RPT-UPDATE 3-P&G to buy German Merck's consumer health unit for $4.2 bln

April 19 (Reuters) - Procter & Gamble Co (P&G) has agreed to acquire Merck KGaA's consumer health unit for 3.4 billion euros ($4.2 billion), giving it vitamin brands such as Seven Seas and greater exposure to Latin American and Asian markets.