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- Describe the difference between an infectious disease and a communicable disease.
- Describe the pathophysiology of influenza, pertussis and cholera.
- Explain the body substance isolation procedures that should be employed when treating the patient with influenza, pertussis and cholera.
- List the signs and symptoms of influenza, pertussis and cholera.
- Discuss the management of the patient with suspected influenza, pertussis and cholera.
An infectious disease is an illness resulting from the presence of a pathogenic biological organism in a host organism. Examples of pathogenic organisms include bacteria, viruses, fungi, protozoa, parasites and prions, all of which are able to cause illness and death in their host. A prion is an infectious agent composed of proteins normally found in the brain. Unlike the other pathogenic organisms, prions do not contain any genetic material. Prions are the cause of a number of diseases in mammals, including bovine spongiform encephalopathy (also known as "mad cow disease") in cattle and Creutzfeldt-Jakob disease (CJD) in humans.
While they are often used synonymously, the terms infectious disease and communicable disease do not have the same meaning. A communicable disease is an infectious disease that is easily spread from one human to another. As such, all communicable diseases are infectious diseases, but not all infectious diseases are communicable.
As EMTs and paramedics, we learn about many infectious and communicable diseases, some of which we see on a regular basis, like influenza, the common cold, croup or sexually transmitted diseases. Other infectious diseases, like epiglottitis, are more obscure. This article discusses influenza, an infectious disease that occurs yearly and affects many persons in the community; pertussis, a disease that until fairly recently has been encountered infrequently, but is presently enjoying a bit of a resurgence in the United States; and discuss cholera, an infectious disease that is not a problem in the United States, but current conditions in other parts of the world and ease of travel make it increasingly likely that emergency care personnel may encounter it in the field here at home.
Influenza, commonly referred to as "the flu," is an acute, contagious respiratory illness caused by infection with one of the many influenza viruses. Symptoms can range from mild illness with fatigue to respiratory failure and death. Three types of influenza are recognized:
- Type A is associated with most epidemics and pandemics and most of the deaths from influenza.
- Type B evolves slower than Type A, and results in regional or widespread epidemics every 2 to 3 years.
- Type C is rare and associated with sporadic cases.
Identifying the type is the first step in naming the influenza virus, followed by the subtype, which is named after the class of surface protein located on the viral surface. The two broad classes of surface proteins are hemagglutinin (HA) and neuraminidase (NA). There are 16 HA subtypes (designated H1-H16) and 9 NA subtypes (designated N1-N9). All of the possible combinations of influenza A subtypes infect birds, but only those containing the H1, H2, H3 and N1 and N2 do so to any great extent. The H5 subtype is considered a candidate for a new sub-type for broad human infectivity, and, as a result, we may be hearing about it in upcoming influenza seasons.
Persons of all age groups are at risk of contracting the influenza virus, although rates of infection are highest among children. Risks for complications, hospitalization and death from influenza are higher among persons aged 65 years and older, young children, and persons of any age with medical conditions that place them at increased risk for complications.1