Arboviruses and Their Transmission

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Questions and Answers

What characteristic is common to alphaviruses?

They are only found in tropical regions.

They do not cause encephalitis in humans.

They are antigenically related. (correct)

All are transmitted exclusively through direct contact.

What is a key property of flaviviruses?

They are primarily spread by direct human transmission.

They have a worldwide distribution. (correct)

They do not have vector transmission.

They can only infect rodents.

How are many encephalitides transmitted to humans?

Via respiratory droplets.

Through foodborne pathogens.

By mosquitoes or other blood-feeding arthropods. (correct)

Through contaminated water supply.

What can affect the distribution of arboviruses across continents?

Viral host and vector interactions during the year. Signup and view all the answers

What is the public health impact of arboviruses in the United States?

There are significant human infections that vary yearly. Signup and view all the answers

Which clinical syndrome associated with arboviruses is characterized by inflammation of the brain?

Encephalitis Signup and view all the answers

Which of the following arboviruses is most commonly identified in the tropical regions?

Dengue Signup and view all the answers

What transmission mechanism is commonly associated with the persistence of arboviruses in arthropods?

Transovarian transmission Signup and view all the answers

Which of these arboviruses is NOT mentioned as being important in the United States?

Zika virus disease Signup and view all the answers

How are rodent-borne viral diseases primarily transmitted?

Direct contact with body fluids Signup and view all the answers

The presence of which type of climatic zone increases the prevalence of arboviruses?

Tropical zones Signup and view all the answers

What factor determines the clinical syndrome caused by individual arboviruses?

Degree of viral multiplication Signup and view all the answers

Which statement best describes the diseases produced by arboviruses?

They can produce multiple clinical syndromes. Signup and view all the answers

What are the main characteristics of arboviruses?

They can be classified into several virus families. Signup and view all the answers

Which family of viruses includes many of the arboviruses known to infect humans?

Arenaviridae Signup and view all the answers

Which of the following best describes the genomic structure of the alphavirus RNA genome?

Positive sense Signup and view all the answers

What is a common characteristic of flaviviruses?

They contain two glycoproteins in their envelope. Signup and view all the answers

How are arboviruses primarily transmitted?

By bloodsucking arthropods. Signup and view all the answers

Which of the following is a known disease caused by arboviruses?

Chikungunya Signup and view all the answers

Which vector is associated with the transmission of Eastern equine encephalitis?

Aedes mosquito Signup and view all the answers

In which geographical area is Western equine encephalitis most commonly found?

Pacific and Mountain regions Signup and view all the answers

What is the significance of urban yellow fever in relation to arboviruses?

It is an example of an urban transmission cycle. Signup and view all the answers

What impact do arboviruses have on public health?

They are emerging infectious diseases and a public health challenge. Signup and view all the answers

What is the estimated case ratio for infants contracting Eastern equine encephalitis?

10:1 Signup and view all the answers

What type of hosts do arboviruses utilize in their transmission cycles?

Nonhuman vertebrates Signup and view all the answers

Which of the following is NOT a characteristic of flaviviruses?

They contain a double-stranded genome. Signup and view all the answers

What is unique about the transmission cycle of tick-borne encephalitis?

It can involve ingestion of contaminated raw milk. Signup and view all the answers

What is the approximate mortality rate for Eastern equine encephalitis infections?

30-70% Signup and view all the answers

Which of the following statements about Zika is accurate?

Zika is primarily transmitted by mosquitoes. Signup and view all the answers

Which other vector besides mosquitoes can transmit some flaviviruses?

Ticks Signup and view all the answers

What distinguishes the flavivirus family from other virus families?

Single-stranded RNA genome organization Signup and view all the answers

What distinguishes arboviruses from other viruses?

They have complex transmission cycles involving vectors. Signup and view all the answers

What factors contribute to the worldwide distribution of flaviviruses?

Presence of various vectors and hosts Signup and view all the answers

What is a key characteristic of Zika virus regarding transmission?

It can pass through the placenta to infect fetal tissue. Signup and view all the answers

Which of the following is NOT a major rodent-borne viral disease mentioned?

Dengue fever Signup and view all the answers

Which geographical distribution is commonly associated with arbovirus infections?

Distinct distributions and vector patterns on each continent. Signup and view all the answers

What is the reservoir host suspected to be for African hemorrhagic fevers like Marburg and Ebola?

Rodents or bats Signup and view all the answers

What characteristic does the genome of Arenaviridae viruses possess?

Double-segmented, negative-sense and ambisense RNA. Signup and view all the answers

Which of the following best summarizes the public health impact of Zika virus?

It can result in birth defects where transmission occurs. Signup and view all the answers

What type of viruses are typically involved in causing Colorado tick fever?

Arboviruses. Signup and view all the answers

Which characteristic best describes the viruses under the Arenaviridae family?

Contain a protective lipid membrane. Signup and view all the answers

Which of the following is an example of a New World Arenavirus?

Sabia virus Signup and view all the answers

Which of the following is a feature of arboviruses?

They require a vector, such as an insect or tick, for transmission. Signup and view all the answers

Study Notes

Arboviruses Overview

Arboviruses are primarily transmitted by arthropods like mosquitoes and ticks, involving complex transmission cycles.
Major arboviral diseases include yellow fever, dengue, Japanese B encephalitis, St. Louis encephalitis, western and eastern equine encephalitis, West Nile fever, chikungunya fever, Zika virus disease, and sandfly fever.
Some arboviruses can be maintained in arthropods via transovarian transmission without causing disease or damage.

Clinical Syndromes of Arbovirus Diseases

Diseases are classified into three clinical syndromes:
- Undifferentiated fevers with possible maculopapular rash; generally benign.
- Encephalitis with high case-fatality rate.
- Hemorrhagic fevers, which can be severe and fatal.
Different arboviruses can manifest multiple clinical symptoms, showcasing the complexity of their effects.

Rodent-Borne Viral Diseases

Rodent-borne viruses are transmitted directly between rodents and do not utilize arthropod vectors.
Transmission occurs via contact with body fluids or excretions, leading to persistent infections.

Major Families and Properties

Arboviruses and rodent-borne viruses belong to several families: Arenaviridae, Bunyaviridae, Flaviviridae, Reoviridae, Togaviridae, and Filoviridae for African hemorrhagic fever viruses.
Many arboviruses are zoonotic, with humans acting as incidental hosts.

Epidemiology and Transmission

Arbovirus infections exhibit geographic distributions, often influenced by local climate and wildlife.
Common vectors include Aedes and Culex mosquitoes, which help transmit viruses from viremic vertebrates.

Key Diseases in the United States

Important arboviral infections include La Crosse encephalitis, West Nile fever, St. Louis encephalitis, eastern equine encephalitis, and western equine encephalitis.
Rodent-borne viruses of significance include hantavirus pulmonary syndrome and Colorado tick fever.

Disease Characteristics

Eastern equine encephalitis shows a case ratio of 10:1 among infants, with mortality rates ranging from 30-70%.
Zika virus can cross the placenta, leading to birth defects in affected regions.

Viral Classification

The classification of arboviruses includes alphaviruses and flaviviruses, all globally distributed and antigenically related.
Flavivirus envelopes consist of two glycoproteins, and their genomes are positive-sense RNA.

Public Health Implications

Emerging infectious diseases such as West Nile, chikungunya, and Zika illustrate the dynamic nature of viral distribution and necessitate ongoing monitoring in their geographic ranges.

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Description

This quiz delves into the world of arboviruses, specifically focusing on their multiplication in arthropod tissues and the diseases they cause, such as dengue and yellow fever. Explore how these viruses are maintained in nature and the geographical areas of their prevalence.