. hominis (p=.028) and C. parvum (p=.001) infected children. In the 3-6 month period after infection however, only C.hominis infected children continued to demonstrate declining HAZ, where asymptomatic children showed even greater declines (p=0.01). C. hominis is more common than C. parvum in favela children, and is associated with heavier infections and greater growth shortfalls, even without symptoms.