Viruses!

What is colorado tick fever caused by?

an dsRNA virus called Coltivirus

When do cases of Colorado tick fever occur?

in April, may, and june

What does Powassan cause?

RNA virus called Flavivirus

What are arboviruses and how do they interact with their vectors?

arboviruses multiply in the tissues of arthropod vectors without causing disease, and the vector stays infected for life.

What are the 3 clinical syndromes caused by arboviruses?

undifferentiated fever (rash), encephalitis (brain inflammation), hemorrhagic fevers

What is the mosquito life cycle?

eggs → larva → pupa → adult

Describe Anopheline

the larvae never have a siphon and lie parallel to water surface

Describe culicinae:

all larvae have a short or long siphon and subtend an angle from the water surface

How is Eastern Equine Encephalitis transmitted to humans and horses?

through bites from infected mosquitoes

Why is eastern equine encephalitis considered serious among arboviruses?

it affects the central nervous system and can cause severe complications or death

Where is eastern equine encephalitis?

in freshwater hardwood swampland in the Atlantic and Gulf Coast states in the eastern part of North America, Central and South America, and the Caribbean

Who are vaccines available for that are infected with EEE?

horses, but not humans

What type of virus causes Chikungunya and what family is it in?

a positive-strand, enveloped RNA virus from the Togaviridae family

How is Chikungunya transmitted to humans?

through bites from Aedes aegypti and Aedes albopictus mosquitoes

What are the acute infection symptoms of Chikungunya?

joint pain, fever, headache, rash

where do Aedes mosquitoes typically lay their eggs?

in containers like cans, tires, and anything that holds water near human homes

How is Chikungunya diagnosed?

by tissue culture, RT-PCR, and detecting antiviral antibodies

What viruses is the leading cause of vaccine-preventable encephalitis in Asia and the western Pacific?

Japanese Encephalitis

What are the vectors of Japanese encephalitis?

culex mosquitoes

What animals are involved in the virus cycle of JE?

mosquitoes, pigs, and wading birds

How can JE be prevented?

using personal protective measures to prevent mosquito bites and vaccination

What mosquito is the main vector of Dengue fever?

Aedes aegypti (asian tiger mosquito)

How is dengue fever transmitted?

by the bite of an infected mosquito

What is the severe form of Dengue fever?

Dengue hemorrhagic fever (dengue shock syndrome)

What does dengue hemorrhagic fever result in?

increased release of cytokines, vascular damage, shock hemmorrhage

Why do antibodies in DHF fail to protect the body?

they bind to the virus but don’t neutralize it, allowing infection to spread

What is the role of the FC portion of the antibody in DHF?

it binds to Fc receptors on monocytes, helping the virus enter and infect them

What are the 3 stages in Yellow fever progression?

initial (high fever, muscle pain, vomit, headache), quiescent (fever dissipates), and final (original symptoms but more severe; multi-organ failure)

What type of vaccine is used for yellow fever?

live-virus vaccine providing lifelong protection after a single dose

What is Rift Valley fever (RVF)?

a viral zoonosis that primarily affects animals but can infect humans

How do most human infections of Rift valley fever occur?

through direct or indirect contact with blood or organs of infected animals

How can humans get infected with rift valley fever virus?

inoculation through cuts, contact with broken skin, or aerosol inhalation during animal slaughter

How can humans ingest the rift valley fever virus?

by ingesting unpasteurized or uncooked milk from infected animals

Which mosquito is the most common vector for RVF?

the Aedes mosquito (blood feeding flies can also transmit it)

Symptoms of rift valley fever:

neck stiffness (mistaken for meningitis), flu-like fever, muscle pain, loss of appetite

What are severe symptoms of of rift valley fever?

ocular disease, meningoencephalitis, and hemorrhagic fever

How is Rift valley fever diagnosed?

by serological tests like ELISA and EIA, detecting specific IgM antibodies to the virus

What kind of virus is West nile virus?

it is an arbovirus that can cause infection/inflammation of the spinal cord and/or brain

What is the main cycle that maintains west nile virus transmission?

it is maintained in a bird-mosquito cycle but can spill over to other animals like humans and horses

How is west nile virus diagnosed?

IgM antibodies or IgG antibodies in serum or CSF

what is Zika Virus Disease?

a disease spread through the bite of an infected Aedes aegypti or Ae. albopictus mosquito

How is Zika virus transmitted?

mosquito bites, from a pregnant woman to her fetus, sex, blood transfusion

How can Zika affect pregnancies?

it may cause microcephaly and other severe brain defects

Microcephaly:

birth defect in which a baby’s head is smaller than expected when compared to babies of the same sex and age

What are other fetal/infant issues caused by Zika?

miscarriage/stillbirth, poorly developed brain structures, eye defects, hearing deficits, and impaired growth

How does Zika relate to Guillain-Barre Syndrome?

it can be triggered by Zika in a small proportion of infections

What is Guillain-Barre Syndrome?

an uncommon syndrome of the nervous system damaging the nerve cells, causing muscle weakness, and paralysis

How is Zika virus diagnosed?

based on a person’s recent travel history, symptoms, and a blood or urine test

What is the treatment for Zika virus?

There is no treatment, but DON’T take aspirin or NSAIDS

What are the most common symptoms of Zika virus?

fever, rash, joint pain, conjunctivitis, muscle pain, headache