The infection of Cysticercus fasciolaris in natural rats (Rattus species) residing in human residence areas, Nakhon Si Thammarat, Thailand

Cysticercus fasciolaris (C. fasciolaris) is the larval stage of a cestode parasite named Taenia taeniaeformis (T. taeniaeformis). C. fasiolaris is found in small rodents, especially rats. Rattus species are listed as intermediate hosts of this parasite, and cats are the main definitive host of C. fasiolaris. The objective of this study was to study the pathological, microscopic, and molecular aspects of C. fasciolaris in rodents residing in human residence areas. One hundred and two rodents were trapped in human settlements and dissected for larva-containing cyst examinations in the body cavity. The larvae of C. fasciolaris were investigated using histopathological examination, microscopic observations under a stereomicroscope and scanning electron microscope, and molecular detection using polymerase chain reaction. The prevalence of hepatic cysts containing larvae was 8.91% (95% CI = 4.16-16.24). In addition, the older larvae also had longer micropapillae. Histopathological investigation revealed normal hepatic tissue containing larvae and a scanty fluid cyst. The cyst capsule contains mostly mononuclear cells and spindle cells in all infected rats. The molecular detection using two primer sets revealed the amplicons were similar to the clade of C. fasciolaris. In the future, more investigation is necessary to fully understand the parasite's molecular pathogenesis and virulent molecules, which are less obvious.

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.

Condition factor and organosomatic indices of parasitized Rattus rattus as indicators of host health

This study describes the influence of parasitism (Trypanosoma lewisi and Cysticercus fasciolaris) on the condition factor, hepato and splenosomatic indices of the common house rat, Rattus rattus Linnaeus, 1758 from Rohilkhand, Uttar Pradesh, India. Examination of R. rattus (n = 389) revealed T. lewisi (prevalence 12.40 %; intensity14 parasites/1000 RBC) from the blood and C. fasciolaris (larval Taenia taeniaeformis) (prevalence 46.70 %; intensity 2-4 par/host) from the liver. Condition factor (K) and organosomatic indices [hepatosomatic index, spleenosomatic index (SSI)] were evaluated in two groups (Group I non pregnant, Group II pregnant) of female rats which were further subdivided into four subgroups each (a Uninfected, b T. lewisi infected, c C. fasciolaris infected, d T. lewisi and C. fasciolaris infected) belonging to three weight groups (A 50-100 g; B 100-150 g; C 150-200 g). The results indicated that reduction in K-factor was more apparent in young rats, Group Ic (weight category A) showing the maximum depletion (21.62 %), hepatomegaly and splenomegaly were frequent outcomes of parasitic infection and maximum change (50 %) was recorded in dual-infected pregnant rats (Group IId) expressed as SSI of the infected rat. The abnormal condition factor and organosomatic indices indicate perturbations in the biological systems at the organismal level. Thus, the information generated through this piece of work is a warning of an incipient or impending problem.

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.

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.

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

The present study reports the natural occurrence and pathomorphological alterations of Capillaria hepatica infection alone and in concurrence with Cysticercus fasciolaris infection in the liver of Bandicota bengalensis. Out of the eighteen mature male B. bengalensis autopsied, livers of eight rats (44.4 %) were found infected with parasites comprising two (11.1 %) rats infected with C. hepatica alone, four (22.2 %) infected with C. fasciolaris alone and two (11.1 %) infected with C. hepatica in concurrence with C. fasciolaris. Gross lesions comprising of pale cystic areas or streaks on the surface of liver in rats revealed the presence of eggs of C. hepatica scattered in the parenchyma of the liver. Histologically, granulomatous reaction around the eggs, adult worms and dead components of parasites were observed.