INFECTIOUS DISEASE—BACTERIA AND VIRUSES
What’s the Difference?
Pandemic
Endemic
Outbreak
Epidemic
The constant presence of a disease at the usual incidence
The incidence increases above endemic levels (often suddenly)
The epidemic has spread globally
The outbreak has spread to larger geographic areas
What are infectious diseases? Infectious diseases are illnesses caused by microorganisms like
What are zoonotic diseases? Zoonotic diseases are illnesses that spread between animals (both wild and domesticated) and people. As many as 60% of known human infectious diseas- es are zoonotic. Often the animals don’t experience symptoms but are reservoirs — live “holding tanks” for the microbe. Spillover events occur when the pathogen jumps from its traditional host to a new species, like humans. Common Zoonotic Diseases and Animal Reservoirs:
bacteria
viruses
fungi
parasites
While most microorganisms are harmless, or even beneficial, a small percent can cause serious disease. These are sometimes described as “pathogens” and are often informally called germs. How do infectious diseases spread? Infections are transmitted in different ways, depending on the type of infection l direct contact with bodily fluids that contain infectious particles l touching a contaminated surface and then touching eyes, nose or mouth l direct or indirect contact with animals or insects l contaminated food or water
Cats .........................toxoplasmosis ........................................ pasteurella ...........................................ringworm
Bats ...................................Ebola virus ....................................................... SARS ...................................................... MERS ...................................................... rabies
Dogs ..................................... rabies ........................................noroviruses ........................................... ringworm ..........................................hookworm
Ticks ............................Lyme disease .............Rocky Mountain spotted fever
Mosquitoes . ..................... malaria . ..............................................dengue ..................................West Nile virus ...........................................Zika virus
Why are pandemics becoming more likely? The number of infectious disease outbreaks around the world has
risen over the last 40 years. The risk that an outbreak expands into an epidemic or pandemic has also increased due to: l Increasing human population and urbanization l Unclean water and poor sanitation l Global trade and travel l Increased contact between humans and animals l Changing climate l Weak healthcare infrastructure in outbreak-prone areas l Increasing drug resistance for disease-causing bacteria
Birds ................bird flu (H1N1, H5N1) . .......................................salmonellosis
Cows ............................ brucellosis ................................Escherichia coli . ......................................... ringworm . .................................. salmonellosis
Rodents ............................hantavirus . ................................................... plague .........................................rat-bite fever
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