Common Vehicle Spread
Unfortunately, the the term "common vehicle spread" is defined in several very different ways by different authors. We will use the expression to refer to transmission of disease via
- blood products, and
- medical devices,
These "common vehicles" potentially expose many people and can be responsible for widespread transmission. Some authors include airborne transmission in this category.
The World Health Organization takes a broad view of the potential for water-related illnesses.
Water-related Diseases (from WHO)
"Water, sanitation and hygiene have important impacts on both health and disease.
Water-related diseases include:
Water also contributes to health, for example through hygiene."
Water is essential to life, but it is also a potential "common vehicle" for disease. Naturally occurring water has impurities, but as human populations grew and began to establish towns and cities, increasingly contaminated water became a major source of illness and premature death. All public drinking water sources in the United States are regulated by the FDA to ensure quality, although there are cases of contamination occasionally. In many parts of the world, clean water is by no means assured.
The five major classes of disease-causing agents that can be found in water are:
- Parasites (e.g., Giardia, Cryptosporidia)
- Bacteria (e.g., Cholera, Shigella, E. coli)
- Viruses (e.g., Norwalk virus, hepatitis A)
- Chemical contaminants (e.g., pesticides, heavy metals, organic solvents)
- Neurotoxins from "algal blooms" (see report of contamination of Toledo, Ohio's water supply in August 2014)
The first three groups of agents often enter water supplies as a result of contamination with human or animal feces. Chemical contaminants are most commonly from man-made pollution, but it can also be naturally-occurring, e.g., arsenic.
Fecal-oral transmission can occur when bacteria or viruses in the stool of one person are swallowed by another. This can occur whenever there is
- Inadequate sanitation resulting in contamination of water supplies with human feces
- Inadequate procedures in daycare settings, where fecal organisms are commonly found on surfaces and on hands of providers
- Contamination of swimming pools and water parks with human feces
- Failure of food handlers to follow proper procedures: hand washing and wearing of gloves
- Fecal-oral transmission can also occur during anal sexual contact. This mode of transmission would be considered direct contact rather than common vehicle transmission.
The fecal-oral route can transmit diseases caused by bacteria, viruses, or protozoa.
|Roll over the tabs to see some of the infectious agents in each of these categories.|
Prevention of Fecal-Oral Transmission
- Practice safe food-handling practices.
- Cleanse hands frequently, especially after toileting or diapering and before eating.
- Teach children not to swallow pool water.
- Day Care: Clean or disinfect commonly touched surfaces (doorknobs, faucet handles, shared toys, sleep mats). Diaper-changing surfaces should never be close to food-preparation areas and should be sanitized between uses. Dispose of soiled diapers properly.
- Promote sanitary disposal of human feces.
- Follow proper sanitary procedures for recreational waters.
Contaminated Drugs, Blood, Blood Products, or Medical Devices
Drugs, transfusions of blood or blood products (e.g., clotting factors for hemophiliacs), and medical devices are all considered "common vehicles," and contamination of these medical products can cause small or large disease outbreaks. In September 2012, the Centers for Disease Control and Prevention (CDC), in collaboration with state and local health departments and the Food and Drug Administration (FDA) , began investigating a multistate outbreak of fungal meningitis and other infections among patients who received contaminated methylprednisolone (an anti-inflammatory steroid) injections. The investigation began when Vanderbilt University contacted the Tennessee Department of Health to report a patient with fungal meningitis after receiving an injection of methylprednisolone. The methlyprednisolone had been prepared at the New England Compounding Center, and three lots of the drug were believed to have been contaminated. The contaminated drugs had been shipped to 75 medical facilities in 23 states, and doses had been administered to approximately 14,000 patients. The contaminated lots were recalled, and hospitals were notified, but as of March 10, 2013, 48 people had died, and 720 were being treated for persistent fungal infections.