Over the past twenty years, there have been several emerging infectious diseases worldwide. To name a few, West Nile Virus outbreaks were seen in New York in 1999, Zika Virus in Micronesia and then again in Brazil in 2015, Ebola hemorrhagic fever in 2014 in West Africa, and Monkey Pox in Nigeria in Nigeria. There are several types of emerging infectious diseases: a zoonotic disease, which originates in animals and are spread to humans by direct transfer; a viral-borne infectious disease which originates in animals and is spread to humans through an intermediate vector such as a mosquito or tick, emerging food and waterborne infectious diseases, sexually transmitted infections, and emerging healthcare-associated infections. Many emerging infectious diseases are viral diseases. Some examples of emerging bacterial diseases are E. coli O157, Helicobacter pylori, and Legionnaires Disease. Additionally, Lyme disease, leptospirosis, babesiosis, rickettsia, Rocky Mountain Spotted Fever, Typhus, cat scratch disease, anthrax, the plague, and tularemia are examples of emerging bacterial infections.

In addition to emerging and re-emerging infectious diseases, drug-resistant infections are also public health threats. In 1992 and 2003, the Institute of Medicine Report identified several factors contributing to the Emergence of Infectious Diseases. The 1992 report listed the following elements: human demographics and behavior, technology and industry, economic development and land use, international travel and commerce, microbial adaptation and change, and the breakdown of public health measures. The 2003 report listed the following factors: human susceptibility to infection, climate and weather, changing ecosystems, poverty and social inequality, war and famine, and lack of political will. 

Other factors that influence zoonotic spillover are:

• Tropical environments.
• High diversity of species.
• Recent deforestation.
• Changes in agricultural practices.
• Increases in the number and density of livestock.
• New wildland-urban interfaces.

Bat species have been identified as the wildlife reservoir for a significant proportion of viral zoonotic spillover to humans. 

Strategies for preventing and containing emerging infectious diseases are: 

• Public health surveillance and response systems.
• Rapid detection of new and unusual patterns of infections.
• Coordination of the CDC with state and local health departments. 
• Collaboration with veterinary health.
• Prevention strategies that encompass the entire food chain, the source of food (agricultural and livestock), and distribution and storage of food. 

There is an additional burden of infectious diseases due to their association with some types of cancer, such as H. pylori infection and gastric lymphoma and gastric carcinoma, Hepatitis C Virus and hepatocellular cancer, and HPV and cervical cancer. 

References:

1 Southwick FS. Emerging Bacterial Infections (Including Zoonotic Pathogens and Biological Weapons). In: Southwick FS. eds. Infectious Diseases: A Clinical Short Course, 4e. McGraw Hill.

2 Ostroff SM, Hughes JM. Emerging Microbial Threats to Health. In: Boulton ML, Wallace RB. eds. Maxcy-Rosenau-Last Public Health & Preventive Medicine, 16e. McGraw Hill; 2022.