Epidemiological Investigations of Four Cowpox Virus Outbreaks in Alpaca Herds, Germany

Abstract

Four cowpox virus (CPXV) outbreaks occurred in unrelated alpaca herds in Eastern Germany during 2012–2017. All incidents were initially noticed due to severe, generalized, and finally lethal CPXV infections, which were confirmed by testing of tissue and serum samples. As CPXV-infection has been described in South American camelids (SACs) only three times, all four herds were investigated to gain a deeper understanding of CPXV epidemiology in alpacas. The different herds were investigated twice, and various samples (serum, swab samples, and crusts of suspicious pox lesions, feces) were taken to identify additionally infected animals. Serum was used to detect CPXV-specific antibodies by performing an indirect immunofluorescence assay (iIFA); swab samples, crusts, and feces were used for detection of CPXV-specific DNA in a real-time PCR. In total, 28 out of 107 animals could be identified as affected by CPXV, by iIFA and/or PCR. Herd seroprevalence ranged from 16.1% to 81.2%. To investigate the potential source of infection, wild small mammals were trapped around all alpaca herds. In two herds, CPXV-specific antibodies were found in the local rodent population. In the third herd, CPXV could be isolated from a common vole (Microtus arvalis) found drowned in a water bucket used to water the alpacas. Full genome sequencing and comparison with the genome of a CPXV from an alpaca from the same herd reveal 99.997% identity, providing further evidence that the common vole is a reservoir host and infection source of CPXV. Only in the remaining fourth herd, none of the trapped rodents were found to be CPXV-infected. Rodents, as ubiquitous reservoir hosts, in combination with increasingly popular alpacas, as susceptible species, suggest an enhanced risk of future zoonotic infections.

Field Trial Vaccination against Cowpox in Two Alpaca Herds

“…In both herds, clusters of CPXV infection occurred and were confirmed by determining CPXV-specific antibody titres and CPXV-specific DNA, as described by [16]. Herd seroprevalences of 16.4% (herd I) and 16.1% (herd II) were determined at that time.…”

“…To prevent further cases of CPXV infection, MVA vaccination was considered to be the best option. There was a period of 13 months (herd I) and three months (herd II) between the last herd investigation [16] and the start of MVA vaccination. A total of 69 animals (64 adults and 5 crias) of herd I and 33 animals (24 adults and 9 crias) of herd II were used in the present study.…”

“…Examples include African rhinoceroses and elephants [2][3][4][5][6] as well as jaguarundis, giant anteaters, ocelots, Patagonian cavies and New World monkeys [7][8][9][10][11]. CPXV infection in South American camelids (SACs) was first described in 1997 [12], and since then, only a few reports of CPXV infection in SACs have been published [13][14][15][16][17]. CPXV infections in SACs occur sporadically.…”

“…The economic value of these animals and the zoonotic potential of CPXV infection justify determination of whether MVA vaccine is effective for the prevention of CPXV-induced disease in SACs. The present study describes the application of the MVA vaccine in a prime-boost immunisation regimen in two alpaca herds in Germany with a history of CPXV infections [16]. The aim of the present study was to assess the safety of a live MVA vaccine in alpacas and to determine its immunogenicity after initial immunisation and one year later.…”

Ethnomedicinal Wisdom

“…Viruses are acellular ultra-microscopic metabolically inert obligate intracellular parasites of cellular hosts (Chattopadhyay et al, 2009b), associated with diverse diseases and are threats to human, wildlife, and livestock (Malosh et al, 2017;Marston et al, 2017;Prkno et al, 2017;Akbari and Elmi, 2017;Vu and Misra, 2018). Many are incurable and have no effective antiviral drugs except a very few (forty) US FDA approved antiviral drugs available for the management of some viral diseases.…”