His wife, Ana de Osorio (1599–1625), is credited as being one of the first Europeans to be treated with quinine, and as the person who introduced that medicine into Europe.

Among his other official acts were the prohibition of direct trade between Peru and New Spain (Mexico) and the persecution of Portuguese Jews, the principal traders in Lima.

In an account published in 1663 by Sebastiano Bado, an Italian, the following claim was made: In 1638, the Countess of Chinchon became severely ill with tertian fever (malaria).

Juan López de Canizares, governor of Loxa, wrote the viceroy, explaining that he had recently been cured by the bark of the quinaquina tree, and recommending the same remedy to the vicereine.

It states that Ana de Osorio, his first countess of Chinchón, died in Spain at least three years before her husband was named viceroy of Peru.

It was his second countess, Francisca Henríquez de Ribera, who accompanied the Count to South America, where she enjoyed excellent health.

Jesuit Barnabé de Cobo (1582–1657), who explored Mexico and Peru, is now credited with taking cinchona bark to Europe.