Test four Flashcards
Plasmodium
Disease organism
Family Culicidae
Mosquitoes
Great habitat diversity
Approximately 40 million years older than humans
Pests as well as vectors of pathogens causing human and animal disease
Subfamily
- Anophelinae - anopheles
2. Culicinae - aedes, culex, Haemagogus, Mansonia, Ochlerotatus and all other genera
Mosquito Characteristics
Bloodfeeding - only females take blood
Males and females feed on plant sugars
Larval biology - 4 stages (instars), aquatic, spiracle for breathing, filter-feeders, some cannibalistic, variable habitats
Malaria
Caused by a protozoan
Curable if promptly diagnosed and treated
Worse type of malaria
Plasmodium falciparum
Life cycle of Malaria
- A mosquito injects sporozoites into the blood stream
- They invade liver cells and transform into merozoites (this process is called exoerythrocytic schizogony. There are no disease symptoms during this stage
- Each cell ruptures, releasing tens of thousands of merozoites. Penetrating a red blood cell, a merozoite multiplies. This is called the erythrocytic stage (this is when clinical features develop)
- Each red cell bursts and releases more merozoites
- They infect more red blood cells and multiply again
- Some merozoites develop into male and female forms called qametocytes
- Feeding on a person with malaria a mosquito ingests the gametocytes
- They reproduce and develop into oocysts, which rupture and release sporozoites
- The sporozoites migrate from the mosquito’s gut to the salivary glands, ready to be injected into a human host
Erythrocytic Stage
intracellular parasite undergoes trophic phase
young trophozoite called ‘ring form’
ingests host hemoglobin
Exoerythrocytic Schizogony
hepatocyte invasion asexual replication 6-15 days 1000-10,000 merozoites no overt pathology
Sporogony
occurs in mosquito (9-21 d) fusion of micro- and macrogametes zygote ookinete (~24 hr) ookinete transverses gut epithelium ('trans-invasion') ookinete --> oocyst asexual replication --> sporozoites sporozoites released sporozoites migrate through hemocoel sporozoites 'invade' salivary glands
Symptoms of Encephalitis
Fever Headache Behavioral changes Altered level of consciousness Seizures
Encephalitis is
Acute inflammatory process affecting the brain
Encephalitis caused by
viruses or arboviruses
Arboviruses are
arthropod born viruses
Major arboviruses that cause encephalitis
Flaviviridae
Togaviridae
Bunyaviridae
Flaviviridae
West nile
st. louis encephalitis
Powassan virus
Togaviridae
E and W equine
Bunyaviridae
La Crosse
West Nile Virus
Primary host – wild birds
Principal arthropod vector – mosquitoes
1999 NY West Nile Outbreak
Crows dying in Queens, late summer
27 Deaths among captive birds
59 Human cases needing hospitalization, 7 deaths
Spread of West Nile in the US: 2000
spread throughout New England and Mid-Atlantic regions.
18 new human cases reported
Spread of West Nile in the US: 2001
spread throughout the entire eastern half of the US
64 cases reported, with NY, FL and NJ accounting for 60%
Spread of West Nile in the US: 2002
spread westward across Great Plains into Western US. Reached California by Labor Day.
By end of 2002 cumulative human cases > 3900, with > 250 deaths
Spread of the West Nile in the US: 2003
US, Canada, Mexico
9,858 cases reported to CDC, including 262 deaths in 45 states and D.C.