Variola virus - Revision history

Aidan: /* Ordinary */

2020-08-05T14:14:14Z

Ordinary

← Older revision		Revision as of 14:14, 5 August 2020
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	* Most common (90%), with 3 phases (incubation, prodrome, and pox)		* Most common (90%), with 3 phases (incubation, prodrome, and pox)
	* Incubation period [[Usual incubation period::12-14 days]] (range [[Incubation period range::7-17 days]])		* Incubation period [[Usual incubation period::12 to 14 days]] (range [[Incubation period range::7 to 17 days]])
	* Prodrome lasts 2 to 4 days, with fever, headache, backache, chills, and vomiting		* Prodrome lasts 2 to 4 days, with fever, headache, backache, chills, and vomiting
	* Followed by rash, starting as a small red spot in the mouth or on the face (called herald spots)		* Followed by rash, starting as a small red spot in the mouth or on the face (called herald spots)

Aidan: /* Clinical Manifestations */

2020-08-05T13:52:28Z

Clinical Manifestations

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	* Most common (90%), with 3 phases (incubation, prodrome, and pox)		* Most common (90%), with 3 phases (incubation, prodrome, and pox)
	* Incubation period 12-14 days (range 7-17 days)		* Incubation period [[Usual incubation period::12-14 days]] (range [[Incubation period range::7-17 days]])
	* Prodrome lasts 2 to 4 days, with fever, headache, backache, chills, and vomiting		* Prodrome lasts 2 to 4 days, with fever, headache, backache, chills, and vomiting
	* Followed by rash, starting as a small red spot in the mouth or on the face (called herald spots)		* Followed by rash, starting as a small red spot in the mouth or on the face (called herald spots)

Aidan: Text replacement - "Varicella zoster" to "Varicella-zoster"

2020-08-04T00:27:23Z

Text replacement - "Varicella zoster" to "Varicella-zoster"

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	== Differential Diagnosis ==		== Differential Diagnosis ==
	* '''[[Varicella zoster virus]]'''		* '''[[Varicella-zoster virus]]'''
	* [[Enterovirus]]		* [[Enterovirus]]
	* [[Monkeypox]]: generally more lymphadenopathy		* [[Monkeypox]]: generally more lymphadenopathy

Aidan: Text replacement - "== Clinical Presentation" to "== Clinical Manifestations"

2020-08-02T12:14:22Z

Text replacement - "== Clinical Presentation" to "== Clinical Manifestations"

← Older revision		Revision as of 12:14, 2 August 2020
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	* Lesions on palms and soles		* Lesions on palms and soles

	== Clinical ~~Presentation~~ ==		== Clinical Manifestations ==

	=== Variola major ===		=== Variola major ===

Aidan: /* Differential Diagnosis */

2019-10-17T14:01:20Z

Differential Diagnosis

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	== Differential Diagnosis ==		== Differential Diagnosis ==
	* '''Varicella'''		* '''[[Varicella zoster virus]]'''
	* Enterovirus		* [[Enterovirus]]
	* Monkeypox: generally more lymphadenopathy		* [[Monkeypox]]: generally more lymphadenopathy
	* [Other ~~vesicular~~ ~~rashes](/Dermatology/Vesicular~~ rash~~.md)~~		* Other causes of a [[vesicular rash]]

	== Risk Classification Algorithm ==		== Risk Classification Algorithm ==

Aidan: updated headers

2019-10-17T14:00:10Z

updated headers

Show changes

Aidan at 23:58, 14 August 2019

2019-08-14T23:58:54Z

← Older revision		Revision as of 23:58, 14 August 2019
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	= ~~Smallpox~~ (variola) =		* Cause of smallpox (i.e. variola)

	== Microbiology ==		= Microbiology =

	* Variola virus is a dsDNA virus in Orthopoxvirus genus		* Variola virus is a dsDNA virus in Orthopoxvirus genus
	* Virus replicats in the cell cytoplasm rather than nucleus		* Virus replicats in the cell cytoplasm rather than nucleus

	== Pathophysiology ==		= Pathophysiology =

	* Virus enters through a respiratory route, a mucosal surface, or a break in the skin		* Virus enters through a respiratory route, a mucosal surface, or a break in the skin
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	* The virus then ultimately seeds skin, causing a characteristic “pock” rash		* The virus then ultimately seeds skin, causing a characteristic “pock” rash

	== Epidemiology ==		= Epidemiology =

	* Human are only known hosts (no animal reservoir)		* Human are only known hosts (no animal reservoir)
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	** Highest during first week of rash		** Highest during first week of rash

	=== Eradication ===		== Eradication ==

	* Contagious during prodrome, but most highly infectious for the first 7 to 10 days following rash and continues until all the lesions have crusted over		* Contagious during prodrome, but most highly infectious for the first 7 to 10 days following rash and continues until all the lesions have crusted over
	* Eradicated worldwide with the last case in Somalia in 1977		* Eradicated worldwide with the last case in Somalia in 1977

	== Differential Diagnosis ==		= Differential Diagnosis =

	* '''Varicella'''		* '''Varicella'''
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	* [Other vesicular rashes](/Dermatology/Vesicular rash.md)		* [Other vesicular rashes](/Dermatology/Vesicular rash.md)

	== Risk Classification Algorithm ==		= Risk Classification Algorithm =

	* Applied to patients with an acute generalized vesicular or pustular rash (AGVPR)		* Applied to patients with an acute generalized vesicular or pustular rash (AGVPR)
	* Source: [https://doi.org/10.1086/524383 Hutchins SS, ''et al''. ''CID''. 2008:46(Suppl 3):S195-S203]		* Source: [https://doi.org/10.1086/524383 Hutchins SS, ''et al''. ''CID''. 2008:46(Suppl 3):S195-S203]

	=== High risk ===		== High risk ==

	# A febrile prodrome (a temperature 38.3C occurring 1–4 days before rash accompanied by prostration, headache, backache, chills, vomiting, or severe abdominal pain);		# A febrile prodrome (a temperature 38.3C occurring 1–4 days before rash accompanied by prostration, headache, backache, chills, vomiting, or severe abdominal pain);
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	# Vesicles or pustules all at the same stage of development on any 1 body part (e.g., face, leg, or arm).		# Vesicles or pustules all at the same stage of development on any 1 body part (e.g., face, leg, or arm).

	=== Moderate risk ===		== Moderate risk ==

	# A febrile prodrome, an AGVPR, and at least 1 other major criterion; or		# A febrile prodrome, an AGVPR, and at least 1 other major criterion; or
	# Afebrile prodrome, an AGVPR, and ≥4 minor criteria		# Afebrile prodrome, an AGVPR, and ≥4 minor criteria

	=== Low risk ===		== Low risk ==

	# An AGVPR with a febrile prodrome and <4 minor clinical criteria; or		# An AGVPR with a febrile prodrome and <4 minor clinical criteria; or
	# Only an AGVPR		# Only an AGVPR

	=== Minor clinical criteria ===		== Minor clinical criteria ==

	Use to distinguish ordinary-type variola from varicella in the prevaccine era:		Use to distinguish ordinary-type variola from varicella in the prevaccine era:
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	* Lesions on palms and soles		* Lesions on palms and soles

	== Clinical Presentation ==		= Clinical Presentation =

	== Variola major ==		= Variola major =

	* Most common clinical form, with a mortality of about 30%		* Most common clinical form, with a mortality of about 30%
	* Four presentations: ordinary (most common), modified (if vaccinated), flat, and hemorrhagic		* Four presentations: ordinary (most common), modified (if vaccinated), flat, and hemorrhagic

	==== Ordinary ====		== Ordinary ==

	* Most common (90%), with 3 phases (incubation, prodrome, and pox)		* Most common (90%), with 3 phases (incubation, prodrome, and pox)
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	* Mortality		* Mortality

	==== Modified ====		== Modified ==

	* Modified form occurs in patients with previous immunization		* Modified form occurs in patients with previous immunization
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	* Mortalilty <10%		* Mortalilty <10%

	==== Flat/malignant ====		== Flat/malignant ==

	* Rare and severe, usually fatal (50%)		* Rare and severe, usually fatal (50%)
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	** Sometimes hemorrhages		** Sometimes hemorrhages

	==== Hemorrhagic ====		== Hemorrhagic ==

	* Rare and severe, usually fatal (~100%)		* Rare and severe, usually fatal (~100%)
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	* Death within 5 to 6 days		* Death within 5 to 6 days

	=== Variola minor ===		== Variola minor ==

	* Lower mortality rate ~1%		* Lower mortality rate ~1%
	* Fewer constitutional symptoms, fewer skin lesions		* Fewer constitutional symptoms, fewer skin lesions

	== Bioterrorism ==		= Bioterrorism =

	* Last case globally in 1977, with no routine vaccination in Canada since 1972, and in Canadian armed forces personel since 1988		* Last case globally in 1977, with no routine vaccination in Canada since 1972, and in Canadian armed forces personel since 1988
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	** Rooms should be decontaminated after they are vacated		** Rooms should be decontaminated after they are vacated

	== Diagnosis ==		= Diagnosis =

	* Samples should be collected by unroofing a lesion and soaking a swab		* Samples should be collected by unroofing a lesion and soaking a swab
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	* Viral culture: technically the gold standard		* Viral culture: technically the gold standard

	== Management ==		= Management =

	* No specific treatment; supportive care		* No specific treatment; supportive care
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	* Patients should be maintained in negative-pressure isolation with HEPA filters (airborne/contact)		* Patients should be maintained in negative-pressure isolation with HEPA filters (airborne/contact)

	=== Post-exposure prophylaxis ===		== Post-exposure prophylaxis ==

	* Contacts may be given vaccine within 4 days of exposure to lessen the severity of symptoms		* Contacts may be given vaccine within 4 days of exposure to lessen the severity of symptoms
	* Canada has developed a new vaccine derived from horsepox (fewer adverse events)		* Canada has developed a new vaccine derived from horsepox (fewer adverse events)

	== Further Reading ==		= Further Reading =

			[[Category:Poxviridae]]

Aidan: Aidan moved page DNA Smallpox (variola) to Variola virus without leaving a redirect

2019-08-14T23:57:50Z

Aidan moved page DNA Smallpox (variola) to Variola virus without leaving a redirect

← Older revision	Revision as of 23:57, 14 August 2019
(No difference)

Maintenance script: Imported from text file

2019-08-11T18:05:51Z

Imported from text file

New page

= Smallpox (variola) =

== Microbiology ==

* Variola virus is a dsDNA virus in Orthopoxvirus genus
* Virus replicats in the cell cytoplasm rather than nucleus

== Pathophysiology ==

* Virus enters through a respiratory route, a mucosal surface, or a break in the skin
* Replicates locally then spreads through local lymphatics, causing a primary viremia
* Then spreads to the reticuloendothelial system, where replication results in secondary viremia
* The virus then ultimately seeds skin, causing a characteristic “pock” rash

== Epidemiology ==

* Human are only known hosts (no animal reservoir)
* Droplet transmission, can be transmitted on fomites (survives 6 to 24 hours on surfaces or cloth)
** There have been outbreaks among hospital laundry staff
** Virus in scabs can survive longer
* Period of communicability is about 3 weeks, from just before first lesions to disappearance of all scabs
** Highest during first week of rash

=== Eradication ===

* Contagious during prodrome, but most highly infectious for the first 7 to 10 days following rash and continues until all the lesions have crusted over
* Eradicated worldwide with the last case in Somalia in 1977

== Differential Diagnosis ==

* '''Varicella'''
* Enterovirus
* Monkeypox: generally more lymphadenopathy
* [Other vesicular rashes](/Dermatology/Vesicular rash.md)

== Risk Classification Algorithm ==

* Applied to patients with an acute generalized vesicular or pustular rash (AGVPR)
* Source: [https://doi.org/10.1086/524383 Hutchins SS, ''et al''. ''CID''. 2008:46(Suppl 3):S195-S203]

=== High risk ===

# A febrile prodrome (a temperature 38.3C occurring 1–4 days before rash accompanied by prostration, headache, backache, chills, vomiting, or severe abdominal pain);
# Characteristic lesions, described as deep-seated, firm, hard, well-circumscribed vesicles or pustules; and
# Vesicles or pustules all at the same stage of development on any 1 body part (e.g., face, leg, or arm).

=== Moderate risk ===

# A febrile prodrome, an AGVPR, and at least 1 other major criterion; or
# Afebrile prodrome, an AGVPR, and ≥4 minor criteria

=== Low risk ===

# An AGVPR with a febrile prodrome and <4 minor clinical criteria; or
# Only an AGVPR

=== Minor clinical criteria ===

Use to distinguish ordinary-type variola from varicella in the prevaccine era:

* Centrifugal rash distribution
* First lesions on the oral mucosa, face, or forearms
* A toxic or moribund appearance
* A slow rash evolution from macules to papules to pustules (1–2 days for each stage)
* Lesions on palms and soles

== Clinical Presentation ==

== Variola major ==

* Most common clinical form, with a mortality of about 30%
* Four presentations: ordinary (most common), modified (if vaccinated), flat, and hemorrhagic

==== Ordinary ====

* Most common (90%), with 3 phases (incubation, prodrome, and pox)
* Incubation period 12-14 days (range 7-17 days)
* Prodrome lasts 2 to 4 days, with fever, headache, backache, chills, and vomiting
* Followed by rash, starting as a small red spot in the mouth or on the face (called herald spots)
** Rash spreads centrifugally from the face to arms and legs (more distal than trunk)
** Includes palms and soles
** Usually spread to entire body within about 24 hours
** Lesions initially maculopapular, followed by firm, well-defined vesicles, often with a central depression
** Vesicles develop into pustules during the second week, then they flatten and scab over by third or fourth week
** Lesions may become confluent
** Lesions progress synchronously, unlike chicken pox
* Mortality

==== Modified ====

* Modified form occurs in patients with previous immunization
* Milder illness
* Atypical rash, with fewer lesions that evolve more rapidly
* Mortalilty <10%

==== Flat/malignant ====

* Rare and severe, usually fatal (50%)
* Similarly severe prodrome
* However, rash is slower to develop, and remains soft and flat and velvety
** Like fine-grained, reddish-coloured crepe rubber
** Sometimes hemorrhages

==== Hemorrhagic ====

* Rare and severe, usually fatal (~100%)
* Pregnancy is a risk factor, but occurs in all age groups and sexes
* Shorter incubation period with severe, prostrating prodrome with high fever, headache, back pain, and abdominal pain
* Erythema follows, then petechiae and skin and mucosal hemorrhages
* Death within 5 to 6 days

=== Variola minor ===

* Lower mortality rate ~1%
* Fewer constitutional symptoms, fewer skin lesions

== Bioterrorism ==

* Last case globally in 1977, with no routine vaccination in Canada since 1972, and in Canadian armed forces personel since 1988
* The majority of people living in the US (and likely Canada) have not been vaccinated
* Limited vaccine reserves still exist in the US; a new horsepox-derived vaccine was developed in Canada in the 2010s
* In case of an outbreak
** Healthcare workers should be vaccinated and, ideally, a single hospital designated for smallpox patients
** Patients should be in negative-pressure isolation with HEPA filter
** Standard precautions using gloves, gowns, and masks
** All laundry and waste should be placed in biohazard bags and autoclaved before being laundered or incinerated
** Rooms should be decontaminated after they are vacated

== Diagnosis ==

* Samples should be collected by unroofing a lesion and soaking a swab
* RG-4 infection, must be processed in a CL-4 lab (i.e. the national micro lab)
* Viral swab with viral transport medium (e.g. NPS swab)
** PCR can be done for routine viruses as well as ''Orthopoxviridae''
* Tissue
** Tzanck smear for intracellular inclusion bodies for HSV/VZV
** Direct immunofluorescence
** Electron microscopy
*** Smallpox and monkeypox virions may be indistinguishable, naturally occurring monkeypox is found only in tropical rain forest areas of Africa
* Viral culture: technically the gold standard

== Management ==

* No specific treatment; supportive care
** May try cidofovir
* Patients should be maintained in negative-pressure isolation with HEPA filters (airborne/contact)

=== Post-exposure prophylaxis ===

* Contacts may be given vaccine within 4 days of exposure to lessen the severity of symptoms
* Canada has developed a new vaccine derived from horsepox (fewer adverse events)

== Further Reading ==