Poxvirus Flashcards
Genus and examples of poxviridae
Orthopox - Mpox, smallpox, vaccinia, camelpox
Parapox - Orf, Bovine papular stomatitis
Yatapoxvirus - yaba monkey tumour virus, tanapoxvirus
Molluscipoxvirus - molluscum contagiousum
Characteristic size/shape of orthopox vs parapox
Both 240-300nm
Ortho - Brick shaped with dumbbell shaped nucleosome and palisaiding surface proteins
Para - Ovoid with criss cross structure - looks like a wee bee hive
Which factors would make you worried about HCID Mpox (as of Nov 2024)
Prodromal viral illness and contact with known epidemiological or zoonotic HCID MPox case in 21 days prior
OR
Mpox rash with travel to at risk countries (most around DRC)
Mpox vaccination - what kind of vaccine, who gets it?
MVA-BN - Imvanex - repplication defective vaccinia vaccine (not live)
Pre exposure - 2 x SC/IM 28 days apart. Given to GBMSM, occupational risk and outbreaks. (Although in practice doses were given 2-3 months apart as evidence shows as longer duration between doses gives longer duration of protection)
Post exposure - limited evidence - 1 dose given up to 4 days following exposure or 14 days if high risk of severe disease.
Mpox - severe disease antiviral treatment and MOA
Tecovirimat - inhibitor of the orthopoxvirus VP37 envelope wrapping protein
Name the two clades of monkeypox and the two subclades that have recently been implicated in epidemics
Clade I (previously Central African/Congo Basin clade)
Clade II (previously West African Clade)
Clade IIb B.1 caused 2022 outbreak mostly in MSM
Clade I causing current HCID outbreak in DRC (subclade Ib)
What are the risk groups for severe mpox disease?
Children (most risk <5 y)
Pregnant women
Immunosuppressed
Elderly (included in guidance as a precaution)
Transmission routes for mpox infection
Respiratory tract
Mucous membranes
Broken skin
Vertical transmission
Close contact is required, transmission via fomites is also possible
Why have their been more mpox outbreaks in recent decades?
Increased deforestation
Increased international travel
Waning herd immunity to smallpox
Clinical features of mpox
Prodrome - fever, myalgia, chills, headache, backache, arthralgia, lymphadenopathy
Maculopapulat rash > papules > pustules > scab over and slough off
Lesions are well circumscribed and usually all at the same stage of development
Clinical manifestations of severe mpox
Secondary bacterial infection
Pneumonia
Corneal infection
D&V
Sepsis
Encephalitis
Myocarditis
Disseminated disease
In which situation would you test semen for mpox and when and for how long?
In recovered patients who are:
1) Undergoing fertility treatment or planning pregnancy
2) Semen storage
3) Have immunocompromised sexual partner
Test from 12 weeks to 6 months post infection (one negative is sufficient)
Name two antiviral options for treatment of mpox
Tecovirimat and brincidofovir (cidofovir has also been used)
Which patients are eligible for tecovirimat?
PCR confirmed mpox with severe symptoms (hospitalised)
How long should sex be avoided during mpox infection
Whilst symptomatic and then condom use for 12 weeks
Suspected mpox case definition
1) Presents with prodrome and known contact within 21 days
2) Presents with unexplained lesions AND - - epi link to case within 21 days
- relevant travel within 21 days
- MSM
- >1 sexual partner within 21 days
- relevant zoonotic link
Steps for suspected HCID mpox case
Contact IFS to discuss risk and management
Negative pressure isolation
Pregnant woman and immunocompromised staff should not care for suspected case
Avoid contact with pets and animals!
Hospital de-isolation rules for HCID mpox case
PCR negative in blood, urine and throat
No new lesions for 48 h
No mucous membrane lesions
All lesion scabs have come off and in tact skin beneath
If clinically well but not fulfilling lesion criteria they can be discharged home to continue isolation as long as no one in household is high risk
Isolation criteria for clade IIb mpox
Can resume activities if all exposed lesions have scabbed over, and other lesions are covered. However they must avoid at risk groups
Difference between smallpox and chickenpox rash
Smallpox = centrifugal rash, all lesions at same stage, febrile prodrome, lesions on hands and soles
Chickenpox = centripetal rash, lesions at different stages, mild prodrome, no lesions on hands or soles
Name some lesser known pox viruses
Tanapox - Africa, febrile illness and lesions
Borealpox - Orthopox, red backed voles and squirrel reservoir, fatal in immunocompromised
Orf - localised painless lesions, diagnosed by EM
Risks of monkeypox in pregnancy?
Severe disease in mum
Vertical transmission in utero or perinatally
Highest risk to foetus in first trimester
Management of baby born to mum with mpox
C-section if genital lesions
Test neonate for mpox with throat, urine, blood and any lesions
Separate mum and baby at birth and vaccinate baby with MVA-BN
Avoid breastfeeding
