Transmission of Salmonella between Swine Farms by the Housefly (Musca domestica)

Abstract

The domestic pig is an important source of human salmonellosis, and houseflies are potential mechanical vectors of foodborne Salmonella pathogens. In 2005, we recovered 144 Salmonella isolates from flies and swine stool samples from 11 farms in Taoyuan County and Hsin Chu County (northwestern Taiwan). A total of 71.5% of the isolates were resistant to at least three antibiotics. There were a total of 14 serotypes, and 8 of these serotypes were present in both flies and swine stool samples. Some multidrug-resistant Salmonella strains coming from different swine farms were found to have identical pulsed-field gel electrophoresis (PFGE). Among four common serotypes, we identified 18 PFGE patterns, 8 of which were present in flies and swine stools. The similarity in PFGE profiles between isolates from swine and flies in different farms indicate the potential of flies to serve as a vector for transmission.

Prevalence and Relative Risk of Cronobacter spp., Salmonella spp., and Listeria monocytogenes Associated with the Body Surfaces and Guts of Individual Filth Flies

“…2a). S. enterica serovar Hadar was also reported from the internal contents and the surfaces of pooled samples of M. domestica collected from an animal facility in Malaysia (16), whereas S. enterica serovar Schwarzengrund and S. enterica serovar Senftenberg were recovered from M. domestica flies collected from swine farms in Taiwan (87). With the exception of S. enterica serovar Brackenridge, all Salmonella serovars isolated from the flies collected in this study have caused foodborne illness in the United States (14).…”

“…Outbreaks of Salmonella have implicated both animal-and produce-based products (25). Salmonella has also been associated with wild flies collected from animal farms (5,32,34,39,58,67,87) and, less frequently, with wild flies collected from urban areas (6,16,85). However, the reported frequencies of Salmonella spp.…”

“…This great variability is explained mainly by the lack of systematic methods used and the use of either individual flies or pooled samples of flies, which varied from 10 to 50 flies per pool. In addition, only a handful of studies have identified Salmonella to the serovar level (16,32,67,87).…”

Fungi Isolated From House Flies (Diptera: Muscidae) on Penned Cattle in South Texas

“…House flies can harbor pathogenic bacteria, excreting viable isolates in their vomitus and feces (Joyner et al 2013, Nayduch et al 2013), and can disseminate them mechanically to various hosts (Levine and Levine 1991, Ahmad et al 2007, Wang et al 2011). Additionally, house flies can disseminate common fungi implicated as incidental pathogens, including Aspergillus spp.…”

Migrating Common Toads (Bufo bufo) in Rural Temperate Regions: Reservoirs ofSalmonella?

“…Infected livestock and crops are prime sources of Salmonella infection in humans. Animals (e.g., rodents, birds, and insects) are considered important reservoirs of Salmonella, maintaining infection cycles in agricultural areas (Wang et al 2011;Umali et al 2012). Although amphibians are generally considered to exert a positive effect in agriculture by consuming large numbers of invertebrates (Stewart and Woolbright 1996), they are also considered asymptomatic reservoirs for Salmonella serotypes such as Enteritidis, Rubislaw, Saintpaul, Montevideo, and Newport (O'Shea et al 1990;Chambers and Hulse 2006;Drake et al 2013).…”