Male Mexican migrants increase high-risk sexual practices including relations with sex workers or other men, under the effects of drugs and alcohol, or in exchange for money, food or lodging, according to the study of 458 men aged 18 to 69 who arrived in the United States in the past five years.
Those who had relations with sex workers increased from 18.1 percent to 29.4 percent and those who had sexual relations under the effect of alcohol rose from 24.6 percent to 41.3 percent, according to the study by the Pilot Program of California-Mexico Epidemiology Vigilance.
However, Mexican workers in the United States also used condoms more often than before migrating.
Some 81.4 percent said they did not regularly use condoms beforehand, compared with 65.1 percent afterwards, according to the study released at the 17th International AIDS Conference currently taking place in Mexico City.
Those most vulnerable to contract HIV/AIDS due to their sexual practices are aged between 18 and 29, said researcher Melissa Sanchez, who presented the document.
The study was carried out in California, home to some 40 percent of Mexicans in the United States, and with Mexican and Californian authorities and social groups.
Relations between Mexico and the United States have been strained over US treatment of millions of illegal immigrants -- including an estimated five million Mexicans -- and efforts to build a wall along much of the 3,000-kilometer (1,600 mile) border they share.