Interfering effect of Isospora suis infection on Salmonella typhimurium infection in swine

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.

Non-typhoidal Salmonella infections in pigs: a closer look at epidemiology, pathogenesis and control

Contaminated pork is an important source of Salmonella infections in humans. The increasing multiple antimicrobial resistance associated with pork-related serotypes such as Salmonella Typhimurium and Salmonella Derby may become a serious human health hazard in the near future. Governments try to anticipate the issue of non-typhoidal Salmonella infections in pork by starting monitoring programmes and coordinating control measures worldwide. A thorough knowledge of how these serotypes interact with the porcine host should form the basis for the development and optimisation of these monitoring and control programmes. During recent years, many researchers have focussed on different aspects of the pathogenesis of non-typhoidal Salmonella infections in pigs. The present manuscript reviews the importance of pigs and pork as a source for salmonellosis in humans and discusses commonly accepted and recent insights in the pathogenesis of non-typhoidal Salmonella infections in pigs, with emphasis on Salmonella Typhimurium, and to relate this knowledge to possible control measures.

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.

Biology of mammalian Isospora

Isospora species are coccidial parasites that can cause serious disease in humans and pigs. Disease is observed less frequently in non-human primates, dogs or cats. Isospora species do not produce disease in horses, domestic ruminants or domestic poultry, and reports of isosporan oocysts in the feces of these hosts probably represents pseudoparasites that originated in feed or water contaminated with wild bird feces. David Lindsay and Byron Blagburn here summarize what is known about the biology of the Isospora species of domestic animals and non-human primates.