Disease Transmission Overview
are those that are transmitted from person to person by direct or indirect
contact. Viruses, bacteria, parasites, and fungi all cause infectious disease. Malaria,
measles, and respiratory illnesses are examples of infectious diseases.
measures, like frequent hand washing, can cut down on disease transmission.
are often spread through direct contact.
are most commonly transmitted through direct person-to-person contact.
Transmission occurs when an infected person touches or exchanges body fluids
with someone else. This can happen before a person is aware that they are ill. Respiratory illnesses and sexually transmitted diseases (STDs)
are some of the diseases that can be transmitted this way.
Pregnant women can
also transmit some infectious diseases to their unborn children via the
placenta. Some STDs, including gonorrhea,
can be passed from mother to baby during childbirth.
The spray of
droplets during coughing and sneezing can spread infectious disease. You can
even infect another person through the droplets created when you speak.
Droplets fall to the ground within a few feet, so this type of transmission
requires close proximity.
Infectious diseases can also be spread indirectly through
the air and other mechanisms.
Some infectious agents can travel long distances and remain
suspended in the air for an extended period of time. You can catch a disease
like measles by entering a room well after someone with measles has departed.
Some organisms can live on objects for a short time. If you
touch an object, such as a doorknob, soon after an infected person, you are
exposed to infection. Transmission occurs when you touch your mouth, nose, or
eyes before thoroughly washing your hands.
Germs can also be spread through contaminated blood products
and medical supplies.
Insect Bites (Vector-borne Disease)
agents are transmitted by insects, especially those that suck blood. These
include mosquitos, fleas, and ticks. The insects become infected when they feed
on infected hosts, such as birds, animals, and humans. The disease is then
transmitted when the insect bites a new host. Malaria, West Nile virus
(WNV), and Lyme disease are all spread
Food and Drinking Water
can be transmitted via contaminated food and water. E. coli is often
transmitted through improperly handled produce or undercooked meat. Improperly
canned foods can create an environment ripe for Clostridium botulinum, which causes botulism.
diseases can be transmitted from an animal to a person. This can happen when an
infected animal bites or scratches you, or when you handle animal waste. The Toxoplasma
parasite can be found in cat feces. Pregnant women and people with
compromised immune systems should take extra care (disposable gloves and good
hand washing) when changing cat litter, or avoid it altogether.
disease transmission can sometimes transfer to humans. Zoonosis occurs when diseases are transferred from vertebrate
animals to people. Zoonotic diseases include anthrax (from sheep), rabies
(from rodents and other mammals), and WNV (from birds). Plague is transmitted through rodents.
Soil, water, and vegetation
containing infectious organisms can also be transferred to people. Hookworm, for example, is transmitted
through contaminated soil. According to the United States Centers for Disease
Control and Prevention (CDC), Legionnaires’
disease is an example of a disease that can be spread by water that
supplies cooling towers and evaporative condensers (CDC, 2013).
How to Prevent Disease Transmission
A few simple precautions can prevent some disease
transmission. The most important of these is to wash your hands thoroughly and often.
When you have a contagious illness, try to avoid direct
contact with other people. Cover your
nose and mouth when you sneeze and cough. When caring for an ill person,
use disposable gloves and wash your hands frequently.
Dangerous organisms can thrive in improperly prepared food.
Avoid cross-contamination by keeping raw meats and produce separate. Use different
preparation surfaces and wash surfaces and utensils thoroughly.
Freeze or refrigerate perishable foods and leftovers
promptly. According to the United States Department of Agriculture (USDA), you should
set your refrigerator to 40°F or
below and your freezer to 0°F or below. Cook meats to a minimum internal
temperature of 145°F. Cook ground meats to 160°F and poultry to 165°F (USDA, 2011).
Be careful about sources of food when visiting foreign
Insects and Animals
When camping or enjoying wooded areas, wear long pants and
long sleeves. Use insect repellent and mosquito netting. Don't touch animals in
Stay up to date on vaccinations, especially when traveling. Don't
forget to keep your pet's vaccinations current, too.