The impact of illegal waste sites on a transmission of zoonotic viruses

Illegal waste disposal impacts public health and causes aesthetic and environmental pollution. Waste disposed in places without permitted and controlled facilities can provide a ready source of nutrition and shelter for rodents and thus promote the spread of their ecto- and endoparasites. The presence of two distinct zoonotic viruses, lymphocytic choriomeningitis virus (LCMV) and tick-borne encephalitis virus (TBEV), was searched at illegal waste sites. The aim of this study was to determine the prevalence of infection with both viruses in rodents and to discuss the virus-rodent relations in such environments.

Rodents sampled between October 2011 and April 2013 at 7 locations in the Istrian peninsula, were identified morphologically and genetically to minimize misidentification. Serological and molecular techniques were used to determine seroprevalence of infection in rodents and to detect viral RNAs. Serological testing was performed by immune fluorescence assay for detection of LCMV and TBEV specific antibodies. Real-time RT PCR was used for the detection of LCMV nucleoprotein gene and TBEV 3' non-coding region. Data were statistically analysed using SPSS statistic v2.0.

Out of 82 rodent sera tested, the presence of LCMV antibodies was demonstrated in 24.93%. The highest prevalence of LCMV infection was found in commensal Mus musculus (47.37%), followed by 11.53%, 19.04% and 25% prevalence of infection in A. agrarius, A. flavicolis and A. sylvaticus, respectively. The highest prevalence of infection in rodents (53.33%) was found in locations with large waste sites and high anthropogenic influence. LCMV seroprevalence was significantly lower in rodents sampled from natural habitats. Viral nucleic acids were screened in 46 samples but yielded no amplicons of LCMV or TBEV. In addition, TBEV specific antibodies were not detected.

Illegal waste sites have considerable impact on the area where they are located. Results have shown that the transmission of human pathogens can be significantly increased by the presence of waste sites. However, the pathogen must be endemic in the environment where the waste site is located. The introduction of a human pathogen as a consequence of the waste site in the area of interest could not be proven.