A memorandum, rediscovered in 2010 in the archives of the FDA, shows that in 1956–57, as part of its in-licensing approach, Smith, Kline and French conducted animal tests and ran a clinical trial of the drug in the US involving 875 people, including pregnant women. In 1956, researchers involved in clinical trials at SKF noted that, even when used in very high doses, thalidomide could not induce sleep in mice. And when administered at doses 50 to 650 times larger than that claimed by Chemie Grünenthal to be "sleep inducing", the researchers could still not achieve the hypnotic effect in animals that it had on humans. After completion of the trial, and based on reasons kept hidden for decades, SKF declined to commercialize the drug. In 1958, Chemie Grünenthal reached an agreement with William S Merrell Company in Cincinnati, Ohio (later Richardson-Merrell, now part of Sanofi), to market and distribute thalidomide throughout the US.The US FDA refused to approve thalidomide for marketing and distribution. However, the drug was distributed in large quantities for testing purposes, after the American distributor and manufacturer Richardson-Merrell had applied for its approval in September 1960. The official in charge of the FDA review, Frances Oldham Kelsey, did not rely on information from the company, which did not include any test results. Richardson-Merrell was called on to perform tests and report the results. The company demanded approval six times, and was refused each time. Nevertheless, a total of 17 children with thalidomide-induced malformations were born in the US.
Balantidiasis is a protozoan infection caused by infection with Balantidium coli. Symptoms and signs
Usually asymptomatic in immunocompetent individuals, but the symptoms of balantidiasis include:
Intermittent diarrhea
Constipation
Vomiting
Abdominal pain
Anorexia
Weight loss
Headache
Colitis
Marked fluid lossThe most common ones are intermittent diarrhea and constipation or inflammation of the colon combined with abdominal cramps and bloody stools. Transmission
Balantidium is the only ciliated protozoan known to infect humans. Balantidiasis is a zoonotic disease and is acquired by humans via the feco-oral route from the normal host, the pig, where it is asymptomatic. “Contaminated water is the most common mechanism of transmission. Equally dangerous, however, is the ingestion of contaminated food.”

Morphology
Balantidium coli exists in either of two developmental stages: trophozoites and cysts. In the trophozoite form, they can be oblong or spherical, and are typically 30 to 150 µm in length and 25 to 120 µm in width. It is its size at this stage that allows Balantidium coli to be characterized as the largest protozoan parasite of humans. Trophozoites possess both a macronucleus and a micronucleus, and both are usually visible. The macronucleus is large and sausage-shaped while the micronucleus is less prominent. At this stage, the organism is not infective but it can replicate by transverse binary fission.In its cyst stage, the parasite takes on a smaller, more spherical shape, with a diameter of around 40 to 60 µm. Unlike the trophozoite, whose surface is covered only with cilia, the cyst form has a tough wall made of one or more layers.