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Hantavirus Pulmonary Syndrome

The hantavirus pulmonary syndrome (HPS) is caused by multiple closely related hantaviruses that have been identified from the western United States, with sporadic cases reported from the eastern United States ( Fig. 299.1 ) and Canada and important foci of disease in several countries in South America. HPS is characterized by a febrile prodrome followed by the rapid onset of noncardiogenic pulmonary edema and hypotension or…

Lymphocytic Choriomeningitis Virus

Lymphocytic choriomeningitis virus (LCMV) is a prevalent human pathogen and an important cause of meningitis in children and adults. Capable of crossing the placenta and infecting the fetus, LCMV is also an important cause of neurologic birth defects and encephalopathy in the newborn. Etiology LCMV is a member of the family Arenaviridae, which are enveloped, negative-sense single-stranded RNA viruses. The name of the arenaviruses is derived…

Ebola and Other Viral Hemorrhagic Fevers

Viral hemorrhagic fevers are a loosely defined group of clinical syndromes in which hemorrhagic manifestations are either common or especially notable in severe illness. Both the etiologic agents and clinical features of the syndromes differ, but coagulopathy may be a common pathogenetic feature. Etiology Six of the viral hemorrhagic fevers are caused by arthropod-borne viruses (arboviruses) ( Table 297.1 ). Four are caused by togaviruses of…

Yellow Fever

Yellow fever is an acute infection characterized in its most severe form by fever, jaundice, proteinuria, and hemorrhage. The virus is mosquito-borne and occurs in epidemic or endemic form in South America and Africa. Seasonal epidemics occurred in cities located in temperate areas of Europe and the Americas until 1900, and epidemics continue in West, Central, and East Africa. Etiology Yellow fever is the prototype of…

Dengue Fever, Dengue Hemorrhagic Fever, and Severe Dengue

Dengue fever is a benign syndrome caused by several arthropod-borne viruses and is characterized by biphasic fever, myalgia or arthralgia, rash, leukopenia, and lymphadenopathy. Dengue hemorrhagic fever (Philippine, Thai, or Singapore hemorrhagic fever; hemorrhagic dengue; acute infectious thrombocytopenic purpura) is a severe, often fatal, febrile disease caused by one of four dengue viruses. It is characterized by capillary permeability, abnormalities of hemostasis, and, in severe cases,…

Arboviral Infections

The arthropod-borne viral infections are a group of mosquito- or tick-transmitted pathogens of several taxa manifested clinically mostly as neurologic infections, influenza-like illnesses, or acute viral exanthems. In temperate countries, arboviruses are transmitted during warmer weather; however, in tropical and subtropical countries, arboviruses may be transmitted year around either in an urban cycle (human to mosquito to human) or by arthropods that feed on other vertebrate…

Human Papillomaviruses

See also Chapter 687 . Human papillomaviruses (HPVs) cause a variety of proliferative cutaneous and mucosal lesions, including common skin warts, benign and malignant anogenital tract lesions, oral pharyngeal cancers, and life-threatening respiratory papillomas. Most HPV-related infections in children and adolescents are benign (see also Chapter 687 ). Etiology The papillomaviruses are small (55 nm), DNA-containing viruses that are ubiquitous in nature, infecting most mammalian and many…

Rotaviruses, Caliciviruses, and Astroviruses

Diarrhea is a leading cause of childhood death in the world, accounting for 5-10 million deaths per year. In early childhood, the single most important cause of severe dehydrating diarrhea is rotavirus infection. Rotavirus and other gastroenteric viruses are not only major causes of pediatric deaths but also lead to significant morbidity. Children in the United States, before vaccine was available, were estimated to have a…

Coronaviruses

Coronaviruses are increasingly recognized as important human pathogens. They cause up to 15% of common colds and have been implicated in more serious diseases, including croup, asthma exacerbations, bronchiolitis, and pneumonia. Evidence also suggests that coronaviruses may cause enteritis or colitis in neonates and infants and may be underappreciated as agents of meningitis or encephalitis. Four coronaviruses are endemic in humans: human coronaviruses (HCoVs) 229E, OC43,…

Rhinoviruses

Human rhinoviruses (HRVs) are the most frequent cause of the common cold in both adults and children. Although HRVs were once thought to cause only the common cold, it is now known that they are also associated with lower respiratory infections in adults and children. Many HRVs do not grow in culture. Recent studies using molecular diagnostic tools such as the polymerase chain reaction (PCR) have…

Adenoviruses

Human adenoviruses (HAdVs) are a common cause of human disease. Conjunctivitis is a familiar illness associated with the HAdVs, but these viruses also cause upper and lower respiratory disease, pharyngitis, gastroenteritis, and hemorrhagic cystitis. HAdVs can cause severe disease in immunocompromised hosts. Outbreaks of HAdV infection occur in communities and closed populations, notably the military. No currently approved antiviral drugs are highly effective against HAdVs. Vaccines…

Human Metapneumovirus

Etiology Human metapneumovirus (HMPV) is a respiratory virus that has emerged as one of the most common causes of serious lower respiratory tract illness in children throughout the world. Etiology HMPV is an enveloped, single-stranded, nonsegmented, negative-sense RNA genome of the family Pneumoviridae, which comprises large enveloped negative-sense RNA viruses. This taxon was formerly a subfamily within the Paramyxoviridae, but was reclassified in 2016 as a…

Respiratory Syncytial Virus

Respiratory syncytial virus (RSV) is the major cause of bronchiolitis (see Chapter 418 ) and viral pneumonia in children younger than 1 yr of age and is the most important respiratory tract pathogen of early childhood. Etiology RSV is an enveloped RNA virus with a single-stranded negative-sense genome that replicates entirely in the cytoplasm of infected cells and matures by budding from the apical surface of the…

Parainfluenza Viruses

Human parainfluenza viruses (HPIVs) are common causes of acute respiratory illness in infants and children and are important causes of lower respiratory tract disease in young children and immunocompromised persons. These viruses cause a spectrum of upper and lower respiratory tract illnesses but are particularly associated with croup (laryngotracheitis or laryngotracheobronchitis), bronchiolitis , and pneumonia . Etiology HPIVs are members of the Paramyxoviridae family. Four HPIVs…

Influenza Viruses

Influenza viral infections cause a broad array of respiratory illnesses that are responsible for significant morbidity and mortality in children during seasonal epidemics . Influenza A viruses also have the potential to cause global pandemics , which can happen when a new (novel) influenza A virus emerges and transmits efficiently from person to person. Etiology Influenza viruses are large, single-stranded RNA viruses belonging to the family…

Human Herpesvirus 8

Human herpesvirus 8 (HHV-8) is an oncogenic virus identified in tissue specimens from patients with Kaposi sarcoma (KS). Because of this association, it is also known as Kaposi sarcoma–associated herpesvirus . HHV-8 is the etiologic agent of two additional lymphoproliferative disorders: primary effusion–based lymphoma (PEL) and multicentric Castleman disease (MCD) . Etiology HHV-8 is a γ 2 -human herpesvirus similar to Epstein-Barr virus. The virus contains…

Roseola (Human Herpesviruses 6 and 7)

Human herpesvirus 6 (HHV-6A and HHV-6B) and human herpesvirus 7 (HHV-7) cause ubiquitous infection in infancy and early childhood. HHV-6B is responsible for the majority of cases of roseola infantum ( exanthem subitum or sixth disease ) and is associated with other diseases, including encephalitis, especially in immunocompromised hosts. A small percentage of children with roseola have primary infection with HHV-7. Etiology HHV-6A, HHV-6B, and HHV-7…

Cytomegalovirus

Human cytomegalovirus (CMV) is ubiquitous in the population, and individuals who become infected remain persistently infected for life, with intermittent shedding of infectious virus from mucosal surfaces. Although CMV rarely causes symptoms in normal individuals, it is an important cause of morbidity and sometimes death in immunocompromised hosts. CMV remains a well-recognized cause of disease in the newborn infant following intrauterine infection (congenital CMV) and the…

Epstein-Barr Virus

Infectious mononucleosis is the best-known clinical syndrome caused by Epstein-Barr virus (EBV). It is characterized by systemic somatic complaints consisting primarily of fatigue, malaise, fever, sore throat, and generalized lymphadenopathy. Originally described as glandular fever, it derives its name from the mononuclear lymphocytosis with atypical-appearing lymphocytes that accompany the illness. Etiology EBV is a double-stranded DNA virus that is a member of the gammaherpesviruses and causes…

Varicella-Zoster Virus

Varicella-zoster virus (VZV) causes primary, latent, and reactivation infections. The primary infection is manifested as varicella (chickenpox) and results in establishment of a lifelong latent infection of sensory ganglionic neurons. Reactivation of the latent infection causes herpes zoster (shingles). Although often a mild illness of childhood, varicella can cause substantial morbidity and mortality in otherwise healthy children. Morbidity and mortality are higher in immunocompetent infants, adolescents,…