Parotid gland
Mumps is seen to be a common cause of parotid gland swelling - 85% of cases occur in children younger than 15 years. The disease is highly contagious and spreads by airborne droplets from salivary, nasal, and urinary secretions. Symptoms include oedema in the area, trismus as well as otalgia. The lesion tends to begin on one side of the face and eventually becomes bilateral. The transmission of the paramyxovirus is by contact with the infected persons saliva. Initial symptoms tend to be a headache and fever. Mumps is not fatal, however further complications can include swelling of the ovaries or the testes. Diagnosis of mumps is confirmed through viral serology, management of the condition includes hydration and good oral hygiene of the patient requiring excellent motivation. However, since the development of the mumps vaccine, given at the age of between 4–6 years, the incidence of this viral infection has greatly reduced. This vaccine has reduced the incidence by 99%.
Impacts of tourism
Examples of invasive species spread by tourism:
-Bigheaded ant (Pheidole megacephala): Is one of the worst invasives and classified under the “worlds 100 worst” invasive species. Originally found in the Galapagos islands in 2007 within ship cargo for tourist supplies. Ants can be spread with the movement of people from one island to another. 
-Cheatgrass (Bromus tectorum): Spread fast, don’t allow native species to grow, can cause forest fires to spread rapidly. Can be carried by people through shoes and gear, pets and other animals can spread the seeds through their travel as well. 
-Zebra Mussels (Dreissena polymorpha): These are believed to have come from the Caspian Sea in Europe in a ships ballast water. They are spread by uncleansed boats from one body of water to another as tourists move to different locations.