Foxes and Parvo Virus (and other viruses)

 

It should be remembered that parvovirus is common in the UK.  Occasionally the UK experiences periods of higher numbers of reported cases. Untreated in an unvaccinated dog, it can often be fatal. I have seen several such peaks in my time and it is important that if you own a pet do or working dog that it is vaccinated against parvo.

I can already see the huffing and puffing amongst the social media fox groups and "Well, my little fluffy visitor is the picture of health" -so were the foxes that then had babesia, leptospirosis, canine pneumonia etc. etc. etc. There will also be the usual silly claims bordering on hysteria that this post is "anti-fox".  Having dedicated myself since 1976 to wild canids and particularly the British fox and its history as well as writing on wildlife (fox) welfare and health such an "anti-fox" claim would be silly in the extreme.

When I set up the Bristol Fox Deaths Project over two years ago there were two reasons why I felt foxes found dead in and around the City needed to be officially examined via post mortem:

1)  Was the growing and often hysterical claim that there was organised poisoning of foxes in Bristol. This claim was featuring on a number of Face Book fox groups and the fact that Bristol City Council refused to help us gather dead foxes increased that hysteria. I was informed on a regular basis of groups of local foxes "vanishing" (outside of dispersal season) but no carcasses were found.  When a brace (pair) of foxes were found dead on several occasions the hysteria started again.

2) my main concern was that there might be a virus/disease at play and this stemmed mainly from my own paranoia having grown up in a village in Germany where rabies was endemic and having seen the results first hand. There had been no rabies outbreak in the UK since circa 1929 so that was not my concern but rather that some other disease may have hit foxes.

In my view 2) was the likeliest and as Bristol has the largest urban fox population outside of London that was concerning. 

What we have found out thanks to the hard work of the pathologist we have there have been a number of discoveries and what is found in Bristol should well be found across the country. It was through the pathologist that I got a number of papers dealing with parvo virus in foxes in the Netherlands, Germany and Turkey as well as connected work.

The first paper, very briefly summarised below was an eye-opener.  

Identification of Multiple Novel Viruses, Including a Parvovirus and a Hepevirus, in Feces of Red Foxes

 Journal of Virology p. 7758–7764 July 2013 Volume 87 Number 13

Rogier Bodewes,a Joke van der Giessen,b Bart L. Haagmans,a Albert D. M. E. Osterhaus,a,c Saskia L. Smitsa,c Department of Viroscience, Erasmus Medical Centre, Rotterdam, The Netherlandsa; National Institute for Public Health and the Environment (RIVM), Centre for Infectious Disease Control, Bilthoven, The Netherlandsb; Viroclinics Biosciences B.V., Rotterdam, The Netherlandsc

"Red foxes (Vulpes vulpes) are the most widespread members of the order of Carnivora. Since they often live in (peri)urban areas, they are a potential reservoir of viruses that transmit from wildlife to humans or domestic animals. Here we evaluated the fecal viral microbiome of 13 red foxes by random PCR in combination with next-generation sequencing. Various novel viruses, including a parvovirus, bocavirus, adeno-associated virus, hepevirus, astroviruses, and picobirnaviruses, were identified."

 "In addition, various viruses were identified that are close relatives to human viruses based on phylogenetic analysis, suggesting that these viruses may have been transmitted from foxes to humans,or vice versa in the past. The newly discovered viruses of the present study are examples of the diversity of viruses that are present in wildlife. Since foxes often live close to humans, the opportunities exist for cross-species transmission to humans or their pets. Since multiple recent outbreaks of viral disease among humans are caused by viruses that originate from (wild) animals, expansion of the current knowledge of viruses that circulate in these animals is needed. A timely identification of reservoir animal hosts in case of novel outbreaks of disease in humans is crucial in mitigating infectious threats"

 We had concerns that dead birds infected with the Avian Flu Virus (AFV) might spread to foxes and it did to a low extent and was one of the reasons why the Wildlife Network for Disease Surveillance brought in a rule that no fox submitted for post mortem could be handled until it was tested for AFV.

The next paper was from Germany and to show that this is not all just guesswork but based on science I have kept the full accreditation.

Survey on viral pathogens in wild red foxes (Vulpes vulpes) in Germany with emphasis on parvoviruses and analysis of a DNA sequence from a red fox parvovirus

Epidemiol. Inf e c t . (1998). 121, 433440

U. TRUYEN (1), T. MULLER (2), R. HEIDRICH (3), K. TACKMANN' AND L. E. CARMICHAEL (4)

1. Institute for Medical Microbiology, Infectious and Epidemic Diseases University of Munich ;Veterinaerstr. 13 ; 80539 Munich, Germany' 

2 Federal Research Institute for Viral Diseases of Animals, Seestr. 55, 16868 Wusterhausen, Germany 

3 State Veterinary Diagnostic Laboratory, Fuerstenwalder Poststrasse 73, I5234 FrankfurtlOder, Germany 

4 James A. Baker Institute for Animal Health, New York State College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA

 (Accepted 6 April 1998)

“The main aim of this study was to examine the seroprevalence of parvovirus infections in a European red fox population. This was based on the hypothesis that CPV most likely emerged in Europe and that the red fox may have been the host of an ancestral canine parvovirus. The study was designed in a way that we could compare fox populations in suburban areas with those in more rural areas which should allow us to estimate the possibility of interspecies transmission among domestic and wild carnivores. An average estimate of 13% seropositive foxes in a random population indicates that parvovirus is widespread among red foxes in Germany."

 How widespread is parvo virus? A paper from Turkey shows that it is very widespread.

First isolation and molecular characterization of canine parvovirus‑type 2b (CPV‑2b) from red foxes (Vulpes vulpes) living in the wild habitat of Turkey

Virology Journal (2023) 20:27

Hanne Nur Kurucay1, Cuneyt Tamer1, Bahadir Muftuoglu2, Ahmed Eisa Elhag1,3*, Seda Gozel1, Yasemin Cicek‑Yildiz4, Sadik Demirtas5, Emre Ozan2, Harun Albayrak1, Semra Okur‑Gumusova1 and Zafer Yazici1*

Abstract

“Background The canine parvovirus, with its many variants, is responsible for a pivotal and common viral infection affecting millions of dogs and other carnivore species worldwide, particularly the wild ones, which are considered as the main reservoir hosts. To that end, this study investigated the presence of canine parvovirus (CPV) in red foxes (Vulpes vulpes) living in wild habitats of several regions of Turkey.

“Methods We randomly collected 630 archival fox stool specimens from rural areas of 22 provinces and used realtime PCR to detect CPV. Results Two of the 630 (0.3%) stool samples were positive for CPV-DNA, named Tr-Fox/128(Aydın) and Tr-

Fox/159(Manisa). We attempted to isolate the virus in a MDCK cell line, and cytopathic effects were observed four days post-inoculation. Three regions corresponding to the CPV capsid protein VP2 gene from extracted DNA of positive samples were amplified by conventional PCR, and the products were visualised, purified, and Sanger sequenced. Three overlapping DNA raw sequence fragments, were read, assembled, and aligned to obtain approximately  1.5 kb-long regions that cover most of the VP2 gene, then deposited in GenBank. After comparing the isolates with parvovirus sequences data of domestic and wild carnivores by BLAST processing, our isolates’ similarity rate with each other was 99.40%, with base differences in 9 nucleotide positions. They were classified as 2b variant closely related to isolates from dogs in Turkey, Egypt, Iraq, Italy, Thailand, and China.

“Conclusion This study presents evidence of interspecies transmission of CPV, of which there are no reports on prevalence in wildlife carnivores of our country. Identification of CPV in red foxes threatens local and hunting dogs, which may contract the infection or disseminate it to other wild animal species or vice-versa."

A point to make is that, yes, we are separated from Europe by the English Channel and so people might counter that this means parvo or one of the other viruses could not possibly be found in their "fur babies". That would require a clear response.

As I have shown through my historical research, of the past five decades, in some areas of England foxes were becoming rare in the 16th century. It was probably around this ti8me that the first importation of foxes occurred. We do know that by the 17th century various masters of the foxhounds (hunts) had perfected construction of artificial dens to place foxes in. They had also  each developed their own formula for feeding up kennelled foxes before release. From the 17th century to 1912 there were thousands of foxes imported by animal dealers to be sent off the hunt masters and this gave us two things and the first was mange that had not been seen in the UK prior to importation of foxes -as foxes were sent around the country so mange spread.

The second thing it gave us was, of course, New foxes that replaced the Old British fox types. The foxes you see today are the descendants of foxes introduced by hunts -and there have been a number of near extinctions of the New foxes but they survived through further importing.

This means that while the Old British fox may not have had mange or parvo or any of the other viruses the New ones very well could have. In fact it is likely since they introduced mange into the UK. So the work that was carried out in Europe where foxes were basically ignored for anything but hunting before is significant. In the UK the amount of resistance to even looking intro fox health issues meant that rumours such as "adenovirus is endemic in the UK fox population" began and continue and yet 60 (I think it may be more) and no adenovirus.

The findings are important because as wild animals foxes (and badgers) should not be coaxed into houses with food or hand fed. If they are going to be fed then observe them from a safe distance -coaxing foxes into homes where there are pet dogs (albeit locked in another room at the time) is creating a risk of a virus hitting the dog let alone the humans involved. I have repeatedly warned about the risk of viruses jumping from host to humans (hence the AFV concern) and that has a lot of implications.

Feeders need to feed from a distance because a virus jumping from fox to human could result in foxes being seen as a threat and large scale culls of urban foxes being carried out. That is not an exaggeration; these are wild canids and not garden pets or "fluffies" to invite into homes.

There are also implications for wildlife rescues and more stringent biohazard rules and procedures. I have already discussed wildlife rescues in a previous post but care should be taken that people with weakened immune systems etc are following strict handling guidelines if they have to handle foxes, etc.

I doubt that rescues will listen to advice as that might bruise egos,

But anyone handling foxes in particular need to be aware of the risks.