The safety of eating Mexican cheese during pregnancy depends entirely on its manufacturing process. The primary factors determining safety are whether the milk used was pasteurized and the cheese’s moisture content. Raw or unpasteurized milk can harbor harmful bacteria, and certain cheese types are more prone to contamination. For expectant mothers, the main concern with many traditional Mexican cheeses is the potential for serious foodborne illness.
Understanding the Listeria Risk in Pregnancy
Soft, fresh cheeses are a particular concern for pregnant individuals because they can be a breeding ground for the bacterium Listeria monocytogenes. This pathogen causes an infection called listeriosis, which is a rare but serious illness. Pregnant women are estimated to be about 10 to 20 times more likely to contract listeriosis compared to the general population due to natural changes in the immune system during pregnancy.
While the mother may experience only mild, flu-like symptoms, the infection can have devastating consequences for the developing fetus. Listeria has the ability to cross the placental barrier, leading to complications such as miscarriage, stillbirth, premature delivery, or life-threatening infections in the newborn. The soft, high-moisture, and low-acidity environment of many fresh cheeses allows Listeria to survive and even multiply, a trait unique among many foodborne pathogens, as it can grow even at refrigeration temperatures. This explains why health authorities advise caution regarding soft and semi-soft cheeses, regardless of whether they are Mexican-style or European.
High-Risk Traditional Mexican Cheeses to Avoid
Many traditional Mexican cheeses are naturally soft, fresh, and high in moisture, making them highly susceptible to Listeria contamination, especially when they are made with raw milk. The cheeses most commonly linked to outbreaks in the United States include Queso Fresco, Queso Blanco, Panela, and Requesón. These varieties are often called “queso fresco-type cheeses” and are consumed fresh, meaning they do not undergo a long aging process that would inhibit bacterial growth.
Historically, many small producers and informal vendors have made these cheeses using unpasteurized milk. Even when pasteurized milk is used, contamination can occur if the production environment or equipment is not clean. Therefore, soft Mexican cheese purchased from informal sources, such as street vendors or small delis, should be avoided unless the producer provides verifiable safety information.
Safe Choices: Verifying Pasteurization and Low-Risk Types
Expectant mothers can safely enjoy many Mexican cheeses by focusing on store-bought products and checking the packaging carefully. The most effective way to ensure safety is to only purchase cheese that is clearly labeled with the word “Pasteurized” or “Made from Pasteurized Milk.” This label confirms that the milk was heated to a temperature high enough to destroy any initial pathogens, including Listeria monocytogenes.
Beyond checking the label, choosing certain cheese types can further reduce risk. Harder, aged Mexican cheeses, such as an aged Cotija, are considered safer because their lower moisture content and higher salt levels create an environment less hospitable to bacterial growth. Processed Mexican cheese products, like those used in commercial dips or shreds, are also usually safe because the processing methods eliminate harmful bacteria. A final safety measure involves thoroughly cooking any soft Mexican cheese until it is steaming hot throughout. For dishes like quesadillas, enchiladas, or baked dips, the internal temperature of the cheese should reach at least 165°F (74°C) to ensure any potential Listeria bacteria are killed.