SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Drug resistance is now recognised as a major cause of the failure of drugs to control coccidiosis in the fowl. In this article, biological, biochemical and genetic aspects of resistance in Eimeria are reviewed and some of the problems that may limit progress in understanding the nature of resistance in coccidia are discussed.
Eimeria oocysts were found in 89% of fecal samples collected from the rectum of 75 sheep from 3 locations in Papua New Guinea. Eighty five percent of the hosts which were positive for coccidia had multiple infections with up to 6 different species of Eimeria. In order of decreasing predominance in the 67 Eimeria-positive samples the species were: E. ovina (72%); E. parva (58%); E. ovinoidalis (48%); E. ahsata (45%); E. crandallis (39%); E. faurei (28%); E. intricata (24%); E. granulosa (4%). Fecal oocyst counts showed the highest mean of 1252 oocysts per gram (o.p.g.) for E. parva and a maximum of 8000 for E. ovina.
Faecal samples from goats were collected per rectum from February 1989 to January 1990. The numbers of oocysts per gram (OPG) of faeces were determined by the McMaster technique and identification of oocysts was made on sporulation. Infection was seen throughout the year, infecting on average 89.9% of 1092 adults and 94.0% of 151 kids. OPG of less than 1000 were found in 61.2% of adults and 43.3% of kids, whereas OPG of 1000-5000 were observed in 29.0% of adults and 34.6% of kids. Two kids showed over 10(6) OPG. Twelve species of Eimeria coccidia were identified. The percentage of animals harbouring different species were: E. alijevi and E. ninakohlyakimovae, 99%; E. hirci, 83.5%; E. arloingi, 80.6%; E. caprina, 77.6%; E. aspheronica, 64.8%; E. ahsata, 63%; E. christenseni 60%; E. granulosa, 42.8%; E. pallida, 6.2%; E. intricata, 2% E. punctata, 0.3%. Two percent of goats harboured three species, 5.6% four, 9.5% five, 26.3% six, 25.7% seven, 23.7% eight, 6.3% nine, 0.6% ten and 0.3% eleven species. E. alijevi was the most predominant species, followed by E. ninakohlyakimovae, E. ahsata, E. arloingi, E. granulosa, E. caprina, E. christenseni, E. hirci, E. aspheronica and E. pallida in decreasing order. E. intricata and E. punctata never showed predominance. All the species are reported from Zimbabwe for the first time.
Fecal samples were collected from 144 llamas, Lama glama, on four premises in northern Colorado and southern Wyoming. Feces were examined for the presence of coccidial oocysts; Eimeria alpacae was found in 55.6%, Eimeria lamae in 67.3% and Eimeria macusaniensis in 1.4% of the samples. An adult female llama was found to be infected with Eimeria macusaniensis at necropsy. This is the first report of these species of coccidia in the llama.
Faecal specimens from 162 piglets, aged 1-5 months, from four farms around Harare were examined for coccidia during 1989-1990. Oocyst count per gram (OPG) of faeces was determined by the McMaster technique. Identification of Eimeria species was done after sporulation of oocysts in 2.5% potassium dichromate solution. Measurements of sporulated oocysts were taken from 20 positive cases by using calibrated eye micrometer. Overall incidence was 25.3% (41/162) varying between 15 and 39.5% at different farms. The OPG ranged between 150 and 11,300. Eight species of Eimeria were identified, namely, Eimeria debliecki, Eimeria perminuta, Eimeria suis, Eimeria polita, Eimeria neodebliecki, Eimeria porci, Eimeria scabra and Eimeria spinosa, shown in the order of their prevalence. Eimeria debliecki was the most predominant, showing highest oocyst counts in 45% of 20 pigs, followed by E. suis (25%) and E. polita (20%). On two occasions only one Eimeria sp. was found while in the other 18 (90%) cases, mixed infections of two to six species were recorded.
A survey of enteric coccidia was made in a Cashmere goat herd in Montana, USA. Eimerian oocysts were found in 97.2% of 616 fecal samples. Newly weaned wethers and does had higher oocyst counts than yearling wethers. Nine Eimeria species were identified, with Eimeria arloingi, Eimeria ninakohlyakimovae and Eimeria alijevi jointly comprising 88.3% of all oocysts recovered. These three species and Eimeria hirci were present in all specimens examined. Prevalence of the other species was as follows: Eimeria caprina, 88.2%; Eimeria jolchijevi, 70.6%; Eimeria christenseni, 32.4%; Eimeria caprovina, 29.4%; Eimeria apsheronica 26.5%.
Eimeria species infect livestock in a host-specific manner and are the cause of the disease, coccidiosis. Control of Eimeria species is essential and is currently dominated by chemotherapy; with vaccination using formulations of live wild-type or attenuated parasites an increasing option. A new generation of subunit, live-vector or DNA vaccination strategies is being sought and determining the identity of suitable antigens remains difficult. Some past and present methods of controlling avian coccidia are discussed briefly and we describe progress with a novel approach to identify immunoprotective antigens as vaccine candidates.
The objective of this study was to evaluate the utility of a simple, efficient, and rapid method for the isolation of Sarcocystis neurona merozoites and Besnoitia darlingi tachyzoites from cultured cells. The efficacy of this purification method was assessed by microscopy, SDS-PAGE, Western blotting, immuno-fluorescence, and three novel quantitative PCR assays. Culture medium containing host cell debris and parasites was eluted through PD-10 desalting columns. This purification method was compared to alternatives employing filtration through a cellulose filter pad or filter paper. The estimated recovery of S. neurona merozoites purified by the column method was 82% (+/-3.7) of the original merozoites with 97.5% purity. In contrast, estimated recovery of S. neurona merozoites purified by filter pad and filter paper was 40% and 30% with 76% and 83% purity, respectively. The same procedures were applied to purify B. darlingi tachyzoites from cultured cells. Of the original cultured B. darlingi tachyzoites, 94% (+/-2.5) were recovered from the PD-10 column with 96.5%, purity whereas percentage recovery of B. darlingi tachyzoites purified by filter pad and filter paper were 51% and 35% with 84% and 88% purity, respectively. All described methods maintained sterility so that purified parasites could be subsequently cultured in vitro. However, purification using a PD-10 column minimized parasite loss and the loss of viability as determined by the trypan blue dye exclusion assay, the rate of parasite production, and plaque forming efficiency in cell culture. Moreover, column-purified parasites improved the sensitivity of an immuno-fluorescent (IFA) analysis and real-time quantitative PCR assays targeted to parasite 18S ribosomal DNA and hsp70 genes. This technique appears generally applicable for purifying coccidia grown in cell cultures.
A case of intestinal infection by Cryptosporidium parvum and another of intestinal Isospora belli infection, both in AIDS patients, are described. The two patients presented pulmonary tuberculosis symptoms and watery diarrhoea. Modified Ziehl-Neelsen stain of stools gave a definitive diagnosis in both cases. They are the first reports of intestinal coccidia infections in AIDS patients described in Mozambique.
Expression of transforming growth factor-betas 2, 3 and 4 (TGF-beta) in the developing chicken intestine and spleen was investigated using specific cDNA probes and antibodies for the different TGF-beta isoforms. Coordinate expression of the mRNAs for TGF-beta s 2, 3 and 4 was detected in the embryonic intestine by 8 days, with maximal expression of the mRNAs for TGF-beta s 2 and 4 occurring at 12 and 19 days, respectively, while expression of TGF-beta 3 mRNA remained constant during this time. While specific antibodies for TGF-beta s 2, 3 and 4 could detect only weak immunohistochemical staining of the intestinal epithelium in 4-, 12- and 16-day-old embryos, intense staining for TGF-beta s 2, 3 and 4 was detected in the tips of the intestinal villi of 19-day-old embryos. In the spleen, expression of the mRNAs for TGF-beta s 2 and 3 increased in the newly hatched chick compared with the embryo and then decreased in the adult to levels that were lower than in the embryo; expression of TGF-beta 4 mRNA increased progressively with developmental age, with expression in the adult spleen being significantly higher than in the embryonic and hatchling spleen. Immunohistochemical staining of spleens showed a selective increase in the level of reactive TGF-beta 4 with increasing developmental age, while staining for TGF-beta s 2 and 3 was constant during development. After infection of 1-month-old chickens with coccidian parasite, expression of TGF-beta 4 mRNAs increased 5-8-fold in intestinal intra-epithelial lymphocytes and 2.5-fold in spleen cells, while expression of the mRNAs for TGF-beta s 2 and 3 remained constant in these cells. The results of this study suggest that TGF-beta may play a role in development of the intestine and spleen in the chicken and that TGF-beta 4 in particular increases after infection of coccidia in the chicken.
The prevalence and intensity of oocysts of coccidia, particularly Eimeria species, and eggs of gastrointestinal nematodes in kids (2-4 months), young goats (5-12 months) and adult goats (>1 year) were determined in five large herds managed extensively in five villages in the dry zone. Of the representative samples examined, oocysts were found in 88% of kids, 91% of young goats and 83% of adults. Seven species of Eimeria were identified in faecal samples by salt flotation. Eimeria ninakohlyakimovae (31%), E. alijevi (29%) and E. arloingi (21%) were the most common species in all age categories. Other species encountered were E. christenseni (7%), E. jolchijevi (6%), E. hirchi (3%) and E. aspheronica (1%). Gastrointestinal nematode eggs were found in 89% of the kids, 94% of the young goats and 84% of the adult goats. Identification of gastrointestinal nematodes revealed Haemonchus contortus (90%) followed by Oesophogostomum spp. (8.5%) and Trichostrongylus spp. (1%) in all three age categories examined. Both Eimeria and gastrointestinal nematodes were found in 77% of the kids, 86% of the young goats and 71% of adult goats. The mean oocyst counts per gram of faeces in kids, young goats and adult goats were 9728, 1946, and 2667, respectively. The oocyst counts were not different significantly between age groups (P>0.05). The mean egg counts per gram of faeces in kids, young goats and adult goats were 1217, 1641 and 1092, respectively. The egg counts in kids were significantly lower than that in young goats (P<0.05). The intensity of Eimeria and gastrointestinal nematode infections between herds were significantly different (P<0.01).
A short list of terms has been compiled which provides for the discussion of variation of coccidia of the genus Eimeria at infrasubspecific levels. Based upon this list, guidelines are given for the designation of strains and lines.
The electrophoretic mobility of glucose phosphate isomerase (GPI) had been used to identify Eimeria acervulina, E. praecox and E. mivati in isolates of coccidia from commercial sites in the United Kingdom. Mixtures of two or three species gave separate bands upon electrophoresis and each species could be identified provided that it formed at least 10-20% of the total number of oocytes present in a sample of 8 x 10(6) oocysts. The principal forms of GPI corresponded to the GPI of E. acervulina (H), E. praecox (H) and E. mivati (W) and were found in 38, 34 and 8 isolates respectively of the 46 examined. Three further variants of GPI are described.
Codon usage has been analysed in individual gene sequences, derived from a variety of parasitic protozoa in the class Sporozoa of the phylum Apicomplexa using metric multidimensional scaling. The two groups of codon usage patterns detected reflect the two main subgroups of organisms studied (the coccidia and the piroplasms), and it is the pattern of usage of synonymous codons that has the largest influence on overall codon usage in the individual genes, rather than being the pattern of amino acid composition of the gene product. The magnitude of the codon usage bias in the sequences was determined using three commonly used indices-NC, GC3S and B. In general, although relatively low levels of codon usage bias were detected in these gene sequences, codon usage bias does explain at least some of the codon usage patterns observed. Codon usage bias was observed to be dependent on the overall base composition of the genes analysed, which in turn was reflected in the types of codons that were either over- or under-represented in the nucleotide sequences. In keeping with observations on prokaryotic organisms, it is speculated that the codon usage patterns detected in these parasitic protozoa are the result of directional mutation pressure on the base composition of the genomic DNA.
We have investigated the influence of heteroxenous coccidia (Apicomplexa: Eimeriorina) on the predation risk of intermediate hosts. Voles infected with Frenkelia spp. were found more frequently in buzzards' (Buteo buteo) prey than among snap-trapped rodents. To eliminate the possibility of traps selecting for uninfected rodents, a laboratory experiment was performed. Mice experimentally infected with Sarcocystis dispersa seemed to be more likely caught by the final host, the long-eared owl (Asio otus); this result was confirmed by a mathematical model. Field data confirmed the adaptive value of parasite-induced changes. The increase of predation is directed towards the specific final host only or is non-specific. In the populations studied the probability of predation of parasitized individuals by the specific predator was increased.
The influence of the number of bradyzoites of the Coccidia Besnoitia inoculated in the culture medium of HeLa cells on their penetration rate was investigated. The intracellular penetration rate increased with the "size of inoculum", then seemed constant when a certain density is reached. Important densities of bradyzoites in the inoculum led to an unequal distribution of intracellular parasites among the cellular sheet. Multiple infective units in a same host cell did not occur randomly. It seems that some cells are more suitable than others to parasite invasion.
The phylogenetic relationships of Goussia janae and Choleoeimeria sp. were analyzed using the small subunit ribosomal RNA gene (SSU rDNA). This is a first attempt to study the molecular phylogeny of coccidian genera parasitizing strictly poikilotherm hosts. The biliary Eimeria-like coccidia of reptiles classified into the genus Choleoeimeria form a sister clade to the family Eimeriidae, which confirms the separate generic status of the genus Choleoeimeria. The position of Goussia is less robustly resolved, since it forms a trichotomy with the Eimeriidae and Sarcocystidae, or alternatively constitutes the earliest branch of the coccidian lineage. Morphological similarities, namely the extracytoplasmic location of the endogenous stages, and the presence of sutures in the sporocyst wall are discussed in the context of the traditional classification of eimeriids. In contrast to the morphology-based systematics, the monophyly of Goussia and Choleoeimeria is not supported by the SSU rDNA data.
Four experiments were run to test the anticoccidial activity of dried Artemisia annua leaves and several of their chemical constituents for possible use as prophylactic feed additives. When fed over a period of 3 wk at a level of 5%, a dried leaf supplement of A. annua provided significant protection against lesions due to Eimeria tenella but not Eimeria acervulina or Eimeria maxima. When fed over a period of 5 wk at a level of 1% to chicks undergoing immunization with a live vaccine, it provided significant protection in partially immunized chicks against E. acervulina and E. tenella lesions from a dual species challenge infection. It also afforded lower mean lesion scores in challenged chicks immunized over a period of 5 wk. Artemisinin, an antimalarial component of A. annua, was present at a level of 0.034% in the dried leaf preparation. A 5% supplement thus afforded about 17 ppm artemisin. When the pure compound was fed at that level for a period of 3 wk, it protected weight gains and significantly reduced lesion scores attributable to E. tenella but not E. acervulina. Other components of A. annua, camphor and 1,8-cineole, at 119 ppm also protected weight gains, and reduced E. tenella lesion scores. Camphor reduced E. acervulina lesions. Artemisinin fed for 4 wk at levels of 2, 8.5, and 17 ppm significantly reduced oocyst output from separate E. acervulina and E. tenella infections and a dual species infection. Pure artemisinin thus appears to be effective against at least two coccidia species when used as a feed additive, and its activity may depend, in part, on the length of time it is administered before a challenge infection.