Why is parasite sex sexy?

Cryptosporidium is a leading cause of severe diarrheal disease around the world.Recent field research points to parasite sex as the source of hyper-transmissibility fuelling continental sweeps, while new laboratory studies took advantage of Cryptosporidium sex to build powerful experimental tools to understand the parasite and its interaction with the host.In the United States, Cryptosporidium was responsible for one of the largest recorded disease outbreaks, the 1993 Milwaukee incident which infected more than 400,000 residents through contaminated drinking water.To this day half of all U.S. outbreaks associated with recreational water are due to this parasite.Globally, infants and toddlers carry the most severe burden of disease and death, and cryptosporidiosis is a key consequence and cause of chronic malnutrition [1].There are neither efficient drugs nor vaccines, and cryptosporidiosis is an important yet neglected disease of those most vulnerable.Multiple Cryptosporidium species and strains infect humans, and this can occur through water and food contamination, human to human contact, or zoonotically.C. hominis predominates in urban settings, while rural life and exposure to animals increases the incidence of C. parvum, meleagridis, and cuniculus, which are transmitted from cattle, poultry, or rabbits, respectively.The pressure to adapt results in rapid evolution and drives host specificity and speciation.However, what defines a species in Cryptosporidium has been the topic of vigorous discussion, as is the