Dynamics of Rodent-Borne Zoonotic Diseases and Their Reservoir Hosts: Invasive Rattus in South Africa

Abstract

Lack of adequate sanitation and pest control, and poor housing conditions that prevail in much of both rural and urban South Africa, cause rodent populations to thrive, promoting contact with humans, which results in increased risk of zoonotic disease transmission. This study focused on bacterial pathogens involved in potential zoonoses present in 3 commensal and invasive Rattus spp., namely Rattus norvegicus, R. rattus, and R. tanezumi, from rural and urban South Africa. Bacterial prevalence and diversity was determined through amplification and sequencing of the mitochondrial 16S gene region, using 4 primer sets: 2 that have a broad bacterial species recognition range, and 2 genus-specific sets that target the genera Streptococcus and Streptobacillus. An overall bacterial prevalence of 32% (n = 84) in kidney samples was obtained using the 16S universal primer sets. Subsequent sequence analyses found bacterial prevalence per host species to be 41% for R. norvegicus, 42% for R. rattus, and 8% for R. tanezumi, with representatives of diverse bacterial taxa such as Clostridium sordelli (toxic shock syndrome), Bacillus cereus (diarrhoeal disease), and Enterococcus faecalis (nosocomial infections) being characterised. The primer set targeting Streptobacillus moniliformis was used to determine the prevalence of this zoonoticallyimportant bacterial taxon, which is transmissible via a bite from Rattus to humans, whilst Streptococcus-specific primers were used to assess environmental shedding of this agent via the urinary route. The results highlight the public health implications especially for immune-compromised individuals, as these rodent-borne pathogens can cause opportunistic infections that in such individuals are not readily diagnosed or treated.