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Adult head lice are gray, about ? inch long, and often have a tiny dot on their backs. A female can lay between 50 and 150 eggs within the several weeks that she is alive. They feed on human blood.
IgA antibodies protect body surfaces exposed to outside foreign substances. IgG antibodies are found in all body fluids. IgM antibodies are the first type of antibody made in response to an infection. IgE antibody levels are often high in people with allergies. IgD antibodies are found in tissues lining the abdomen and chest.
Complications of influenza include: bacterial pneumonia, ear and sinus infections, dehydration, and worsening of chronic conditions such as asthma, congestive heart failure, or diabetes.
Blood is approximately twice as thick as water because of the cells and other components found in it.
Vaccines prevent between 2.5 and 4 million deaths every year.