Microbiology trans

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Questions and Answers

What is the estimated number of people living in areas at risk for dengue transmission?

10 million

5 billion

1 billion

2.5 billion (correct)

Which age group has the highest incidence of dengue?

50 years and older

0-4 years

5-14 years (correct)

15-49 years

What is the hallmark of dengue that causes signs and symptoms?

Severe headaches

Low blood pressure

Increased vascular permeability (correct)

High white blood cell count

During the recovery phase of dengue, what happens to the hematocrit (HCT) level?

It stabilizes or is slightly lower Signup and view all the answers

Which symptom indicates a potentially severe case of dengue?

Persistent vomiting Signup and view all the answers

What effect do inflammatory cytokines have in the context of dengue infection?

They influence vascular permeability Signup and view all the answers

What does ELISA stand for?

Enzyme-linked immunosorbent assay Signup and view all the answers

Which genus is associated with the New World Arenaviruses?

Arenavirus Signup and view all the answers

Which of the following viruses is not classified under Bunyaviridae?

Dengue virus Signup and view all the answers

What does the term 'HI' refer to in the context of virology?

Hemagglutination inhibitor Signup and view all the answers

Which of the following viruses is a part of the Old World Arenaviruses?

Junin Signup and view all the answers

What is the primary role of the non-structural protein 1 (NS1)?

To neutralize host immune response Signup and view all the answers

Which insect genera are associated with the Bunyaviridae family?

Anopheles A and B Signup and view all the answers

Which of the following tests is typically used for viral serotyping?

Hemagglutination test Signup and view all the answers

What does RT-PCR stand for?

Reverse transcription polymerase reaction Signup and view all the answers

Which genus of rodent-borne viruses is associated with hemorrhagic fever?

Hantavirus Signup and view all the answers

What is a characteristic structure found in filoviruses?

Enveloped Signup and view all the answers

Which of the following represents a disease caused by a member of the Flavivirus genus?

Dengue fever Signup and view all the answers

Which of the following represents an appropriate treatment option for viral infections?

Vaccination Signup and view all the answers

What is the pathophysiological feature associated with yellow fever?

Liver necrosis Signup and view all the answers

Which arbovirus is known for causing dengue fever?

Dengue virus Signup and view all the answers

What type of genome do most flaviviruses possess?

Single-stranded RNA Signup and view all the answers

Which virus is associated with hantavirus pulmonary syndrome?

Hantaan virus Signup and view all the answers

Which broad category do arboviruses and rodent-borne viruses belong to?

Viral infections Signup and view all the answers

Which disease is characterized by renal syndrome due to a rodent-borne virus?

Seoul virus infection Signup and view all the answers

What is the primary vector for dengue fever transmission?

Female Aedes mosquito Signup and view all the answers

Which of the following is a characteristic of dengue fever?

Cross-protection between serotypes is of short duration Signup and view all the answers

What is the most severe manifestation of dengue fever?

Dengue hemorrhagic fever Signup and view all the answers

Which factor is NOT a common mode of transmission for arbovirus infections in humans?

Bite of a male mosquito Signup and view all the answers

Which genus does the dengue virus belong to?

Flavivirus Signup and view all the answers

Dengue fever is rampant in which geographical regions?

Subtropics and tropical countries Signup and view all the answers

What is the typical clinical spectrum of dengue fever?

Nonspecific viral syndrome to severe hemorrhagic disease Signup and view all the answers

What is the role of humans in the viral life cycle of arbovirus infections?

Accidental hosts with no essential role Signup and view all the answers

How many distinct serotypes of dengue virus are known?

Four Signup and view all the answers

Which is NOT a method of dengue virus transmission?

Exposure to contaminated water Signup and view all the answers

What is the role of the host in the life cycle of the flavivirus?

The host reservoir allows the disease to spread to other species. Signup and view all the answers

What type of illness can flavivirus infection cause?

Acute febrile illness Signup and view all the answers

Why are humans considered dead-end hosts for flavivirus?

Humans do not develop high virus levels to transmit it. Signup and view all the answers

What is the primary method of entry for the flavivirus into host cells?

Receptor-mediated endocytosis Signup and view all the answers

What type of genomic material does flavivirus possess?

Positive sense RNA Signup and view all the answers

Which of the following is a potential consequence of flavivirus infection?

Encephalitis with potential high mortality Signup and view all the answers

Which statement correctly describes the process of flavivirus replication?

Viral replication takes place in the cytoplasm. Signup and view all the answers

What kind of fevers can be associated with flavivirus infections?

Hemorrhagic fevers Signup and view all the answers

In what way are humans considered hosts in the case of Urban Yellow Fever and Dengue?

Humans are the primary reservoirs for the viruses. Signup and view all the answers

What is a common result of encephalitis caused by flavivirus?

High mortality rates Signup and view all the answers

Study Notes

Arbovirus and Rodent-Borne Virus Classification

Arboviruses: Include Alphaviruses, Flaviviruses, and Bunyaviruses. Transmission primarily via arthropod vectors (mosquitoes).
Rodent-borne viruses: Arenaviridae (e.g., Lassa, Junin), Hantaviridae (e.g., Hantaan, Seoul), Filoviridae (e.g., Ebola, Marburg). Transmission via rodents.

Flaviviridae Family

Genus Flavivirus: Includes dengue, Japanese encephalitis, yellow fever, Zika, West Nile viruses. Positive-sense single-stranded RNA viruses.
Dengue virus (DENV): Four serotypes (DEN-1, -2, -3, -4). Lifelong immunity to the infecting serotype, but cross-protection between serotypes is short-lived.
Dengue fever: Spectrum ranges from mild febrile illness to severe hemorrhagic fever. Major mosquito-borne viral disease affecting humans. Transmitted primarily by Aedes mosquitoes. 50-100 million infections annually, with 500,000 dengue hemorrhagic fever (DHF) cases and 22,000 deaths.

Dengue Pathophysiology and Clinical Manifestations

Infection begins with subcutaneous infection of DENV from the mosquito's salivary glands.
Replication occurs in macrophages and dendritic cells, leading to viremia and dissemination to organs.
Innate and adaptive immune responses are activated.
Increased vascular permeability is a hallmark of dengue, causing characteristic symptoms.

Dengue in the Philippines (Bravo et al., 2000-2011)

Highest incidence: 5-14 year olds, followed by 0-4 year olds, then 15-49 year olds.
Highest case fatality rate among children.

Dengue Diagnosis

During acute phase, serologic tests for IgM and IgG are not recommended.
White blood count (WBC) starts rising after defervescence.
A positive result may be observed after 3, 5, or 7 days of illness (depending on the source).

Flavivirus Replication

Virus binds to host cells and enters via receptor-mediated endocytosis.
Fusion with endosomal membrane, genome uncoating.
Positive-sense RNA genome serves as mRNA for viral protein synthesis (structural and non-structural).
Replication occurs in the cytoplasm.

Dengue Transmission

Primarily via Aedes mosquito bites (female).
Rare transmission routes: vertical (mother to fetus), blood transfusion, breast milk, organ transplant.

Clinical Syndromes of Arboviral Infections

Undifferentiated fevers (acute febrile illness).
Encephalitis (inflammation of the brain; often high mortality).
Hemorrhagic fevers (highly severe and fatal).

Togavirus and Flavivirus Properties

Table 2 (missing from provided text) likely detailed properties of Togaviruses and Flaviviruses (structure, replication, pathogenesis).

Arbovirus Hosts and Vectors

Reservoir hosts: Maintain the virus in nature.
Bridge vectors: Other mosquito species infected, expanding the transmission cycle.
Dead-end or incidental hosts: Humans and other mammals. Don't usually have high enough viral loads to infect mosquitoes. Humans are typically accidental hosts, except in urban yellow fever and dengue.

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Description

Test your knowledge on arboviruses and rodent-borne viruses, including their classifications and key examples. Delve into the Flaviviridae family with a focus on the dengue virus and its serotypes, along with the transmission methods and pathophysiology associated with them.

Microbiology trans - RNA III