If 3 sneezes in a row is a sign of good luck, 10 sneezes is more likely to mean your luck has run out – and you probably have hayfever. Also known as allergic rhinitis, hayfever

HIV (Human Immunodeficiency Virus), like other viruses, targets specific cells, in this case T4 cells. T4, or Helper T cells, are agents of our immune systems. Helper T cells are i