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Section IV: Infectious Diseases

Deficits in the complement membrane attack complex (C5–8) are associated with infections of what variety?

A. Catalase-positive bacteria

B. Neisseria meningitidis

C. Pseudomonas aeruginosa

D. Salmonella spp

E. Streptococcus pneumoniae

The answer is B. (Chap. 144) Deficiencies in the complement system predispose patients to a variety of infections. Most of these deficits are congenital. Patients with sickle cell disease have acquired functional defects in the alternative complement pathway. They are at risk of infection from Streptococcus pneumoniae and Salmonella spp. Patients with liver disease, nephrotic syndrome, and systemic lupus erythematosus may have defects in C3. They are at particular risk for infections with Staphylococcus aureus, S pneumoniae, Pseudomonas spp, and Proteus spp. Patients with congenital or acquired (usually systemic lupus erythematosus) deficiencies in the terminal complement cascade (C5–8) are at particular risk of infection from Neisseria spp, such as Neisseria meningitidis or Neisseria gonorrhoeae.

All of the following statements regarding global infectious diseases are true EXCEPT:

A. Drug-resistant tuberculosis is common in the former Soviet bloc countries.

B. Infectious diseases are the leading cause of death worldwide.

C. Over 60% of deaths in sub-Saharan Africa were related to infectious diseases (2010).

D. The absolute number of infectious disease–related deaths has remained relatively constant in the past 20 years.

E. The rate of infectious disease–related death has dropped notably in the past 20 years.

The answer is B. (Chap. 144) Infectious diseases remain the second leading cause of death worldwide, with cardiovascular disease the leading cause. Although the rate of infectious disease–related deaths has decreased dramatically over the past 20 years with a growing worldwide population, the absolute numbers of such deaths have remained relatively constant, totaling just over 12 million in 2010. As shown in Figure IV-2, these deaths disproportionately affect low- and middle-income countries; in 2010, 23% of all deaths worldwide were related to infectious diseases, with rates >60% in most sub-Saharan African countries. Given that infectious diseases are still a major cause of global mortality, understanding the local epidemiology of disease is critically important in evaluating patients. Diseases such as human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) have decimated sub-Saharan Africa, with HIV-infected adults representing 15%–26% of the total population in countries like Zimbabwe, Botswana, and Swaziland. Moreover, drug-resistant tuberculosis is rampant throughout the former Soviet bloc countries, India, China, and South Africa. The ready availability of this type of information allows physicians to ...

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