Articles on Medical Diseases and Conditions

Entries for the ‘Viral Infections’ Category

Hantavirus Pulmonary Syndrome

This disease first appeared in a small epidemic among New Mexico Navaho Indians in mid1993 as a fatal respiratory infection with resemblance to influenza or mycoplasma disease. It subsequently affected some Europeans and Hispanics. Symptoms began as an upper respiratory infection with fever and myalgias, after which acute respiratory failure developed. Thrombocytopenia was present in […]


Human disease from rabies virus infection is very uncommon in the United States. The number of human cases in the United States is usually less than five per year, and only nine were reported from 1980 to 1987. However, there are always questions about the disease, and several thousand cases of animal rabies are confirmed […]

Human Papillomavirus (HPV)

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 Virus

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

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

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)

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) and 7 (HHV-7)

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 […]