25: Circulatory and Lymphatic System Infections
Yellow fever was once common in the southeastern US, with annual outbreaks of more than 25,000 infections in New Orleans in the mid-1800s. 1 In the early 20th century, efforts to eradicate the virus that causes yellow fever were successful thanks to vaccination programs and effective control (mainly through the insecticide dichlorodiphenyltrichloroethane [DDT]) of Aedes aegypti , the mosquito that serves as a vector. Today, the virus has been largely eradicated in North America.
Elsewhere, efforts to contain yellow fever have been less successful. Despite mass vaccination campaigns in some regions, the risk for yellow fever epidemics is rising in dense urban cities in Africa and South America. 2 In an increasingly globalized society, yellow fever could easily make a comeback in North America, where A. aegypti is still present. If these mosquitoes were exposed to infected individuals, new outbreaks would be possible.
Like yellow fever, many of the circulatory and lymphatic diseases discussed in this chapter are emerging or re-emerging worldwide. Despite medical advances, diseases like malaria, Ebola, and others could become endemic in the US given the right circumstances.
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- 25.1: Anatomy of the Circulatory and Lymphatic Systems
- The circulatory and lymphatic systems are networks of vessels and a pump that transport blood and lymph, respectively, throughout the body. When these systems are infected with a microorganism, the network of vessels can facilitate the rapid dissemination of the microorganism to other regions of the body, sometimes with serious results. In this section, we examine some of the key anatomical features of the circulatory and lymphatic systems, as well as general signs and symptoms of infection.
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- 25.2: Bacterial Infections of the Circulatory and Lymphatic Systems
- Bacterial infections of the circulatory system are almost universally serious. Left untreated, most have high mortality rates. Bacterial pathogens usually require a breach in the immune defenses to colonize the circulatory system. Most often, this involves a wound or the bite of an arthropod vector, but it can also occur in hospital settings and result in nosocomial infections.
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- 25.3: Viral Infections of the Circulatory and Lymphatic Systems
- Viral pathogens of the circulatory system vary tremendously both in their virulence and distribution worldwide. Some of these pathogens are practically global in their distribution. Fortunately, the most ubiquitous viruses tend to produce the mildest forms of disease. In the majority of cases, those infected remain asymptomatic. On the other hand, other viruses are associated with life-threatening diseases that have impacted human history.
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- 25.4: Parasitic Infections of the Circulatory and Lymphatic Systems
- Some protozoa and parasitic flukes are also capable of causing infections of the human circulatory system. Although these infections are rare in the US, they continue to cause widespread suffering in the developing world today. Malaria, toxoplasmosis, babesiosis, Chagas disease, leishmaniasis, and schistosomiasis are discussed in this section.
Footnotes
- 1 Centers for Disease Control and Prevention. “The History of Yellow Fever.” http://www.cdc.gov/travel-training/local/HistoryEpidemiologyandVaccination/page27568.html
- 2 C.L. Gardner, K.D. Ryman. “Yellow Fever: A Reemerging Threat.” Clinical Laboratory Medicine 30 no. 1 (2010):237–260.
Thumbnail: This "classic" bull's-eye rash is also called erythema migrans. A rash caused by Lyme does not always look like this and approximately 25% of those infected with Lyme disease may have no rash. (Public Domain; CDC/ James Gathany).