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Giardia is one of the most common intestinal parasites worldwide, and infects up to 20% of the world population, mostly in poorer countries with inadequate sanitation. Infections are most common in children, though chronic Giardia is more common in adults.
Only 12 hours after an egg cell is fertilized by a sperm cell, the egg cell starts to divide. As it continues to divide, it moves along the fallopian tube toward the uterus at about 1 inch per day.
Asthma occurs in one in 11 children and in one in 12 adults. African Americans and Latinos have a higher risk for developing asthma than other groups.
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
Prostaglandins were first isolated from human semen in Sweden in the 1930s. They were so named because the researcher thought that they came from the prostate gland. In fact, prostaglandins exist and are synthesized in almost every cell of the body.
![When Union troops pushed toward Richmond in June of 1862, these slaves crossed the Rappahannock Rive](https://biology-forums.com/gallery/47/medium_376021_22_08_15_1_40_22_22353567.jpeg)
![Maxine Williams was the founder and first president of the AAMA. Printed with permission of American](https://biology-forums.com/gallery/47/medium_27_19_05_16_12_15_22_235081321.jpeg)