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Questions and Answers
What are the common neurological manifestations associated with West Nile Virus?
Which demographic groups are at greater risk for severe forms of West Nile Virus?
What is the main method used for diagnosing West Nile Virus?
What family and genus does the West Nile Virus belong to?
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Besides serology, what are alternative methods for diagnosing West Nile Virus?
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What is one of the potential severe clinical manifestations of dengue?
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Which bodily fluid is capable of isolating dengue virus for several months?
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What is a complication associated with severe dengue infection?
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How many serotypes of dengue virus are known to exist?
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Which symptom does NOT typically occur during dengue infection?
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What causes the expansion of the paracortical area in normal lymphoid tissue?
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What is a characteristic feature of hyperplastic lymphoid tissue?
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What histological finding is associated with liver involvement in viral infections?
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How do centrocytes differ from centroblasts?
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What is the appearance of the nucleus in centroblasts compared to centrocytes?
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What histological change is often noted in the spleen during viral infections?
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The liver histology in viral infections may show atypical lymphocytes in which areas?
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Which feature best distinguishes centroblasts from other lymphoid cells?
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What is a common complication of CMV mononucleosis?
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Which of the following is NOT associated with congenital CMV infections?
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What age group is primarily affected by EBV, also known as 'Kissing Disease'?
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Which symptom is commonly associated with infectious mononucleosis?
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How is CMV commonly transmitted?
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Which of the following best describes the typical course of symptoms in CMV mononucleosis?
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Which of the following is specifically a characteristic of congenital infections caused by CMV?
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Which symptom is NOT typical of infectious mononucleosis caused by EBV?
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What population is primarily at risk for developing complications from EBV infection?
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What is a characteristic appearance in the blood of individuals with infectious mononucleosis?
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What causes the progression of hemoconcentration in patients with severe dengue infection?
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Which histological feature is characteristic of Diffuse Alveolar Damage (DAD) observed in dengue patients?
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What is a potential consequence of excessive intravenous fluid therapy in dengue patients?
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What primarily alters the integrity of the blood vessel wall in severe dengue infection?
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Which of the following is NOT a complication associated with severe plasma leakage in dengue?
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What monitoring is crucial for patients receiving isotonic intravenous fluids in dengue treatment?
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What type of cells predominantly infiltrates the lung tissue during the inflammation observed in dengue?
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What is the time frame in which patients may continue to experience leakage after proper resuscitation?
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Which of the following correctly describes how the alveolar septa appear in a lung infected with dengue?
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How much increase in hematocrit level indicates severe plasma leakage in dengue patients?
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Study Notes
West Nile Virus
- An acute systemic viral infection
- It can cause mild, self-limited infections or neuroinvasive disease
- The neuroinvasive disease is associated with long-term neurological sequelae
- The virus belongs to the Flaviviridae family, Genus Flavivirus
- It has a broad geographic distribution, including:
- The Old World
- Africa
- The Middle East
- Europe
- Diagnosis is mainly done through serology
- Other diagnostic methods include:
- Viral culture
- PCR
Epstein-Barr Virus
- Causes infectious mononucleosis
- It's a usually benign, self-limiting lymphoproliferative disorder
- Associated with various human tumors, including:
- Lymphomas
- Nasopharyngeal carcinoma
- Characterized by:
- Fever
- Sore throat
- Generalized lymphadenopathy
- Splenomegaly
- Appearance of mononucleosis cells in the blood
- Atypical activated T lymphocytes in the peripheral blood
- Certain individuals may also develop:
- Hepatitis
- Meningoencephalitis
- Pneumonitis
- Transmitted through close human contact
- Often spreads through saliva, especially during kissing, earning it the nickname "Kissing Disease"
- Usually occurs in late adolescents or young adults
- More common among upper socioeconomic classes in developed nations
Cytomegalovirus
- Commonly infects healthy young children and adults
- Usually asymptomatic
- About 50-100% of adults have CMV antibodies globally, indicating prior exposure
- The most common clinical manifestation:
- Infectious mononucleosis-like illness
- Fever
- Atypical lymphocytosis
- Lymphadenopathy
- Hepatitis
- Marked hepatomegaly
- Abnormal liver function tests
- CMV Mononucleosis:
- Affects children and adults
- Almost always symptom-free
- Infants with CMV or transplacental CMV infection:
- Might experience permanent deficits, such as:
- Intellectual disability
- Hearing loss
- Neurologic impairments
- May develop congenital infections, including:
- Interstitial pneumonitis
- Hepatitis
- Neurologic disorders
- Perinatal Infections:
- Transmitted through the birth canal or breast milk
- Usually asymptomatic due to protective maternal antibodies
- Many individuals secrete CMV in urine and saliva for months or years
- Less common complications:
- Interstitial pneumonitis
- Failure to thrive
- Rash
- Hepatitis
Dengue Virus
- Transmitted by Aedes aegypti mosquitos
- Clinical manifestations range from mild to severe:
- Fever with headache
- Macular rash
- Severe myalgias (breakbone fever)
- Severe dengue (Dengue hemorrhagic fever):
- Bleeding
- Liver failure
- Reduced consciousness
- Organ failure
- Plasma leakage
- Severe dengue leads to shock and respiratory distress
- Widespread hemorrhages throughout the body with:
- Hepatic necrosis
- Mononuclear infiltrates
- Septal thickening
- Hyaline membrane formation in the lung
- The immune response to dengue virus dictates the severity of infection
- Dengue virus has four serotypes:
- Each serotype infection provides protective immunity to that specific serotype
- Mechanism of increasing vascular permeability in severe dengue:
- Not fully understood
- Evidence suggests reactive oxygen species, enzymes, and proinflammatory molecules breakdown the glycocalyx layer
- Allows plasma to reach intercellular junctions and leak out into the tissues
- The blood vessel wall integrity is altered
Histologic Analysis of Lung Tissue in Dengue
- Diffuse Alveolar Damage (DAD) is observed:
- Previously known as acute respiratory distress (ARDS)
- Characterized by alveolar collapse
- Some alveoli are collapsed, while others are distended
- Lined by a hyaline membrane
- Dense, thick, pink bands of proteinaceous material
- Accompanied by inflammation
- Inflammatory infiltrates consist mainly of mononuclear cells, similar to dengue (macrophages and lymphocytes)
Pathology of Viral Infections
- Comparison of lymphoid tissues
- Normal lymphoid tissues:
- Paracortical area (dark purple area surrounding the germinal center)
- Expansion is due to T cell activation (immunoblasts)
- Hyperplastic lymphoid tissues:
- Shows an expansion of white pulp follicles (paracortical area) and red pulp sinusoids
- Vulnerable to rupture
- T cell proliferation may be exuberant
- Makes it difficult to differentiate nodal morphology
- Follicles (B cell area) might exhibit mild hyperplasia
Liver Pathology
- The liver is usually involved to some extent
- Moderate hepatomegaly
- Histology:
- Atypical lymphocytes in portal areas and sinusoids
- Scattered isolated cells or foci of parenchymal necrosis
Spleen Pathology
- Enlarged spleen
- The organ often shows:
- Expansion of white pulp follicles
- Expansion of red pulp sinusoids
- Vulnerable to rupture
Centrocytes vs. Other Cells
- Centrocytes:
- Small, cleaved cells with a cleft nucleus
- Nucleus is centrally located
- Centroblasts:
- Larger cells with a nucleus located at the periphery
- Open chromatin
- Several nucleoli
- Modest amount of cytoplasm
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