Protozoa - Giardia and Cryptosporidium
The microorganisms giardia and cryptosporidium have become the two largest concerns for the water treatment industry, due to their resistance to chlorine disinfection. Recent, widespread outbreaks of disease caused by these two microorganisms have infected thousands of individuals, causing severe gastrointestinal disorders. The most severe epidemic case occurred in Wisconsin in 1993 when 400,000 people were infected by cryptosporidium, causing more than 60 deaths.
Giardia lamblia is a tiny protozoan that makes its
way into surface water sources primarily through the contamination
of water via animal feces. Cryptiopsoridium is a protozoan,
similar in size and effect to giardia, which also enters
drinking water sources through animal fecal matter. Protozoa
are uniquely designed to survive in water. They are larger in
size than either bacteria or viruses. Some species can secrete
a protective covering and enter a resting stage called a cyst
(Lingireddy, 2002). These cysts are then protected from disinfection,
and they continue to be powerful disease-causing pathogens.
Scientists presume that giardia and crpytosporidium have always maintained a presence in drinking water sources. Due to recent improvements in sanitation, most people now have a low immunity to the protozoa. This low immunity makes them all the more vulnerable to the effects of the microorganisms when sanitation breaks down.
Exposure to giardia and cryptosporidium can cause symptoms similar to the flu. Severe diarrhea, vomiting, abdominal pain, and/or fever often accompany the diseases. Though the majority of people recover from the disease within a week, individuals with low or developing immune systems (AIDS patients, children, and the elderly) can die from the effects of exposure to these pathogenic protozoa. There is currently no disinfection technique that can eliminate the presence of these two microorganisms in drinking water.