Prevalence of Endo and Ecto Parasitic Infection of African Giant Rat (Cricetomys gambianus) in North Eastern Nigeria

Rodents are one of the most important groups of mammalian animal with more than 42%of the known mammalian species, with 1700 species which belongs to three different families include Muridae, microtidaie and sigmodontidae. The aim of this study is to examine endo and ecto parasitic infection of African Giant rat (Cricetomys Gambianus). Intestinal parasite were detected and identified from the stool samples using formalin ethyl-acetate concentration technique. A total of 18 African giant rats were captured, all of the captured rats were found infected with at least one or more endoparasites (100%). Whereas there’s no any ectoparasites identified from the rat. 16(89%) of the rats captured were found positive for haemoparasite. Therefore, the results of this study have shown that the rats are infected with parasite species that may play an important role in transmission of certain zoonotic diseases to humans. Keywords: African Giant rat, Cricetomys Gambianus, endo and ecto parasitic infection, Rodents, zoonotic disease.

Occurrence and Prevalence of Macroparasites of African Giant Rats (Cricetomys Gambianus) in a Savanna Region of Nigeria

Rodents play an important role in the transmission of zoonotic diseases since they serve as reservoirs of these infections. A survey of ecto and intestinal parasites of the African giant rat (Cricetomys gambianus) was carried out between January and May, 2018 in Il-orin to access their potential as reservoirs of zoonoses. A total of 60 African giant rats were caught live using single catch rat traps which were set around bushes, near human habitation. The giant rats were euthanized with chloroform and thoroughly examined for ectoparasites. The giant rats were dissected and the alimentary canal removed. Direct smear floatation and sedimentation methods were used to detect endoparasites in the animals. The prevalence of different types of endoparasites were: Hymenolepis nana (33.3 %), Hymenolepis diminuta (25.0 %), Aspicularis tetraptera (29.2 %), and Acanthocephala spp. (12.5 %), while the ectoparasites were: Ixodes rasus (37.9 %), Xenopsylla cheopis (44.8 %) and Ornithonyssus bacoti (17.2 %). African giant rats harbour quite a number of infections that can be spread to humans especially in developing countries where most communities are economically disadvantaged, thus the need to properly enlighten the populace.

Ultrastructural Morphology of the Ependyma and Choroid Plexus in the African Giant Rat (Cricetomys gambianus)

Ependymal cells line the interface between the ventricular surfaces and the brain parenchyma. These cells, in addition to the choroid plexus, form the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB) and serve important functions in the protection and regulation of brain metabolism. The African giant rat (AGR) has been used as sentinels to detect potential neuropathology arising from ecotoxicological pollutions. This study examined the lateral ventricular lining by using histology, immunohistochemistry and electron microscopy. Marked variations were observed in some regions of the ventricles which showed multi-layering of ependymal cells that differed from the typical single layered ependymal cells at the apical surface, while subependymal structures revealed indistinctive neuropil and glia following histological examinations. The ependymal cells which form the epithelial lining of the ventricles were comprised of cuboidal or low columnar cells, with the plasmalemma of abutting cells forming intercellular bridge appearing links by: tight junctions (zonula occludens), intermediate junctions (zonula adherens), desmosomes (macula adherens) and infrequent gap junctions. The choroid plexus revealed cells of Kolmer with several cilia and microvilli. The possible functional components of the ependyma and choroid plexus morphology of the AGR are discussed and thus provide a baseline for further research on the AGR brain.

Effects of Graded Crude Protein Diet on Haematological Indices and Body ‎Weight of African Giant Rat (Cricetomys gambianus)‎

The domestication of the African giant rat (AGRs) (Cricetomys gambianus) to compliment the inadequate animal protein supplies in Nigeria and its potential to serve as a model for biomedical research is yet to be fully exploited. This study determines the effects of varied crude protein (CP) diet on haematological indices and body weight of AGRs. Blood samples were obtained from the orbital sinus of 30 apparently healthy adult male and female AGRs. The AGR’s were kept in captivity and divided into 6 rats per group (A, B, C, D and E). Group A served as control group. The groups werefed with graded levels of crude protein (CP) of (E) 9.83%, (D) 14.79%, (A) 21.21%, (C) 23.93% and (B) 27.84%. Each chloroform pre-anaesthetized AGRs were weighed at days 0 and 14, 28, 42 and 56, while blood samples were collected at days 28 and 56. The samples were each analyzed for erythrocyte and leucocyte parameters and platelet counts by standard methods. All data collected were subjected to analysis of variance and student t-test. At 28 days post-feeding, AGRs fed with 27.84% CP showed no significant elevations in erythrocyte and leucocyte values compared with control values (21.21% CP). However, at 56 days post-feeding, RBC, Hb, PCV, total WBC, eosinophil, lymphocyte and monocyte counts were significantly lowered in the group fed with 27.84% CP. No significant differences in body weights were observed in rats that were fed 27.84%, 21.21%, 14.8% and 9.8% crude protein diets for 28 and 56 days.This study shows improved body weight with 27.84% CP compared with other crude protein percentage used while 14.79% CP had the best haematological parameters when compared with other crude protein groups.

Structural Modifications of the Small Intestine of the African Giant Rat (Cricetomys gambianus, Waterhouse): Implications for Dietary demands and Improved Domestication

The African giant rat (Cricetomys gambianus, Waterhouse) is a wild rodent in sub-Saharan Africa widely hunted as popular meat delicacy. Domestication of this rat has been poor, probably due to nutrition among other factors. Developmental studies of the duodenum, jejunum and ileum as well as investigations of diet-based structural modifications of the small intestine were carried out in the rats using neonates, juveniles and adults with the aim of providing useful research information which could lead to improved domestication. The mean body weights of the animals were 39.67±1.45 g, 225.00±25.00 g and 742.90±62.13 g, respectively for the neonate, juvenile and adult rats. Significant differences were also observed in the villus height, villus width and crypt depth between the neonates and juveniles, unlike between juvenile and adult rats. These changes in intestinal morphology between the neonate and juvenile rats could be a measure of the neonates’ adaptation to shifts from digestion of maternal milk to the consumption of solid and semisolid forages. Respectively for neonates, juvenile and adult rats, 188%, 228% and 30% increases in villus height for the duodenum, jejunum and ileum respectively, were observed. This is suggestive of larger surface area of the small intestine for digestion and absorption. This study elucidates the structural modifications of the small intestine which can be applied to dietary modifications in response to age in an effort to achieve a more successful domestication of the animal.

Preliminary Anatomical Assessment of the Eye of the African Giant Rat (Cricetomys gambianus)

Eleven African giant rats were caught, bilaterally enucleated and the globes were routinely processed for light microscopy. Eye weight, vertical and horizontal corneal diameters, as well as vertical, horizontal and axial eye diameters were obtained from each globe. Observed external macroscopic ocular features were typical of mammalian eyes comprising cornea, sclera and attached extraocular muscles. The eye dimensions were however generally smaller than those of humans. The large mean corneal diameter to mean eye diameter ratio of 0.86 as well as the scanty retinal ganglion cells observed are associated with morphological adaptations for nocturnal vision. Pigments observed in the retinal epithelium suggests absence of tapetum lucidum, indicating a sub-optimal nocturnal visual capability. This study has provided scientific documentation of some ocular morphological characteristics of the giant rat and has shown that the eye of this species will be anatomically unsuitable for xenotransplantation in humans.

Effects of dietary energy level on reproductive characteristics in male African giant rat Cricetomys gambianus

Background: The study was conducted to assess the effects of the digestible dietary energy level on some reproductive characteristics in African giant rat.Methods: Sixteen young males were randomly distributed into 4 groups of 4 animals each. To each group was attributed randomly one of the 4 dietary energy levels (3600 Kcal/kg, 3800 Kcal/kg, 4000 Kcal/kg or 4200 Kcal/kg). The daily distribution of experimental diets last six months, ie ended when cricetoma were 8 months old. At the end of that period, all animals were sacrificed.Results: Results showed an increase in testes weight with the augmentation of dietary digestible energy level (0.79±0.13, 0.88±0.17, 1.02±0.28 and 1.02±0.16 respectively for 3600 Kcal/kg, 3800 Kcal/kg, 4000 Kcal/kg and 4200 Kcal/kg). The serum testosterone level, the sperm mobility (76.67, 62, 63 and 57%) and count per cauda epididymis (18.25±3.75, 16.38±4.19, 10.83±2.02 and 10.13±2.9) and per gram cauda epididymis (39.09±11.82, 27.01±4.23, 15.41±3.31 and 17.40±7.28) significantly (p<0.05) decreased with the increasing level of digestible energy in the feed.Conclusions: The dietary digestible energy level that gave the higher reproductive performances in male African giant rat was 3600 Kcal/kg DM.