Prevalence and genetic characteristics of Blastocystis hominis and Cystoisospora belli in HIV/AIDS patients in Guangxi Zhuang Autonomous Region, China.

Blastocystis hominis and Cystoisospora belli are considered to be common opportunistic intestinal protozoa in HIV/AIDS patients. In order to investigate the prevalence and genetic characteristics of B. hominis and C. belli in HIV/AIDS patients, a total of 285 faecal samples were individually collected from HIV/AIDS patients in Guangxi, China. B. hominis and C. belli were investigated by amplifying the barcode region of the SSU rRNA gene and the internal transcribed spacer 1 (ITS-1) region of the rRNA gene, respectively. Chi-square test or Fisher's exact test were conducted to assess the risk factors related to B. hominis and C. belli infection. The prevalence of B. hominis and C. belli was 6.0% (17/285) and 1.1% (3/285) respectively. Four genotypes of B. hominis were detected, with ST3 (n = 8) and ST1 (n = 6) being predominant, followed by ST6 (n = 2) and ST7 (n = 1). Females had a statistically higher prevalence of B. hominis (11.6%) than males (4.2%). The statistical analysis also showed that the prevalence of B. hominis was significantly associated with age group and educational level. Our study provides convincing evidence for the genetic diversity of B. hominis, which indicates its potential zoonotic transmission and is the first report on the molecular characteristics of C. belli in HIV/AIDS patients in China.

Coccidiosis in dogs-100 years of progress.

Until 1970, coccidian parasites of dogs were considered to have a direct fecal-oral life cycle like Eimeria in poultry. They were thought to be non-host specific and infect both dogs and cats. Studies conducted in the 1970s revealed that dog coccidia were host-specific and had transport or paratenic hosts that were infected with an encysted stage containing a single organism, the monozoic tissue cyst. There are still considerable confusion and uncertainties concerning the life cycles and pathogenicity of coccidian parasites of dogs. The present paper reviews the history, taxonomy, life cycles, pathogenicity, epidemiology, diagnosis, and treatment of conventional coccidian parasites previously called Isospora spp., currently designated Cystoisospora spp. that infect canines.

Prevalence and Risk Factors of Intestinal Parasites in Cats from China.

The prevalence of intestinal parasites in cats from China was largely unknown prior to this study. The aim of the present study was to investigate the presence of intestinal parasites in cats from central China and also identify risk factors for parasitism. Fecal samples from 360 cats were examined using sugar flotation procedure and fecal smear test by microscope. Cats had mixed two or three kinds of parasites infections. Of the 360 cats feces, intestinal parasites positive feces were 149 (41.39%). 64 (17.78%) were infected with Toxocara cati, 61 (16.94%) with Isospora felis, 41 (11.39%) with Isospora rivolta, 33 (9.17%) with Paragonimus, 23 (6.39%) with hookworms, 11 (3.06%) with Toxoplasma-like oocysts, 10 (2.78%) with Trichuris, 4 (1.11%) with lungworm, 2 (0.56%) with Sarcocystis, and 1 (0.28%) with Trematode. The cats' living outdoor was identified as risk factor by statistical analysis. These results provide relevant basic data for assessing the infection of intestinal parasites in cats from central region of China. In conclusion, there was high prevalence of intestinal parasites in cats from China.

Which factors influence the outcome of experimental infection with Cystoisospora suis?

For reliable predictions of clinical and parasitological outcome of experimental infections with parasites, different models must be evaluated for possible influences of infection time point, infection dose and host-specific parameters such as breed or litter size. To address these issues for Cystoisospora (syn. Isospora) suis, the causative agent of porcine neonatal coccidiosis, 181 piglets from 90 litters (hybrid crosses of different breeds) were included in a retrospective study to evaluate differences in time point and dose of infection in four different experimental models ((1) 1,500 oocysts on the 4th day of life, d.o.l.; (2) 1,000 oocysts, 4th d.o.l.; (3) 1,000 oocysts, 1st d.o.l.; (4) 5,000 oocysts, 4th d.o.l.). The target variables body weight gain, faecal consistency and oocyst excretion were evaluated during the acute phase of infection (5-10 days post infection), and the influences of the dependent variables breed or litter size were estimated. Despite differences in the time course of excretion and faecal consistency, neither the average amount of excretion nor the average faecal consistency differed among models, breeds or litters of different size. High individual variability was seen in all four models as described earlier for higher infection doses. When infections on the 1st vs. 4th day of life were compared, no differences in averages could be found, in contrast to previous observations on the influence of age. Other, not yet defined, variables appear to have a greater impact on the outcome of infection than doses and time points in the tested range, despite the reliable outcome of infection with high excretion rates and signs of clinical disease.

Necrotic enteritis due to simultaneous infection with Isospora suis and clostridia in newborn piglets and its prevention by early treatment with toltrazuril.

In this study, 51 piglets originating from five different sows were included in the investigations. The animal source of all sows had a history of Clostridium perfringens type A (ß2) infection. The piglets of three sows (n = 31) were experimentally infected with Isospora suis within the first 4 h after birth and were randomly assigned to the treatment group or the sham-dosing group. The piglets of the two remaining sows (n = 20) served as I. suis-uninfected controls. Twelve hours post-infection, the animals in the treatment group (n = 15) were treated with toltrazuril (20 mg/kg BW, Baycox® 5% suspension). During an observation period of 14 days faecal consistency, faecal oocyst counts, faecal germ counts, mortality, body weight development and clinical status were recorded. One piglet per study group and litter was necropsied, and intestinal tissue samples were taken for histopathological investigations and in situ hybridisation on study days (SDs) 3 and 14. I. suis-infected but untreated piglets showed clinical disease resulting in liquefaction of faeces and decreased body weight development. In 59.2% of the observations, I. suis-infected but untreated piglets showed abnormal faecal consistencies whereas only 12.0% or respectively 4.4% of the faecal samples had a pasty consistency in the I. suis-infected-treated or in the control animals. The mean body weight at the end of the study was 3.37 kg in the I. suis-infected but untreated piglets while the average body weight in the I. suis-infected-treated animals was calculated as 4.42 kg and the control animal's mean body weight was 4.45 kg. Moreover, mortality, occurring between SDs 8 and 14, in this study group was 38.5% (n = 5), with 30.8% (n = 4) died from necrotic enteritis. In contrast, no piglets died in the I. suis-uninfected control group or in the toltrazuril-treated study group. The results of this study corroborate the hypothesis that simultaneous infection with I. suis and C. perfringens type A soon after birth leads to distinct interactions between the two pathogens and result in an increase in clinical disease, mortality and metabolically active C. perfringens type A.

Efficacy of emodepside plus toltrazuril suspension (Procox(®) oral suspension for dogs) against prepatent and patent infection with Isospora canis and Isospora ohioensis-complex in dogs.

Three randomised, blinded and placebo-controlled laboratory studies were conducted to evaluate the efficacy of emodepside plus toltrazuril suspension (Procox(®) suspension for dogs) against Isospora canis and Isospora ohioensis-complex. Unweaned puppies were experimentally infected with sporulated oocysts of I. canis and/or I. ohioensis-complex. In each study, one group was treated during prepatency (2 or 4 days post infection) while dogs in the second group were treated individually after the onset of oocyst excretion of the respective coccidia species. The dogs were treated with the minimum therapeutic dose of 0.45 mg emodepside and 9 mg toltrazuril per kg body weight. Daily faecal oocyst counts from both groups were compared to placebotreated control groups to determine efficacy.Dogs treated during prepatent I. canis or I. ohioensis-complex infection showed significantly lower oocyst counts for up to 12 days compared to the control group. Oocyst counts were reduced by 90.2 - 100 % while the control groups continued to exhibit an adequate infection, except for one study where efficacy against prepatent I. canis infection faded 13 days after treatment. Following treatment of patent I. canis or I. ohioensis-complex infections, significantly lowered oocyst counts were observed for up to 9 days compared to the control group. Faecal oocyst counts were reduced by 91.5 - 100 %. In all three studies the number of days with diarrhoea was significantly lower when dogs were treated during prepatent Isospora spp. infection compared to the control groups. No adverse drug reactions were observed during the studies. In conclusion, the studies demonstrated that emodepside plus toltrazuril suspension is an efficient coccidiocide for dogs.

Field evaluations of the efficacy and safety of Emodepside plus toltrazuril (Procox® oral suspension for dogs) against naturally acquired nematode and Isospora spp. infections in dogs.

Three controlled, blinded and randomised multicentre field studies evaluated the efficacy and safety of a new formulation containing emodepside plus toltrazuril (Procox® suspension for dogs) against naturally acquired parasite infections in dogs. In two studies dogs positive for gastrointestinal nematodes and/or Isospora spp. were treated with emodepside/toltrazuril suspension (at least 0.45 mg emodepside plus 9 mg toltrazuril per kg body weight) or a reference product containing either milbemycin oxime plus praziquantel (Milbemax®) or sulfadimethoxine (Kokzidiol SD®) at recommended dose rates. The third study investigated efficacy against prepatent natural Isospora spp. infections in comparison to an untreated control group by enrolling Isospora- negative dogs that were at risk to develop a patent infection during the study.No suspected adverse drug reactions were observed in any of the 403 dogs enrolled in the three studies including 234 dogs treated with emodepside/toltrazuril suspension. In dogs treated with emodepside/toltrazuril suspension against nematode infection faecal egg counts were reduced by 100 % (reference product: 99.7 %). Similarly, in the dogs that had been treated against patent Isospora spp. infection, faecal oocyst counts were reduced by 100 % (reference product: 99.0 %). In both studies, statistical analysis demonstrated non-inferiority and even superiority to the reference products (p ≤ 0.009). Dogs treated with emodepside/toltrazuril suspension during suspected prepatent Isospora spp. infection had 98.7 % lower faecal oocyst counts after treatment compared to untreated dogs (p < 0.0001).The studies demonstrated that emodepside/toltrazuril suspension is safe and highly efficacious against nematodes and Isospora spp. under field conditions.

Cystoisospora canis Nemeséri, 1959 (syn. Isospora canis), infections in dogs: clinical signs, pathogenesis, and reproducible clinical disease in beagle dogs fed oocysts.

Canine intestinal coccidiosis is a cause of diarrhea in young dogs and dogs that are immunocompromised. Reports in the literature indicate that experimental reproduction of clinical coccidiosis with Cystoisospora canis (syn. Isospora canis) is difficult, and few studies have been done with C. canis. Experimental oral infections were attempted in 22, 6- to 8-wk-old female beagles with 5 x 10(4) (n = 2) or 1 x 10(5) (n = 20) sporulated C. canis oocysts. Diarrhea was observed in all inoculated dogs. Diarrhea began 2-3 days before oocyst excretion. Five of the 22 dogs were given an anticoccidial (sulfadimethoxine) because of their clinical signs. The mean prepatent period was 9.8 days (range, 9-11 days, n = 22 dogs), and the patent period was 8.9 days (range, 7-18 days, n = 20 dogs). Two dogs exhibiting clinical coccidiosis were examined at necropsy 10 days after infection. Developmental stages of C. canis were present in cells in the lamina propria throughout the entire small intestine in both dogs. Microscopic lesions observed in both of these dogs were villous atrophy, dilation of lacteals, and hyperplasia of lymph nodes in Peyer's patches. Results of bacterial and viral examinations of these 2 dogs were negative, indicating that intestinal coccidiosis was the cause of the diarrhea. Our study indicates that C. canis can be a primary cause of diarrhea in young dogs.

Porcine isosporosis: infection dynamics, pathophysiology and immunology of experimental infections.

Isospora suis, an intestinal protozoan parasite of swine, is the causative agent of neonatal coccidiosis, a disease with high morbidity in affected pig-breeding units and consequently of high economic importance. Infection leads to damage of the mucosal surface in the jejunum and ileum and to non-haemorrhagic diarrhoea. As a result, weight gain of piglets is reduced and secondary infections with other enteric pathogens may lead to increased mortality. Despite its economic and veterinary importance, host-parasite interactions are still poorly understood. To examine these interactions experimental infection models are established using outbred piglets infected with defined numbers of parasites on different days of life. This review discusses the life cycle of Isospora suis and the clinical and parasitological characteristics of porcine neonatal coccidiosis including pathology, and compare the different experimental infection models and the tools for studying Isospora suis in vitro. Moreover, it summarises findings about natural age resistance of pigs against infections with Isospora suis, our current knowledge about immune response to other coccidial infections, e.g. with Eimeria spp. in different hosts, and gives a short overview on peculiarities of the porcine immune system and its development in young animals which may play a role in porcine coccidiosis.

Host resistance and parasite virulence in greenfinch coccidiosis.

The question why different host individuals within a population differ with respect to infection resistance is of fundamental importance for understanding the mechanisms of parasite-mediated selection. We addressed this question by infecting wild-caught captive male greenfinches with intestinal coccidian parasites originating either from single or multiple hosts. Birds with naturally low pre-experimental infection retained their low infection status also after reinfection with multiple strains, indicating that natural infection intensities confer information about the phenotypic ability of individuals to resist novel strains. Exposure to novel strains did not result in protective immunity against the subsequent infection with the same strains. Infection with multiple strains resulted in greater virulence than single-strain infection, indicating that parasites originating from different host individuals are genetically diverse. Our experiment thus demonstrates the validity of important but rarely tested assumptions of many models of parasite-mediated selection in a wild bird species and its common parasite.

Isospora suis: an experimental model for mammalian intestinal coccidiosis.

Piglets experimentally infected with 10,000 oocysts of Isospora suis in three identical trials (n = 50) were examined clinically and coproscopically from 5 to 11 days post-infection (d.p.i.), weighed in weekly intervals until the fourth week of life and compared to age-matched asymptomatic controls (n = 17). Furthermore, 17 infected piglets were histologically examined on days 5-14 p.i. Infected animals had a significantly lower weight gain than the controls and showed diarrhoea throughout, with maximum prevalence and intensity on 6 d.p.i. Half of the animals had diarrhoea for only 2 days or less. The number of diarrhoea days was negatively correlated with weight gain. Oocyst excretion started on 5 d.p.i. with peak prevalences and declined afterwards; a smaller peak was seen on 10 d.p.i. All animals excreted parasites at least once, and most of them excreted for 5-7 days. Oocyst excretion intensity paralleled the prevalence and ranged from 220 to 251,501 oocysts per gram of faeces (opg). Most samples contained 4 x 10(3) to 4 x 10(4) opg. The opg values were negatively correlated with faecal scores (samples with diarrhoea contained less oocysts) of the same day and the previous day. Histologically, necrosis followed by atrophy of the villi was most pronounced in the early stage of infection throughout the jejunum and ileum but declined thereafter. On 14 d.p.i., villous atrophy was still noticeable in the jejunum. Histology is difficult to quantify and requires large animal numbers, although the effects are visible for some time. Weight gain and faecal score can be affected by other factors than parasite infection. From the compiled data, we conclude that the established model is suitable to study piglet isosporosis with oocyst excretion being the most reliable parameter, although individual variations are considerable. A negative correlation between excretion and diarrhoea may be responsible for the difficulties in the detection of the parasite in field samples.

An outbreak of adenoviral infection in inland bearded dragons (Pogona vitticeps) coinfected with dependovirus and coccidial protozoa (Isospora sp.).

Thirty of 200 (15%) hatchling inland bearded dragons were found dead after a short period (48 hours) of weakness and lethargy. The most common clinical signs were head tilt and circling. Six bearded dragons with neurological signs were euthanized, and postmortem examination revealed no gross abnormalities. Microscopically, severe, randomly distributed hepatocellular necrosis with large basophilic intranuclear inclusion bodies in numerous hepatocytes was noted. Small-intestinal enterocytes contained intracytoplasmic coccidial protozoa (Isospora sp.) and occasional enterocytes had basophilic intranuclear inclusion bodies. Transmission electron microscopy revealed both 80- and 20-nm-diameter viral particles, which were consistent with adenoviruses and dependoviruses, respectively. Adenoviral outbreaks in groups of animals are uncommon. An adverse synergistic effect of the coccidiosis with the adenoviral infection may have played a critical role in the high morbidity and mortality in this case.

The role of Isospora suis as a pathogen in conventional piglet production in Germany.

In order to evaluate the prevalence of Isospora suis in conventional piglet production in Germany, pooled faecal samples from 327 pig litters from 18 pig production units (20-320 sows each) were examined. At least 10 litters from each farm were investigated. I. suis was present on 83% of the farms and 42.5% of the litters, the infection rate being highest in the third week of age (48.2%). I. suis was found more frequently in samples of diarrhoea than in firm faeces (49.2% compared to 22.2%). Twenty naturally infected piglets from six of these farms underwent examination post mortem, including histology, virology and bacteriology. Histological examination revealed atrophy of the villi in various degrees, mild crypt hyperplasia, fusion of the villi, metaplastic epithelium, erosions and necrosis, especially in the medium and the posterior jejunum and in the ileum. Asexual and sexual developmental stages of the parasite were found in varying numbers in the epithelium of the whole of the small intestine. Bacteria and viruses were mostly excluded as the cause of diarrhoea, and it was concluded that I. suis was the primary pathogen inducing distinct changes and clinical symptoms of diarrhoea.

[Diarrhea, pup mortality and Cystoisospora species (coccidiosis)]. / Diarree, pupsterfte en Cystoïsospora-species (coccidiose).

A review of coccidiosis in dogs is given on the basis of an autopsy of a puppy from a kennel in which other puppies had diarrhoea and stunted growth. Coccidiosis especially affects puppies from kennels and leads to poor growth, diarrhoea, and even death. Its occurrence is probably underestimated.

Occurrence of Isospora suis in larger piglet production units and on specialized piglet rearing farms.

Mixed fecal samples of 264 litters from five piglet production farms (155-238 sows/farm) were investigated three times during the suckling period for the occurrence of Isospora suis over the period of 1 year. On all five farms Isopora suis was found to be a common endoparasite with infection rates being highest in litters of 3-4 weeks of age. By the end of the third investigation period the cumulative infection rate was 53.8% of the litters ranging from 20.0% to 81.5% for the single farms. During the suckling period the infection rate increased from 18.6% to 32.6% and then to 37.7%. Diarrhea was present in 66.3% of the sampled litters with the highest rates at the end of the suckling period. 63.4% of the litters which showed diarrhea and 34.8% of those without diarrhea excreted I. suis within the study period. Diarrhea was recorded for 78.2% of the I. suis-positive litters and for 52.5% of the Isospora-negative litters. In summer and fall the occurrence of I. suis was higher (66.3% and 61.0%, respectively) than in spring and winter (47.7% and 37.9%, respectively). In litters with diarrhea and pathogenic E. coli I. suis often occurred simultaneously. Above-average hygiene measures and mainly perforated pen floors seemed to lower the risk of isosporosis. With the exception of Strongyloides ransomi other parasites were not found in the fecal samples of suckling piglets. Two specialized piglet rearing farms, a conventional large-scale rearing unit and a farm managed according to the segregated early weaning (SEW) system were examined three times during the 6-7 week rearing period. In both units I. suis was common, but was not correlated with diarrhea. In the SEW unit the infection rates decreased from 37.5% to 20.2% and to 4.1%, while the infection rate in the conventional unit slightly increased from the first (17.2%) to the second (21.9%) investigation and stayed at this level at the third sampling.