Effectiveness of praziquantel for treatment of peritoneal larval cestodiasis in dogs: a case report

Gastrointestinal parasites of cats in the Middle East (2000-2023): A literature review

BACKGROUND/OBJECTIVE

Gastrointestinal parasites in stray cats are of significant clinical and zoonotic importance and pose a potential threat to public health. Hence, the current review has practical implications as it aims to present the diversity and the prevalence of cat parasites in Middle Eastern countries.

METHODS

The research process was rigorous and thorough, spanning from 2000 to 2023. Data collection and analysis were conducted utilizing multiple international and national databases, including Google Scholar, Scopus, PubMed, and Irandoc. This meticulous approach ensures the reliability and validity of the findings, providing a solid foundation for further research and preventive measures.

RESULTS

A total of 159 articles were collected and comprehensively reviewed. Among these, 85 articles were from Iran, 25 from Türkiye, 20 from Iraq, 11 from Egypt, five from Qatar, three from Cyprus, three from Kuwait, and one each from the UAE, Saudi Arabia, Syria, Lebanon, Jordan, Israel, and Palestine. Toxocara cati was the most prevalent nematode, exhibiting the highest prevalence in Iran, ranging from 8% to 90%, followed by Egypt, with a range of 8.23% to 58.7%. In comparison, the lowest prevalence was recorded in Qatar at 8%. Hydatigera taeniaeformis, a common cestode in the feline, showed the highest prevalence in Qatar, with a range of 73.6% to 75.8%, while the lowest was in Kuwait at 0.8%. In Iran, the prevalence ranged from 0.9% to 64.7%. Toxoplasma gondii, a cosmopolitan protozoan, showcased the highest prevalence in Lebanon at 78.1% and the lowest in the UAE at 0.8%. In Iran, the prevalence ranged between 1.2% and 90%. Additionally, noteworthy patterns regarding the distribution and potential risk factors associated with these parasites were observed. While gender variations were not significant, environmental conditions such as high humidity and absence of sunlight exposure, along with the age and behavior of cats, were among the risk factors associated with the prevalence of parasites.

CONCLUSION

The prevalence of parasites among stray cats in Iran and other Middle Eastern countries remains notably high. This emphasizes the urgent need for a series of control and preventive measures. Implementing effective anti-parasitic strategies and emphasizing the development of multiple diagnostic methods are essential.

Successful treatment of pleural and peritoneal larval mesocestoidosis with fenbendazole in two dogs

Mesocestoides spp. are common intestinal tapeworms of dogs and cats. The presence of numerous larval stages in the pleural or peritoneal cavities causes larval mesocestoidosis, that is a potentially life-threatening disease in massive infection. In vivo diagnosis of larval mesocestoidosis is challenging and confirmed diagnosis is often made post-mortem. For this reason, therapeutic recommendations are empirical and there is currently no data on the best treatment options in dogs and cats. Both fenbendazole and praziquantel have been used to treat canine larval mesocestoidosis but failure of complete clearance of larvae has been described for both. Treatment with fenbendazole at 100 mg/kg orally twice a day, for 1-3 months has been reported as being effective. However, it is known that administration of high, off-label doses of fenbendazole can lead to adverse reactions. Here, we report the efficacy of fenbendazole at a lower dosage (50 mg/kg twice a day) in two dogs with pleural and peritoneal mesocestoidosis.

Subcutaneous Taenia crassiceps Cysticercosis Mass Excision from an 11-Year-Old Mixed-Breed Dog

An 11 yr old mixed-breed dog presented with a 2 × 3 cm semimovable subcutaneous soft-tissue mass overlying the right hip region that grew to 8 × 5 cm over a 6 mo period. Two separate fine needle aspiration cytology samples showed marked pyogranulomatous inflammation with no cytologically apparent infectious etiology or neoplasia. Computed tomography imaging revealed a well-marginated, heterogeneous, contrast-enhancing soft-tissue mass extending into the adjacent fat, suggestive of neoplasia. A 14G needle biopsy showed similar chronic inflammatory changes without evidence of neoplasia or infectious etiology. Excisional biopsy of the mass was performed, and ex vivo sectioning revealed Taenia crassiceps cysticerci. Histopathology confirmed severe chronic pyogranulomatous cellulitis and myositis with intralesional cysticerci. Anthelmintic treatment was administered postoperatively, and no evidence of local recurrence has been noted as of 6 mo after the operation. To our knowledge, this is the first case report describing the cytological, histological, cross-sectional imaging characteristics and treatment outcome of T crassiceps cysticercosis in a dog.

First description of peritoneal and pleural metacestodosis caused by Mesocestoides vogae in a European wild cat (Felis silvestris silvestris)

Tapeworms of the genus Mesocestoides (Cestoda: Cyclophyllidea: Mesocestoididae) are still enigmatic to scientists, due to their high morphological variability, low host specificity, and unknown details of their life cycle. They are found worldwide, with carnivorous mammals as the main definitive hosts, and the disease is potentially zoonotic. After ingestion by a definitive host, the tetrathyridium can occasionally migrate through the intestinal wall and reach the peritoneal cavity or abdominal organs causing peritoneal metacestodosis. Here, we report on a case of metacestodosis of a European wild cat (Felis silvestris silvestris) found dead in Croatia. At necropsy, a large number of white, rice-like structures were found free in the abdominal and thoracic cavities, as well as along the serous surfaces and in the lungs. DNA isolated from the nodules was genotyped and based on a 320-base pair long 12S fragment classified as Mesocestoides vogae. Although post-mortem changes were advanced, severe emaciation due to the severe parasitic infection and gastrointestinal bleeding was diagnosed as the likely cause of death. Intestinal cestodosis was previously reported in wild cats, but according to our knowledge, this is the first description of peritoneal and pleural metacestodosis caused by M. vogae tetrathyridia (metacestodes) in any wild carnivore species.

Clinical forms of peritoneal larval cestodiasis by Mesocestoides spp. in dogs: diagnosis, treatment and long term follow-up

Canine peritoneal larval cestodiasis (CPLC) is a little-known parasitological infestation of the peritoneal cavity of wild and domestic carnivores with Mesocestoides spp. larvae. While adult Mesocestoides tapeworms reside within the small intestine, the larvae occasionally penetrate the host's intestinal wall, causing a potentially life-threatening peritonitis. Severity of infection as well as the host response influences the prognosis significantly, and early diagnosis and treatment are essential. However, due to the lack of specific symptoms, this condition is underdiagnosed and, furthermore, no clear effective treatment has yet been described. The aim of this study is therefore to report two clinical cases of CPLC in dogs and to illustrate their clinical presentation and follow-up to serve as a reference for clinicians and researchers alike. Both animals were presented with abdominal distention as their main complaint. They underwent clinical examination, abdominal ultrasonography, abdominocentesis, and laparotomy followed by biochemical, cytological, parasitological, and molecular examination of the collected samples. After surgical lavage, the dogs received anthelmintic treatment with either fenbendazole (FBZ) or praziquantel (PZQ). Overall, timely and prolonged administration of high doses of FBZ seems to be the most effective treatment method. Irrespective, to date, no treatment capable of complete eradication of the infection and prevention of recurrence of disease has been found. In conclusion, further investigation into appropriate treatment plans as well as diagnostic development is needed.

Severe Pleural Effusion in a Dog Affected by Larval Mesocestodiasis

A 4-year-old, 20 kg, female mixed breed dog was referred to our Veterinary Teaching Hospital for severe respiratory distress. Thoracic ultrasonography revealed severe pleural effusion with multiple anechoic cystic structures within the fluid. Abdominal cavity presented few small and irregular cystic structures. Diagnosis of infection by larval stages of Mesocestoides spp. on the basis of a PCR approach was performed and therapy with oral fenbendazole was started. Due to an incomplete clinical response, the dog underwent to remove metacestodes cysts by surgical debridement. The dog showed no recurrence of clinical signs for 12 months after the surgery. Pleural larval cestodiasis should be added as a differential diagnosis in the list of diseases causing pleural effusion in dogs.

Species delimitation based on mtDNA genes suggests the occurrence of new species of Mesocestoides in the Mediterranean region

BACKGROUND

This study is the first contribution to the molecular taxonomy of Mesocestoides spp. from domestic and wild carnivores in the Mediterranean area. A total of 13 adult worms and 13 larval stages of Mesocestoides spp. were collected from domestic and wild carnivore hosts in Italy and Tunisia. Samples collected in the Slovak Republic were used as comparative samples from outside the Mediterranean. The genes cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1) of the mitochondrial genome were used as molecular markers to investigate the presence of cryptic Mesocestoides species in the area analysed.

RESULTS

Results were consistent in showing three well-supported clusters of Mesocestoides spp. in southern Italy and Tunisia, which were strongly divergent from Mesocestoides litteratus, M. corti and M. lineatus. High levels of genetic variation and no evidence of geographical structuring was found between the clusters.

CONCLUSIONS

Considering the low dispersal capability of the intermediate hosts of Mesocestoides spp., the lack of geographical structuring among the Mediterranean regions could be due to a high potential for dispersion of the definitive hosts. This study provides a foundation for future formal descriptions of new species of the genus Mesocestoides in the Mediterranean area.

Slow-release praziquantel for dogs: presentation of a new formulation for echinococcosis control

BACKGROUND

Echinococcosis is a serious, zoonotic, parasitic disease with worldwide distribution. According to a epidemiological survey in 2012 in China, there are 20,000 infected patients and more than 50 million people at the risk. As the dog is the main, definitive host, the Government of China encourages monthly praziquantel treatment of every dog. However, this is difficult to achieve in geographically challenging areas, such as the Tibetan plateau, where there are also many dogs without owners. To overcome these problems, we investigated the transmission blocking capacity of a slow-release formulation of praziquantel administered by subcutaneous injection.

METHODS

The impact of a slow-release preparation of two pharmacokinetically stereoselective praziquantel enantiomers, i.e., R-(-)-praziquantel (R-PZQ) and S-(+)-praziquantel (S-PZQ) absorbed into a biodegradable polymer was studied in beagle dogs (N = 6). The preparation was given by subcutaneous injection using a single dose of 100 mg/kg. Chiral-selective, high-performance liquid chromatography (HPLC) and high-resolution mass spectrometry (HRMS) were applied to measure the praziquantel enantiomers in the plasma of the dogs. The lower limit for estimating plasma concentrations accurately for R-PZQ was 4 ng/ml and for S-PZQ 20 ng/ml. The pharmacokinetic parameters were calculated by a noncompartmental analysis model using Drug Analyze System (DAS) software 2.0. The SPSS 19.0 software was used for statistical analysis, and the statistical comparison between enantiomers was assessed using the two-tailed t-test.

RESULTS

Two hours after administration, peak concentrations of R-PZQ and S-PZQ: 321 ± 26 and 719 ± 263 ng/ml, respectively, were achieved. After 180 days, the average plasma concentration of R-PZQ in the six dogs had decreased to 13 ng/ml. The average concentration value of S-PZQ was higher than that of R-PZQ in the first 90-day period but fell afterwards and could not be accurately estimated when dropping below 20 ng/ml (the lower methodological limit for this enantiomer). Taking all the dogs into account, the average maximum concentration (Cmax) of S-PZQ in plasma over the first 3 months was higher than that of R-PZQ by 114.0% (P < 0.05), while the average mean retention time (MRT) of R-PZQ in plasma was higher than that of S-PZQ by 96.3% (P < 0.05).

CONCLUSIONS

Praziquantel given as an in situ slow-release formulation by subcutaneous injection resulted in concentrations of the active principle in beagle dogs, which should be capable of resisting new Echinococcus infections for at least 6 months. The new formulation of praziquantel represents a potential, alternative way of presenting medication against tapeworm infections in dogs.

[Canine peritoneal larval cestodosis caused by Mesocestoides spp. larval stages]

In a female dog with unspecific clinical symptoms, sonography detected a hyperechoic mass in the middle abdomen and blood analysis a middle grade systemic inflammatory reaction. Laparotomy revealed a peritoneal larval cestodosis (PLC). The diagnosis of an infection with tetrathyridia of Mesocestoides spp. was confirmed by parasitological examination and molecularbiological analysis. Reduction of the intra-abdominal parasitic load as well as a high dose administration of fenbendazole over 3 months led to a successful treatment which could be documented sonographically and by decreased concentrations of C-reactive protein (CRP). Seven months after discontinuation of fenbendazole administration, PLC recurred, pre-empted by an elevation of serum CRP values. According to the literature a life-long fenbendazole treatment was initiated. In cases of unclear chronic granulomatous inflammations in the abdominal cavity in dogs, PLC should be considered. CRP concentration and sonographic examinations are suitable to control for treatment success and a possibly occurring relapse.

Efficacy of a single dose of milbemycin oxime/praziquantel combination tablets, Milpro(®), against adult Echinococcus multilocularis in dogs and both adult and immature E. multilocularis in young cats

Two single-site, laboratory, negatively controlled, masked, randomised dose confirmation studies were performed: one in dogs, the other in cats. After a period of acclimatisation, both the dogs and cats were orally infected with Echinococcus multilocularis protoscoleces. In the dog study, 10 dogs received a single dose of Milpro® tablets at a minimum dose of 0.5 mg/kg milbemycin oxime and 5 mg/kg praziquantel 18 days post-infection and 10 dogs received no treatment. In the cat study, 10 cats received a single dose of Milpro® tablets at a minimum dose of 2 mg/kg milbemycin oxime and 5 mg/kg praziquantel 7 days post-infection, 10 cats received a single dose of the treatment 18 days post-infection and 10 cats remained untreated. In both studies, intestinal worm counts were performed 23 days post-infection at necropsy. No worms were retrieved from any of the 30 treated animals. Nine of 10 control dogs had multiple worms (geometric mean 91, arithmetic mean 304) and all 10 control cats had multiple worms (geometric mean 216, arithmetic mean 481). The difference in worm counts between all three treated groups and their controls was highly significant (ANOVA p values of log transformed data <0.0001). Efficacy of 100 % was demonstrated for the elimination of adult E. multilocularis in dogs and cats as well as for elimination of immature E. multilocularis in cats as evidenced by the effectiveness of treatment 7 days post-infection. The treatments were well accepted and tolerated, and there were no adverse drug reactions observed.

Tetrathyridiosis in a domestic shorthair cat

CASE SUMMARY

This report describes the clinical and parasitological findings in a domestic shorthair cat with isolated thoracic tetrathyridiosis. The cat was a stray from Malta that had lived in Germany for several years since as an indoor-only cat. Therefore, the process of infection remains very unusual. In this case it must be considered that the cat had been infected years previously while in Malta, and had lived at least 4 years without any clinical signs. It was possible to diagnose this uncommon disease and initiate an effective treatment with fenbendazole, praziquantel and supportive care. Clinical signs, as well as radiographic findings, were regressive with this treatment.

RELEVANCE AND NOVEL INFORMATION

Tetrathyridiosis is a rare finding in cats, especially in Germany, but it seems to be a potential differential diagnosis of pleural effusion. Mesocestoides corti, which was the causative parasite in this case, has not previously been isolated in Germany. Because tetrathyridiosis is only diagnosed post mortem in most cases, little is known about effective therapeutic options. Furthermore, clinical signs of this disease can be absent for several years and can potentially be triggered by neoplastic conditions or immunosuppression. Tetrathyridiosis seems to be a treatable disease that can be controlled by adequate antiparasitic therapy.

First case of peritoneal cysticercosis in a non-human primate host (Macaca tonkeana) due to Taenia martis

Background

Infections with larval stages (metacestodes) of a variety of taeniid species have been described in primates, including humans, with partial to severe clinical consequences. Taenia martis is a tapeworm of mustelids, and martens are mainly their definitive hosts in Central Europe. In the rodent intermediate host cysticerci develop in the pleural and peritoneal cavities. The present report describes a case of T. martis peritoneal cysticercosis in a Tonkean macaque.

Findings

An abdominal mass was detected in a 3-year-old male Tonkean macaque (Macaca tonkeana) born and raised in a primate colony in France. Examination of the mass after laparotomy showed numerous vesicles identified as cysticerci of T. martis, based on the morphology of scolex and hooks, with confirmation by PCR amplification and sequence analysis of the mitochondrial cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1) genes. Exeresis of the lesion was not possible and praziquantel (5.7 mg/kg) was given twice at an interval of 3 days. The abdominal mass was greatly diminished upon examination 2 months later and no signs of recurrence were noticed during the following 4 years.

Conclusions

This is the first report of T. martis cysticercosis in a monkey. This record and the recent first description of an ocular T. martis cysticercosis in a human show the susceptibility of primates to T. martis and its zoonotic potential. This taeniid species must be considered in the differential diagnosis of cysticercosis in primates.

Case report: protein-losing enteropathy caused by Mesocestoides vogae (syn. M. corti) in a dog

An eight-year-old, neutered, female Shetland Sheepdog presented with a 6-week history of small intestinal diarrhea. Regenerative anemia, hypoproteinemia, and an increased plasma C-reactive protein concentration were detected on blood examination. Fecal examination and abdominal radiography were unremarkable. Abdominal ultrasonography showed diffusely hyperechoic mucosa in the small intestine. Gastroduodenoscopy, performed under general anesthesia, revealed mucosal edema and increased granularity in the duodenum and jejunum. Histopathological examination of the endoscopically biopsied small intestinal mucosa revealed tapeworm infection. A single administration of a combined anthelmintic drug (5mg/kg praziquantel, 14.4 mg/kg pyrantel pamoate, and 15 mg/kg febantel) was successful for deworming, and the dog fully recovered. The parasites were removed from stored frozen duodenal mucosa and morphologically identified as Mesocestoides sp. immature adult worms. Mitochondrial (mt) 12S rDNA and mt cytochrome c oxide subunit 1 genes were amplified from the parasites. DNA sequence analysis showed that the genes shared 100% identity with those of reported M. vogae (syn. M. corti). This is the first reported case of protein-losing enteropathy caused by M. vogae in a dog.

Case report: First confirmed case of canine peritoneal larval cestodiasis caused by Mesocestoides vogae (syn. M. corti) in Japan

Canine peritoneal larval cestodiasis (CPLC) is an unusual parasitic disease in dogs that is caused by asexual proliferation of larval Mesocestoides. A 12 year-old spayed Shetland sheepdog with abdominal distension was referred to the Animal Medical Center at Nihon University, Japan. The presence of ascites was confirmed by abdominal ultrasonography and X-ray imaging. In addition, a number of parasites were observed in the ascitic fluid collected by abdominal paracentesis. Each of the whitish colored parasites was less than 1mm in size. The parasites were morphologically identified as Mesocestoides sp. tetrathyridia. The parasites had four suckers and calcareous corpuscles, but no hooks or rostellum. Mitochondrial (mt) 12S rDNA and mt cytochrome c oxidase subunit 1 DNA amplified from the tetrathyridia were used for molecular identification to species level. DNA sequence analysis showed that the tetrathyridia shared more than 99% identity with M. vogae (syn. M. corti) for each gene. The patient was treated with a standard dose (5mg/kg) of praziquantel, which was administered subcutaneously twice at an interval of 14 days. This resulted in successful deworming. This is the first case that CPLC was diagnosed in a dog that had never been taken outside of Japan, indicating that M. vogae is distributed in this country.

Cestode infection in 2 dogs: cytologic findings in liver and a mesenteric lymph node

Mesocestoides cestode infections in dogs are well known for causing severe peritonitis with larvae or larval fragments (metacestodes, tetrathyridia, or calcareous corpuscles) frequently observed cytologically in peritoneal fluid samples. This case report describes the cytologic and clinical features of 2 dogs infected with cestode larvae, with one case confirmed and the other presumed to be Mesocestoides sp. In these 2 unusual cases, cestode larvae or larval fragments were found in fine-needle aspirates of the liver and a mesenteric lymph node, but no organisms were found in peritoneal fluid samples. The data presented in this report indicate that clinical pathologists should not rule out Mesocestoides sp cestodiasis based on the absence of larvae in peritoneal fluid samples from dogs.

Solid lipid nanoparticle suspension enhanced the therapeutic efficacy of praziquantel against tapeworm

Hydatid disease caused by tapeworm is an increasing public health and socioeconomic concern. In order to enhance the therapeutic efficacy of praziquantel (PZQ) against tapeworm, PZQ-loaded hydrogenated castor oil solid lipid nanoparticle (PZQ-HCO-SLN) suspension was prepared by a hot homogenization and ultrasonication method. The stability of the suspension at 4°C and room temperature was evaluated by the physicochemical characteristics of the nanoparticles and in-vitro release pattern of the suspension. Pharmacokinetics was studied after subcutaneous administration of the suspension in dogs. The therapeutic effect of the novel formulation was evaluated in dogs naturally infected with Echinococcus granulosus. The results showed that the drug recovery of the suspension was 97.59% ± 7.56%. Nanoparticle diameter, polydispersivity index, and zeta potential were 263.00 ± 11.15 nm, 0.34 ± 0.06, and −11.57 ± 1.12 mV, respectively and showed no significant changes after 4 months of storage at both 4°C and room temperature. The stored suspensions displayed similar in-vitro release patterns as that of the newly prepared one. SLNs increased the bioavailability of PZQ 5.67-fold and extended the mean residence time of the drug from 56.71 to 280.38 hours. Single subcutaneous administration of PZQ-HCO-SLN suspension obtained enhanced therapeutic efficacy against tapeworm in infected dogs. At the dose of 5 mg/kg, the stool-ova reduction and negative conversion rates and tapeworm removal rate of the suspension were 100%, while the native PZQ were 91.55%, 87.5%, and 66.7%. When the dose reduced to 0.5 mg/kg, the native drug showed no effect, but the suspension still got the same therapeutic efficacy as that of the 5 mg/kg native PZQ. These results demonstrate that the PZQ-HCO-SLN suspension is a promising formulation to enhance the therapeutic efficacy of PZQ.