Know Your Risk: What are Vector-borne Diseases?

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- Vector-borne diseases are increasing in the United States.

However, before we can discuss vector-borne diseases, we need to define what a vector is and learn some terms.

A pathogen is a bacterium, virus or other microorganism that can cause a disease.

A vector, in our case, is an insect or another arthropod, like a tick that carries and transmits disease causing pathogens, often called agents, to humans or other animals.

Ticks, mosquitoes and fleas are some common vectors you may already know.

Vector-borne diseases then are the illnesses that result from the parasites, viruses, bacteria, or other pathogens that are transmitted by vectors.

Keep in mind that just because a potential vector, like this tick, could carry a pathogen, it doesn't mean they always will.

Most of the time, they'll need to become infected first.

Often a vector can be infected with a pathogen by feeding on another animal carrying the pathogen.

These animals are called reservoir hosts.

A reservoir host is an animal that serves as a source of infection and sustains the pathogen in nature.

Some animals are better reservoir hosts than others.

For example, white-footed mice and chipmunks are good reservoir hosts for the Lyme disease pathogen in the northeastern United States.

Other animals may get a pathogen if bitten by a vector, but cannot transmit those pathogens back to another vector.

These are called dead end hosts.

Whitetailed deer and humans are dead end hosts for the pathogen that causes Lyme disease.

So in summary, vector-borne diseases are those that are caused by pathogens, transmitted by vectors, and often are maintained by reservoir hosts in the environment.

Knowing a little bit more about vectors and the pathogens they can transmit can help you better understand how to reduce your risk of vector-borne disease.