“Little Boy Blue! Come blow your horn! The sheep’re in the meadow and the cow’s in the corn!” Little Miss Muffin shouted. Shaking her head at the sleeping boy under the haystack, she wandered over to the frog pond. She was thirsty after fleeing from that dreadfully ugly jumping spider and the resulting fall. Her thirst got the better of her, so she plodded to the stream flowing into the pond. She scooped up the clear water with cupped hands. It sparkled in the sunlight. It was clear, far prettier than the scum-covered water of the pond.
Then she remembered. Pulling off her pack, she unzipped it and pulled out a bottle of Potable Aqua iodine tablets and an empty 28 oz. bottle. She filled the bottle with the stream water and dropped in a tablet. After five minutes in the scorching sunshine, she was simply parched and refused to wait the recommended thirty minutes. “The water is clear and came out of that lovely mountain. I’m sure it’s safe.” She chugged the partially sanitized water.
As Miss Muffin quietly sat next to the babbling stream, she noticed a white-tailed deer ease through the tall fragrant grass further upstream. As she paused to sip the cool waters, the doe’s ears perked and her bright eyes scanned the area. Catching sight of Miss Muffin, the doe turned and leaped back into the forest, scattering some fecal pellets on the bank of the stream. Some of them bounced into the water and began floating downstream toward Miss Muffin. “Yuck,” she muttered with a nagging conscience, “Good thing that I use these tablets.”
The refreshing swig of water containing dozens of tiny transparent spheres was propelled by peristaltic muscle contractions down Miss Muffin’s esophagus and into her stomach, where the strongly acidic environment allowed the tough spheres, or cysts, to break open in just ten minutes (1). About ten percent of the cysts’ spawn survived to the journey into the small intestines. These spawn each were pear-shaped protozoa* with four flagella* and two nuclei*, and had an almost clown-faced appearance (2). They were smaller than many of Miss Muffin’s cells (she’s human, by the way), but a bit larger than her red blood cells and most bacteria. Giardia lamblia was now in its vegetative* form and ready to replicate. Miss Muffin should have waited the entire recommended thirty minutes.
In 1681, the great Antony van Leeuwenhoek peered through a microscope as he examined what he called “animalcules” in his feces. Gross, right? He noted the trophozoite version of what Miss Muffin just ingested and described them as “somewhat longer than broad, and their belly was flatlike, furnisht with sundry little paws, where with they made such a stir in the clear medium and among the globules that you might e’en fancy you saw a pissabed [dandelion] running up against a wall; and albeit they made a quick motion with their paws, yet for all that they made but slow progress. (3)”
In its vegetative state, the behavior of G. lamblia resembles that of a mooching college kid. It mostly hangs out in group housing with lots of its peers, doesn’t work, and depends on the labors of others for its sustenance. Maneuvering within the intestines until encountering the intestinal wall. G. lamblia attached a concave “ventral disk” – basically a gigantic sucking mouth piece—to the intestinal villi.
To be continued.
What will happen to Miss Muffin? Will the Giardia make Miss Muffin ill? Does Giardia have any enemies? Will Little Boy Blue ever wake and blow his horn?
Flagella A thread-like appendage for movement in a fluid environment
Nucleus pl. nuclei. The cell structure containing DNA. Cells typically contain one nucleus, unless the cell is undergoing division.
Protozoa Animal-like single-celled microbes, usually with motile capabilities
Vegetative Not to be confused with vegetables, the active feeding and dividing form of a protozoan or bacterium, as opposed to an inactive cyst stage.
- Adam RD (2001) Biology of Giardia lamblia. Clin Microbiol Rev 14: 447–475.
- Murray Patrick, Ken Rosenthal, George Kobayashi, and Michael Pfaller. Medical Microbiology, 4th Ed. St. Louis, Mosby, Inc, 2002.
- Dobell, C. 1932. Anthony van Leeuwenhoek and His “Little Animals.” London: Staples Press. (page 224)
About the author:
Theresa Adams graduated from Washington State University, Pullman, with a BS in Microbiology. She is married to a handsome guy named Ethan and has two little boys who are not aware of the of term “germs” and instead are occasionally reminded of “icky microbes.” She agrees with King David, that we are “fearfully and wonderfully made,” Ps. 139:14.