1 - The Complexity of Health Flashcards
What is a zoonotic disease
disease or infection that is naturally transmissible from vertebrate animals to humans or humans to animals
What is one health
Managing threats at the interface between ecosystem health, animal health and human health
Health of people,animals and the ecosystem of which we are a part, are interconnected.
How many dengue deaths per year? Who?
22,000
primarily children
How is dengue transmitted? How many serotypes?
Mosquito borne
4 serotypes
What are the mosquito control methods to prevent dengue?
Release of genetically modified mosquitoes to control population
Stop warming temperatures
Why is dengue vaccine development difficult?
Because of the multiple serotypes
Two categories of dengue, describe symptoms.
Dengue fever: higher fever, headache, eye pain, joint/muscle pain, nausea, vomiting, loss of appetite, lasts ~1 week
Dengue hemorrhagic fever: previous symptoms, plus bleeding (red patches, bleeding from nose, mouth, gums, vomiting blood), black tar stool, belly pain, shock
Hemorrhagic dengue results from…
secondary dengue infection with a different serotype
Types of mosquitoes that transmit dengue
Aedes aegypti
Aedes albopictus
What diseases does Aedes aegypti transmit? Where does it originate? Where does it breed
Dengue, chikungunya, yellow fever, zika
Originated in Africa
Breeds in man-made containers (water storage, old tires)
How was aedes aegypti nearly eradicated?
By DDT in 1950s and 60s in Latin America
What diseases does Aedes albopictus transmit? Where is it native to
Dengue, chikungunya, yellow fever, zika
Native to southeast asia
Aedes albopictus feeds on… What makes dangerous in North America?
Humans and other mammals
Invasive, cold hardy
Role of the structural vs nonstructural proteins in the dengue genome
Structural are the viral coat, deliver RNA to target cell
Nonstructural produce new viruses
Recovery from first dengue infection leads to…
lifelong immunity against that serotype
partial and transient protection against subsequent infection by other three serotypes
Dengue vaccines are only effective if
they induce a protective immune response against all dengue viruses simultaneously (multi-valent)
What was the issue with the Dengvaxia vaccine?
Seronegative children given Dengvaxia were at significant risk of severe dengue infection
If children had never had dengue and were given the vaccine, their next infection was likely to be hemorrhagic dengue
Protective efficiency of Dengvaxia
DENV1: 50%
DENV2: 42%
DENV3: 74%
DENV4: 77%
Four ways to combat mosquitoes
- reduce habitat
- insecticide
- genetic manipulation: population control (transgenic mosquitos)
- genetic manipulation: population replacement (Wolbachia)
Example of genetically engineering mosquitoes to control populations
OX513A
Male that, when mates with females, causes death in offspring
Late-acting dominant lethal gene
How many species of vultures? They are…
23 (14 endangered)
Obligate scavengers
Declines in vulture populations causing…
- increase in mammalian scavengers
- increase in carcass decomp times
- increase in pathogens (usually destroyed in vulture GI tract)
Why are vulture numbers declining in Africa and Asia
- Diclofenac
- livestock poisoning
- ivory poaching
- traditional medicine (killed for body parts)
What is felled livestock poisoning
Livestock killed by predators are poisoned by herders to kill the predators
Vultures are inadvertently poisoned
What is Diclofenac? What is it used for in India
Non-steroidal anti-inflammatory drug used to treat mild-to-moderate pain, inflammation, arthritis, swelling, stiffness, joint pain
In India, cattle are considered sacred, and there are many old cattle. Used to treat lameness
How does Diclofenac kill vultures?
Remains in tissue of cattle upon death
When vultures feed on carcasses, are poisoned and suffer from liver failure
How has vulture decline caused rabies in India?
Higher carcass availability has led to increase in feral dog populations, and human rabies deaths
Anthrax affects mostly what animals?
Herbivores (livestock: beef, bison, dairy, sheep, goats, horses)
What animals are resistant to anthrax? Who is it not common in?
Carnivores are resistant
Rare in birds
How does an anthrax infection occur in animals
Ingesting spores from soil
How long do anthrax spores survive
In the environment for years to decades
How do humans get anthrax?
Handling animal products “Woolsorters’ disease”
Meat
Is anthrax contagious
No, not in people or animals
Small risk of direct infection from the lesions on another person’s body
How to deal with anthrax
Effective vaccines
Antibiotic treatments
Four routes of anthrax infection
Cutaneous
Gastrointestinal
Inhalation (Pulmonary)
Injection
What is cutaneous anthrax
Handling infected animals or products e.g. butchering, skinning, dissecting, handling hides, wool, hair
> 90% if human cases, but 80% survival without treatment
What is gastrointestinal anthax
Consumption of raw or undercooked meat
50% survival without treatment
What is inhalation (pulmonary) anthrax
Wool mills, slaughterhouses, tanneries
10-15% survival (without treatment)
60% survival (with treatment)
What is injection anthrax
Drug users (heroin packed inside animal hides)
Europe 2009-2010
What is the agent causing anthrax?
Bacillus anthracis
Gram positive, rod-shaped bacteria
Two different forms of Bacillus anthracis
Rod shaped during vegetative cycle in host (low O2 env)
Sporulates when exposed to air (requires O2 for sporulation) when in environment; resistant to inactivation
What was discovered at London’s King Cross Station in 2002?
Anthrax spores identified in sample of plaster
Horse hair used to bind plaster, but was stopped ~100 years prior (environmentally stable!)
Age of anthrax spores identified in South Africa
~200 years old
Where is Anthrax a real problem?
India and regions of Africa
Continuous problem in Western China
Sporadic outbreaks in Europe and NA
Recap anthrax outbreaks in Canada
Last human case was Sask 2006
A few animal cases per year
Alberta 2022 - 31 cattle and 3 bison in Northern AB
Recap the anthrax outbreak in Siberia in 2016
Western Siberia, first outbreak since 1941
~2500 reindeer died of disease
~100 ppl hospitalized
One human death (11 year old boy)
Why did anthrax appear suddenly in Siberia
Decline in reindeer vaccination rates (program stopped because pop was increasing without any cases)
Heatwave in 2016; melting permafrost released 75 year old anthrax spores
