More than 50 human papillomavirus strains (types) have been reported. The most common clinical manifestations are warts (on skin) and condylomata (papilloma lesions) in the genital area. HPV-1 is usually associated with warts on the sole of the foot and HPV-2 in nonplantar skin warts. In the female cervix, HPV-6 and 11 are found most […]
Influenza produces upper and lower respiratory tract infection. There are 3 major types or subgroups: A, B, and C. Antigenic mutations occur frequently in type A, permitting reinfection; but are much less common in types B and C. The best laboratory test is culture of nasopharyngeal secretions, especially by the newer and much more rapid […]
Respiratory syncytial virus (RSV) is the most common cause of severe lower respiratory illness of infants and young children, causing 5%-40% of pneumonias and 60%-90% of bronchiolitis episodes. Peak incidence is at 2-3 months of age. About 30%-50% of children have been infected by 12 months of age and about 95% by age 5 years. […]
Mumps is a disseminated virus infection, although the main clinical feature is salivary gland enlargement. Evidence of nonsalivary gland involvement is most commonly seen in adults. In men, orchitis (usually unilateral) is reported in about 20% of cases. Adult women occasionally develop oophoritis. Persons of any age may be affected by meningoencephalitis, the most serious […]
Measles (rubeola) is still important, even though widespread vaccination has begun. Measles is spread by droplet inhalation. Incubation lasts about 9-11 days, followed by 3-4 days of fever, cough, and sometimes conjuctivitis. Koplik’s spots appear on the oral mucosa in 50%-90% of patients about 2-3 days after symptoms begin. These last about 6-7 days. The […]
Parvovirus B19 belongs to a genus that infects both animals and humans. These are small DNA viruses without an outer envelope. Replication appears to take place in erythroid precursors of the bone marrow. The two most common diseases produced are erythema infectiosum (“fifth disease”), a condition somewhat resembling rubella, but with a rash that has […]
Varicella-zoster virus (VZV) is a member of the herpesvirus group. Infection is spread through direct contact with skin lesions or through droplet inhalation. The incubation period is about 14 days (range, 9-21 days). Primary infection is usually varicella (chickenpox). The period of skin rash lasts about 4-6 days. This may be preceded by a short […]
Human herpesvirus 6 (HHV-6) was first isolated and characterized in 1986. It infects predominately T-lymphocytes of the CD4 (helper) type, but also B-lymphocytes, megakaryocytes, and probably other cells. It is the sixth described member of the Herpesvirus family (the others being HSV-1, HSV-2, EBV, CMV, and varicella-zoster). Infection takes place mainly in the first 2-3 […]
HSV infection is characterized by a primary infection, often asymptomatic, after which the virus remains dormant in the dorsal root ganglia of peripheral nerves interrupted in some patients by one or more episodes of recurrent disease. Primary infection usually requires a person without preexisting HSV antibody. However, a person can have antibody against one strain […]
These are closely related retroviruses somewhat distantly related to HIV-1. Transmission is similar to that of HIV-1 (contaminated blood products, less frequently by sexual intercourse or breast feeding). HTLV-I is found predominantly in Southern Japan, some of the Caribbean islands, parts of Central and South America, and sub-Saharan Africa. HTLV-I has been detected in U.S. […]
