ORGB 423 Lecture Notes - Lecture 6: Aedes Albopictus, Chikungunya, Dengue Virus
12 Jun 2018
School
Department
Course
Professor
MIMM466: Viral Pathogenesis
2018-01-15 LEC 6 Emerging viruses: Arboviruses
Dr. Anne Gatignol
Mosquitos
• Most dangerous animal in the world in terms of human deaths (2-3 million per year)
• Adult female is most dangerous and transmits disease
o Carries: malaria, YFV, dengue, various types of encephalitis, Rift Valley Fever, West Nile,
Chikungunya, Zika
• 2 main species: Aedes aegypti & Aedes albopictus
o Lay eggs in water containers, live around households
o Peak feeding is during the day time
• Transmission cycles:
o Sylvatic (jungle) cycle: virus cycles between mosquitos and 2 types of monkeys
o Epidemic (urban) cycle: mosquito transmits virus to humans, then virus cycles between humans and
mosquitos
Aedes aegypti
Aedes albopictus
Transmits: Dengue, Chikungunya, YFV, Zika
Environment: concentrated in the tropics
• A more efficient vector because the female
almost exclusively feeds on humans
Transmits: Dengue, Chikungunya, Zika (likely)
Environment: wider spread, less concentrated
Dengue and dengue hemorrhagic fever virus: DENV
• 4 related viruses (DENV 1-4)
• Flaviviridae
• Aedes aegypti is primary vector, humans are primary amplifying host
• Genome: RNA virus, 5’-structural genes, 3’-non-structural genes
• Replication cycle: Entry à release of viral RNA à translation à assembly at the ER à maturation & export
• Symptoms:
o DF : severe flu-like illness, headache, retro-orbital pain, myalgia, arthralgia, maculopapular rash
o DHF (5-10%): Severe, hemorrhagic fever – 41C plasma leakage with shock or respiratory distress
§ Occurs when people are infected a second time with a different strain
o Subsequent infection with different type of dengue virus increases risk for severe disease due to
Antibody-Dependent Enhancement
o Enlargement of liver and circulation failure
• History: dengue is not a new disease but has recently increased geographic range, incidence, severity
o The four dengue viruses originated in monkeys and independently jumped to humans in Africa or
Southeast Asia between 100 and 800 years ago
o Geographically restricted until 1950.
o DHF first documented 1950s in Philippines and Thailand
o 1981: Caribbean and Latin America
• Global burden: the global reach of dengue is expanding
o Prior to 1970, 9 countries had DHF, now more than 100.
o 2.5 billion people (40% of the world's population) are now at risk, with 400M annual infections
o 500 000 with DHF, 2.5% die
o Occurs mostly in urban and semi-urban areas in tropical and sub-tropical climates
• Treatment: no specific treatment, maintaining circulating fluid volume can decrease fatality
• Immunization: vaccine must immunize against all 4 serotypes, because re-infection (even with a different
serotype) is even more severe, 5 candidates currently in phase 3 trials
o Dengvaxia: licensed in 2015 (Mexico), 2016 (WHO)
§ Recommended for people aged 9-45 in endemic areas
§ Not to be administered to people previously infected with dengue
Document Summary
Mosquitos: most dangerous animal in the world in terms of human deaths (2-3 million per year, adult female is most dangerous and transmits disease, carries: malaria, yfv, dengue, various types of encephalitis, rift valley fever, west nile, Environment: wider spread, less concentrated: a more efficient vector because the female almost exclusively feeds on humans. Occurs when people are infected a second time with a different strain: subsequent infection with different type of dengue virus increases risk for severe disease due to. Antibody-dependent enhancement: enlargement of liver and circulation failure, history: dengue is not a new disease but has recently increased geographic range, incidence, severity, the four dengue viruses originated in monkeys and independently jumped to humans in africa or. Immunization: vaccine must immunize against all 4 serotypes, because re-infection (even with a different serotype) is even more severe, 5 candidates currently in phase 3 trials: dengvaxia: licensed in 2015 (mexico), 2016 (who) Recommended for people aged 9-45 in endemic areas.
