In advance of the 2016 Summer Olympics in Rio de Janero, the European Centre for Disease Prevention and Control (ECDC) has released an official risk assessment for travelers worried about potential illnesses while traveling in Brazil. According to the report, hepatitis A virus (HAV) and gastrointestinal illnesses are the biggest threats to foreign tourists, while the risk of dengue, chikungunya and Zika virus infections are also considered to be a risk, Outbreak News Today reports.

According to recent surveillance data of gastrointestinal infections in Brazil, travelers to the Rio Games are most at risk for developing food-related illnesses like salmonellosis, E. coli, campylobacteriosis, giardiasis (a parasitic infection) and viral gastrointestinal illness. The ECDC also pointed to a substantial risk for hepatitis A, which is also commonly passed via food.

European health authorities also say the risk of mosquito-borne infections, such as Zika, dengue and chikungunya, is likely to be “moderate” in the North and Northeast regions of Brazil, and “low” in the South and Southeast regions of the country, including the city of Rio de Janieiro. Malaria risk is also considered to be “moderate” for travelers in Brazil’s North and Central-West regions. Those planning to attend football matches in the Amazonian city of Manaus in the North as part of the Olympic Games have been advised to take steps to avoid the infection. Fortunately, the Summer Olympics will be taking place during Brazil’s dry, winter season, which will help to reduce mosquito populations.

Key preventive measures for travelers hoping to stay healthy at the Rio Games include remaining vigilant about hygiene standards for food and water, preventing mosquito bites with repellents, and ensuring that all vaccinations are up to date, such as the hepatitis A and yellow fever vaccines. European health authorities have also advised visitors to avoid all contact with stray cats and dogs, and to avoid sexual risks.