Cryptosporidiosis and malnutrition in children.

Cryptosporidiosis is caused by Cryptosporidium ssp., an emerging human pathogen. It is one of the most common causes of diarrheal infection in highand low-income countries. Cryptosporidium in healthy people causes self-limiting diarrhoea. This opportunistic parasite often affects children and adults with immune deficiency failures, such as those with HIV/AIDS and malnourished individuals. In these groups, the infection causes severe, chronic and devastating diarrhoea that may lead to life-threatening complications. In addition, the loss of the small intestine microvillus border can lead to malabsorption in patients with diarrhoea (Tzipori and Ward, 2002). Malnutrition is the most important cause of immunodeficiency in children in low-income countries. It affects the child’s immune system and alters the physicochemical characteristics of the intestine; therefore, it causes a significant increase in the pathogenesis of Cryptosporidium. In children suffering from malnutrition, the frequent diarrhoea caused by Cryptosporidium is long-lasting and more severe in comparison with healthy children (Gendrel et al., 2003). Malnutrition increases the susceptibility to cryptosporidiosis, which in turn intensifies the malnutrition. Consequently, a vicious cycle is created that can threaten the patient’s life (Costa et al., 2011). A prospective study in Haitian children aged < 2 years showed that children with acute cryptosporidiosis usually suffered from malnutrition, including vitamin A deficiency. These children often were not breastfed, since breastfeeding plays a protective role against Cryptosporidium infection (Kirkpatrick et al., 2002). Another prospective study of malnourished children in Dhaka denoted that cryptosporidial diarrhoea was significantly more prevalent among children aged 2–5 years (Mondal et al., 2009). Nowadays, Nitazoxanide is the drug of choice in cryptosporidial infection. It is an effective drug for cryptosporidial diarrhoea in immunocompetent people, but in the absence of adequate immune response, especially those with HIV or malnourished children, Nitazoxanide will not be able to eradicate the infection (Costa et al., 2011). In fact, an effective antiparasitic drug is not available for severely malnourished children, so the improvement of nutrition and hydration along with antiparasitic therapy are necessary to treat cryptosporidiosis in children (Costa et al., 2011; Kirkpatrick et al., 2002; Mondal et al., 2009). Clearly, the infection with Cryptosporidium has an adverse effect on the growth and cognitive development of children, which manifest itself more seriously in malnourished children (Kirkpatrick et al., 2002). Thus, it is necessary to monitor children for cryptosporidial infection, especially in malnourished children to avoid adverse effects of the infection on their growth and health.