Occupational infections are human diseases caused by work-associated exposure to microbial agents, including bacteria, viruses, fungi, and parasites. it's been hypothesized that certain infectious diseases like malaria, dengue , and cholera will become more prevalent with global climate change . An infection is distinguished as occupational by some aspect of the work that involves contact with a biologically active organism. Occupational infection can occur following contact with infected persons or surfaces, as within the case of health care workers; with infected animal or human tissue, secretions, or excretions, as in laboratory workers; with asymptomatic or unknown contagious humans, as happens during business travel; or with infected animals, as in agriculture.