[04.41] Agents of Childhood Infections V2.pdf

Icosahedral, non-enveloped, single-stranded DNA viruses

What are the general characteristics of the family Parvoviridae?

"Parvum"

What Latin word means "small," giving the Parvovirus family its name?

Parvovirus B19 and Human Bocavirus

What two viruses are included in the family Parvoviridae?

Erythrovirus

What genus does Parvovirus B19 belong to?

Red blood cells (erythro)

What is Parvovirus B19 associated with due to its genus name?

Host cell nucleus

Where does Parvovirus B19 replicate?

Erythroid progenitor cells

What cells does Parvovirus B19 take advantage of for replication due to their high cell division rates?

Sites of hematopoiesis (i.e., bone marrow, or heart and liver during fetal development)

To what locations does Parvovirus B19 travel to replicate after entering the blood circulation?

Respiratory tract

Through what route does Parvovirus B19 enter and shed?

Vertical transmission

What process allows fetal infection when a pregnant mother is infected with Parvovirus B19?

Age of the person infected

What determines the clinical presentation of Parvovirus B19 infection?

Erythema Infectiosum

What syndrome is associated with a cutaneous rash in children infected with Parvovirus B19?

Arthralgia-arthritis

What is the clinical feature of Parvovirus B19 infection in adults?

Transient Aplastic Crisis

What syndrome presents as severe acute anemia in patients with underlying hemolysis infected with Parvovirus B19?

Pure Red Cell Aplasia

What syndrome presents as chronic anemia in immunocompromised individuals with persistent Parvovirus B19 infection?

Hydrops Fetalis

What condition presents as fatal anemia in a fetus infected with Parvovirus B19?

Fifth Disease

What is Erythema Infectiosum also known as, based on the traditional list of childhood infections with a skin rash?

"Slapped cheek" appearance

What is the characteristic erythematous facial rash seen in Erythema Infectiosum?

Viral incubation (1-2 weeks)

What is the initial phase of Parvovirus B19 infection before symptoms appear?

Viremia

What phase of Parvovirus B19 infection presents with flu-like symptoms such as fever, malaise, myalgia, chills, and itching?

Immune complex formation

What causes the short-lived erythematous facial rash, arthritis, and arthralgia in Erythema Infectiosum?

Children

In what host population does Parvovirus B19 cause cutaneous rash (Fifth disease)?

Abrupt cessation of erythropoiesis

What defines Transient Aplastic Crisis (TAC)?

Absence of erythroid precursors

What is the underlying cause of the abrupt cessation of erythropoiesis in TAC?

Chronic hemolytic anemia (e.g., Sickle cell disease, Thalassemias)

What pre-existing condition does TAC complicate?

Seven days

How long is the interruption in erythropoiesis that is clinically apparent in a patient with chronic hemolytic anemia infected with Parvovirus B19?

Viremic phase

What phase of Parvovirus B19 leads to rapid worsening anemia in transient aplastic crisis?

Chronic suppression of erythropoiesis

What defines Pure Red Cell Aplasia?

Persistent Parvovirus B19 infection

What brings about the chronic suppression of erythropoiesis in Pure Red Cell Aplasia?

Immunocompromised individuals

In what population does Pure Red Cell Aplasia occur?

Severe chronic anemia

What is the expected clinical feature of Pure Red Cell Aplasia?

Edema during fetal development

What is Hydrops Fetalis?

Vertical transmission of Parvovirus B19

What may cause Hydrops Fetalis to occur?

Fetal anemia

What leads to fetal heart failure in Hydrops Fetalis?

Fetal heart failure

What condition facilitates fluid build-up in fetal tissue (e.g., ascites, pleural effusion, pericardial effusion) in Hydrops Fetalis?

Before the 20th week of gestation

When may fetal death occur due to Hydrops Fetalis?

Bocavirus

What genus does Human Bocavirus belong to?

Respiratory tract

What body part is presumed to be infected by Human Bocavirus?

Pneumonia

What is a respiratory pathology associated with Human Bocavirus?

Gastrointestinal symptoms and infections

What other symptoms are associated with Human Bocavirus presentation?

Co-infections with other viruses

What factor makes the pathogenesis or exact pathology of human Bocavirus unclear?

Neutralizing virus-specific antibodies

What confers immunity after Parvovirus B19 infection?

Immune deficiency

In what patients does persistent Parvovirus infection occur?

Polymerase Chain Reaction (PCR)

What diagnostic test is used to detect viral DNA for Parvovirus B19?

Immune-deficient patients

For what patient population is PCR preferred for Parvovirus B19 diagnosis?

Enzyme-Linked Immunosorbent Assay (ELISA)

What diagnostic test is used to detect virus-specific antibodies for Parvovirus B19?

Symptomatic and supportive treatment

What type of treatment is available for Parvovirus B19 infection?

Blood transfusion

What treatment is done for severe anemia brought about by viral interference with erythropoiesis?

Immunoglobulin Therapy (Passive Immunization)

What treatment is used to ameliorate persistent viral infection in immune-deficient patients?

Schools

Where do Parvovirus B19 outbreaks commonly occur?

Good hygienic practices

What is important to control the spread of Parvovirus B19?

Up to 60% of all adults and 90% of elderly people

What estimated percentage of the population may be seropositive for Parvovirus B19 virus-specific antibodies?

No vaccine

What control measure is currently unavailable for humans for Parvovirus B19 and Human Bocavirus?

Pleomorphic, enveloped, single-stranded, negative-sense RNA viruses

What are the general characteristics of the family Paramyxoviridae?

Parainfluenza, Respiratory Syncytial Virus, Human Metapneumovirus, Measles, Mumps, Hendra Virus, Nipah Virus

What seven paramyxoviruses are listed in the Paramyxoviridae family?

Rubella virus

What virus is epidemiologically considered a Paramyxovirus but is NOT taxonomically grouped with the family Paramyxoviridae?

Mucus

What does the root word "myxa" (from Paramyxoviridae) mean?

Mucosal infection and secretion

What is central to the Paramyxoviridae and Orthomyxoviridae families?

Fragile

What is a characteristic of the envelope of Paramyxoviruses?

Highly infectious

How are Paramyxoviruses characterized in terms of infectivity compared to other viruses, despite their labile envelope?

Mucosal surfaces, infecting the respiratory tract

Where does the Paramyxoviridae virus enter?

Cytoplasm of the host cell

Where does the Paramyxoviridae virus replicate?

Antigenically stable

How are Paramyxoviridae viruses characterized in general, regarding their antigens?

Respirovirus and Rubulavirus

What two genera are the 5 serotypes of Parainfluenza Viruses (hPIVs) categorized under?

Type 1 and 3

What hPIV serotypes belong to the genus Respirovirus?

Type 2, 4a, and 4b

What hPIV serotypes belong to the genus Rubulavirus?

Limited to the respiratory tract

Where is hPIV infection limited to in immunocompetent individuals?

Viremia

What is uncommon in Parainfluenza Virus infection?

Croup

What clinical presentation is characteristic of hPIV Types 1 and 2?

Barking cough

What is the characteristic sound associated with croup due to inflammation of the larynx?

Steeple sign

What radiologic imaging sign, showing tapering of the upper trachea, is suggestive of croup?

Pneumonia

What does hPIV Type 3 present as in children?

Does not present with serious disease

What is the typical presentation of hPIV Type 4?

Lacks cross-neutralization between serotypes

What is characteristic of the immunity provided by Parainfluenza Viruses?

IgA (mucosal antibodies)

What type of antibody develops upon hPIV infection and confers immunity, but disappears within a few months?

Modify disease presentation (non-febrile colds)

What do antibodies do during reinfection with Parainfluenza Virus?

RT-PCR

What diagnostic test is used to detect viral RNA for Parainfluenza Viruses?

Immunofluorescence test

What diagnostic test is used to detect viral antigen in nasopharyngeal epithelial cells for Parainfluenza Viruses?

4-fold rise in antibody titers

What ELISA result is needed to suggest an ongoing disease presentation for hPIVs?

No specific treatment

What is the specific treatment for Parainfluenza Viruses?

Ribavirin

What antiviral has been used with some benefit in immunocompromised patients with serious lower respiratory tract disease due to hPIV?

Lower respiratory tract disease

What major problem does hPIV cause in young children?

Direct contact and large-droplet aerosols

What are the two ways hPIV is spread from person to person?

Contact isolation precautions

What is advisable to prevent nosocomial outbreaks of hPIV in admitted patients?

Pneumovirus

What genus does Respiratory Syncytial Virus (RSV) belong to?

Bronchiolitis

What distinct clinical syndrome is associated with RSV infection?

Inflammation of smaller caliber airways

What is bronchiolitis?

Syncytial formation

What cytopathic effect, which is the fusion of multiple host cell plasma membranes, is induced by RSV?

Asymptomatic or common colds to pneumonia and bronchiolitis

What is the range of clinical presentations of RSV in infants?

Wheezing

What symptom may occur in RSV infection due to the narrowing of smaller airways (bronchiolitis)?

Vertically transmitted maternal antibodies

What is critical for protection against the more serious lower respiratory tract illness caused by RSV?

Viral-specific IgE secretion

What antibody is correlated with bronchiolitis in RSV infection?

Modify (lessen) severity of disease

What is the effect of antibodies (except IgE) in RSV reinfection?

Most important cause of lower respiratory tract disease

What is RSV considered in infants?

Major pediatric respiratory tract pathogen

What is the overall significance of RSV in pediatric health?

No specific treatment

What is the specific treatment for RSV?

Aerosolized Ribavirin

What antiviral has been used for severe RSV presentation in infants?

Immunoglobulin therapy (humanized monoclonal antibodies)

What therapy may be marginally beneficial for RSV treatment?

Metapneumovirus

What genus does Human Metapneumovirus (HMPV) belong to?

Respiratory epithelial cells

Where is HMPV viral replication limited to?