Characterization of stage-specific and cross-reactive antigens from Eimeria acervulina by chicken monoclonal antibodies

The characterization of five chicken monoclonal antibodies (mAbs) that were developed against apical complex antigens of Eimeria acervulina sporozoites is realized and the mAbs reactivity to merozoites belonging to this species is tested. Using immuno-fluorescence assay (IFA), one mAb (HE-4) that recognized apical antigens common to sporozoites of E. acervulina and E. brunetti bound antigens localized on the apical tip of merozoites from all stages of development examined. The mAb 8E-1, reactive with antigens found on the apical tip of all chicken Eimeria sporozoites, also showed binding to antigens common to merozoites from all generations. Another mAb, 8C-3, which identified an antigen shared by sporozoites apical tip and sporocysts wall of E. acervulina reacted very weak and inconstantly with the merozoites from all generations whereas the mAbs 5D-11 and 8D-2 that recognized antigens shared by the sporozoites of E. acervulina and E. maxima (mAb 5D-11) and E. acervulina and E. brunetti (mAb 8D-2) did not react with the merozoites from any generation. Collectively, these results showed that the invasive stages of chicken Eimeria share cross reactive apical complex antigens which are inter-species and inter-generation-specific that might be components of a potential recombinant vaccine.     

Analysis of cross-reactivity of five new chicken monoclonal antibodies which recognize the apical complex of Eimeria using confocal laser immunofluorescence assay

For Apicomplexa (members) the host cell invasion is realized with the help of the organelles located at the apical tip of parasites. In this research paper the characterization of five chicken monoclonal antibodies (mabs) produced against Eimeria acervulina sporozoites is described. All mabs reacted with molecules belonging to the apical complex of chicken Eimeria sporozoites. On immunofluorescence assay (IFA) one mab, 8E-1, recognized an apical tip molecule present on all chicken Eimeria sporozoites, two mabs (8D-2 and HE-4) recognized an antigen present on the apical tip of the same two Eimeria species (E. acervulina and E. brunetti), another mab (5D-11) recognized an antigen present on the apical tip of other two species (E. acervulina and E. maxima) while one mab (8C-3) identified antigens present on the sporozoites and sporocysts wall of only E. acervulina. Besides the apical tip antigens, two mabs (HE-4 and 8D-2) recognized some proteins located in the anterior half of the sporozoites. Collectively, these mabs proved that the apical complex of chicken Eimeria sporozoites share one or more antigens that are expected to play a role in host cell recognition and invasion.     

Levels of detection of Cryptosporidium oocysts in mussels (Mytilus galloprovincialis) by IFA and PCR methods

Cryptosporidium spp. are monoxenous protozoan parasites that cause gastrointestinal diseases in humans and animals. Shellfish harvesting areas can become contaminated by the infectious stage of the parasite and humans are therefore at risk of infection either by consumption of shellfish, or by taking part in recreational activities in these areas. In the present study we determined the levels of detection, by IFA and PCR techniques, of Cryptosporidium oocysts in mussels experimentally contaminated with a theoretical number of oocysts. There was a significant correlation between the results obtained by both techniques (P<0.05). IFA and PCR were also applied to a total of 222 samples of mussels (Mytilus galloprovincialis) destined for human consumption. In the naturally contaminated samples, we detected a 31.1% of contamination and only Cryptosporidium parvum (previously denominated C. parvum genotype II) was identified.     

Prevalence of Microsporidia, Cryptosporidium spp., and Giardia spp. in beavers (Castor canadensis) in Massachusetts.

Feces from 62 beavers (Castor canadensis) in Massachusetts were examined by fluorescence microscopy (IFA) and polymerase chain reaction (PCR) for Microsporidia species, Cryptosporidium spp., and Giardia spp. between January 2002 and December 2004. PCR-positive specimens were further examined by gene sequencing. Protist parasites were detected in 6.4% of the beavers. All were subadults and kits. Microsporidia species were not detected. Giardia spp. was detected by IFA from four beavers; Cryptosporidium spp. was also detected by IFA from two of these beavers. However, gene sequence data for the ssrRNA gene from these two Cryptosporidium spp.-positive beavers were inconclusive in identifying the species. Nucleotide sequences of the TPI, ssrRNA, and beta-giardin genes for Giardia spp. (deposited in GenBank) indicated that the four beavers were excreting Giardia duodenalis Assemblage B, the zoonotic genotype representing a potential source of waterborne Giardia spp. cysts.     

The effect of heating against Cryptosporidium oocysts

The effect of heat treatment was examined against oocysts of Cryptosporidium parvum, Cryptosporidium muris and chicken Cryptosporidium sp. isolated in Japan. The oocysts of these species were exposed at 50, 55, 60 and 70 degrees C for 5, 15, 30 and 60 sec in water bath, respectively. To determine the infectivity of heated oocysts, the nice and chickens were inoculated with the treated oocysts and the oocyst output in the feces after inoculation was examined. In C. parvum and chicken Cryptosporidium sp., the oocysts were not detected from mice or chickens which were received oocysts heated at 55 degrees C for 30 sec, 60 degrees C for 15 sec and 70 degrees C for 5 sec. In C. muris, the oocysts were not detected from mice which were received oocysts heated at 55 degrees C for 15 sec, 60 degrees C for 15 sec and 70 degrees C for 5 sec. Consequently, it was clarified that the infectivity of Cryptosporidium oocysts to mice and chickens was lost by heating at 55 degrees C for 30 sec, 60 degrees C for 15 sec and 70 degrees C for 5 sec.     

Prevalence of Giardia sp. Cryptosporidium parvum and Cryptosporidium andersoni (syn. C. muris) [correction of Cryptosporidium parvum and Cryptosporidium muris (C. andersoni)] in 109 dairy herds in five counties of southeastern New York

A cross-sectional study was undertaken to determine the prevalence of Giardia sp. (G. duodenalis group), Cryptosporidium parvum and Cryptosporidium andersoni (C. muris) [corrected] in dairy cattle in three different age groups, and to evaluate the association of age and season with prevalence. One hundred and nine dairy farms, from a total of 212 farms, in five counties of southeastern New York volunteered to participate. On these farms, 2943 fecal samples were collected from three defined age groups. The farms were randomly assigned for sampling within the four seasons of the year. Each farm was visited once during the study period from March 1993 to June 1994 to collect fecal samples. Demographic data on the study population was collected at the time of sampling by interviewing the farm owner or manager. At collection, fecal samples were scored as diarrheic or non-diarrheic, and each condition was later related to positive or negative infection with these parasites. Fecal samples were processed using a quantitative centrifugation concentration flotation technique and enumerated using bright field and phase contrast microscopy. In this study, the overall population prevalence for Giardia sp. was 8.9%; C. parvum, 0.9%; and C. muris, 1.1%. When considering animals most at the risk of infection (those younger than 6 months of age) Giardia sp. and C. parvum was found in 20.1 and 2.4% of the animals, respectively. Giardia sp. and C. muris were found in all age groups. There was no significant seasonal pattern of infection for any of these parasites.     

Prevalence of Giardia and Cryptosporidium in beef cows in southern Ontario and in beef calves in southern British Columbia

In 1998 and 1999, fecal samples were collected from 669 beef cows on 39 farms located within 10 counties of Ontario. Overall prevalences of Giardia, Cryptosporidium muris, and Cryptosporidium parvum in cows were 8.7%, 10.6%, and 18.4%, respectively. Of the 39 farms sampled, Giardia was detected on 64%, Cr. muris on 72%, and Cr. parvum on 90%. Cryptosporidium parvum was detected in 28% of the cows in 1998 and in 5.2% in 1999. Differences between the 2 y were attributed to sampling during calving in 1998 and during gestation in 1999. In 1998, Giardia, Cr. muris, and Cr. parvum were detected in herds provided with municipal water. In 1998, 193 calves were sampled from 10 farms, representing 4 watersheds, in British Columbia. Thirty-six percent of the calves exhibited signs of diarrhea. Overall prevalences of Giardia and Cryptosporidium spp. in calves were 36% and 13%, respectively. There was evidence that calves with Giardia were more likely to develop scours. Restricting cattle from surface water during periods of high shedding may reduce watershed contamination.     

The prevalence of Cryptosporidium spp. oocysts in wild mammals in the Kruger National Park, South Africa

This study determined the prevalence of Cryptosporidium spp. oocysts in faecal samples from elephant (Loxodonta africana), buffalo (Syncerus caffer) and impala (Aepyceros melampus) in the Kruger National Park (KNP) and an adjacent game reserve in South Africa. Two of the study areas were in close proximity to rural communities on the western KNP boundary and the third study area was located in the centre of the KNP. Fresh stool samples (n=445) were collected and tested using an immunofluorescent antibody test (IFA) for Cryptosporidium parvum. A total of 278 of these were randomly selected (approximately 90 samples per wildlife species) and tested with the modified Ziehl Neelsen staining technique (ZN) for Cryptosporidium spp. The prevalence of Cryptosporidium spp. was highest in elephants (25.8% [95% confidence interval: 17.3, 35.9]), compared to buffalo (5.5% [1.8, 12.4]) and impala (4.3% [1.2, 10.5]). C. parvum showed similar patterns, being most prevalent in elephants (4.2% [1.5, 8.8]), compared to buffalo (1.4% [0.2, 5.1]) and impala (1.9% [0.4, 5.3]). 29 samples, including ZN positive and IFA positive samples, were retested using a real time PCR (rtPCR) technique. Of the 28 ZN-positive samples, 14 (50%) were positive with rtPCR and of the 9 IFA-positive samples 6 (67%) were confirmed positive by rtPCR. The prevalence of Cryptosporidium oocysts was significantly higher in both of the two study areas adjacent to the western KNP boundary compared to the area in the centre of the KNP (OR=3.2 [1.2, 9.0]; P=0.024). Our study demonstrates for the first time the presence of Cryptosporidium spp. in wildlife in South Africa. The transmission of this parasite between wildlife, domestic animals and humans is a plausible hypothesis and represents a potential risk for immunodeficient human populations.     

抗鼠隐孢子虫单克隆抗体的研究

利用鼠隐孢子虫卵囊脱囊物免疫ＢＡＬＢ／Ｃ小鼠，取脾细胞与ＳＰ２／Ｏ细胞融合，经过３￣４次有限稀释法克隆化，获得５株持续分泌抗体的杂交瘤细胞株。所获抗体均属ＩｇＧ１。ＩＦＡ检测结果表明：２Ｇ７株单抗作用于卵囊壁抗原，而ＩＡ４、２Ｅ７、３Ｇ３、４Ａ７株单抗作用于子孢子表面抗原。诱生腹水经过反复冻融、冻干及硫酸铵沉淀后，抗体活性无明显变化。５株单抗均不与贝氏隐孢子虫及柔嫩艾美尔球虫产生交叉反应，与小孢隐     

Molecular identification of Cryptosporidium spp. in animal and human hosts from the Czech Republic

To study the diversity of Cryptosporidium spp. in various hosts, we used the variability of the small-subunit rRNA gene and the Cryptosporidium oocyst wall protein genes. Oocysts from humans, cattle, horses, dogs, field mice, chickens, reptiles, deer, goat, cat, antelope and from a sample of water reservoir were assayed. The zoonotic C. parvum bovine genotype sequence was found to be present in the most of isolates. This study shows a complex epidemiology pattern for C. parvum bovine genotype infections. The identification of cattle, horse, and deer isolates emphasizes a transmission route for C. parvum via these hosts, and identifies a potential source for human infection in the Czech Republic. Furthermore, C. andersoni from a cow, C. baileyi from a chicken, C. felis from a cat, C. meleagridis from a dog, and C. saurophilum and C. serpentis from reptiles were also identified in the isolates from the Czech Republic.     

Prevalence of selected zoonotic and vector-borne agents in dogs and cats in Costa Rica

To estimate the prevalence of enteric parasites and selected vector-borne agents of dogs and cats in San Isidro de El General, Costa Rica, fecal and serum samples were collected from animals voluntarily undergoing sterilization. Each fecal sample was examined for parasites by microscopic examination after fecal flotation and for Giardia and Cryptosporidium using an immunofluorescence assay (IFA). Giardia and Cryptosporidium IFA positive samples were genotyped after PCR amplification of specific DNA if possible. The seroprevalence rates for the vector-borne agents (Dirofilaria immitis, Borrelia burgdorferi, Ehrlichia canis, and Anaplasma phagocytophilum) were estimated based on results from a commercially available ELISA. Enteric parasites were detected in samples from 75% of the dogs; Ancylostoma caninum, Trichuris vulpis, Giardia, and Toxocara canis were detected. Of the cats, 67.5% harbored Giardia spp., Cryptosporidium spp., Ancylostoma tubaeforme, or Toxocara cati. Both Cryptosporidium spp. isolates that could be sequenced were Cryptosporidium parvum (one dog isolate and one cat isolate). Of the Giardia spp. isolates that were successfully sequenced, the 2 cat isolates were assemblage A and the 2 dog isolates were assemblage D. D. immitis antigen and E. canis antibodies were identified in 2.3% and 3.5% of the serum samples, respectively. The prevalence of enteric zoonotic parasites in San Isidro de El General in Costa Rica is high in companion animals and this information should be used to mitigate public health risks.     

Detection of Assemblage A, Giardia duodenalis and Eimeria spp. in alpacas on two Maryland farms

Sixty-one fecal samples were collected from adult alpacas and crias (ages 10 weeks to 10 years) on two farms in central Maryland. The farms raised both suri (silky-haired) and huacaya (crimpy-haired) breeds. Females and crias were housed together on pasture, whereas older/breeding males were maintained on separate pastures. Samples were subjected to a density gradient centrifugation protocol to concentrate parasites and remove fecal debris and were examined by immuno-fluorescent and differential interference contrast microscopy. Oocysts of Eimeria spp. were noted in 14 fecal samples, 6 on MD-1 and 8 on MD-2. Based on oocyst morphometrics two species of Eimeria were present: E. punoensis (19.2 microm x 16.5 microm) and E. alpacae (23.7 microm x 19.5 microm). Five animals shed exclusively E. punoensis, seven shed exclusively E. alpacae, and two had mixed infections. The Eimeria infections were not associated with obvious clinical signs. To determine the presence of Cryptosporidium and Giardia species and genotypes, DNA was extracted from feces and subjected to PCR utilizing specific primers for the ssu-rRNA gene for both parasites. All PCR positive samples were further analyzed by DNA sequencing to identify the species or genotypes that were present. Assemblage A, G. duodenalis was detected in fecal samples from two alpacas on MD-1 and in one alpaca on MD-2. Assemblage E, G. duodenalis and Cryptosporidium spp. were not detected on either farm. Although the prevalence on these two farms was low, alpacas can harbor zoonotic G. duodenalis, and this should be borne in mind by persons interacting with the animals.     

Development and characterization of monoclonal antibodies to first-generation merozoites of Eimeria bovis.

Merozoites of Eimeria bovis were harvested from bovine monocyte cell cultures and used to immunize BALB/C mice. Spleens from immunized mice were removed and the cells fused with mouse myeloma cells. Supernates from resulting hybridoma cell lines were examined for antibodies to first-generation E. bovis merozoites using an indirect immunofluorescent antibody (IFA) assay. Three positive cell lines were identified and cloned by limiting dilution. All three cell lines produced immunoglobulins of the IgG1 isotype that recognized antigens in the anterior half to two-thirds of the merozoites. Specificity of the monoclonal antibodies was examined with the IFA assay against sporozoites of E. bovis, sporozoites and merozoites of Eimeria papillata from mice and Eimeria tenella from chickens, sporozoites of Isospora suis from pigs, and tachyzoites of Toxoplasma gondii and Neospora caninum from cell cultures. Monoclonal antibodies from the three clones reacted with the anterior end of E. bovis sporozoites, but did not react with the other parasites examined. None of the monoclonal antibodies reacted with merozoite antigens in immunoblots.     

Presence and molecular characterisation of Giardia and Cryptosporidium in alpacas (Vicugna pacos) from Peru

The presence of Giardia and Cryptosporidium was investigated in 274 faecal samples of alpacas (Vicugna pacos) from 12 herds from Peru by immunofluorescence microscopy and PCR amplification and sequencing of fragments of the ssu-rRNA and β-giardin genes from Giardia spp., as well as the ssu-rRNA gene from Cryptosporidium spp. A total of 137 samples (50.0%) were positive for Giardia spp., and 12 samples (4.4%) for Cryptosporidium spp. In ten samples (3.6%), co-infection by both pathogens was found. Herd prevalence was found to be 91.7% (11/12 herds) for Giardia and 58.3% (7/12 herds) for Cryptosporidium. Regarding the age of the animals, although Giardia was detected in animals as young as 1 week, the prevalence increased with age, reaching 80% by 8 weeks. Similarly, the highest percentage of Cryptosporidium detection (20%) was also found in the 8 week-old group. By PCR, 92 of the 274 analysed samples were positive for Giardia. Sequencing of the amplicons showed the existence of Giardia duodenalis assemblage A in 67 samples; G. duodenalis assemblage E in 24 samples; and inconsistent results between the two molecular markers used in a further sample. Cryptosporidium was only detected by PCR in 3 of the 274 samples; Cryptosporidium parvum was identified in two samples and Cryptosporidium ubiquitum in one sample. This study is the first performing molecular characterisation of both parasites in Peruvian alpacas, and the first report of C. ubiquitum in this host. The identification of G. duodenalis assemblage A, C. parvum and C. ubiquitum, suggests that zoonotic transmission of these enteropathogens between alpacas and humans is possible.     

水源中隐孢子虫种类和基因型鉴定技术研究进展

目前，隐孢子虫有效种有20个。隐孢子虫的分子流行病学研究表明，隐孢子虫具有宿主特异性。目前，感染人的隐孢子虫种和基因型有C．horninis、C.parvum、C．meleagridis、C.felis、C.canis、C.nuris、C．suis genotype和C．cervine genotype等。水源性隐孢子虫暴发，具有重要的公共卫生意义。分子鉴定技术已广泛应用于检测水中隐孢子虫，水中检测到的隐孢子虫有9个。通过分析其分子组成特性表明，成年牛可能是水污染的主要根源，除了居民用水和农业污染外，鹿、麝鼠、田鼠、鸟和其它野生动物可能也与水污染有关。隐孢子虫分子基因型鉴定工具可能为水源保护性研究提供一个更有力的溯源追踪工具。     

Giardia and Cryptosporidium in dairy calves in British Columbia.

A study was undertaken to determine the prevalence of Giardia infections in dairy calves and to compare Giardia and Cryptosporidium infections in calves of different ages. Fresh fecal samples were collected from 386 male and female Holstein calves (newborn to 24 wk) in 20 dairies located in the lower Fraser river valley area of British Columbia. Giardia intestinalis, Cryptosporidium parvum, and Cryptosporidium muris were enumerated in each sample after concentration by sucrose gradient centrifugation and immunofluorescent staining. Giardia was identified at all farm locations. The overall prevalence of Giardia in calves was 73% with a geometric mean cyst count of 1180 cysts per gram of feces (CI, 41 to 5014). Cryptosporidium parvum and C. muris were identified in 80% and 40% of the farms, respectively. The prevalence of C. parvum was 59%, and the geometric mean for oocysts was 457 oocysts per gram of feces (CI, 18 to 160). The prevalence of C. muris was only 2% and the mean oocyst counts were 54 oocysts per gram of feces. Giardiasis was not age dependent, and approximately 80% of the calves from 2 to 24 wk were infected. In contrast, C. parvum infections were predominant in calves 2 to 4 wk, while C. muris was demonstrated in calves older than 4 wk. Fourty-seven percent of calves with diarrhea had high numbers of Giardia cysts in their feces. Giardia infections are highly prevalent in dairy calves and should be considered in animals with diarrhea or failure to thrive.     

Intestinal parasitism in the animals of the zoological garden "Peña Escrita" (Almuñecar, Spain)

Gastrointestinal parasites cause serious diarrhoea in captive animals. Therefore, we have undertaken this study to establish programmes to prevent, control, and treat intestinal parasitism in the animals of the zoological garden "Pe?a Escrita" of Almu?ecar (Granada). An annual survey was conduced to estimate the occurrence of gastrointestinal parasites and the seasonality of this parasitism. Between June 2006 and May 2007, 432 samples were collected from primates, carnivores, perissoodactyla, artiodactyla, rodentia, diprotodontia, galliformes, anseriformes and struthioniformes. One or more intestinal parasites were identified in 72.5% of the animals. The most frequent pathogenic endoparasites were Eimeria spp. (17.3%), Trichuris spp. (5.1%), Strongyloides spp. (4.5%), Cyclospora spp. (4.5%), Cryptosporidium spp. (3.2%) and Isospora spp. (2.6%). Iodamoeba butschlii, Parascaris equorum and Trichuris spp. did not vary with season and Cryptosporidium spp., Dicrocoelium dendriticum, Metastrongylus spp. and Cylicospirura spp. appeared exclusively in Artiodactyla. Multiple parasitic infections were common, 70% of animals presented with at least two parasites (maximum=6). The most frequent cases of multiple parasitism were Eimeria spp. plus Blastocystis spp. and Eimeria spp. plus Nematodirus spp., in the last case the animals presented explosive diarrhoea. In accord with our results, after each sampling, some of the affected animals were treated and the corresponding programmes of prevention and control were designed.     

Prevalence of Cryptosporidium, Giardia and Eimeria infections in post-weaned and adult cattle on three Maryland farms

The prevalence of Cryptosporidium, Giardia and Eimeria, in healthy, asymptomatic, post-weaned and mature cattle was investigated on three Maryland farms. One farm, a dairy research facility, had 150 multiparous Holstein milking cows; 24 were examined and Cryptosporidium andersoni was detected in three (12.5%) but neither Giardia nor Eimeria was detected. The second farm, a commercial dairy, had 57 multiparous Holstein milking cows and an equal number of heifers. Of 19 cows examined, C. parvum, Giardia duodenalis, and Eimeria bovis and/or E. ellipsoidalis were detected in two (10.5%), two (10.5%) and one (5.26%) cow, respectively. Of 23 heifers examined, C. parvum, Giardia, and E. bovis and E. ellipsoidalis, was detected in two (8.7%), four (17.4%), and five (21.7%), heifers, respectively. The third farm, a beef cattle breeding and genetics research facility, had 180 7- to 9-month old purebred black Angus. Of 118 examined for C. parvum and Giardia, 34 (28.8%) and 44 (37.3%) were positive, respectively, of 97 examined for E. bovis and/or E. ellipsoidalis 32 (33.0%) were positive. These findings, based on a method with a minimum detection level of 100 oocysts of C. parvum/g of feces, which underestimates the number of infected cattle, clearly demonstrate the presence of low level, asymptomatic infections in post-weaned and adult cattle in the United States and indicate the potential role of such cattle as reservoirs of infectious parasites.     

Parasitic health of olive baboons in Bwindi Impenetrable National Park, Uganda

This study examined the endoparasite load of a group of olive baboons (Papio cynocephalus anubis) that share their habitat with a population of mountain gorillas (Gorilla gorilla berengei) in Bwindi Impenetrable National Park, Uganda. During a 2-week period in June 2002, shared habitat was substantiated by noting the ranging patterns of both species and recording observations and trail remains with a global positioning system (GPS). Parasite load was determined by collecting fecal samples preserved in 10% formalin and analyzed by sedimentation techniques and immunofluorescent antibodies (IFA). Bwindi baboons were infected with Cryptosporidium, Giardia, Eimeria, Ascaris spp., Strongyloides spp., Trichuris spp., Hymenolepis spp., and Ternidens diminuta. Of these, the Bwindi mountain gorillas had previously been found to carry Cryptosporidium, Giardia, Strongyloides spp., and Trichuris spp., but not Eimeria, Ascaris, Hymenolepis, or T. diminuta. This study is the first to record Giardia in olive baboons and demonstrates that at least three parasite species in Bwindi baboons have yet to be found in Bwindi gorillas. Early monitoring is essential to the health and well being of both of these sympatric primate species, especially as they continue to interact more often and over a larger area.     

Efficacy of amine-based disinfectant KENO™COX on the infectivity of Cryptosporidium parvum oocysts

Cryptosporidium parvum is a zoonotic protozoan parasite that may cause severe neonatal diarrhoea or even mortality in newborn ruminants: its oocysts are extremely resistant to normal environmental conditions and to most common disinfectants. KENO?COX, a patent pending amine-based formula, was tested for its ability to inactivate C. parvum oocysts. The Daugschies assay (2002), a standardized assay for chemical disinfection initially described for Eimeria spp., was adapted for C. parvum oocysts. KENO?COX diluted in water at 2% and 3% concentration and incubated with oocyst suspensions for 2h, allowed a significant reduction in viability, lysing 89% and 91% of oocysts respectively. Infectivity of the remaining C. parvum oocysts was assessed by inoculation to C57 Bl/6 neonatal mice. Each mouse received 2.5 μl of a suspension initially containing 500,000 oocysts before contact with KENO?COX. Six days post inoculation, the intestinal parasite load was significantly reduced by 97.5% with KENO?COX 2% compared to that of the mice inoculated with untreated parasites. KENO?COX 3% completely eliminated infectivity of oocysts. The number of oocysts remaining infectious in the inoculum treated with KENO?COX 2% was calculated from an inoculated dose-response curve: it was estimated at about 48.6 oocysts among the 500,000 oocysts initially treated corresponding to 99.99% of inhibition. These results demonstrate the high efficacy of KENO?COX against C. parvum oocysts. Combined with an appropriate method of cleaning, the application of KENO?COX may be a useful tool to reduce cryptosporidial infectious load on farm level.