Poxvirus

Question 1

Genus and examples of poxviridae

Answer 1

Orthopox - Mpox, smallpox, vaccinia, camelpox

Parapox - Orf, Bovine papular stomatitis

Yatapoxvirus - yaba monkey tumour virus, tanapoxvirus

Molluscipoxvirus - molluscum contagiousum

Question 2

Characteristic size/shape of orthopox vs parapos

Answer 2

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

Question 3

Which factors would make you worried about HCID Mpox (as of Nov 2024)

Answer 3

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)

Question 4

Mpox vaccination - what kind of vaccine, who gets it?

Answer 4

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.

Question 5

Mpox - severe disease antiviral treatment and MOA

Answer 5

Tecovirimat - inhibitor of the orthopoxvirus VP37 envelope wrapping protein

Question 7

Name the two clades of monkeypox and the two subclades that have recently been implicated in epidemics

Answer 7

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?)

Question 8

What are the risk groups for severe mpox disease?

Answer 8

Children (most risk <5 y)
Pregnant women
Immunosuppressed
Elderly (included in guidance as a precaution)

Question 9

Transmission routes for mpox infection

Answer 9

Respiratory tract
Mucous membranes
Broken skin

Close contact is required, transmission via fomites is also possible

Question 10

Why have their been more mpox outbreaks in recent decades?

Answer 10

Increased deforestation
Increased international travel
Waning herd immunity to smallpox

Question 11

Clinical features of mpox

Answer 11

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

Question 12

Clinical manifestations of severe mpox

Answer 12

Secondary bacterial infection

Pneumonia

Corneal infection

D&V

Sepsis

Encephalitis

Myocarditis

Disseminated disease

Question 13

In which situation would you test semen for mpox and when and for how long?

Answer 13

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)

Question 14

Name two antiviral options for treatment of mpox

Answer 14

Tecovirimat and brincidofovir (cidofovir has also been used)

Question 15

Which patients are eligible for tecovirimat?

Answer 15

PCR confirmed mpox with severe symptoms (hospitalised)

Question 16

How long should sex be avoided during mpox infection

Answer 16

Whilst symptomatic and then condom use for 12 weeks

Question 17

Suspected mpox case definition

Answer 17

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

Question 18

Steps for suspected HCID mpox case

Answer 18

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!

Question 19

Hospital de-isolation rules for HCID mpox case

Answer 19

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

Question 20

Isolation criteria for clade IIb mpox

Answer 20

Can resume activities if all exposed lesions have scabbed over, and other lesions are covered. However they must avoid at risk groups

Question 21

Difference between smallpox and chickenpox rash

Answer 21

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

Question 22

Name some lesser known pox viruses

Answer 22

Tanapox - Africa, febrile illness and lesions

Borealpox - Orthopox, red backed voles and squirrel reservoir, fatal in immunocompromised

Orf - localised painless lesions, diagnosed by EM