Similar to the American Revolutionary War, the Mexican-American War saw little in the way of actual combat casualties and more due to disease. Of the 13,283 recorded deaths, only 1,733 were actually attributed to battle.
The Mexican-American war was fought exclusively in and around Texas, New Mexico, California and Northern and Central Mexico between 1846 and 1848.
Personnel and casualties can be found in the following book Mexican-American-War-Roster