Plague
The first pandemic that reliably killed an estimated 100 milling people in the 6th century AD
rat-infested ships
How was the plague in the late 1800’s transmitted around the world?
port of San Francisco
The plague was brought to the US through the
Pneumonic, bubonic and septicmic
3 types of the bacterium causing plague
Gram negative rod
What gram stain and shape is the bacteria that causes the plague
Safety Pin
Plague Bi-polar staining looks like a:
rats squirrels and dogs
The reservoir for the Plague
a flea
The vector for the Plague
Bubonic plague
(Bacterial growth in blood and lymph)
• Bacterium injected through a flea bite
• Enters the lymph and is filtered by a lymph node
• Infection causes inflammation and necrosis of the node
• Results in a swollen lesion called a bubo, usually in the groin or
axilla
• Incubation period: 2 to 8 days, ending with the onset of fever,
chills, headache, nausea, weakness, and tenderness of the bubo
• Bacterium injected through a flea bite
• Enters the lymph and is filtered by a lymph node
• Infection causes inflammation and necrosis of the node
• Results in a swollen lesion called a bubo, usually in the groin or
axilla
• Incubation period: 2 to 8 days, ending with the onset of fever,
chills, headache, nausea, weakness, and tenderness of the bubo
Septicemic plague
when the case progresses to massive
bacterial growth in the blood (Septic shock)
bacterial growth in the blood (Septic shock)
Pneumonic plague
respiratory disease (bacteria in lungs)
Plasminogen
activation of lead to clotting, preventing phagocytosis and that kill the phagocyte
a gene for capsule formation and a gene for plasminogen activation
Yersinia pestis carries two additional genes that help cause disease in mice and and to survive the flea vector
small. only 3-50 cells
The number of bacteria needed to initate a plague infection is
Enterobacteriaceae
What family is Yersinia pestis belong?
gastrointestinal tract diseases in humans
Y. enterocolitica and Y. pseudotuberculosis cause
Africa, South America, Mideast, Asia, Soviet Union, and India
The plague still exists endemically in what parts of the world
increased rat population caused by monsoon floods
Surges of plague cases are caused by
contact with wild and domestic animals
In the US sporadic causes are caused by
Gram staining of blood, and Bubo aspirate
How can the plague be diagnosised
quatantine
The plague is prevented and treated by
trapping rodents, poisoning their burrows with insecticides to kill fleas.
The plague is controlled by
Streptomycin or gentamicin
Treatments for the plague are
droplet contact, direct contact with body fluids.
Y. pestis modes of transmittion
Lyme Disease
Borrelia burgdorferi
– a spirochete is a chemical agent for
– a spirochete is a chemical agent for
Deer
Reservior of Lyme Disease
Ticks: Ixodes scapularis, the black‐legged deer tick
Vector for Lyme Disease
Bulls-eye rash
First symptoms for Lyme Disease
Irregular heartbeat, encephalitis,
cardiac and neurological symptoms develop
cardiac and neurological symptoms develop
Second stage for Lyme Disease
Arthritis
Third stage for Lyme Disease
stiff neck, swollen joints, malaise, and fatigue
Symptoms that follow the rash
erythema migrans
Bull’s-eye lesions are called
Antigenic shifting:
– It changes its surface antigens while it is in the tick
and again once it is in the mammalian host
– Immune evasion
• Multiple proteins for attachment to host cells
– It changes its surface antigens while it is in the tick
and again once it is in the mammalian host
– Immune evasion
• Multiple proteins for attachment to host cells
Lyme Disease Virulence factors:
hikers, backpackers, and people living in newly developed communities near woods or forest
Who is at higher risk for Lyme disease?
Northeastern
What part of the US has the highest reported cases of Lyme Disease?
ELISA, test for spirochetal DNA, seeing the ring-shaped lesion
What test is used to diagnosis Lyme Disease
Use insect repellent containing DEET, avoid ticks
Prevention for Lyme Disease.
antibiotics
Treatment for late Lyme Disease.
Rocky Mountain Spotted Fever
Causative agent: Rickettsia rickettsii causes:
Dogs, wood
Rocky Mountain Spotted Fever Reservoir:
Ticks of the genus Dermacentor Ex.
Dermacentor variabilis, a dog tick
Dermacentor variabilis, a dog tick
Rocky Mountain Spotted Fever vector:
Rocky Mountain Spotted Fever
Are Signs and symptoms of what:
– Measles‐like rash, except that the rash also
appears on palms and soles
– In most severe untreated cases, enlarged lesions
merge and become necrotic
– Other manifestations: cardiovascular disruption;
conditions of restlessness, delirium, convulsions,
tremor, and coma
– Measles‐like rash, except that the rash also
appears on palms and soles
– In most severe untreated cases, enlarged lesions
merge and become necrotic
– Other manifestations: cardiovascular disruption;
conditions of restlessness, delirium, convulsions,
tremor, and coma
Spring and Summer
What time of year do most RMSF infections occur?
Southeast and eastern seaboard
Where do most US causes of RMSF occur?
20-40 cases per 10,000 poplulation
The yearly rate of RMSF is
fever, chills, headache, and muscular pain
First symptoms of RMSF are usually
2-4 days after prodrome
When does the RMSF rash develop
20% of untreated, 5-10% of treated
Rates of fatalities of RMSF
antibotic
To treat RMSF use the drug of choice
wear protective clothing, use insect sprays and fastidiously removing ticks
Prevention of RMSF
isolating and staining rickettsias from the patients blood or tissues
RMSP early diagnosis is possible by
Malaria
Caused by a protozoa: Plasmodium species
a mosquito of the genus Anopheles
Malaria vector
Anopheles mosquito (vertical)
Malaria’s host
– Plasmodium vivax
– P. ovale
– P. malariae
– P. falciparum
– P. ovale
– P. malariae
– P. falciparum
Four forms of Malaria
malaise, fatigue, vague aches,
and nausea with or without diarrhea
and nausea with or without diarrhea
First symptoms of Malaria:
bouts of chills, fever, and
sweating
sweating
Second round of Malaria symptoms:
48‐ or 72‐hour intervals as a result of red blood cells rupturing
When do Malaria symptom occur?
The interval, length, and regularity of symptoms
What reflects the type of Malaria had
10 to 16‐days
How long is Malaria’s incubation period
Malaria
The world’s dominant protozoan disease
Multiple life stages, multiple antigenic types, ability to scavenger glucose, GPI, cytoadherence
Virulence of Malaria
blood smear, serological methods
Diagnoses of Malaria
Mosquito control, bed nets, weekly doses of prophylactic drugs, elimination of standing water, insecticides,
Prevention of Malaria
Quinine, artemisinin. antimalarial drugs
Treatment of Malaria
Falciparum
Type of malaria that is the most virulent type, manifest persistent fever, cough, and weakness for weeks without relief
cerebral malaria: small blood vessels in the brain become obstructed due to the increased ability of red blood cells to adhere to vessel walls.
The most serious complications of falciparum are
cytoadherence
small blood vessels in the brain become obstructed due to the increased ability of red blood cells to adhere to vessel walls.
apicomplexans
What lives in animal host and lack locomotor organelles in the mature state
asexual and sexual
Two phases of Malaria
sporozoites
motile spindle-shaped asexual cells
