Midguts of Culex pipiens L. (Diptera: Culicidae) as a potential source of raw milk contamination with pathogens

Abstract

AbstractDespite their importance, only few studies focused on the mosquitoes borne microbial diseases, especially bacterial and fungal diseases, their vectorial capacity toward microorganisms, and their important role in raw milk contamination with pathogens in some unsanitary dairy farms. In Egypt, whereCulex pipiensis the historical main vector of lymphatic filariasis, only few studies discussed the isolation of pathogens from the midguts of different stages ofC. pipiens. This study aims to isolate and identify the pathogenic symbiotic microorganisms inside the midgut of adult femaleC. pipiensas well as investigate its ability to transmit their midgut pathogens to raw milk. A total of 750 field strain C. pipiens larvae of the second and third larval instars were collected from ponds water around the livestock farms in Mariotteya, Giza, Egypt, for microbial pathogen isolation and identification. All collected larval instars were transported to the laboratory at the Research and Training Center on Vectors of Diseases (RTC), Ain Shams University, where they were maintained for further studies. Six groups ofC. pipienswere tested for the incidence of various pathogenic microorganisms in their midguts and their possibility to contaminate commercial sterilized milk. Traditional PCR assays and sequencing method detected and identified 16srRNA genes of the predominant hemolytic isolates from milk and midguts of femaleC. pipiens. The phylogenetic analyses of the obtained isolates were performed based on NCBI data. Three strains ofBacillus anthracisstrain CPMESA 2021,Staphylococcus warneristrain CPSAME 2021, andBacillus cereusstrain CPSEMA 2021, which represent most food pathogens, were found in the midguts ofC. pipiensand were submitted to the GenBank database with the accession numbers OK585071, OK576651, and OK585052, respectively. The isolation of these strains from mosquitoes raises contemporary issues concerning milk safety, such as bacterial isolates, the degree of the vectorial capacity of mosquitoes, milk production and processing conditions, and human pathogenicity. Such serious issues need further investigation.