Pathological alterations in natural cases of Capillaria hepatica infection alone and in concurrence with Cysticercus fasciolaris in Bandicota bengalensis

Histopathological features and prevalence of Capillaria hepatica infection in Rattus spp. in Philippine Mount Makiling forest reserve and its adjacent areas

Rats are recognized as reservoir hosts of several pathogens that pose a threat to human health. Although rats are reported to be hosts of a large number of pathogens, a survey of Capillaria hepatica carried by rats in various settings such as residential, agroforestry, and agricultural areas in the Philippines has not been conducted. A total of 90 rats composed of Rattus norvegicus, Rattus tanezumi, and Rattus exulans were collected through trapping in selected residential, agroforestry, and agricultural areas in Los Baños Laguna, Philippines. The overall prevalence of C. hepatica among rats was 21.11%. Among the rat species collected, R. norvegicus showed the highest prevalence (55.56%), followed by R. exulans (14.29%), then R. tanezumi (5.36%) (differences significant at p < 0.05). Moreover, residential areas had the highest prevalence of C. hepatica infection (50%), followed by agroforestry and agricultural areas at 6.7% each (significant at p < 0.05). However, the difference in C. hepatica infection between male (11.43%; 4/35) and female (27.27%; 15/55) rats was not significant (p > 0.05). Most of the infected rats were moderately infected (68.42%), while few were lightly and severely infected (15.78% each). Lastly, the presence of C. hepatica in liver is suggestive of presence of lymphocytes, amyloid, granuloma, and the occurrence of necrosis, hypertrophy, fibrosis, and cholestasis in the liver of the host. Capillariasis could be occurring in Philippine human populations, hence there is need for screening the population with appropriate means and to create awareness of this emerging disease.

Prevalence and diversity of gastrointestinal helminths in free-ranging Asian house shrew (Suncus murinus) in Bangladesh

Background and Aim

Asian house shrew (Suncus murinus), a widely distributed small mammal in the South Asian region, can carry helminths of zoonotic importance. The aim of the study was to know the prevalence and diversity of gastrointestinal (GI) helminths in free-ranging Asian house shrew (S. murinus) in Bangladesh.

Materials and Methods

A total of 86 Asian house shrews were captured from forest areas and other habitats of Bangladesh in 2015. Gross examination of the whole GI tract was performed for gross helminth detection, and coproscopy was done for identification of specific eggs or larvae.

Results

The overall prevalence of GI helminth was 77.9% (67/86), with six species including nematodes (3), cestodes (2), and trematodes (1). Of the detected helminths, the dominant parasitic group was from the genus Hymenolepis spp.(59%), followed by Strongyloides spp.(17%), Capillaria spp. (10%), Physaloptera spp. (3%), and Echinostoma spp.(3%).

Conclusion

The finding shows that the presence of potential zoonotic parasites (Hymenolepis spp. and Capillaria spp.) in Asian house shrew is ubiquitous in all types of habitat (forest land, cropland and dwelling) in Bangladesh. Therefore, further investigation is crucial to examine their role in the transmission of human helminthiasis.

Cysticercus fasciolaris infection induced oxidative stress and apoptosis in rat liver: a strategy for host-parasite cross talk

Parasitic helminths have developed various strategies to induce or inhibit apoptosis in the cells of their host, thereby modulating the host's immune response and aiding dissemination to the host. Cysticercus fasciolaris, the larval form of Taenia taeniaeformis, parasitized different intermediate hosts like rats, rabbits, etc. and is cosmopolitan in distribution. In the present study, we have investigated host-parasite interactions and the resulting effect of C. fasciolaris in the liver of rat. Histology of the infected livers showed dilation and damages of hepatic cells near the parasite. Infected liver cells showed an increase in DNA fragmentation and chromatin condensation compared to the normal liver. Acridine orange and ethidium bromide dual staining revealed the presence of apoptotic cells in the infected liver. The decline in the mitochondrial membrane potential in the infected liver suggested that the observed apoptosis is mitochondria mediated. Occurrence of an elevated level of active executioner caspases 3/7 in the infected rat liver further confirms the occurrence of apoptosis. Different antioxidant enzymes were also evaluated and revealed a notable decline in the level of glutathione and glutathione-S-transferase activity leading to the augmented generation of reactive oxygen species. Results of the present study revealed that C. fasciolaris infection leads to apoptosis in the liver of rats which may be a surviving strategy for the parasitic larvae.

Patho-physiological observations in natural concurrent infections of helminth parasites of zoonotic importance in the wild rodents, Bandicota bengalensis

Screening of 83 mature wild rodents of Bandicota bengalensis (52 male and 31 females), live trapped from premises near railway station, fish market and agricultural fields in Ludhiana district of Punjab province, India was carried out to assess the natural occurrence of helminth parasites and their potential as reservoirs of zoonoses. On necropsy, intestine of rats was found infected with adult cestode parasites of Hymenolepis diminuta and H. nana. Liver was found infected with Capillaria hepatica and Cysticercus fasciolaris. These parasites were present either alone or as concurrent infection. In overall, 68.67 % rats were found infected of which 59.65 % were infected with nematode parasite, C. hepatica and 75.44 % with cestode parasites. Grossly, pathognomonic lesions of C. hepatica and C. fasciolaris were seen clearly and microscopic changes were observed only in severely infected cases. Overall investigation on the effect of these parasitic infections on pathophysiology of the host revealed that rodents serve as reservoirs of these parasitic infections without having much pathogenic effect on their vital organs, fecundity and enzyme activities. Because of its close association with human habitations, B. bengalensis may act as an important source of zoonotic infections and thus direct or indirect contact with excrements and carcasses of this rodent species, should be avoided.

Histopathological and morphological studies on natural Cysticercus fasciolaris infection in liver of Wistar rats

Descriptive morphology of multifocal hepatic cysts found in eight of forty five (17.78 %) Wistar rats sacrificed during pharmacological studies related to herbal formulations was studied. The creamish to white cysts were of varying sizes, ranging from 3-8 mm in diameter. Morphological studies of these cysts depicted the presence of metacestodes of Taenia taeniaeformis i.e. Cysticercus fasciolaris inside them. The scolex of metacestode revealed four suckers and rostellum armed with two distinct rows of characteristic pen knife shaped hooks (characteristics of taeniid cestodes). The average size of large hooks was 392.92 ± 10.12 µ and that of small hooks was 240.64 ± 14.26 µ. The average size of suckers was 304.36 ± 12.33 µ. Histopathology of hepatic tissue surrounding the cysts revealed zones of fatty change, inflammation, granulation tissue and metaplasia. However, the histopathology of stomach and small intestines didn't show any significant lesions.

An overview of the host spectrum and distribution of Calodium hepaticum (syn. Capillaria hepatica): part 1-Muroidea

Calodium hepaticum (syn. Capillaria hepatica) is a worldwide-distributed species of zoonotic nematodes with a high affinity to the liver. Several rodent species of the superfamily Muroidea serve as main hosts for this pathogen. C. hepaticum has been found in Muroidean hosts in more than 60 countries in Europe; North, Central, and South America; Asia; Africa; and Oceania. C. hepaticum was documented in more than 90 Muroidean rodent species (Murinae, Deomyinae, Arvicolinae, Neotominae, Cricetinae, Sigmodontinae, Gerbillinae, and Cricetomyinae). Globally, the Norway rat (Rattus norvegicus) seems to be the main host species for this nematode. However, locally high prevalences (above 50 %) have also been observed in several other synanthropic (commensal and non-commensal) Muroidea species (e.g., Rattus tanezumi, Ondatra zibethicus, Apodemus sylvaticus). This review gives an overview of the distribution and host spectrum of C. hepaticum in Muroidea host species.

Potential of eucalyptus oil as repellent against house rat, Rattus rattus

Rodent repellents are chemicals which by taste or odour or possibly by both will prevent animal from feeding or gnawing. Such substances may be used in protecting an area from rodent infestation or in protecting packaged food, packing materials, electric cables, and other important vulnerable materials. Mature and healthy house rat, Rattus rattus of both sexes, was exposed to 5, 10, and 20% eucalyptus oil applied as spray in laboratory pens in bichoice tests. Each concentration was applied through three different modes of application, that is, daily, once, and alternatively in a week. Repellent effect of the oil was assessed based on food consumption from treated and untreated sides for four days. In overall, food consumption was significantly (P < 0.0001) low from treatment side compared to the untreated side indicating significant repellent effect of the oil at all the three concentrations tested. Repellent effect of the oil was, however, not found to differ significantly between the two sexes. Percent repellency in both male and female rats was apparently more with daily application of 5 and 10% eucalyptus oil. Present studies reveal the potential of eucalyptus oil in repelling away R. rattus; however, further studies may be conducted to enhance the persistence of repellent effect for longer period of time.