Which organisms should be considered in a waterborne outbreak of diarrheal disease?

Choosing Giardia lamblia and Cryptosporidium spp. is appropriate for a waterborne outbreak of diarrheal disease because both are well-known protozoan pathogens that are commonly associated with contaminated water sources. Giardia lamblia causes giardiasis, which manifests as diarrhea and gastrointestinal distress, and it is frequently transmitted through drinking water or recreational water that has been contaminated with fecal matter.

Cryptosporidium spp. also are significant causes of gastrointestinal illness, known as cryptosporidiosis, characterized by watery diarrhea. Similar to Giardia, Cryptosporidium is resistant to chlorine disinfection, making it particularly problematic in waterborne outbreaks where sewage contamination occurs.

In contrast, while Endolimax nana and Entamoeba histolytica are parasitic organisms, Entamoeba histolytica is the only one directly linked to diarrheal disease, specifically amoebic dysentery. Endolimax nana, on the other hand, is considered a non-pathogenic intestinal amoeba.

Blastocystis hominis has been associated with gastrointestinal symptoms, but its link to severe diarrheal disease is less clear, and Trichomonas vaginalis primarily causes a sexually transmitted infection rather than a waterborne disease.

Toxoplasma gond