Parapox Infections in Queensland

Alcorn K1, McMahon J2, Robson J1 1Sullivan Nicolaides Pathology, 2Queensland Health and Forensic Scientific Services

Introduction Parapoxviruses (PPVs) are a common cause of disease in cattle, goats and sheep worldwide and have long been known to cause a zoonotic infection in humans. Human infection occurs in those with occupational exposure to infected animals or contaminated fomites including herdsmen in sheep and goat raising countries, veterinarians, farmers and slaughtermen. Domestic animals can also be infected and transmit the virus to humans.1,2 We reviewed cases of PPVs in Queensland between 2008 and 2014 at Sullivan Nicolaides Pathology (SNP).

Virology Methods PPVs belong to the family Poxviridae and subfamily Chordopoxviridae. Patients who had a clinical specimen tested for Parapox PCR since 2008 PPVs are linear, double stranded DNA viruses that have a complex structure. from the SNP database were reviewed. Additional patients were found by Other members of Poxviridae, which cause human disease, include the searching the histopathological database for the term ‘ORF’. If histology genera Orthopoxvirus, Yatapoxvirus and Molluscipoxvirus. Perhaps the most results were suggestive of PPV infection, paraffin shavings were famous of the Orthopoxvirus is Variola virus, the cause of smallpox. Of the forwarded to Queensland Health Scientific Services for confirmation by genera Parapoxvirus, Orf virus (ORFV), Pseudocowpox virus (PCPV) and PCR. Clinical details were gleaned from scrutiny of pathology requests Bovine papular stomatitis virus (BPSV) can cause the human infections Orf and by communication with referring clinician and patients. (contagious pustular dermatitis), Milker’s nodules and papular stomatitis respectively (Table 1).3 Although DNA sequencing can differentiate the Results various parapox species, this is usually only available in a research setting. 23 patients had Parapox PCR performed on clinical samples, of which eight were positive. Zoonotic Usual Human Five of these specimens also tested negative by viruses Genus Other hosts Animal infection animal infection PCR for Orthopox virus. A search of Parapoxvirus host histopathology reports revealed 11 patients with Goats and Scabby mouth (contagious ecthyma small of sheep; contagious pustular biopsy results suggestive of Parapox virus Orf virus (ORFV) Sheep ruminants dermatitis) (see Fig.3) ORF infection and of these, three were Parapox PCR Pseudocowpox virus positive. Table 2 outlines case characteristics. (PCPV) Cattle Pseudocowpox Milker's nodule Bovine paplar Nine of the PCR positive patients had stomatitis virus Bovine papular stomatitis exposures to sheep and/or cattle, one was (affects muzzle) (BPSV) Cattle Papular stomatitis unable to be contacted and one patient lived in Table 1. The species of Parapoxvirus which cause human infection3. Other species have been shown to cause sporadic human infection only.4 urban Brisbane (Fig. 6) with no documented animal or farm equipment exposure. The Clinical picture differential diagnosis for those with histological Infection occurs after exposure to an infected animal and inoculation into a features of PPV but negative PCR were contact skin or mucosal defect leading to a localized skin lesion. The lesion starts dermatitis, eczema, Sweet’s Syndrome, lichen simplex, abscess and unknown. with a pustule, macule or vesicle and will progressively ulcerate, scab and Figure 6. Map of Queensland showing SNP catchment and heal over a 5-6 week period (figure 1,2). location of positive cases.

Case Sex Age Site Animal Occupation Clinical Histology Outcome DDx Postcode exposure* features and duration 1 M 51 Ring finger Sheep* Agricultural Unavailable Insufficient Resolved Nil 4370 school specimen teacher 2 F 48 R wrist Poddy calves Unknown Unavailable Possible Excised Bite 2460 3 M 50 L dorsum Cattle* Farmer Unsure Not tested Resolved Nil 4671 hand 4^ F 40 R ring finger Cattle,* Hobby farm 6 weeks, mild Not tested Resolved Bacterial 4756 horses, dogs pain Ψ Figure 1. Skin lesion of Case 1 Parapox PCR Figure 2. Case 5 with multiple finger lesions Figure 3. Typical ‘scabby mouth lesions in a 5 F 50 Multiple Lamb*, cattle, Farmer 10 weeks, Not tested Resolved Bacterial 4498 positive lamb5 sites face, dogs painful hands 6 M 57 L index Sheep, cattle, Hobby farm Few weeks Suggestive Resolved Nil 4207 finger horses but has recurred 7 M 52 Thigh Cattle Farmer Few weeks Suggestive resolved Bacterial 4674 Diagnosis 8 M 38 L palm Sheep, cattle Police Few weeks; Possible excised Nil 4815 officer very painful PPV infection can be diagnosed with Electron 9 M 17 R big toe Nil Unemployed Excised after Possible Excised HPV 4069 Microscopy (figure 4) but is more commonly diagnosed few days 10 M 59 L forearm Goats (rarely Farmer Excised after Suggestive Excised Nil 4490 with histology and Parapox PCR. Histological features sheep,cattle) few days, not are shown in Figure 5. The clinical and histopathological painful 11 M 48 L thumb Unavailable Unavailabe Unavailable Suggestive Unavailable Wart 4800 characteristics of the PPVs in human infection are Table 2. PCR positive patients and patient characteristics indistinguishable and are differentiated largely on the * Animal infected; ^ Suspected second episode; Ψ Other contacts suspected infected history of initial host exposure.

Figure 4. Electron Microscopy picture of ORF

Conclusions Parapox infections are a significant cause of protracted cutaneous infections in animal handlers in Queensland and should form part of the differential diagnosis. A higher index of suspicion and early histology and PCR testing may decrease inappropriate antibiotic use and wide local excisions.

References

1. Frandsen J, Enslow M, Bowen AR 2011, ‘Orf Parapoxvirus infection from a cat scratch’, Dermatology Online Journal, vol. 17, no. 4 (9), viewed 1 March 2014, http://escholarship.org/uc/item/7kt9w318#4 2. Damon, I 2007, ‘Poxviuses’, in R. Murray (ed.), ‘Manual of Clinical Microbiology’, ASM press, Washington 3. Krauss H, Weber A, Appel M, Enders B, Isenberg H et al. (Eds.) (2003) ‘Zoonoses’ ASM press, Washington 4. Mercer AA, Schmidt A, Weber o, (eds.) 2007, ‘Poxvirus Advances in Infectious Diseases’, Birkhauser, p.127 5. Dr. John King image #13581 Photo viewed 2/7/2014 http://www.uwyo.edu/vetsci/undergraduates/courses/patb_4110/2009_lectures/10_enteric_cattle_sheep/html/class_notes.htm. Figure 5. Histology of case 6. Histological features suggestive of PPV infection include ballooning degeneration and eosinophilic cytoplasmic inclusions (arrow) , epidermal proliferation and rete pegs with mixed inflammatory infiltrate of lymphocytes