TY - JOUR
T1 - Pathogenic Mechanisms of Cryptosporidium and Giardia
AU - Certad, Gabriela
AU - Viscogliosi, Eric
AU - Chabé, Magali
AU - Cacciò, Simone M.
PY - 2017/7/1
Y1 - 2017/7/1
N2 - Intestinal protozoa are important etiological agents of diarrhea, particularly in children, yet the public health risk they pose is often neglected. Results from the Global Enteric Multicenter Study (GEMS) showed that Cryptosporidium is among the leading causes of moderate to severe diarrhea in children under 2 years. Likewise, Giardia infects approximately 200 million individuals worldwide, and causes acute diarrhea in children under 5 years. Despite this recognized role as pathogens, the question is why and how these parasites cause disease in some individuals but not in others. This review focuses on known pathogenic mechanisms of Cryptosporidium and Giardia, and infection progress towards disease. Infection by Cryptosporidium or Giardia can result in symptoms in some individuals but can lead to an asymptomatic state in others. Common effects on host epithelial cells include disruption of the mucus layer, attachment to (Giardia and Cryptosporidium) and/or invasion of epithelial cells (Cryptosporidium), release of effector molecules into the host cell cytoplasm and secretion of toxins. However, pathogenic mechanisms are not identical. For instance, Giardia is the only unicellular eukaryote that escapes the host immune reaction in the gut by antigenic variation. While both protozoa cause disruption of tight junctions, only C. parvum has the ability to induce gastrointestinal cancer linked to cytoskeleton alterations, at least in an animal model. To fully understand their pathogenicity, it is essential to consider the complex ecologic interactions of these protozoa with gut microbiota, as well as nutritional and host-related factors.
AB - Intestinal protozoa are important etiological agents of diarrhea, particularly in children, yet the public health risk they pose is often neglected. Results from the Global Enteric Multicenter Study (GEMS) showed that Cryptosporidium is among the leading causes of moderate to severe diarrhea in children under 2 years. Likewise, Giardia infects approximately 200 million individuals worldwide, and causes acute diarrhea in children under 5 years. Despite this recognized role as pathogens, the question is why and how these parasites cause disease in some individuals but not in others. This review focuses on known pathogenic mechanisms of Cryptosporidium and Giardia, and infection progress towards disease. Infection by Cryptosporidium or Giardia can result in symptoms in some individuals but can lead to an asymptomatic state in others. Common effects on host epithelial cells include disruption of the mucus layer, attachment to (Giardia and Cryptosporidium) and/or invasion of epithelial cells (Cryptosporidium), release of effector molecules into the host cell cytoplasm and secretion of toxins. However, pathogenic mechanisms are not identical. For instance, Giardia is the only unicellular eukaryote that escapes the host immune reaction in the gut by antigenic variation. While both protozoa cause disruption of tight junctions, only C. parvum has the ability to induce gastrointestinal cancer linked to cytoskeleton alterations, at least in an animal model. To fully understand their pathogenicity, it is essential to consider the complex ecologic interactions of these protozoa with gut microbiota, as well as nutritional and host-related factors.
KW - Cryptosporidium
KW - Giardia
KW - parasite–host factor interaction
KW - virulence
UR - http://www.scopus.com/inward/record.url?scp=85015767750&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85015767750&partnerID=8YFLogxK
U2 - 10.1016/j.pt.2017.02.006
DO - 10.1016/j.pt.2017.02.006
M3 - Review article
C2 - 28336217
AN - SCOPUS:85015767750
VL - 33
SP - 561
EP - 576
JO - Trends in Parasitology
JF - Trends in Parasitology
SN - 1471-4922
IS - 7
ER -