Challenges in understanding the immunopathogenesis of Cryptosporidium infections in humans

Water and foodborne enteric cryptosporidiosis is a globally emerging public health issue. Although the clinical manifestations of enteric cryptosporidiosis are generally limited to intestinal infection and subsequent diarrhoea, extra-intestinal invasion has also been diagnosed in immunocompromised individuals, particularly in those infected with human immunodeficiency virus (HIV) or AIDS. Due to an inadequate understanding of Cryptosporidium immunopathogenesis in humans, the development of vaccines or therapeutic agents and their application in diseases management is difficult. Current therapeutic measures are not fully effective in the treatment of the disease. Therefore, the implementation of strategies designed to control the chain of cryptosporidiosis transmission (environment ↔ human ↔ food/water ↔ animal) is a critical but challenging issue to public health authorities across the world. Several excellent studies have been done on innate, acquired and mucosal immunity against Cryptosporidium infections using animal models, in vitro human cell lines and human volunteers. However, there are still multiple challenges in understanding the intestinal immune response (immunopathogenesis) to Cryptosporidium infection in humans. This paper reviews recent updates on immunopathogenesis and immune responses to Cryptosporidium infection in humans, while also discussing the current limitations that exist regarding a precise understanding of the immunopathological mechanisms.