Lecture 17 Flashcards
Malaria Data: WHO vs IHME — Key Differences
Different methods → different estimates.
Biggest discrepancies in Africa (where >90% of deaths occur).
IHME estimates 30–50% more deaths than WHO.
Trends since 2005 are similar despite number differences.
What factors contributed to the decline in malaria cases and deaths since 2000?
Increased funding:
US$ 100M (2000) → US$ 2.7B (2016) → US$ 3.0B (2019)
Improved access to:
Personal protection
Treatment & prophylaxis
Vector control
Boost in R&D
P. falciparum vector
anopheles gambae
What are effective malaria vector control strategies?
Local, seasonal efforts to reduce/treat mosquito breeding sites.
Use of larvicides, oils, toxins, insecticides.
Biological controls = mostly ineffective.
Individual protection is key:
Insect repellent
Indoor residual spraying
Insecticide-treated nets (ITNs)
Recent Medical Developments in Malaria Control
Mass distribution of ACT (artemisinin-based combination therapy)
Seasonal malaria chemoprevention for children <5
RTS,S vaccine
What recent funding issue is threatening malaria control progress?
2025 freeze of several USAID programs is expected to cause major and immediate increases in malaria cases and deaths.
Arboviruses – Key Facts
Need host cells to replicate
Mostly Flaviviridae
Often cause fever, but can lead to:
Hemorrhagic fevers (e.g., dengue, YF)
Encephalitis (e.g., WNF, EEE)
Birth defects (e.g., Zika)
What happens in the vertebrate host during arbovirus infection?
Infected cells are damaged or lysed after releasing many virions
Viremia (virus in blood) occurs
Length of viremia varies by virus
What happens in the insect host during arbovirus infection?
Cellular infection occurs without cytopathology
Amplification takes about 10 days
Types of Arbovirus Transmission
Horizontal transmission: Between vector and host
Vertical transmission: Within vector population
Transtadial: Pathogen passed through life stages
Generational: Passed to offspring
Venereal: Passed through mating
Dengue Virus – Key Facts
4 serotypes: DENV 1, 2, 3, 4
Humans = main amplifying host, but other primates also infected
Vector: Primarily Aedes aegypti, widespread in tropical/subtropical areas
Transmission:
Mother to fetus (possible)
Blood transfusion (rare, due to short viremia)
Dengue Virus – Incubation and Symptoms
Incubation: 5-8 days after bite
Replication: Mainly in macrophages and endothelial cells
Impact: Inflammation + vascular permeability changes
Viremia: Short (2-7 days), longer in secondary infections (different serotype)
Primary infection: ~50% asymptomatic or mild fever
Secondary infection (1-3 years later): Higher symptomatic rate + more complications
