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Rubeola Virus: Measles and Subacute Sclerosing Panencephalitis

Rubeola (i.e., measles) is an acute, highly contagious, vaccine-preventable viral infection. , In the prevaccination era, measles was an almost universal experience during childhood. The incidence of measles declined markedly in the US after the licensure of a live measles vaccine in 1963. In 2000 the US declared elimination of endemic measles (i.e., absence of sustained virus transmission for >12 months) due to high rates of…

Human Metapneumovirus

Description of Pathogen Human metapneumovirus (HMPV, MPV) was first described in 2001 by Dutch investigators who collected a number of unidentified virus isolates over a 20-year period. Electron micrograph and biochemical studies of the virus showed that it was pleomorphic with a lipid envelope ( Fig. 226.1 ). Reverse transcription-polymerase chain reaction (RT-PCR) and sequence analysis of the virus genome identified it as a pneumovirus, formerly…

Respiratory Syncytial Virus

Lower respiratory tract disease caused by respiratory syncytial virus (RSV) in the US and other industrialized countries results in hospital admission for approximately 2% of all children in the first 12 months of life. By 2 years of age, most children have been infected at least once by RSV, making this infection one of the most common diseases of childhood. Most RSV infections among otherwise healthy…

Mumps Virus

Mumps (i.e., epidemic parotitis) is an acute, vaccine-preventable disease of childhood that typically involves swelling of one or both parotid glands, although many different organs can be infected. Childhood mumps has become uncommon in the US since the widespread implementation of measles-mumps-rubella (MMR) vaccination. Reports of mumps outbreaks involving highly vaccinated populations in the US and other countries have prompted re-evaluation of current mumps vaccination strategies.…

Parainfluenza Viruses

Parainfluenza viruses (PIVs) were first identified in humans in the late 1950s. Human PIVs (PIVs) were initially described in children with croup and subsequently recognized as an important cause of acute respiratory tract infections in patients who are immunocompromised, have chronic conditions, or are elderly. In otherwise healthy children, PIVs cause upper and also lower respiratory tract infections (URIs and LRIs, respectively) such as pneumonia, bronchiolitis,…

Human Coronaviruses

Overview of the Viruses Coronaviruses are included in the Coronaviridae family under the order Nidovirales. They are enveloped, non-segmented, single-stranded, positive-sense RNA viruses named after their corona-like or crown-like surface projections seen on electron microscopy that correspond to large surface spike proteins ( Figs. 222.1 and 222.2 ). Four genera of coronaviruses have been described. Coronaviruses are host-specific and can infect humans and a variety of…

Rubella Virus

Rubella (i.e., German measles) is a benign, self-limited, vaccine-preventable viral illness. Acquired rubella is characterized by an exanthem and lymphadenopathy, although infants and children with rubella frequently are asymptomatic. Much of the morbidity attributed to rubella virus (RuV) occurs from in utero transmission, especially during the first trimester, resulting in miscarriage, stillbirth, fetal death, or congenital rubella syndrome (CRS). Sequelae of CRS include growth retardation, deafness,…

Hepatitis C Virus

Hepatitis C virus (HCV) was first identified in 1989. Although substantially more prevalent among adults, HCV infection does occur in children and should be considered when relevant clinical or epidemiologic factors are present. , In recent years, new HCV infections have increased among women of childbearing age and the number of infants born to HCV-infected mothers has risen, resulting in vertically transmitted infections. , Curative treatment…

Bunyaviruses

Description of Pathogen The family Bunyaviridae was recently reclassified, with Bunyavirales becoming an order and several new family names being designated. , However, the genera that have important human pathogens have remained relatively unchanged and include Orthohantavirus, Orthonairovirus, Bandavirus, Phlebovirus , and Orthobunyavirus. A wide range of clinical syndromes in humans exist among the pathogenic bunyaviruses, with the severity of human infections ranging from mild febrile…

Flaviviruses

The flaviviruses are single-stranded, enveloped RNA viruses that are transmitted to humans primarily through the bites of arthropods. Although >40 arthropod-borne flaviviruses have been described, this chapter discusses those that are most important in causing human illness: yellow fever virus (YFV), dengue viruses, Japanese encephalitis virus (JEV), West Nile virus (WNV), tickborne encephalitis virus (TBEV), and Zika virus (ZIKV). Other flaviviruses not discussed in this chapter…

Togaviridae: Alphaviruses

Alphaviruses are arthropod-borne members of the family Togaviridae. They are small, enveloped, positive-sense RNA viruses. , Members of the western equine encephalitis, eastern equine encephalitis, and Venezuelan equine encephalitis serocomplexes cause encephalitis in equines and humans. Members of the Semliki Forest serocomplex, such as chikungunya, o’nyong-nyong, Mayaro, and Ross River viruses, cause epidemic fever and arthralgia. Epidemiology and Clinical Manifestations Chikungunya Virus Chikungunya virus is transmitted…

Rotaviruses

Before the availability of rotavirus vaccines, rotaviruses were the most common cause of severe infant and childhood gastroenteritis worldwide, responsible for 40% of all diarrheal hospitalizations and more than half a million deaths among children aged <5 years annually. To mitigate this substantial disease burden, rotavirus vaccines were developed and are now licensed in many countries. By 2020, 103 countries had introduced rotavirus vaccines in their…

Coltivirus (Colorado Tick Fever)

Colorado tick fever (CTF) is an acute febrile illness caused by CTF virus, a double-stranded RNA virus in the Coltivirus genus of the family Reoviridae ( Box 215.1 ). , The virus is transmitted to humans through the bite of an infected Rocky Mountain wood tick, Dermacentor andersoni ( Fig. 215.1 ). BOX 215.1 Colorado Tick Fever: Agent and Epidemiology Agent Colorado tick fever virus, Coltivirus…

Human Parvoviruses (Parvovirus B19 and Bocavirus)

Parvoviruses—small (20–25 nm), nonenveloped, icosahedral, single-stranded DNA viruses with a linear genome of between 4500 and 5600 nucleotides—are common infectious agents of animals, including birds and insects, as well as humans. At least five different genera of parvovirus have been detected in humans: bocaparvoviruses, dependoparvoviruses, erythroparvoviruses, protoparvoviruses, and tetraparvoviruses. Human bocavirus (HBoV) has been identified in respiratory secretions of young children with acute wheezing and lower…

Hepatitis B and Hepatitis D Viruses

Hepatitis B Virus Description of the Pathogen Hepatitis B virus (HBV), a member of the Hepadnaviridae family, is an enveloped virus that contains a circular partially double-stranded DNA genome that is 3.2 kb in length. The small genome consists of four overlapping reading frames. , Because the presence of HBV is necessary for infection with the hepatitis delta virus (HDV), both pathogens are discussed in this…

BK, JC, and Other Human Polyomaviruses

Polyomaviruses are a subgroup of small, ubiquitous DNA viruses that belong to the family Papovaviridae. The two most commonly known human polyomaviruses are the BK virus and JC virus, which were first described in 1971. , Subsequently, 12 other human polyomaviruses have been identified. WU polyomavirus and KI polyomavirus in 2007, Merkel cell polyomavirus in 2008, human polyomavirus-6, human polyomavirus-7, and trichodysplasia spinulosa virus in 2010,…

Human Papillomavirus

Papillomaviruses are species specific and widely distributed among mammals and nonmammalian animal species. Human papillomaviruses (HPVs) are strictly epitheliotropic and cause infections and cancer of the skin and mucous membranes. Clinical conditions include anogenital and oral infections and cancers, as well as recurrent respiratory papillomatosis. The Virus And Pathogenesis HPVs are non-enveloped, double-stranded DNA viruses with a small circular genome of approximately 8000 base pairs. HPV…

Adenoviruses

Acknowledgement The author acknowledges substantial contributions of Gail J. Demmler-Harrison to this chapter in previous editions. Adenoviruses are relatively small, nonenveloped double-stranded DNA viruses belonging to the family Adenoviridae (from adenos, the Greek word meaning “gland”). They were first isolated from adenoid tissue, and there are 51 human serotypes, which are defined by biologic characteristics, including immunochemical methods, such as serum neutralization and hemagglutination. The use…

Human Herpesvirus 8 (Kaposi Sarcoma–Associated Herpesvirus)

In 1872, Moritz Kaposi, a Hungarian dermatologist, first described in five men an aggressive, pigmented, multicentric sarcoma of the skin that disseminated to multiple sites. It was rare and received little attention until similar lesions were observed in African children and adults and subsequently were found in association with HIV infection in the 1980s. Although the cause of Kaposi sarcoma (KS) was suspected to be infectious,…

Epstein-Barr Virus (Mononucleosis and Lymphoproliferative Disorders)

Epstein-Barr virus (EBV), a ubiquitous herpesvirus of humans, was discovered in 1964. The causal relationship between EBV and infectious mononucleosis (IM) was observed in 1968. The spectrum of associated infections ranges from asymptomatic to self-limited mononucleosis in healthy hosts to progressive infections in patients with acquired or inherited disorders of immunity. Description Of The Pathogen EBV is a γ-herpesvirus. Mature, infectious particles are 150–200 nm in…