Combined effects of heavy metals and parasite infections on the haematological and biochemical profiles of wild rats from Awotan Municipal Dumpsite in Ibadan City

The combined effects of heavy metals and parasitic infections on wild rats from Awotan municipal dumpsite in Ibadan city southwest Nigeria were determined. A total of thirty rats were captured from the dumpsite and five rats from a control site using live traps. Rats were identified, weighed and body length measured to determine body condition index. Blood samples were collected from the rats using the cardiac puncture method. Rats were euthanized and dissected to extract various organs (kidney, liver and intestine). Intestinal helminths were extracted, identified and preserved. Blood parasites were identified using Giemsa staining technique of thick and thin films while intestinal helminths recovered were preserved and identified to species level. Organs, intestinal helminths and blood samples were digested and concentrated for heavy metals (Fe, Cu, Cr, Cd, and Pb) using Atomic Absorption Spectrophotometry (AAS). Cortisol level was determined using ELISA technique. All statistical significance was at probability value p < 0.05. Three species of rats were captured, Rattus rattus, Rattus novergicus and Cricetomys gambianus. The mean ± sd of the body condition index of the rats from dumpsite and control groups were 1.82±0.17 and 1.59± 0.38 respectively. There were significant differences in the mean values of eosinophils, platelets and white blood cell counts of rats from the two study sites. Overall parasite prevalence in dumpsite and control were 76.6% and 20% respectively. The overall prevalence of parasite species from dumpsite was in the order Hymenolepis diminuta (26.6%) >Monoliformis monoliformis (20%) >Plasmodium spp (20%) >Trypanosoma spp (10%). The mean concentration (mg/kg) of heavy metals in kidney, liver, intestine and blood of wild rats from both dumpsite and control decreased in the order Fe> Cr> Cu> Cd> Pb. Cortisol level was higher in infected rats from dumpsite (351±58.83ng/ml) than in uninfected rats from dumpsite (237.22± 44.46ng/ml), indicating exposure to immune stressors. A higher prevalence of parasitic infection, heavy metal pollution and the elevated cortisol concentrations in infected rats showed that the animals’ health and well-being are compromised.

Update on the Phylodynamics of SADS-CoV

Coronaviruses are known to be harmful and heterogeneous viruses, able to infect a large number of hosts. Among them, SADS-CoV (Swine Acute Diarrhea Syndrome Coronavirus), also known as PEAV (Porcine Enteric Alphacoronavirus), or SeA-CoV (Swine Enteric Alphacoronavirus), is the most recent Alphacoronavirus discovered, and caused several outbreaks reported in Chinese swine herds between late 2016 and 2019. We performed an upgraded phylodinamic reconstruction of SADS-CoV based on all whole genomes available on 21 June 2021. Results showed a very close relationship between SADS-CoV and HKU2-like CoV, which may represent the evolutionary intermediate step towards the present SADS-CoV. The direct progenitor of SADS-CoV is so far unknown and, although it is well known that horseshoe bats are reservoirs for Rhinolophus bat coronavirus HKU2-like (HKU2-like CoVs), the transmission path from bats to pigs is still unclear. The discrepancies in the phylogenetic position of rodent CoV, when different molecular markers were considered, corroborate the recombination hypothesis, suggesting that wild rats, which are frequent in farms, may have played a key role. The failure of the attempt at molecular dating, due to the lack of a clock signal, also corroborates the occurrence of a recombination event hypothesis. Zoonotic infections originating in wildlife can easily become a significant threat for human health. In such a context, due to the high recombination and cross-species capabilities of Coronavirus, SADS-CoV represents a possible high-risk pathogen for humans which needs a constant molecular monitoring.

Morphological Peculiarities of Parasitic (Trichosomoides crassicauda) Infection in Rat Urinary Bladder

Trichosomoides crassicauda (T. crassicauda) is a parasite commonly localized in the urinary bladder (UB) of laboratory and wild rats. The presence of these helminths can influence the prediction of pathological changes in the UB. Therefore, the purpose of this research was to make a comprehensive study of the features of the morphological changes in the UB wall of white laboratory rats as a result of T. crassicauda infestation. The study was performed on male rats using histological (Hematoxyline-Eosin and Alcian Blue staining) and immunohistochemical (Ki-67, Hsp70, Hsp90α, CD3 and CD20) methods. T. crassicauda was detected in both urine and UB samples. Morphological changes were observed as disruption in urothelial cell stratification and insignificant proliferative and immune responses in the UB. Increased heat shock protein levels were observed which may suggest a natural body’s resistance to this parasite.

The parasitic nematode Strongyloides ratti exists as populations of long-lived asexual lineages.

Nematodes are important parasites of people and animals, and in natural ecosystems they are a major ecological force. Strongyloides ratti is a common parasitic nematode of wild rats and we have investigated its population genetics using single worm, whole genome sequencing. We find that S. ratti populations consist of mixtures of asexual lineages, widely dispersed across the host population. Genes that underly the parasitic phase of its life cycle are hyperdiverse, compared with the rest of the genome. These patterns of parasitic nematode population genetics have not been found before and may also apply to Strongyloides spp. that infect people.

Seroprevalence of Toxoplasma gondii in Wild Rats (Rattus rattus) in Northern Iran

Rodents are considered as reservoir hosts for various pathogens (such as Toxoplasma gondii) and have been revealed to play an important role in the spread of several infectious diseases to humans and other animals. The aim of this investigation was to survey the prevalence of anti-T. gondii IgG antibodies in wild rats in Northern Iran. One hundred rats were caught using rat traps set in different areas in Northern Iran (September 2017). The thoracic cavity of each rat was opened, and then the blood sample was collected from the heart. IgG anti-Toxoplasma gondii antibodies were detected using the modified agglutination test (MAT) with a cutoff value equal to 1 : 40. Overall, 56% of rats were infected by T. gondii. Considering the sex of rats, 45% of male and 55% of female rats were seropositive, but the differences were not statistically significant. There was a significant difference between seropositivity and habitat types and age of rodents. Our findings have public health implications and confirm the high seroprevalence of T. gondii infection in northern Iran. The study established that wild rats represent an important and persistent wildlife intermediate host reservoir for T. gondii.

Preliminary Study: Detection of Ecto and Endoparasites Among Wild Rats From Urban Area in Blimbing, Malang, East Java

Zoonotic parasitic infections is one of the global public health issues. The complex parasite transmission allows for the relationship between people, animals, vectors, and the environment. The existence of rat in the environment has an important role as a host and reservoir for various types of ecto and endoparasites. This study was conducted to collect informative data on the parasitic infection of wild rats in Blimbing sub-district, Malang city, East Java. A total number of eight wild rat were captured using live-traps from landfills during 4 days. They were classified by sex, weight and body length. The rats were anesthetized, collecting for any ectoparasites and then their carcasses were dissected for examinations of endoparasites. The result of this study show succesfull live-trap of rodents including Rattus norvegicus (87.5%) and Suncus murinus (12.5%). 50% of sampled rodents were male, 37.5% were female, and 12.5% of female the musk shrew. The presence of helminthes infection in all wild rats, namely Hymenolopis nana, Syphacia obvelata, Nippostrongylus brasiliensis. Furthermore, the ectoparasites identification were Xenopsylla cheopis, Echinolaelap echidninus, and blood protozoa identifications Trypanosoma lewisi. Based on the results show 100% of wild rats positive infections of endo-ectoparasites. This study indicates to continuous study among rodents’ parasites in wild rats in different urban areas and analysis of their potential impact on public health.

Metagenomic profiling of gut microbiota in urban and rural rats: A comparative study

Mammals have a symbiotic relationship with various microorganisms called microbiota throughout their lives. These microorganisms are known to affect the host's physiology, health, and even mental balance. The development of the gut microbiota is regulated by a complex interaction between host and environmental factors, including diet and lifestyle. Herein, it is aimed to elucidate the changes in the gut microbiota of rats living in urban and rural habitats. All taxonomic changes in the gut microbiota of wild rats belonging to Rattus rattus species caught from urban and rural areas of Western Anatolian (Bilecik province) were examined comparatively by 16S rRNA next-generation sequencing technique. Laboratory rats were used as a control group for comparison. Thus, 2000 different bacterial species were identified in gut microbiota. According to the Shannon and Simpsons values ​​calculated, laboratory rats showed the highest species diversity. When the similarities of microbiota profiles were compared with the principal coordinate analysis (PcoA), bacterial populations showed variability among different habitats. The comparison of species richness between the groups with the species rarefaction technique revealed higher species richness in all wild rats, especially in the rural habitat, compared to laboratory rats.

Complete Genome Sequences of Two Rat Pegivirus Strains in Indonesia

ABSTRACT The entire genome sequences of two pegivirus strains recovered from serum samples of wild rats (Rattus rattus) in Indonesia were determined. They possessed 11,013 to 11,014 nucleotides and differed from the reported rodent pegivirus strains within the Pegivirus J species of the genus Pegivirus by 12.7% to 40.9% in the near-entire coding region sequences.

Histopathology of the kidney and seroprevalence of leptospirosis in wild rats in Baghdad Province, Iraq

Background and Aim: Leptospirosis, caused by pathogenic leptospires, is a globally emerging infectious disease affecting both humans and animals, which act as reservoirs, with large outbreaks worldwide. The role of rats in dispersing leptospirosis was never investigated in Iraq. Because of the seriousness of the disease and the scarce data regarding this disease in Iraq, this study determines the incidence of leptospirosis in rats and its renal histopathological profile. Materials and Methods: Of 211 captured rats, 82 apparently healthy rats were included in this study. After euthanatizing, 3-5-ml blood was collected by cardiac puncture. Approximately 0.5 cm3 of the kidney was collected for routine histopathology and stained using hematoxylin and eosin (H&E) and Warthin–Starry (WS) stains. Blood smears were prepared and stained with the WS stain. Results: All rats (100%) with different age groups were immunoglobulin G (IgG)-positive, and 90.24% of them had the IgG against leptospiral antigens in kidney tissues. The juvenile age group had higher IgG levels than other age groups. Considering sex, no significant differences in the overall results were observed. Serum concentrations of blood urea nitrogen and creatinine showed significant increments in the sub-adult and adult IgG- positive groups compared with the IgG-negative groups. No significant alterations were observed in the juvenile group. Using WS stains, 13 and 1 blood smears and 0 and 8 kidney tissues were positive for leptospires in the sub-adult and adult groups, respectively. Microscopical findings of the renal cortex and medulla in the sub-adult IgG-positive group showed hemorrhage, glomerular deterioration, tubular cell degeneration and necrosis with cast formation, periarterial edema, and focal hemorrhage with congestion of peritubular arteries. The adult IgG-positive group revealed deterioration similar to that in the sub-adult group and tended to be chronic. No leptospires were observed using H&E staining. Conclusion: IgG-positive carrier rats refer to previously exposed or infected rats. Understanding the risk of transmitting the disease to human and animals through a carrier rat's urine is highly predicted and possible mitigation of zoonotic transmission.