There are blank spaces in the following passage which have been numbered . These numbers are printed below the passage and against each some words are suggested . Find out the word that best fit the blank spaces. Global Strategies to control infective diseases have historically included the erection of barriers to international travel and ___ (24) _______. Keeping people with such deadly disease outside national borders has ___ (25) _______ as an important public health policy in the human immunodeficiency virus (HIV) epidemic . Between 29 and 50 countries ___ (26) _____ to have introduced border restrictions on HIV _ positive foreigners ,usually those planning an ___ (27) ___ stay in the country , such as students , workers or seamen.