The rash in scarlet fever is characterized by small, raised, red bumps that feel like sandpaper when touched. These bumps, known as "Pastia lines," are particularly prominent in skin folds. The rash is caused by the exotoxins produced by Streptococcus pyogenes and typically occurs with a strep throat infection.

While high LDL cholesterol is a significant risk factor for atherosclerosis, it is not a lifestyle factor. It is a metabolic condition that can be influenced by diet and physical activity.

Hyperemesis gravidarum is severe nausea and vomiting during pregnancy that can lead to dehydration and electrolyte imbalances. The patient's symptoms and signs of dehydration (low blood pressure and decreased urine output) support this diagnosis.

The primary cellular defect caused by HIV infection is the depletion of CD4+ T-helper cells, which are essential for a properly functioning immune system. This leads to a compromised immune system that is susceptible to opportunistic infections.

According to the provided risk factor list for atherosclerosis, men are considered at increased risk for coronary heart disease starting at the age of 45 years.