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CELL MICRO S1 > Viruses Blood and Insect borne > Flashcards

Viruses Blood and Insect borne Flashcards

1
Q

give some examples of physical barriers to infection

A
  • skin (physical barrier)
  • stomach pH
  • GI flora
  • mucous in lungs
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2
Q

how do blood and insect borne viruses infect?

A

they get past skin as a barrier

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3
Q

what are the 2 shared features of blood and insect borne viruses?

A

1) direct introduction to bloodstream

2) require high levels of viraemia (presence of blood in bs)

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4
Q

what are the 4 unique features of blood and insect borne viruses?

A

1) different entry into the bs (insect bite, skin damage, medical)
2) cell/tissue tropism may be different (blood cells/liver cells)
3) clinical symptoms may vary by virus
4) epidemiology (person to person vs intermediate host transmission)

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5
Q

what is a tropism?

A

cells/tissues of a host that support growth of a particular tissue

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6
Q

how much of blood is plasma? what does it do?

A
  • ~1/2 is plasma
  • mostly water, ions to maintain isotonic
  • proteins
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7
Q

what are the formed elements of blood?

A
  • mostly RBC
  • platelets
  • leukocytes
  • neutrophils etc
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8
Q

give 4 examples of blood borne viruses?

A

1) HIV
2) Hep B,C,D
3) HCMV (human cytomegalovirus)
4) HTLV1 (human T-cell lymphotropic virus)

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9
Q

what are the common ways of transmission for blood borne viruses?

A
  • unprotected sex
  • mother to baby
  • sharing injecting equipment
  • contaminated blood transfusions & organ transplants
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10
Q

where are viruses that cause blood borne disease found in the body?

A
  • blood
  • semen
  • vaginal secretions
  • other fluids that may contain blood (but aren’t supposed to) i.e urine, saliva
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11
Q

what is the family of HIV?

what is the genus?

A

Retroviridae

Lentivirus

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12
Q

what are 2 strains of HIV?

A

HIV-1 (global)

HIV-2 (West Africa)

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13
Q

how does HIV cause long term persistence?

A

integrates into the host genome

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14
Q

what is the tropism for HIV?

A

immune cells: CD4+ T cells, macrophages and dentritic cells

- infection results in DESTRUCTION OF CD4+ T cells

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15
Q

what does initial infection w/ HIV cause?

A

mild symptoms

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16
Q

what happens after long incubation periods in HIV?

A

causes AIDS (acquired immunodeficiency syndrome)

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17
Q

how do patients with AIDS die? how?

A

die from opportunistic infections
(HIV itself doesn’t kill)
- CD4+ T cells (normally 600 cells/mm3) are attacked but if AIDS, it drops below 200 cells/mm3

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18
Q

what can AIDS cause?

A
  • HIV related Encephalopathy
  • Cytomegalovirus Retinitis
  • Atypical Pneumonia
  • Chronic Intestinal Cryptosporidiosis
  • Invasive Cervical Cancer
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19
Q

describe the progression of HIV to AIDS

A 
week 0 (point of infection)
- replication of virus begins

week 6

  • peak in virus replication
  • ACUTE phase
  • seeding in all lymphoid organs
  • non specific symptoms
  • dip in CD4+Tcells

week 12

  • virus paritially controlled by immune syst
  • increase in CD4+ T cells
  • but virus NOT CLEARED
  • virus integrates into CD4+ T cell genome

week 12–> year 7

  • clinical latency
  • CD4+ T cellcount decreases
year 7 onwards
- CD4+ T cells reach below 200 cells/mm3
AIDS
-less able to fight infection
- immune system less able to control HIV O massive increase in HIV replication

DEATH (v late, 9/10 years)

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20
Q

are there vaccines for HIV?

A

no

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21
Q

what is the treatment for HIV?

does it cure?

A

highly active antiretroviral therapy (HAART)

  • combination drug therapy
  • prevents progression to AIDS
  • not curative
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22
Q

Hep B, C and D are all what?

A

chronic, without integration into the host genome

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23
Q

what is the family and genus of Hep C?

A

Flaviridae

Hepacivirus

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24
Q

what is the family and genus of Hep B?

A

Hepadnaviridae

Orthohepadnavirus

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25
Hep D is what?
a VIROID (subviral satellite)
26
describe Hep D
- can only replicate in the presence of HBV - transmitted with HBV, or to a chronic HBV patient - inc SEVERITY of HBV disease
27
what is the tropism of Hepatitis blood borne?
- liver cells (hepatocytes) | - infection causes chronic liver inflammation
28
what are the symptoms of intial infection with Hep?
mild symptoms
29
what does a long incubation period cause in Hep?
liver failure and cancer
30
how does Hep progress?
- initial inf - replication in liver 75-85% get chronic Hep: inflammation of liver causes FIBROSIS - 20-25 years later CIRRHOSIS (extensive scarring, loss of blood flow, reduced liver function - 25-30 years later HCC (hepatocellular carcinoma) ESLD (end stage liver disease) Death Hepatocellular carcinoma end stage liver disease
31
is there a vaccine for Hep C?
no
32
what is the treatment for Hep C? how long for? | does it cure?
- direct antiviral drugs - 12 week treatment - curative - expensive
33
how is Hep C prevented?
good medical practice (screening of blood supply, no reuse of needles)
34
is there a vaccine for Hep B?
yes, also protects against HDV
35
what is the progression of HCV?
- initial inf - 1-3 weeks viral particles in bs due to replication - jaundice/flu like MAY RECOVER FROM THIS if antibodies formed IF NOT continuous replication 20-30 years later, liver damage causes death
36
what can transmit arthropod borne viruses?
1) insects - mosquitos - sandflies - midges 2) ticks
37
what are the major insect borne viruses that affect humans?
- Flaviviruses genus Flavivirus - Alphavirus - Bunyavirus - Rhabdovirus
38
why are arboviruses limited to certain regions?
they are limited to the area in which the vector is found
39
what is the name of the human-vector-human cycle of mosquito virus transmission?
urban epidemic cycle
40
what is the enzootic cycle in mosquito borne transmission?
transmission in the wild, mosquitos---> non-human animals | this can spill over to humans (DEAD END HOST)
41
what is the epizootic cycle in mosquito borne transmission?
spillover of the enzootic cycle into domesticated animals, then possibly spill over to humans (DEAD END HOST)
42
what is a dead end host?
one that won't transmit the disease on further
43
what is the species of mosquito that causes yellow fever?
Aedes aegypyti
44
Aedes albopictus is called what? what is it more tolerant to?
Asian tiger mosquito | more tolerant to cold
45
where are New World Alphaviruses found? give an example of one
Americas | Venezuelan Equine Ecephalitis
46
what do New World Alphaviruses cause generally?
encephalitis
47
where are Old World Alphaviruses found? give an example of one
Africa, Asia | Chikungunya
48
what do Old World Alphaviruses cause generally?
Arthiritis
49
what is the family of Chikungunya virus?
Togaviridae
50
what is the genus of Chikungunya virus?
Alphavirus
51
what is the tropism for Chikungunya virus?
broad - immune cells (macrophages & dendritic cells) - fibroblasts (connective tissue) - endothelial (lining of blood vessels) - myocytes
52
what are the symptoms of inital Chikungunya virus?
acute inital | some develop CHRONIC ARTHIRITIS (lasts ~2 years)
53
what transmits Chikungunya virus?
Ae. aegypti, Ae. albopictus | via urban transmission
54
where is Chikungunya found?
worldwide
55
is there vaccine/treatment for Chikungunya virus?
no, only prevention via mosquito control
56
what are the symptoms of Chikungunya?
- fever - headache - rash - myalgia - ARTHIRITIS
57
describe the infection life cycle of Chikungunya?
- infected mosquito bites human, virus introduced into skin and bloodstream - virus replicates in fibroblasts of dermis and disseminates through bs to tissues - viral REPLICATION in target tissues (muscle, liver, joints, spleen, meninges in neonates & immunocompromised) - inflammation of joints
58
what family and genus is Venezuelan equine encephalitis (VEE)?
Togaviridae Alphavirus
59
what is the tropism of VEE?
- immune cells and CNS - initial replication in DENDRITIC cells in blood - inf of PNS (nose, mouth) - spread along nerves to CNS
60
is there persistence of VEE?
no, acute inf only
61
what is the major symptom of VEE? what are other symptoms?
ENCEPHALITIS - severe headache - photophobia - chills - malaise - fever etc
62
how did VEE emerge into humans?
the virus can infect multiple mosquito species (Culex)
63
what is the enzootic cycle of VEE? | what changes when there is an outbreak of VEE?
Culex breeds in permanent water sources | - flooding attracts new types of mosquitos that can transmit the virus to human (inc in population)
64
in VEE outbreaks tend to occur in what animal before humans?
horses (hence name V EQUINE E)
65
in VEE humans are wjat kind of host?
dead end host - VIRAEMIA IS HIGH - mosquitos involved in transmission do NOT bite humans often enough to sustain urban human transmission cycles
66
are there vaccines for VEE? | how else can VEE be prevented?
veterinary vaccine for horses | prevented by mosquito control
67
what is the family and genus of the virus that causes West Nile virus?
Flaviviridae Flavivrus
68
what is the tropism of West Nile virus?
immune cells, endothelial cells, and CNS
69
where is initial replication of West Nile virus? | where does it spread to?
endothelial cells, monocytes, macrophages and dendritic cells spread to neurones
70
is West Nile virus persistent?
no
71
what isWest Nile virus transmitted by?
Culex spp mosquitos
72
where is West Nile virus found?
worldwide
73
what are the natural vertebrate hosts for West Nile virus? how does it infect humans?
birds (epizootic) | sporadic spillover to humans/horses (dead end hosts as VIRAEMIA IS NOT HIGH ENOUGH FOR TRANSMISSION BACK TO HOST).
74
what are the symptoms of West Nile virus?
``` in 20-30% - fever - headache - EYE PAIN - MACULOPAPULAR RASH (self lim) NEUROINVASIVE (1/150 cases) - encephalitis - meningitis - movement disorders - long term cognitive and neurological impairment - 10% mortality (high in older people) ```
75
how is West Nile virus treated?
no specific antiviral or vaccine | can be prevented by mosquito control

CELL MICRO S1 (16 decks)

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