ABSTRACT
There are three groups of microorganisms that may travel through porous geologic media: protozoa, bacteria, and viruses. These organisms differ greatly in size and survival in the environment. Each of these groups of organisms have members that are capable of causing disease (pathogenic) in humans and other mammals (Table 9.1). Although transport of bacteria is also important in bioremediation, this section will focus on transport of pathogens. In particular we will emphasize virus transport, since their small size makes them more likely to be transported through the vadose zone. Some Important Human Pathogens That May Be Transported Through the Vadose Zone
Microorganism and Size
Disease
Viruses (0.02–0.10 μm)
Adenoviruses
Respiratory disease
Polioviruses
Poliomyelitis
Echoviruses
Meningitis
Coxsackie viruses
Myocarditis, meningitis
Hepatitis A virus
Infectious hepatitis
Rotaviruses
Diarrhea
Bacteria (0.5–1.0 μm)
Campylobacter fetus
Diarrhea
Escherichia coli (pathogenic)
Diarrhea
Salmonella typhi
Typhoid fever
Shigella spp.
Bacillary dysentery
Vibrio cholerae
Cholera
Protozoans (1.0-12 μm)
Giardia lamblia
Diarrhea
Cryptosporidium spp.
Diarrhea