Molecular detection of canine parvovirus in flies (Diptera) at open and closed canine facilities in the eastern United States

Abstract

More than thirty years have passed since canine parvovirus (CPV) emerged as a significant pathogen and it continues to pose a severe threat to world canine populations. Published information suggests that flies (Diptera) may play a role in spreading this virus; however, they have not been studied extensively and the degree of their involvement is not known. This investigation was directed toward evaluating the vector capacity of such flies and determining their potential role in the transmission and ecology of CPV. Molecular diagnostic methods were used in this cross-sectional study to detect the presence of CPV in flies trapped at thirty-eight canine facilities. The flies involved were identified as belonging to the house fly (Mucidae), flesh fly (Sarcophagidae) and blow/bottle fly (Calliphoridae) families. A primary surveillance location (PSL) was established at a canine facility in south-central South Carolina, USA, to identify fly-virus interaction within the canine facility environment. Flies trapped at this location were pooled monthly and assayed for CPV using polymerase chain reaction (PCR) methods. These insects were found to be positive for CPV every month from February through the end of November 2011. Fly vector behavior and seasonality were documented and potential environmental risk factors were evaluated. Statistical analyses were conducted to compare the mean numbers of each of the three fly families captured, and after determining fly CPV status (positive or negative), it was determined whether there were significant relationships between numbers of flies captured, seasonal numbers of CPV cases, temperature and rainfall. Flies were also sampled at thirty-seven additional canine facility surveillance locations (ASL) and at four non-canine animal industry locations serving as negative field controls. Canine facility risk factors were identified and evaluated. Statistical analyses were conducted on the number of CPV cases reported within the past year to determine the correlation of fly CPV status (positive or negative) for each facility, facility design (open or closed), mean number of dogs present monthly and number of flies captured. Significant differences occurred between fly CPV positive vs. negative sites with regard to their CPV case numbers, fly numbers captured, and number of dogs present. At the ASL, a statistically significant relationship was found between PCR-determined fly CPV status (positive or negative) and facility design (open vs. closed). Open-facility designs were likely to have more CPV outbreaks and more likely to have flies testing positive for CPV DNA.

Enteropathogen infections in canine puppies: (Co-)occurrence, clinical relevance and risk factors

“…Interestingly the four puppies that were hEC infected and severely diseased were under 9,5 weeks old, suggesting that there could be an age effect but this effect was not observed between the age categories used in our study. Previously seasonality for CPV was described with the predominant occurrence of CPV in summer months while others reported spring and early summer as the seasons with the highest occurrence of CPV (Houston et al, 1996;Bagshaw et al, 2014). The prevalence of CPV and CCoV positive puppies in our study varied by season, with CPV risk increasing in winter and spring compared to summer, and CCoV increasing in winter.…”

“…Logistic regression was also used to sort out which pathogens were associated with acute diarrhoea and/or severe clinical signs. For these pathogens logistic regression was used to assess the association with previously published risk factors for gastrointestinal infections in dogs, namely age, breed (purebred vs. mixed breed), gender, vaccination history (fully vaccinated vs. partially or not vaccinated), sampling season (Summer: June-August; Autumn: September-November; Winter: December-February; Spring: March-May), and whether the puppy originated from a highvolume dog breeder (Houston et al, 1996;Stavisky et al, 2011;Ling et al, 2012;Saevik et al, 2012;Dupont et al, 2013;Bagshaw et al, 2014;Grellet et al, 2014). Age was categorized in 2 groups: younger than 3 months and older than 3 months, as 3 months is the age at which maternal immunity is expected to have diminished to an insignificant level for the majority of puppies and at which the final puppy vaccines generally are administered in the Netherlands (Davis-Wurzler, 2014).…”

“…It is therefore important to screen for multiple pathogens in faeces of both healthy and diarrhoeic puppies to gain more insight into the role co-infections might play. Putative risk factors for acute infectious diarrhoea in puppies include breed, gender, vaccination history, age, season, breeder-origin, and/or stay in kennel (Houston et al, 1996;Stavisky et al, 2011;Ling et al, 2012;Saevik et al, 2012;Dupont et al, 2013;Bagshaw et al, 2014;Grellet et al, 2014). However these risk factors for infection with specific enteropathogens have mainly been reported in dogs housed in shelters or breeding facilities.…”

Assessing the feasibility of fly based surveillance of wildlife infectious diseases

“…Finally, the genetic material of a number of hitchhiked microorganisms was already detected in flies, including food borne bacteria, e.g. Salmonella spp., and enteric viruses18192021. For example, Newcastle disease virus (NDV) RNA was detected in, and even virions were isolated from, flies collected in the vicinity of infected chickens.…”

The widely distributed hard tick, <i>Haemaphysalis longicornis</i>, can retain canine parvovirus, but not be infected in laboratory condition

“…Subsequently, viremia occurs, which is associated with the isolation from a variety of organs and tissues, and then finally, CPV is excreted through the feces to the environment [ 27 ]. Recently, it has been also suggested that insect vectors, such as flies, play a role in the virus transmission in terms of indirect exposure to susceptible animals, which reflects the ability of CPV to persist in the environment with stable [ 4 ].…”