Field study of coccidial and rotaviral diarrhoea in unweaned piglets

Presence and characterization of pig group A and C rotaviruses in feces of Belgian diarrheic suckling piglets

The importance of group A and C rotaviruses (RVA and RVC) in the pathogenesis of diarrhea in Belgian suckling pigs is poorly investigated, and it is not known which strains are circulating in the Belgian suckling pig population. Obtaining better insights in the occurrence of both viral species in the swine population is essential in order to develop accurate diagnostic, therapeutic and prophylactic strategies to protect suckling pigs against diarrhea in a durable manner. In the present study, viral loads of RVA and RVC were quantified in diarrhea samples of suckling piglets less than 2 weeks old, collected on 36 different Belgian farms. On 22 of 36 farms tested (61%), high viral loads of RVA (6.96-11.95 log10 copies/g feces) and/or RVC (5.40-11.63 log10 copies/g feces) were detected. Seventeen RVA isolates were genotyped for their outer capsid proteins VP7 and VP4. Four different G-genotypes (G3, G4, G5 and G9) for VP7 were found together with 4 different P-genotypes (P[6], P[7], P[13] and P[23]) for VP4, in 8 different G/P combinations. All characterized RVC strains belonged to genotype G6 (VP7), except for one strain possessing the G1 genotype. VP4 genes of Belgian RVC strains were genetically heterogeneous, but were classified in the genotype P5. Most rotavirus positive samples also contained Escherichia coli, whereas Clostridium perfringens infections were mainly detected in rotavirus negative samples. Results of the present study offer better insights in the occurrence of RVA and RVC infections in Belgian diarrheic suckling piglets. As a conclusion, routine diagnostic testing for both viral species in cases of diarrhea in suckling pigs is highly recommended. Furthermore, the present findings also offer valuable information for the development of new prophylactic measures against rotavirus. Finally, the relatedness between RVC strains from pigs and other host species is described, and their possible implications in interspecies transmission events are discussed.

Parasitism and production in farm animals

The impact of internal and external parasitism on productivity of farm animals is considered for cattle, sheep, pigs and poultry. The parasitic challenge experienced and the outcome of that challenge is a dynamic one in which environment, management practices, including housing or grazing management, nutritional status, the host's ability to develop effective immunity and the speed with which this can occur, play a significant role. Much of our assessment of the impact of infection comes from pathophysiological and nutritional studies with contrived infestations. A common feature of all infestations is reduced efficiency of food utilization through reduction in food intake, though in some cases increases in nutrient requirement are induced as a result of damage to or loss of host tissue. Assessment of the impact on productivity in the field is technically very difficult and must take account of fluctuating challenge, determined by environmental and management decisions, and the manager's objectives for the performance of a particular category of livestock. This review attempts to integrate the assessment of losses in productivity based on pathophysiological studies with those based on protection of groups of livestock in production systems by regular pesticide use. Throughout the review the limitations inherent in both approaches and in our knowledge of how parasites impair productivity of the host are emphasised.

Age, not infection dose, determines the outcome of Isospora suis infections in suckling piglets

Data from 13 trials involving 124 suckling piglets experimentally infected with Isospora suis were evaluated for the effects of infection dose and age on the clinical and parasitological outcome of infection in four different models, infections with 1,000 oocysts on the 1(st) day of life (d.o.l.) (model 1; 9 piglets/3 litters), 1,000 oocysts on the 4(th) d.o.l. (model 2; 25 piglets/11 litters), 1,500 oocysts on the 4(th) d.o.l. (model 3; 40 piglets/20 litters) and 10,000 oocysts on the 4(th) d.o.l. (model 4; 50 animals/10 litters). Weights were determined on the day of birth and in weekly intervals. Faecal consistency and quantitative oocysts excretion were evaluated for 2 weeks starting 4 days after infection (d.p.i.). The weight gain depression was most noticeable in model 2 (infection on the 1(st) d.o.l.), where animals only gained 2.08 x their birth weight until the 22(nd) d.o.l., compared to 2.31-2.52 x in the other groups. This correlated with the occurrence of watery diarrhoea which was found in 37 % of the samples in the acute phase (4-11 d.p.i.) in model 2 but only in 12-20 % of the samples in the other models. Median oocyst excretion peaked earlier in the models with higher infection doses but reached the highest values in model 2 (early infection). As in previous studies, this cross-sectional analysis of a larger number of animals confirms the influence of age on the outcome of isosporosis in suckling piglets, stressing the need to control the infection at an early life phase.

Prevalence of Enteropathogens in Suckling and Weaned Piglets with Diarrhoea in Southern Germany

Faecal samples from suckling (n=205) and weaned piglets (n=82) with diarrhoea from 24 farms in Southern Germany were examined for shedding of important metazoic parasitic, viral and bacterial pathogens using culture, microscopic and electronmicroscopic methods. Escherichia coli isolates were tested further for the enterotoxin genes est‐Ia and elt‐I by colony blot hybridization. Isospora suis was diagnosed in 26.9 % and Cryptosporidium parvum in 1.4 % of the piglets investigated. The proportion of coronavirus‐positive animals was 13.4 % and 4 % were positive for rotavirus. It was found that 17.6 % of the animals were infected with enterotoxigenic E. coli (ETEC; 10.1 % ETEC‐ST‐Ia and 8.6 % ETEC‐LT‐I, respectively). The occurrence of the pathogens was significantly associated with the age of the animals examined (P < 0.001). Isospora suis was predominantly isolated from suckling piglets (in the second and third week of life), while in weaned piglets (fourth week of life) rotavirus and ETEC were most prevalent. On 22 of the 24 piglet production farms examined at least one of the investigated pathogens was detected. Coronavirus was diagnosed in 66.7 %, I. suis in 62.5 %, rotavirus in 20.8 % and C. parvum in 8.3 % of the farms. These results underline the fact that despite the hygienic, technical and immune preventive efforts during the last years, enteropathogens are still common in German piglet production units.

Detection of hepatitis E virus shedding in feces of pigs at different stages of production using reverse transcription-polymerase chain reaction

The aim of this study was to determine at which production stages hepatitis E virus (HEV) is shed by the highest number of pigs and to estimate the relative risk associated with each stage. For this purpose, 146 fecal samples of pigs from 21 farms were studied. In addition, 1 sample from the manure ditch and another sample of drinking water, collected directly from the trough located in the pen, were taken from 16 farms. HEV RNA was detected in fecal samples from 34 pigs (23.29%). The production stages in which most pigs excreted HEV were weaners (41.7%) and pigs in the first month of feeding (60%). The results of the statistical analysis showed that the principal significant risk stage in HEV shedding was the first month of feeding (odds ratio [OR] 19.5, 95% CI 3.59-106.07, P = 0.001) followed by the weaners stage (OR 9.3, 95% CI .78-48.42, P = 0.008). In 8 out of 16 farms tested (50%) HEV RNA was detected in raw manure and in the water trough of only 1. Detection of HEV in manure ditches raises the concern of how to deal with manure of swine origin, because it is used as soil fertilizer.

Prevalence of enteropathogens in suckling and weaned piglets with diarrhoea in southern Germany

Faecal samples from suckling (n = 205) and weaned piglets (n = 82) with diarrhoea from 24 farms in Southern Germany were examined for shedding of important metazoic parasitic, viral and bacterial pathogens using culture, microscopic and electronmicroscopic methods. Escherichia coli isolates were tested further for the enterotoxin genes est-Ia and elt-I by colony blot hybridization. Isospora suis was diagnosed in 26.9% and Cryptosporidium parvum in 1.4% of the piglets investigated. The proportion of coronavirus-positive animals was 13.4% and 4% were positive for rotavirus. It was found that 17.6% of the animals were infected with enterotoxigenic E. coli (ETEC; 10.1% ETEC-ST-Ia and 8.6% ETEC-LT-I, respectively). The occurrence of the pathogens was significantly associated with the age of the animals examined (P < 0.001). Isospora suis was predominantly isolated from suckling piglets (in the second and third week of life), while in weaned piglets (fourth week of life) rotavirus and ETEC were most prevalent. On 22 of the 24 piglet production farms examined at least one of the investigated pathogens was detected. Coronavirus was diagnosed in 66.7%, I. suis in 62.5%, rotavirus in 20.8% and C. parvum in 8.3% of the farms. These results underline the fact that despite the hygienic, technical and immune preventive efforts during the last years, enteropathogens are still common in German piglet production units.

Biology of Isospora spp. from humans, nonhuman primates, and domestic animals

Coccidial parasites of the genus Isospora cause intestinal disease in several mammalian host species. These protozoal parasites have asexual and sexual stages within intestinal cells of their hosts and produce an environmentally resistant cyst stage, the oocyst. Infections are acquired by the ingestion of infective (sporulated) oocysts in contaminated food or water. Some species of mammalian Isospora have evolved the ability to use paratenic (transport) hosts. In these cases, infections can be acquired by ingestion of an infected paratenic host. Human intestinal isosporiasis is caused by Isospora belli. Symptoms of I. belli infection in immunocompetent patients include diarrhea, steatorrhea, headache, fever, malaise, abdominal pain, vomiting, dehydration, and weight loss, blood is not usually present in the feces. The disease is often chronic, with parasites present in the feces or biopsy specimens for several months to years. Recurrences are common, Symptoms are more severe in AIDS patients, with the diarrhea being more watery. Extraintestinal stages of I. belli have been observed in AIDS patients but not immunocompetent patients. Treatment of I. belli infection with trimethoprim-sulfamethoxazole usually results in a rapid clinical response. Maintenance treatment with trimethoprim-sulfamethoxazole is needed because relapses often occur once treatment is stopped.

The use of toltrazuril for the prevention of coccidiosis in piglets before weaning

To determine the efficacy of toltrazuril as a prophylactic treatment for coccidiosis in piglets caused by Isospora suis (I suis), a single 1.0 mL dose of toltrazuril was administered orally to 1056 piglets between 3 and 6 days of age, in 5 piggeries. Prophylactic treatment of piglets reduced the occurrence of coccidiosis in litters from 71% to 22%. The number of antibacterial treatments given and the number of piglets affected per litter were also significantly reduced, resulting in some improvement in growth rates to weaning. The severity of diarrhoea was significantly reduced, as was the amount of oocyst excretion. The number of days that piglets excreted oocysts in the faeces was reduced from 4.9 days to 2.5 days. The detection of I suis in piglets with diarrhoea was reduced from 84% in the untreated piglets to 6% in the piglets given the prophylactic treatment.

Pathogenesis of experimental combined infections with Isospora suis and rotavirus in conventional and gnotobiotic piglets

51 gnotobiotic and 63 conventional, one-, or two-days-old piglets were divided into five groups and infected orally either with Isospora suis or rotavirus alone, or with both agents simultaneously or successively with alternative sequences and various intervals. 15 gnotobiotic and 10 conventional piglets served as controls. The development of small intestinal lesions after infection with I. suis was biphasic. The dominant alteration resulting from rotavirus infection was villus atrophy, considerably more pronounced and extensive in gnotobiotic than in conventional piglets. Synergistic action of I. suis and rotavirus was manifested both clinically, and morphologically. This action culminated at the time of the actual, or presumed development of merogony of I. suis, i.e. on DPI 3 to 5. The action develops only if the intestinal epithelium is damaged functionally and morphologically by a preceding rotavirus infection. It is concluded that the synergistic action is based on a competition of rotavirus and I. suis for mature, enzymatically active absorptive cells.

Isospora suis infection in piglets. A review

Recently several reports have been published on the association of Isospora suis with diarrhea in piglets. A review is given of I. suis infection in piglets, in which the taxonomy, life cycle, pathogenicity, immunity, and treatment of I. suis and related organisms are discussed.