The Food and Drug Administration has urged caution when eating melons, after three cases of Listeria were reported from the New Mexico region, as well as one from Colorado where they are grown.

The fatal cases included a 63 year old woman, a 93 year old man and a 61 year old woman all from different regions of New Mexico. A further death in Colorado was not identified, according to the state health departments of Colorado and New Mexico.

"While the investigation into the source of the listeria outbreak is continuing, it is prudent for people who are at high risk for listeria infection to avoid consumption of cantaloupe," said Chris Urbina, chief medical officer for Centers for Disease Control and Prevention (CDC).

Listeria, a bacterium-type illness, is found in soil and raw foods, and can be found in dairy products if cows are infected.

This likely infection could have come from anywhere including the soil in Colorado, trucks contaminated with animal feces in New Mexico. The infection’s origions may also include anywhere on the melon's journey, which includes at least four. There have been a total of 11 confirmed cases.

Those at risk of infection are over 60 and include anyone who has a weakened immune system.

Nine of the confirmed cases included people who ate cantaloupe before contracting the disease.