Johan E. Peeters

A review of the importance of cryptosporidiosis in farm animals

Abstract Cryptosporidium species are coccidian parasites with a large capacity to reproduce and to disseminate. Several species are known to infect farm animals, although the economic importance of cryptosporidiosis is highly host species dependent. This paper reviews the impact of cryptosporidial infections in livestock and poultry. For different farm animals, the Cryptosporidium spp. that occur, as well as their clinical and pathological features, and their interactions with other pathogens, are described. In addition, data concerning the prevalence, the transmission and the epidemiology of the disease are mentioned and a description of the economic losses associated with cryptosporidiosis in each of the hosts is given. Cryptosporidiosis seems to be mainly a problem in neonatal ruminants. Cryptosporidium parvum is considered to be an important agent in the aetiology of the neonatal diarrhoea syndrome of calves, lambs and goat kids, causing considerable direct and indirect economic losses. Avian cryptosporidiosis is an emerging health problem in poultry, associated with respiratory disease in chickens and other Galliformes, and with intestinal disease in turkeys and quails. Because of limited availability of effective drugs, the control of cryptosporidiosis relies mainly on hygienic measures and good management.

Comparison of Two Commercial Kits for Biochemical Characterization of Paenibacillus Larvae Larvae in the Diagnosis of AFB

colony for 26 days to remove varroa. At this time the strips were removed, and the queen was caged for nine days. There was only capped brood in the colony at the end of this period. A single patch of 400–500 eggs (aged about 18 h) on a brood comb was placed in the colony, and the 73 tagged mites were added to the colony. The queen remained caged until the end of the test. The frame that had contained the eggs was removed after another 15 days. At this time, the worker bee pupae had tan coloured bodies. Only 40 of the original 73 mites were recovered, and 37 of those mites had laid eggs. They averaged 3.450 ± 0.75 progeny, which is not different from the 3–4 progeny expected from unmarked mites found on host pupae at the same age (Ifantidis, 1983). The families produced by marked mites appeared normal (most had adult males, protonymphs, deutonymphs, and adult daughters). No attempt was made to locate tagged mites on the adult bees at the end of the test.

Specific interferon-gamma, IgA and IgM responses after experimental infection of neonatal calves with Cryptosporidium parvum.

The in vitro interferon-gamma production by peripheral blood mononuclear cells and the local antibody build up was monitored in neonatal calves experimentally infected with Cryptosporidium parvum and in negative controls of the same age. From day 6 p.i. on, an infection-induced interferon-gamma response was observed in lymphocyte cultures after stimulation with Cryptosporidium oocyst antigen preparation. Only the Cryptosporidium-infected calves developed local IgA and IgM responses from day 6 p.i. on, with peak values at day 10 p.i. These antibodies disappeared quickly, perhaps due to the strict hygienic measures and consequently the absence of a continuous antigenic stimulation.

A Cryptosporidium parvum oocyst low molecular mass fraction evokes a CD4+ T-cell-dependent IFN-γ response in bovine peripheral blood mononuclear cell cultures

T-Cell antigens that induce the in-vitro interferon-gamma response during Cryptosporidium parvum infection of neonatal calves were identified. A total oocyst extract was separated into a high and a low Mr fraction by a microfiltration technique. Both the high and low Mr fractions evoked an in-vitro interferon-gamma response in naturally infected animals, although strong individual differences between the hosts were observed. Using a complement-mediated technique CD4+ T-cells or WC1+gammadelta T-cells were depleted, whereupon the remaining lymphocyte cultures were stimulated with the different antigen preparations. It was shown that the in-vitro interferon-gamma response of Cryptosporidium-infected calves is CD4+ T-cell-dependent.

Protection of rabbits against enteropathogenic Escherichia coli(EPEC) using an intimin null mutant

BackgroundDiarrhea and mortality resulting from infections with enteropathogenic Escherichia coli (EPEC) are of major economic importance in the rabbit meat industry. There is a growing need for an effective vaccine to cope with these problems and to reduce the use of antibiotics. EPEC are characterized by an attaching and effacing virulence mechanism. This is partly mediated by the intimate binding between an adhesin, called intimin, and a translocated receptor (Tir) of prokaryote origin. We constructed an intimin deletion mutant of the rabbit EPEC (REPEC) wild-type strain 97/241.6 (bio-/serogroup 3-/O15) and examined its protective capacity.ResultsAfter verifying its complete loss of virulence, we used the attenuated strain in vaccination-challenge experiments in which complete protection against a homologous, but virulent, strain was observed. The attenuated strain was able to persist in the intestinal lumen, where it elicited an immune response against EPEC-related virulence proteins, as was shown using an EspB-specific ELISA. Despite the priming of an immune response and the generation of specific antibodies, the intimin mutant was not able to fully protect rabbits against challenges with REPEC strains of other bio-/serogroups.ConclusionThese data indicate that protection against REPEC infections is at least partly bio-/serogroup dependent and a multivalent vaccine may be needed for protection against the full range of REPEC types. Such a combination vaccine may be developed using intimin null mutants, as the latter were clearly shown to be safe and effective against homologous infections.