Essentials of Anatomy and Physiology

522

Table 22–4 DISEASES CAUSED BY VIRUSES (Continued)

Virus Discussion/Disease(s) Caused

Hepatitis viruses:

types A,B, and C

Human immuno-

deficiency

virus(HIV)

Variola major

SARS virus

Hepatitis: anorexia, nausea, fatigue, jaundice (may not be present in mild cases). HAV is spread

by the fecal–oral route; contaminated shellfish or food prepared by people with mild cases.

No carriers after recovery. HBV is spread by sexual activity or contact with blood or other

body fluids. Carrier state is possible; may lead to liver cancer or cirrhosis. HCV transmission is

similar to that of HBV. Carrier state is possible. There are vaccines for hepatitis A and B. Other

hepatitis viruses are designated D, E, F, and G.

AIDS: destruction of helper T cells and suppression of the immune system; opportunistic infec-

tions; invariably fatal, often after many years. HIV is spread by sexual activity, contact with

blood, or placental transmission. No vaccine.

Smallpox: declared eradicated in the wild by the WHO in 1980. Is a potential biological weapon.

A contagious disease characterized by a hemorrhagic rash and internal hemorrhages. Fatality

rate is 30%–50%. In the U.S., childhood vaccination was stopped in 1982.

Severe acute respiratory syndrome: a pneumonia in which the lungs fill with fluid. The reservoir

of the virus is the horseshoe bat of China. The first cases of SARS were in China in 2002; the

virus mutated and spread easily among people. Plane travel carried the virus to Europe and

North America. From 2002 through 2003, there were approximately 8000 cases, which

resulted in 800 deaths; then the human form of the virus disappeared. Vaccines are in the

development stage.

Table 22–5 DISEASES CAUSED BY FUNGI

Fungus Genus Discussion/Disease(s) Caused

Microsporum, Trichophyton,

Epidermophyton

Candida albicans(and other

species)

Cryptococcus

Histoplasma

Coccidioides

Rhizopus

Aspergillus

Pneumocystis jiroveci

Ringworm (tinea): scaly red patches on the skin or scalp; loss of hair. Tinea pedis is ath-

lete’s foot. May also infect damaged nails. Spores of these fungi are acquired from

people or animals.

Yeast infections: mucosal infections are called thrush; may be oral or vaginal; yeasts have

come from resident flora. Systemic infections include pneumonia and endocarditis.

Important nosocomial pathogens.

Cryptococcosis: pulmonary infection that may progress to meningitis, especially in AIDS

patients. Spores are carried in the air from soil or pigeon droppings.

Histoplasmosis: pulmonary infection that is often self-limiting. Progressive disease

involves ulcerations of the liver, spleen, and lymph nodes; usually fatal. Spores are car-

ried by the air from soil.

Coccidioidomycosis: pulmonary infection that is often self-limiting. Progressive disease

involves the meninges, bones, skin, and other organs; high mortality rate. Spores are

carried by the air.

Common bread mold that is harmless to most people, but may cause invasive disease in

those with compromised immune systems or poorly controlled diabetes. The spores

may be inhaled or ingested and establish themselves in tissues, leading to systemic

infection characterized by clotting and necrosis. Also causes digestive disease in cattle

and pigs.

A common mold found on fruits, harmless to healthy people. In those who are immuno-

compromised it may cause sinusitis, otitis, pneumonia, or more invasive disease.

Pneumonia: only in very debilitated or immunosuppressed persons, such as people with

AIDS. Although its antibiotic susceptibility is that of a protozoan, its DNA sequences

are more similar to those of fungi. Many people become infected during childhood,

but a normal immune system prevents any damage. Such a latent infection may

become symptomatic and very serious when cell-mediated immunity is impaired.