Eimeria Necatrix Research Articles

Prevalence of Eimeria species in domestic chickens in Anhui province, China.

Prevalence studies can adequately assist in the design of prophylaxis strategies for disease control. Here, the prevalence of Eimeria species in chickens was investigated in Anhui province, China, from July to September 2016. A total of 171 samples were tested by microscopic examination and molecular methods. The prevalence of coccidiosis in Anhui province was found to be 87.75% (150/171). Eimeria tenella was the most prevalent species (80.67%, 121/150), and Eimeria necatrix, Eimeria mitis, Eimeria maxima, Eimeria brunetti and Eimeria acervulina were 68% (102/150), 55.33% (83/150), 54.67% (82/150), 44.67% (67/150) and 2.67% (4/150), respectively. Eimeria praecox was not detected at all. The most common combinations are E. tenella, E. maxima, E. necatrix, E. brunetti and E. mitis (26.67%, 40/150), followed by E. tenella, E. maxima and E. necatrix (19.33%, 29/150). Eimeria necatrix exhibited the highest participation in multiple infections. The results of the present study suggested that Eimeria infection is mixed, severe and widespread in chickens, Therefore, integrated strategies should be performed to prevent and control coccidial infection in chickens in Anhui province.

Dry season prevalence of avian Coccidia infection in domesticated chickens (Gallus domesticus) in Jere Council, Borno State, Nigeria

The present study was carried out between the months of October, 2014 to April, 2015 and aimed at determining the dry season prevalence of avian coccidia infection and their degree of severity among domesticated chickens (Gallus domesticus) in Jere Council, Borno State, Nigeria. A total of 430 fresh faecal and gut samples were collected from chickens of both exotic and local breeds. The samples were examined using floatation and intestinal impulsion smear techniques. The study was conducted among breeds (exotic vs. local), sexes (male vs. female), ages (young vs. adult), management systems (intensive vs. extensive) and housing (cage vs. deep litter). Out of the 430 faecal samples examined, 54 (12.60%) were positive for various Eimeria species. Infection was more in the exotic (7.90%) than the local breed (4.70%). Coccidia infection found in young (10.0%) was higher (P= 0.0001) than in adult chickens (2.60%), while female ones had higher (P= 0.03) number of coccidia than the males. Chickens reared under poor management system showed higher infection (10.20%) compared to the good management one (2.30%). Chickens reared under intensive deep litter housing has higher coccidial load (9.30%) than those reared under extensive system (3.30%). Eimeria necatrix had the highest degree (42.60%) of severity score (+4), followed by Eimeria acervulina (27.80%), Eimeria tenella (24.10%) and E. maxima (5.60%) with degrees of severity scores +3, +4 and (+3) respectively. In conclusion, there was presence of coccidia infection in Jere area of Borno State, Nigeria.

Cloning and expression of Eimeria necatrix microneme5 gene in Escherichia coli

Background: Coccidiosis caused by Eimeria necatrix has the most economic impact onpoultry production. Micronemal proteins in Eimeria necatrix are thoughtto be critical ligands determining host cell specificity at the time ofinvasion. OBJECTIVES: Isolation and purification of Eimeria necatrix oocysts from Khuzestan province of Iran was performed. AcDNA encoding microneme 5 (EnMIC5) protein was cloned and expressed asrecombinant protein before the evaluation of its immunogenicity by Westernblotting. METHODS: A primer pair was designed based on the publishednucleotide sequence of Eimeria necatrix LZ strain micronem5 gene. APartial cDNA sequence fragment of 758 bp coding for microneme 5 protein(EnMIC5) was amplified by semi- Nested RT-PCR. PCR products were cloned andexpressed in a Maltose Binding protein (MBP) containing expression vector(pMAL-c2x) in Escherichia coli. The cDNA which is encoded for 252 aminoacids shows high degree of conservation. It contains the adhesive plasmapre-kallikrein and seven hydrophilic motifs. RESULTS: The results of SDS-PAGErevealed that the recombinant protein with a molecular weight of 70 kDa wasover-expressed after induction with IPTG. Western blotting results revealedthat the expressed recombinant protein was reacted with sera of the chicksinfected with Eimeria necatrix. It was suggested that this proteinshould have a good immunogenicity and can be used for further studies. CONCLUSIONS: In conclusion, the high degree of sequence homology indicates that thisprotein is immunogenic and might be aninteresting vaccine target, and deserves further investigation

Cryptic Eimeria genotypes are common across the southern but not northern hemisphere

The phylum Apicomplexa includes parasites of medical, zoonotic and veterinary significance. Understanding the global distribution and genetic diversity of these protozoa is of fundamental importance for efficient, robust and long-lasting methods of control. Eimeria spp. cause intestinal coccidiosis in all major livestock animals and are the most important parasites of domestic chickens in terms of both economic impact and animal welfare. Despite having significant negative impacts on the efficiency of food production, many fundamental questions relating to the global distribution and genetic variation of Eimeria spp. remain largely unanswered. Here, we provide the broadest map yet of Eimeria occurrence for domestic chickens, confirming that all the known species (Eimeria acervulina, Eimeria brunetti, Eimeria maxima, Eimeria mitis, Eimeria necatrix, Eimeria praecox, Eimeria tenella) are present in all six continents where chickens are found (including 21 countries). Analysis of 248 internal transcribed spacer sequences derived from 17 countries provided evidence of possible allopatric diversity for species such as E. tenella (FST values ⩽0.34) but not E. acervulina and E. mitis, and highlighted a trend towards widespread genetic variance. We found that three genetic variants described previously only in Australia and southern Africa (operational taxonomic units x, y and z) have a wide distribution across the southern, but not the northern hemisphere. While the drivers for such a polarised distribution of these operational taxonomic unit genotypes remains unclear, the occurrence of genetically variant Eimeria may pose a risk to food security and animal welfare in Europe and North America should these parasites spread to the northern hemisphere.

Poultry coccidial infection in local chicken from three selected districts of North Gondar Zone, Ethiopia

A cross-sectional study was conducted to determine the prevalence of poultry coccidial infection and to identify Eimeria species on local chicken in three selected districts of North Gondar, Northwest Ethiopia from October 2010 to March 2011. Two hundred sixty local chickens were purchased from three selected districts (Wogera, Dembya and Gondar town) which represent two agro-ecological zones. Identification of Eimeria species was based on the Oocyst morphology, predilection site, gross and histopathological changes in the intestine. The study indicated that 16.92% (44/260) of the chickens were infected with coccidia oocysts. Four Eimeria species were identified, namely, Eimeria maxima, Eimeria acervulina, Eimeria necatrix and Eimeria tenella with the prevalence estimate of 36.3%, 29.5%, 18.2%, and 15.9%, respectively. Age unlike sex was found to be significantly (P < 0.05) associated with coccidial infection. This study showed that coccidial infection (16.92%) could be important in the backyard system which was supposed to be low.Keywords: Coccidial infection, Eimeria species, Ethiopia, Local chicken, Prevalence

Prevalence of Eimeria spp. in Broilers by Multiplex PCR in the Southern Region of Brazil on Two Hundred and Fifty Farms.

Parasitic infections caused by Eimeria species are responsible for most economic losses in poultry production. Prevalence studies can adequately assist the design of prophylaxis strategies for disease control. Therefore, stool samples from 251 flocks of broilers from 28 to 48 days old were collected in 21 municipalities in the state of Santa Catarina, Brazil, to detect and examine the prevalence of Eimeria acervulina, Eimeria maxima, Eimeria tenella, Eimeria mitis, Eimeria praecox, Eimeria necatrix, and Eimeria brunetti. The oocysts were recovered and quantified, and the species were identified by a multiplex PCR technique. Amplicons of seven Eimeria species originating from the PCR-positive samples were cloned. Microscopy studies demonstrated that 96% of the farms were positive for the Eimeria. Seven species were identified, as follows: E. maxima (63.7%) and E. acervulina (63.3%) were the most prevalent species, followed by E. tenella (54.6%), E. mitis (38.6%), E. praecox (25.1%), E. necatrix (24.3%), and E. brunetti (13.1%). The average number of species detected per farm was 2.96, and the most common were E. acervulina, E. maxima, and E. tenella (9.16%). The sequencing of the clones confirmed the specificity and effectiveness of multiplex PCR for the identification of seven species of Eimeria, so this tool can be useful in studying circulating species in poultry farms, thereby assisting prophylactic measures against coccidiosis.

Induction of protective immunity against Eimeria tenella, Eimeria necatrix, Eimeria maxima and Eimeria acervulina infections using multivalent epitope DNA vaccines

Avian coccidiosis is mostly caused by mixed infection of several Eimeria species under natural conditions and immunity to avian coccidiosis is largely dependent on T-cell immune response. In this study, 14 T-cell epitope fragments from eight antigens of Eimeria tenella (E. tenella), Eimeria necatrix (E. necatrix), Eimeria maxima (E. maxima) and Eimeria acervulina (E. acervulina) were ligated with pVAX1 producing 14 monovalent DNA vaccines, respectively. Protective immunity of the monovalent DNA vaccines was assessed by in vivo challenge experiments and then four most protective fragments of each species were chosen to construct multivalent epitope DNA vaccines with or without chicken IL-2 as genetic adjuvant. Protective efficacies of the epitope DNA vaccines on chickens against E. tenella, E. necatrix, E. maxima and E. acervulina were evaluated. The results showed that the constructed multivalent epitope DNA vaccines significantly increased body weight gain, alleviated enteric lesions and reduced oocyst output of the infected birds. Especially, the multivalent epitope DNA vaccines of pVAX1-NA4-1-TA4-1-LDH-2-EMCDPK-1 and pVAX1-NA4-1-TA4-1-LDH-2-EMCDPK-1-IL-2 not only significantly increased body weight gain, alleviated enteric lesions and reduced oocyst output of the infected birds, but also resulted in anti-coccidial index (ACI) more than 170 against E. tenella, E. necatrix, E. maxima and E. acervulina, which indicated they could induce protective immunity against E. tenella, E. necatrix, E. maxima and E. acervulina. Our findings suggest the constructed multivalent epitope DNA vaccines are the potential candidate multivalent vaccines against mixed infection of Eimeria.

English

A cross sectional study was conducted between November, 2013 and June, 2014 to determine the prevalence of chicken coccidiosis, identify Eimeria species and assess different risk factors in free ranging and intensively managed chickens. Test tube flotation technique was used for qualitative study of coccidian oocysts. Of 384 chickens examined, an overall prevalence of 19.5% (75) was found. The prevalence of coccidiosis was accounted 17.7% (95%CI = 13.2 - 23.0), 44.8% (95%CI = 33.2 - 56.8) and 4.7% (95%CI = 1.3 - 11.6) in Chelaleki, Burka-jato and Bake-jama, respectively. The prevalence was significantly different between breed (χ2 = 5.1, p = 0.021), management (χ2 = 15.9, p = 0.000) and age (χ2 = 7.1, p = 0.008). However, no statistically significant difference (χ2 = 0.03, p = 0.865) was found in the prevalence of coccidiosis between sex. Among different species of Eimeria isolated Eimeria tenella and Eimeria acervulina were identified to be the major cause of the disease and each accounted 29(38.7%) of the total isolate of infected birds followed by 13.33% Eimeria necatrix and 9.33% Eimeria maxima. In conclusion, the present study showed that coccidiosis was an important disease of poultry in the study area and therefore, poultries infected with this parasite should be treated, chicken house should be periodically cleaned and disinfected as well as effective biosecurity measures should be in place. Key words: Coccidiosis, Eimeria, flotation, prevalence, oocyst.

Effects of Artemisia annua extracts on sporulation of Eimeria oocysts.

The present study aimed to compare the effect of different Artemisia annua extracts on sporulation rate of mixed oocysts of Eimeria acervulina, Eimeria necatrix, and Eimeria tenella. Three types of A. annua extracts including petroleum ether (PE), ethanol 96° (E), and water (W) extracts were prepared. Artemisinin, a sesquiterpene lactone endoperoxide derived from the A. annua analysis of each extract was done by high-performance liquid chromatography with ultraviolet detection (HPLC-UV). Fresh fecal samples containing three Eimeria species were floated and counted, and the oocysts were transferred into 50 tubes, each containing 10(5) oocysts per milliliter. Five tubes were control. Each of the other 45 tubes contained one of three doses (1 part per thousand (ppt), 2 ppt, and 5 ppt) and one of three extracts (PE, E, and W extracts) with five replications. The tubes were incubated for 48 h at 25-29 °C and aerated. Sporulation inhibition assay was used to evaluate the activity of extracts. The results showed that the E and PE extracts inhibit sporulation in 2 and 5 ppt concentrations, but the W extract stimulates it in all concentrations. The proportions of oocyst inhibition relative to control were 31 % (5 ppt) and 29 % (2 ppt) for PE and 34 % (5 ppt) and 46 % (2 ppt) for E extract. Furthermore, many oocysts in PE and E groups were wrinkled and contained abnormal sporocysts. The proportions of sporulation stimulation relative to control were 22 % (5 ppt), 24 % (2 ppt), and 27 % (1 ppt) in W extract. Our study is the first to demonstrate that all types of A. annua extracts do not necessarily have a similar activity, and the interaction of all contents and their relative concentrations is an important factor for sporulation stimulation or inhibition. It seems, some parts of unmetabolized excreted PE and E extracts could inhibit oocyst sporulation and eventually affect infection transmission.

Seasonal prevalence of gastrointestinal parasites in desi fowl (Gallus gallus domesticus) in and around Gannavaram, Andhra Pradesh.

A study was carried out to know the prevalence of gastrointestinal parasites in desi fowl in and nearby villages of Gannavaram, Andhra Pradesh for a period of 1year. Screening of 492 samples comprising faecal samples and gastrointestinal tracts from freshly slaughtered desi birds at local poultry shops and samples from post mortem examinations at NTR College of Veterinary Science, Gannavaram revealed 63.21% of gastrointestinal parasites. Faecal samples were examined by floatation technique using salt solution and samples positive for coccidian oocysts were sporulated in 2.5% potassium dichromate solution for species identification. Adult worms were identified after routine processing and mounting. The species identified includes Davainea proglottina, Raillietina cesticillus and Raillietina echinobothrida in cestodes (32.47%), Ascaridia galli, Capillaria annulata, Heterakis gallinarum in nematodes (39.87%), Eimeria tenella, Eimeria acervulina and Eimeria necatrix in Eimeria spp. (39.87%). Ascaridia galli and R. cesticillus and A. galli and Eimeria spp. were common in mixed infection (12.86%). Ascaridia galli was the more prevalent species. No trematode parasite was identified during the study period. Significant (p=0.001) relationship between the seasonality and prevalence of gastrointestinal parasites was observed (χ2=17.46, df=2). Data revealed high prevalence in rainy season (43.41%) followed by summer (38.91%) and winter (17.68%) seasons for all parasites except for A. galli and C. annulata infections which were higher in summer season. Results indicated high prevalence of gastrointestinal parasites in desi fowl in study area emphasizing the need of improved management practices of backyard poultry.

Comparison of the anticoccidial effect of granulated extract of Artemisia sieberi with monensin in experimental coccidiosis in broiler chickens

Coccidiosis is the most important parasitic disease of the poultry production industry. Due to increasing resistance to conventional anticoccidial agents, it is necessary to find new anticoccidial compounds. Herbal compounds such as those from Artemisia species are promising weapons in this regard since preliminary studies have shown its anticoccidial effects. To compare the anticoccidial effect of a granulated extract of Artemisia sieberi (GEAS) versus monensin in experimental broiler coccidiosis, 120 one-day old Ross 308 broiler chickens were divided in four groups, each with three replicates (n=10). Group 1 was separated as an uninfected negative control and received no treatment. At 21days of age, groups 2, 3 and 4 were inoculated with a mixed suspension of 2×105 oocysts of Eimeria tenella, Eimeria maxima, Eimeria acervulina and Eimeria necatrix. Group 2 was maintained as an infected positive control and received no treatment while groups 3 and 4 received GEAS (5mg/kg feed), and monensin (110mg/kg feed) from the first day until 42days of age as a feed additive, respectively. Five days after inoculation, the number of oocycts per gram (OPG) of feces for 7 successive days was measured. Also, mean body weight (MBW), weight gain (WG), feed intake (FI) and feed conversion ratio (FCR) were determined weekly in all groups and replicates. The results showed that GEAS and monensin improved performance attributes (FI, MBW, WG, FCR) and significantly (P<0.05) decreased OPG in inoculated broiler chickens.

Cloning and characterization of an Eimeria necatrix gene encoding a gametocyte protein and associated with oocyst wall formation

BackgroundGametocyte proteins of Eimeria (E.) spp. are important components of the oocyst wall and some have been used to develop transmission-blocking vaccines against avian coccidiosis.MethodsTotal RNA isolated from E. necatrix gametocytes was utilized as templates for RT-PCR amplification and sequencing of cDNA encoding a gametocyte protein using gene-specific primers. The cDNA was cloned into the bacterial expression vector pET28a(+) and expressed in E. coli BL21 cells. The antigenicity of the recombinant gametocyte protein and its localization in different E. necatrix life-cycle stages were determined by western blot and indirect immunofluorescence analyses, respectively.ResultsA 731-nucleotide sequence of cDNA [GenBank: KF649255] of E. necatrix had 97.7% identity to that of Etgam22 of E. tenella. The cDNA ORF encoded a 186-amino acid protein containing a histidine-proline-rich region. The recombinant gametocyte protein (rEnGAM22) was predominately expressed in the insoluble inclusion body and recognized by antiserum from chickens immunized with oocysts of E. necatrix, E. maxima and E. tenella. A specific antibody to the rEnGAM22 protein recognized the wall-forming bodies in macrogametocytes and the walls of oocysts and sporocysts.ConclusionsThe gene cloned from E. necatrix gametocytes is an ortholog to Etgam22 of E. tenella and presents a potential target for future recombinant subunit vaccines against coccidiosis.

Effect of Artemisia absinthium essential oil on antioxidative systems of broiler's liver

The effect of Artemisia absinthium essential oil (AAEO) on enzymatic activity of super-oxide-dismutase (SOD), glutathione-peroxidase (GSHPx), glutathione-reductase (GR), peroxidase (POD), xantine-oxidase (XOD) and non-enzymatic (content of lipid peroxides (LPx) and gluthathione (GSH)) antioxidative status of broilers infected with mixture of oocysts of Eimeria tenella, Eimeria mitis and Eimeria necatrix in comparison to coccidiostat salinomycin was investigated. The in vivo investigation were carried out on 120 Arbor acres broilers of both sexes. Broilers were randomly distributed into four groups. Group A was uninfected and untreated; group B was infected and was kept untreated; group C preventively received coccidiostatic salinomycin in quantity of 60 mg/kg of feed and was inoculated with coccidia species at 21st day-of-age and group D received in feed AAEO in quantity of 3 g/kg and was infected with Eimeria oocysts at 21st day-of-age. Livers were collected for the subsequent evaluation of antioxidative status. It was concluded that AAEO added in feed for broilers prevented the development of coccidia oocysts and therefore it can be used as prophylactic feed additive.

Anticoccidial effects of a novel triazine nitromezuril in broiler chickens

The anticoccidial efficacy of 2-(3-methyl-4-(4-nitrophenoxy)phenyl)-1,2,4-triazine-3,5(2H,4H)-dione (nitromezuril, NZL), a novel triazine compound, was evaluated in three different studies under experimental conditions. The anticoccidial efficacy was chiefly evaluated using the anticoccidial index (ACI). The resistance level was determined by calculating ACI, percentage optimum anticoccidial activity (POAA), reduction in lesion scores (RLS) and relative oocyst production (ROP). In the dose determination study (study A), NZL was added to the diet at doses of 1, 2, 3, 4, 5 and 6mg/kg to test its efficacy against coccidiosis caused by Eimeria tenella. Groups treated with NZL 1mg/kg feed could observe the faecal dropping scores and caecal lesions. ACIs of NZL-treated groups reached 179–199. In the study on the anticoccidial efficacy of 3mg/kg NZL in the diet (study B), only a few faecal oocysts and slight lesions were observed. NZL significantly promoted weight gain (WG) and reduced lesion scores (LS) compared to controls receiving diclazuril (DZL) (P<0.05). ACIs of NZL-treated groups were 193, 192, 191 and 163 for E. tenella, Eimeria necatrix, Eimeria acervulina and Eimeria maxima, respectively, whereas those of DZL-treated groups were 185, 176, 176 and 148. In the cross-drug resistance study (study C), ACIs of NZL and toltrazuril (TZL)-treated groups ranged from 188 to 204, which were significantly higher than those of DZL-treated groups (P<0.05). NZL- and TZL-treated groups were sensitive to experimentally induced DZL-resistant E. tenella, whereas DZL-treated groups showed complete resistance. No cross-resistance was observed between DZL and NZL or TZL. Based on the abovementioned studies, it was concluded that diets containing 3mg/kg NZL had an excellent efficacy in preventing coccidiosis in broiler chickens. The activity of 3mg/kg NZL in the diet was equal or superior to that of 1mg/kg DZL. These results are of great significance for the future applications of NZL; however, its actual mechanism of action remains unknown. NZL is a potential novel anticoccidial agent suitable for further development.

In vitro anticoccidial activity of Thonningia sanguinea extract on Eimeria tenella and Eimeria necatrix sporozoites cells

Avian coccidiosis is a parasitic disease which causes considerable economic loss in poultry. The emergence of anticoccidial drug resistance enhances the need for development of novel approach and alternative controls strategies such as plants extract. The anticoccidial activity of the aqueous extract of Thonningia sanguinea (AE-THOS) was evaluated on Eimeria tenella and Eimeria necatrix sporozoites cells invasions in vitro. The Madin-Darby-Bovine-Kidney (MDBK) cells invasions rates of E. tenella and E. necatrixsporozoites untreated and treated with AE-THOS were determined at 3, 12 and 24 h post-infection (PI). The results have shown that AE-THOS concentrations above 2.5 mg/mL inhibits significantly (p < 0.05) the cells invasions of sporozoites of both species ofE. tenella and E. necatrix. AE-THOS could be use against avian coccidiosis. Key words: Thonningia sanguinea, Eimeria tenella, Eimeria necatrix, MDBK cells, sporozoites.

English

The present study was conducted to investigate the prevalence of&nbsp;Eimeria&nbsp;species in native chickens reared under semi-scavenging system and were allowed to scavenge in the yard, in crop fields near water reservoirs. We studied 200 scavenging native chickens in villages around Shiraz City in Southwest Iran. These chickens had no history of vaccination against coccidiosis and had never been given coccidiostat drugs. The chickens were submitted for post-mortem and parasitological examinations. All the villages had chickens that were positive for different&nbsp;Eimeria&nbsp;spp. From a total of 200 native chickens examined, 128 (64%) were infected with coccidiosis.&nbsp;Eimeria tenella&nbsp;was the most prevalent species (24%) followed by&nbsp;Eimeria acervulina&nbsp;(18%),&nbsp;Eimeria&nbsp;necatrix(12%), and&nbsp;Eimeria&nbsp;maxima&nbsp;(10%). Prevalences varied by management and did not vary by flock size. &nbsp; Key words:&nbsp;Eimeria, native chickens, prevalence, Shiraz, Iran.

Prevalence and risk factors for subclinical coccidiosis in broiler chicken farms in Mazandaran province, Iran

Coccidiosis is a disease of almost universal importance in Poultry production. The subclinical form of coccidiosis has most significant economic impact due to impaired growth rate and feed conversion. Some factors such as: age, size of flock, season, etc., may effect on severity of this disease. In this study, the relationships between some major risk factors and prevalence of subclinical coccidiosis were investigated. This study was done in 120 broiler farms in five different cities of Mazandaran province, north of Iran. Five chicks (3-8 weeks of ages) were taken randomly from every 120 farms and post-mortem and parasitological examinations were performed. Five Eimeria spp. were recognized: Eimeria tenella, Eimeria maxima, Eimeria acervulina, Eimeria brunetti, and Eimeria necatrix. The prevalence rate of subclinical coccidiosis among them is 75% (90 farms out of 120). E. acervulina was the most prevalent species (65.5%) followed by E. maxima (17.7%), E. tenella (15.5%), E. brunetti (10%), and E. necatrix (5.5%). According to what the results approve, the occurrence of subclinical coccidiosis is significantly related to the age and size of flock, whereas the other factors such as the season of year, industrial strains, chicken's keeping system, and anticoccidial drugs do not affect this phenomenon remarkably.

Molecular prevalence and preponderance of Eimeria spp. among chickens in Tamil Nadu, India

Coccidosis is one of the most commonly prevalent and economically important parasitic diseases of poultry worldwide. Chicken coccidia are protozoan parasites of the genus Eimeria. This study aimed at analysing the molecular prevalence of seven species of Eimeria infecting chickens in Tamil Nadu, India. Tissue samples (caecum, rectum and upper and mid intestines) collected from chickens exhibiting symptoms of coccidiosis were used for DNA extraction, followed by amplification of the internal transcribed spacer (ITS) region of Eimeria genome with genus-specific primers and speciation in nested polymerase chain reaction (PCR) with species-specific primers. Of 43 tissue samples examined, 25 were positive in ITS PCR and all the seven species could be identified. However, the prevalence of each species varied. In broilers, Eimeria necatrix was present in all infected chickens with Eimeria brunetti, Eimeria tenella, Eimeria maxima and Eimeria acervulina present in more than 50% of infected chickens, while Eimeria praecox and Eimeria mitis were only present in 11% to 16%. Although only 7 samples were positive among layers, the prevalence was largely similar, but with a higher prevalence of E. praecox and E. mitis and a lower prevalence of E. tenella. Multiple infections were most common, with 2-6 Eimeria species infecting the same chickens. In order to estimate the preponderance of each infecting species of Eimeria, a random cloning technique was adopted. The genus-specific ITS PCR product was cloned in a TA vector and ten clones were randomly picked and used as template for amplification of all the seven genera of Eimeria. If the specific species of Eimeria is preponderant, then the frequency of the clones showing that species-specific PCR amplification would be higher. Using this method, the most preponderant species present in the rectum, mid and upper intestines of layers was assessed to be E. acervulina, E. brunetti and E. necatrix. E. acervulina was present in 60-90%, E. necatrix in 10-30% and E. brunetti in 10-20% of the clones screened, indicating that these species could be the most preponderant Eimeria species. Intervention strategies should aim at these species. This new method of estimating preponderance of infecting Eimeria species could be used to assess the relative importance of each species at the farm or region level instead of relying only on prevalence estimates.

Cross immunity of DNA vaccine pVAX1-cSZ2-IL-2 to Eimeria tenella, E. necatrix and E. maxima

The study describes cross protection experiments with chimeric DNA vaccine pVAX1-cSZ2-IL-2 to determine its efficacy against four important Eimeria species. Seven-day-old chickens were randomly divided into nine groups; group 1 negative control, groups 2, 3, 4, 5 positive controls; and groups 6, 7, 8 and 9 experimental groups. On days 7 and 14, groups 1–5 were injected with TE buffer, and groups 6–9 with the vaccine. At 21 days of age, all chickens were inoculated with 5 × 10 4 sporulated oocysts except for the negative control. Groups 2 and 6 were inoculated with Eimeria tenella, groups 3 and 7 with Eimeria necatrix, groups 4 and 8 with Eimeria acervulina and groups 5 and 9 with Eimeria maxima. Seven days later, all chickens were weighed and slaughtered to obtain intestinal samples. Efficacy of immunization was evaluated on the basis of oocyst decrease ratio, lesion score, body-weight gain and anti-coccidial index. The results indicated that the recombinant plasmid can induce host immune responses by alleviating intestinal lesions, body weight loss and oocyst ratio and imparting good protection against E. tenella and E. acervulina, medium protection against E. necatrix but little effect against E. maxima. It is concluded that the conserved antigen can provide cross protection and should be explored further.

Studies on Clinical, Gross, Histopathological and Biochemical Parameters in Broiler Birds Suffered from Eimeria necatrix Infection in Aizawl District of Mizoram, India

Studies were undertaken to evaluate the clinical, gross, histopathological and some biochemical parameters in broiler birds suffered from E. necatrix infection in a local broiler farm in the Aizawl district. Clinically, 20 birds out of 100 no. (aged between 4-6 weeks) showed loss of appetite, unthriftiness and bloody diarrhoea with mucus. Postmortem examination revealed anaemic pale musculature, distended small intestine with petechial haemorrhages. Similar changes were also observed in some areas of th e large intestine and caecum. Histopathological examination showed severe haemorrhagic enteritis with necrosis and disintegration of glandular epithelial cells. Several schizonts were observed in the epithelial cells along with merozoites, infiltrating neutrophils and eosinophils. Biochemically, the infected broilers presented hypoglycaemia associated with a reduction in liver glycogen level. Biochemical serum analysis of coccidia infected chickens also showed a significant increase (p<0.01) in alanine amino transferase levels (2.9-245.2) and there were also changes in total protein and cholesterol level in the serum.