Histopathological and morphological characterization of Cysticercus fasciolaris isolated from domestic and wild rodents in Morocco

Cysticercus fasciolaris is a parasitic helminth that usually infects feline and canine mammal hosts. The intermediate hosts (rodents, occasionally lagomorphs, and humans) get infected by the consumption of feed or water contaminated with eggs. Rodents are vectors of disease and reservoirs of various zoonotic parasites. The current survey was aimed at determining endoparasitic helminth infections in rodents in central Morocco. Sampled rodents after specific identification were sacrificed and examined to identify parasitic helminths following ethical guidelines. Parasites were identified using morphological characteristics. A total of 197 specimens of rodents were collected and examined in this study. Ten rodent species were identified morphologically as Rattus rattus, R. norvegicus, Apodemus sylvaticus, Mus musculus, M. spretus, Mastomys erythroleucus, Meriones shawi, M. libycus, Gerbillus campestris, and Lemniscomys barbarus. The parasitological results showed that metacestode of tapeworms was found encysted in the liver, the larval stage of Taenia taeniaeformis develops large multinodular fibrosarcomas which envelope the tapeworm cysts in the liver of the R. rattus and R. norvegicus. Based on morphological data, the metacestode was identified as C. fasciolaris in 23 (23/80) R. rattus 2 (2/8) and R. norvegicus with a prevalence of 11.7 % and 1.0 %, respectively. Rodents are major vectors of human and domestic animal diseases worldwide, and therefore, important parasitic zoonotic agents (C. fasciolaris), which are transmitted by black rats (R. rattus) and brown rats (R. norvegicus), must be considered to prevent the infectivity of humans, domestic animals, and livestock such as cattle, sheep, and rabbits.

Population structure, dispersion patterns and genetic diversity of two major invasive and commensal zoonotic disease hosts (Rattus norvegicus and Rattus tanezumi) from the southeastern coast of China

Background: The invasive brownrat (Rattus norvegicus) and the Oriental rats (Rattus tanezumi) are common commensal murid that are important hosts for rodent-borne diseases in southeast Asia. Understanding their population structure and genetic diversity is essential to uncover their invasion biology and distribution dynamics that are essential for controlling rodent-borne diseases. Methods: TA total of 103 R. norvegicus and 85 R. tanezumi were collected from 13 to 9 coastal areas of six provincial monitoring sentinel sites, respectivelyto assess patterns in their microsatellite loci and their mitochondrial coxl gene region. Results: Eleven sampled populations of R. norvegicus were divided into two major clusters by region. The observed heterozygosity values of all regional populations were smaller than expected genetic diversity heterozygosity values and deviated from Hardy-Weinberg equilibrium Nine sample populations of R. tanezumi were divided into three clusters; two that included sample from Hainan and Fujian provinces, and one that included samples from the other provinces and cities. The genetic diversity of R. tanezumi was highest in samples from Jiangsu and Guangdong provinces. Conclusion: The data in this paper confirm the two invasive rodent species from the southeastern coastal region of China may have relied on maritime transport to spread from the southern region of China to the Yangtze River basin. R. tanezumi may then hanve migrated unidirectionally, along the southeastern provinces of China towards the north, while R. norvegicus spread in a complex and multidirectional manner in Hainan, Fujian, Zhejiang and Jiangsu Provinces of the country.

Prevalence of Diarrheagenic Escherichia coli (DEC) and Salmonella spp. with zoonotic potential in urban rats in Salvador, Brazil

Studies evaluating the occurrence of enteropathogenic bacteria in urban rats (Rattus spp.) are scarce worldwide, specifically in the urban environments of tropical countries. This study aims to estimate the prevalence of diarrhoeagenic Escherichia coli (DEC) and Salmonella spp. with zoonotic potential in urban slum environments. We trapped rats between April and June 2018 in Salvador, Brazil. We collected rectal swabs from Rattus spp., and cultured for E. coli and Salmonella spp., and screened E. coli isolates by polymerase chain reaction to identify pathotypes. E. coli were found in 70% of Rattus norvegicus and were found in four Rattus rattus. DEC were isolated in 31.3% of the 67 brown rats (R. norvegicus). The pathotypes detected more frequently were shiga toxin E. coli in 11.9%, followed by atypical enteropathogenic E. coli in 10.4% and enteroinvasive E. coli in 4.5%. From the five black rats (R. rattus), two presented DEC. Salmonella enterica was found in only one (1.4%) of 67 R. norvegicus. Our findings indicate that both R. norvegicus and R. rattus are host of DEC and, at lower prevalence, S. enterica, highlighting the importance of rodents as potential sources of pathogenic agents for humans.

Vkorc1 sequencing suggests anticoagulant resistance in rats in New Zealand

BACKGROUND

Anticoagulant toxins are used globally to control rats. Resistance of Rattus species to these toxins now occurs in at least 18 countries in Europe, America and Asia. Resistance is often associated with single nucleotide polymorphisms (SNPs) in the Vkorc1 gene. This study gives a first overview of the distribution and frequency of Vkorc1 SNPs in rats in New Zealand. New Zealand is unusual in having no native rodents but three species of introduced Rattus - norvegicus Berk., rattus L. and exulans Peale.

RESULTS

Sequence variants occurred in at least one species of rat at all 30 of the sites sampled. Three new SNPs were identified, one in kiore and two in ship rats. No SNPs previously associated with resistance were found in Norway rats or kiore, but seven ship rats were heterozygous and one homozygous for the A74T variant. Its resultant Tyr25Phe mutation has previously been associated with resistance to both first- and second-generation anticoagulants in ship rats in Spain.

CONCLUSIONS

This is the first evidence of potential resistance to anticoagulant toxins in rats in New Zealand. Further testing using blood clotting response times in dosed rats is needed to confirm resistance potentially conferred by the Tyr25Phe mutation. Assessment is also needed of the potential of the other non-synonymous variants (Ala14Val, Ala26Val) recorded in this study to confer resistance to anticoagulant toxins. © 2016 Society of Chemical Industry.

An active second dihydrofolate reductase enzyme is not a feature of rat and mouse, but they do have activity in their mitochondria

The identification of a second functional dihydrofolate reductase enzyme in humans, DHFRL1, led us to consider whether this is also a feature of rodents. We demonstrate that dihydrofolate reductase activity is also a feature of the mitochondria in both rat and mouse but this is not due to a second enzyme. While our phylogenetic analysis revealed that RNA-mediated DHFR duplication events did occur across the mammal tree, the duplicates in brown rat and mouse are likely to be processed pseudogenes. Humans have evolved the need for two separate enzymes while laboratory rats and mice have just one.