Dallas County is suffering through an infectious disease outbreak that has nothing to do with mosquitoes. Dallas County Health and Human Services announced Thursday that 13 residents have suffered from brucellosis so far in 2016, way up from the 2 to 6 cases the county normally sees in a given year.

Each of the 13 cases stems from people eating unpasteurized cheese from Mexico that was either brought back to the U.S. from Mexico by friends or relatives, consumed during travel in Mexico, or purchased unlabeled from Dallas street vendors, DCHHS says. Unpasteurized cheese, while often delicious, is illegal in the United States. The only exception is cheese made from raw milk, provided the cheese has been aged a minimum of 60 days and is clearly labeled as unpasteurized.

Brucella bacteria can affect common dairy livestock like cows, sheep and goats. Humans can then ingest the bacteria in unpasteurized dairy products made from the milk of the animals. Brucellosis infections are also common in lab settings because the bacteria can easily be made airborne by common lab practices and relatively little needs to be ingested to cause infection.

Primary symptoms of Brucella infections are fever, fatigue, weakness, weight loss, night sweats, joint pain and headache, but severe symptoms like meningitis can occur in some cases. Brucella patients are required to be on antibiotics for weeks and sometimes months after getting sick.

DCHHS asks Dallas doctors to be aware of brucella and ask about travel history and potential exposure to dairy products from patients exhibiting consistent symptoms. If brucellosis is confirmed, labs are asked to put special security measures in place to avoid the bacteria becoming airborne. Dallas residents, obviously, are advised to avoid any unpasteurized or potentially unpasteurized cheese.

