Studies ofStreptococcus suis type 2 infection in pigs

Investigations into the immunology, pathogenesis and epidemiology ofStreptococcus suis type 2 infections were carried out in experimental pigs and in naturally-occurring field outbreaks of disease.The capsular polysaccharide fromStr. suis type 2 was shown to induce opsonic antibodies in pigs when injected with Freund's incomplete adjuvant, but difficulties encountered in experimental production of the disease prevented a study of their protective effects.Problems with the bactericidal tests led to an investigation of other assays for antibodies againstStr. suis type 2, namely, a phagocytic test with pig neutrophils, a mixed reverse passive antiglobulin haemagglutination test and an indirect haemagglutination test. There was evidence that with modifications both the latter tests would be useful.Transmission studies in 39 conventionally-reared and 7 hysterectomy-derived, colostrum-deprived pigs yielded interesting results with regard to the distribution of the organism in relation to the disease process.Tonsil carriage in clinically-healthy pigs was demonstrated after experimental and natural infection. Detectable carrier rates varied between 0 and 59%. The organism was shown to persist in the presence of circulating opsonic antibodies and in pigs on penicillin-medicated feed. Attempts to isolate the organism from the genital tract were unsuccessful.Medicated early weaning and classical SPF techniques applied to infected herds appeared to be effective in producing pigs free fromStr. suis type 2 infection.     

Efficacy of the avermectins against filarial parasites: A short review

The avermectins are macrocyclic lactones produced byStreptomyces avermitilis. One of them has been chemically modified and given the non-proprietary name invermectin. The compounds have shown efficacy against various stages of filarial parasites. With respect to pre-adult stages in the mammalian host, activity has been observed againstDirofilaria immitis in ferrets and dogs, andDipetalonema viteae andLitomosoides carinii in jirds (Meriones); but activity has not been observed against the developing stages ofBrugia spp. in jirds orOnchocerca spp. in cattle. The compounds have not shown activity against adult filarial worms, except in the case ofSetaria equina in horses and possiblyDipetalonema viteae in jirds. With respect to the first stage larva (microfilaria) in the mammalian host, efficacy has been observed againstDirofilaria immitis in dogs,Brugia malayi in multimammate rats (Mastomys),Dipetalonema viteae andLitomosoides carinii in jirds andOnchocerca spp. in horses and cattle; but activity has not been observed against microfilariae ofBrugia pahangi in jirds or cats. Efficacy against filarial parasites has been observed following oral or parenteral administration of drug, sometimes at extremely low dosage. For example, a single oral dosage of 0.05 mg/kg was highly active against the third and fourth larval stages and microfilariae ofD. immitis in dogs.     

Intestinal helminths of cats in the Kainji Lake area Nigeria

Six parasitic helminths detected wereAncylostoma sp.,Opisthorchis felineus,Toxocara mystrax,Hepaticola hepatica,Taenia sp. andHydatigera taeniaeformis. The prevalence ofH.hepatica,T.mystrax andH.taeniaeformis is associated with rodents hunted by cats, and that ofO.felineus with fish fed to cats. The role of cats as primary host and reservoir for these helminths, which could be of zoonotic importance, is briefly mentioned.     

Heavy sarcocystosis in the ocular musculature of cattle and buffaloes

A high prevalence of 71.5 per cent and 69.7 per cent of sarcocystosis was observed in the ocular musculature of cattle and buffaloes respectively, in Bihar, India. The concentration of cysts in the eye muscle was also usually heavy. Ocular musculature appears to be a preferred site for the development ofSarcocystis in these intermediate hosts, second only to the heart muscle. The species ofSarcocystis involved in the present study were morphologically indistinguishable fromS. cruzi in cattle andS. levinei in buffaloes. This appears to be the first report on the occurrence ofS. cruzi andS. levinei in ocular musculature.     

Immunogenicity of a soluble antigen againstPasteurella haemolytica-associated pneumonia in calves

Three experiments were performed to evaluate the immunogenic potency of a soluble fraction ofPasteurella haemolytica against pneumonic pasteurellosis in calves. A soluble antigen was extracted by a 2.5% saline solution fromP.haemolytica. Weaned Holstein bull calves, seronegative for infectious bovine rhinotracheitis virus (IBRV) and the pasteurella antigen, were vaccinated either by repeated subcutaneous (SC) vaccination, or by exposure 3 times to the aerosol ofP.haemolytica antigen. Challenge exposure to aerosol ofP.haemolytica was preceded by infection with IBRV, or in experiments 2 and 3, the virus exposures were combined with a stress treatment. The lung lesions were examined at necropsy 3 to 8 days post infection. In the first experiment, all the vaccinated calves produced specific antibody response to the pasteurella antigen, and none of the calves including controls showed significant lesions in the lung. In the second experiment 2 aerogenically vaccinated calves had no lesions. One of the two SC-vaccinated calves had mild consolidated lesions. Two control calves, one of which died 3 days following the challenge, developed severe fibrinous pneumonia with consolidation of 50% or more of the lung surfaces.P.haemolytica was isolated only from the 2 control animals. In the third experiment, 2 of the 3 control calves developed moderate to severe consolidation, butP.haemolytica was isolated only from one of them. Two of the three aerosol-vaccinated calves also developed significant lesions and one of them yielded the bacteria from the lung. Three SC-vaccinated calves had slight lesions and the organism was not isolated from their lungs. The results did not consistently indicate an immunogenic potential of the soluble antigen againstP.haemolytica-related pneumonia. The effect of stress on the pathogenesis of bovine viral penumonia and correlation between pneumonic lesions and antibacterial resistancein situ are discussed.     

Effect of some drugs on the skin response of tick-resistant cattle to an allergenic extract of larvalRhipicephalus appendiculatus

When a larval extract fromRhipicephalus appendiculatus was inoculated intradermally into tick-resistant cattle, a cutaneous swelling or bulla was induced, but this did not occur when tick-naive cattle were similarly inoculated. Certain drugs, infused around the inoculation sites just before administration of the extract, affected the development of the swelling. The size of the bulla was lessened by mepyramine maleate, whereas levamisole enhanced the response to the extract. Acetylsalicylic acid and phenylbutazone had no observable effect on the skin reaction. Intravenously administered cyclophosphamide enhanced the response. It is suggested that histamine plays a major role in inducing the skin swelling.     

Microbiology of the genitalia of nulliparous and postpartum Savanna Brown goats

A study of the bacterial flora of the genitalia of nulliparous Savanna Brown does was carried out both before breeding and at different intervals postpartum to investigate the type of microbial organisms that could be present in the uterus, cervix and the vagina respectively.Of 29 pre-breeding vaginal swabs, Staphylococcus sp. was isolated from 20 goats, Streptococcus sp. from 15 goats and Micrococcus sp. from four goats. Mycoplasma agalactiae was isolated from five goats.The postpartum vagina did not show any appreciable change in the microbial flora, except that Escherichia coli was encountered in two cases. The uterus yielded E. coli from the goats slaughtered 2 days postpartum; Micrococcus sp. from goats slaughtered 12 days postpartum; Staph. aureus from goats slaughtered 16 days postpartum and Staph. aureus from goats slaughtered 24 days postpartum.Also in these two cases — a goat slaughtered at two days postpartum (dpp) and a goat slaughtered 16 dpp — E. coli was present in the uterus. Other isolates from the uteri of slaughtered goats were Micrococcus sp. (12 dpp), Staph. aureus and Micrococcus sp. (16 dpp) and Staph. aureus (24 dpp).     

Decontamination of Campylobacter jejuni on chicken drumsticks using chemicals and radiation

A trial was conducted to compare the efficacy of four disinfectants and radiation to reduce the level of C. jejuni contamination on poultry meat. Two levels of each treatment were applied to chicken drumsticks inoculated with a known concentration of a strain of Campylobacter jejuni, biotype 1, isolated from a human patient with diarrhea.Radiation using a cobalt-60 source at a level of 0.5 KGy effected a 99% surface reduction in C. jejuni. With a mean initial surface contamination level of 1.1 × 10³ Colony Forming Units/cm², 1 KGy completely eliminated C. jejuni. Glutaraldehyde at 0.5% concentration for 30 minutes had an efficacy similar to the lower dose of radiation. Chlorine showed a negligible effect on C. jejuni. Succinic acid and Poly (hexamethylenebiguanide hydrochloride) were statistically similar in their effectiveness, ranking between glutaraldehyde and chlorine.These results strongly indicate that, of the alternatives tested, low-dose radiation is the method of choice for reducing Campylobacter contamination of poultry products.     

Campylobacter jejuni contamination of eggs

Contamination of commercial table eggs with a fecal suspension containing 4.4×10⁶ CFU/gCampylobacter jejuni resulted in shell penetration in 3/70 eggs and recovery of the organism from homogenized egg contents in 1/70 eggs. Viability ofC. jejuni on the shell surface was retained for only 16 hours, attributed to desiccation of the fecal suspension. A field survey of three commercial laying farms and their associated egg-packing plants showed that hens demonstrated to be fecal shedders ofC. jejuni (12% to 62% incidence) did not produce infected eggs. The organism could not be detected in the environment of the packing plant, including grading machinery and effluent.     

Etiology and pathogenesis of necrotic enteritis

Sporulated oocysts ofEimeria acervulina were administered orally to cage-housed broilers at a dose of 3.5×10⁵ resulted in mild subclinical coccidiosis.Clostridium perfringens incorporated in feed at a level of 2.5×10⁸ organisms/g. produced lesions characteristic of necrotic enteritis. Mortality of 8% (7/80) occurred in birds fed a ration inoculated withCl. perfringens alone. Mortality of 35% (28/80) was observed in birds which received an oral dose ofE. acervulina and which were fed simultaneously with a ration containingCl. perfringens. Birds which were fed an inoculated ration two days after an oral dose ofE. acervulina showed 41% (33/80) mortality. Birds which received an inoculated ration for two days before administration of an oral dose ofE. acervulina demonstrated 18% mortality (15/80). Birds which were fed an inoculated ration four days after an oral dose ofE. acervulina showed 10% mortality. Infection withE. acervulina reduced the pH of intestinal contents with a simultaneous depression in serum protein. A 39% increase in intestinal passage time from 178 to 248 minutes occurred on the fifth day after infection withE. acervulina. These experiments suggest that necrotic enteritis, attributed to proliferation of a toxigenic strain ofCl. perfringens, followed intestinal stasis and minimal lesions induced by mild intestinal coccidiosis.     

Isolation and transmission ofCowdria ruminantium (causal agent of heartwater disease) in Blue Nile Province,Sudan

Heartwater was diagnosed in sheep at the Umm Banein Livestock Research Station, Blue Nile Province, Sudan.Cowdria ruminantium was isolated from sheep by subinoculation of blood into a goat. AdultAmblyomma lepidum ticks fed as nymphs on this goat transmitted heartwater to a Friesian (Bos taurus) calf. Brain stabilates from this calf, either snapfrozen into liquid nitrogen or frozen slowly in a deepfreezer at –70°C, with DMSD as cryoprotectant, were infective to cattle when inoculated subcutaneously.     

Kinetics of levamisole-induced potentiation of lymphocyte blastogenic responses inMycobacterium bovis sensitized lymphocyties

A study was conducted to determine the kinetics of levamisole-induced potentiation of lymphocyte blastogenesis inMycobacterium bovis sensitized and nonsensitized cattle lymphocytes. It was observed that levamisole significantly potentiated PPD-induced blastogenic responses when it (levamisole) was added toM. bovis sensitized lymphocyte cultures 24 hours prior to the addition of PPD. Levamisole-induced either minimal or suppressed the PPD-induced lymphocyte stimulation response inM. bovis nonexposed control lymphocytes. The implications of possible use of levamisole in cellularin vitro assays for studying anergy or general unresponsiveness are discussed.     

Faecal bacteria of wild ruminants and the alpine marmot

Faecal samples from 60 red deer (Cervus elaphus), 13 roe deer (Capreolus capreolus), 7 chamois (Rupicapra rupicapra), 41 alpine marmot (Marmota marmota) and soils mixed with deer faeces from the Stelvio National Park were examined forCampylobacter sp. andSalmonella sp. with negative results.The same material, especially deer faeces, was a habitat highly suitable forYersinia sp.:Y. enterocolitica (two biotypes) was isolated twice,Y. kristen-senii (two serotypes) was isolated 19 times,Y. frederiksenii andY. intermedia were isolated once.Antibiotic-resistantEscherichia coli were isolated from 16 specimens from wild ruminants, one from marmot and two from feeding places.This article was presented as a paper at the 8th International Symposium Enteric Infections and their Control of the World Association of Veterinary Microbiologists, Immunologists and Specialists in Infectious Diseases (Perth, Western Australia, 20 August 1983).     

Bovine babesiosis in the European community

There are apparently three species of bovineBabesia within the European Community-B. divergens,B. major andB. bovis. The former is the principal cause of disease, but lack of information about the other two, particularly about the ability of the tickIxodes ricinus to act as their vector, makes further investigation essential. The potential hazard of indiscriminate movement of cattle within the E.C. is discussed, and a plea is made for the introduction of routine serological screening of cattle before their export.

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Kurzfassung In der Europäischen Gemeinschaft scheint es drei Arten vonRinderbabesia zu geben,B. divergens,B. major undB. bovis. Die erste Art ist die Hauptkrankheitsursache, aber mangelnde Kenntnisse über die anderen beiden, besonders über die Fähigkeit der ZeckeIxodes ricinus als übertrager zu dienen, lässt weitere Untersuchungen wesentlich erscheinen. Die potentiellen Gefahren durch uneingeschränkte Viehbewegungen innerhalb der EG werden erörtert, und es wird für die Einführung routinemässiger serologischer Untersuchungen der Tiere vor ihrer Ausfuhr plädiert.

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Resume Il existe apparemment trois sortes debabésia bovine dans la Communauté Européenne-B. divergens,B. major etB. bovis. La première est la cause principale de la maladie, mais le manque d'informations concernant les deux autres, particulièrement la capacité de la tiqueIxodes ricinus d'agir en tant que vecteur de ces maladies, rend des recherches complémentaires absolument nécessaires. Le danger virtuel que constituent les mouvements désordonnés de bétail à l'intérieur de la Communauté Européenne fait l'objet d'un discussion, et il est préconisé l'analyse systématique du sérum du bétail avant son exportation.

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Riassunto Nella Comunità europea pare esistano tre specie diBabesia bovina cioè-B. divergens,B. major eB. bovis. Principale causa di malattia è la prima, ma la mancanza di sufficienti informazioni sulle altre due, soprattutto riguardo al ruolo della zeccaIxodes ricinus come vettore, richiede lo svolgimento di ulteriori ricerche. I rischi potenziali inerenti al movimento indiscriminato dei bovini nella C.E. sono oggetto di discussione e si suggerisce l'istituzione di regolari controlli sierologici dei bovini prima che gli stessi vengano esportati.

     

Diseases caused byTrypanosoma evansi,a review

The literature on the diseases caused byTrypanosoma evansi is reviewed and the gaps in the available information are emphasized.Trypanosoma evansi, on the basis of combined similarities in morphology, biological behaviour, and to some degree based on geographical distribution, is a species closely related to and probably originating fromT.brucei. The distribution ofT. evansi is very wide in the Old and New World and it is transmitted by biting flies and vampire bats. It has a patchy distribution in any region and new foci of infection have a high incidence. Diagnosis is made on demonstration of trypanosomes, biochemical tests detecting increase in serum proteins, and on specific serological tests. The clinical signs vary with the acuteness of the syndrome, often being characterized by a chronic course with lack of pathognomonic signs. There is very little information on the pathology of the diseases in various species of animals, but the lesions apper to be similar to those caused byT. brucei and are associated with the distribution of trypanosomes in solid tissues. Immunological studies habe been limited primarily to serology in connection with diagnostic procedures. Laboratory models have been studied and the syndromes are similar to those produced byT.brucei. Chemotherapy is varied and to some degree dependent on the species of host. More information on the incidence and severity of diseases is required to identify priorities for further research.

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Kurzfassung Die Literatur über Erkrankungen, die durchTrypanosoma evansi hervorgerufen werden, wird besprochen. Dabei werden Lücken in der vorhandenen Information aufgezeigt.Trypanosoma evansi ist aufgrund der Ähnlichkeit in Morphologie, biologischem Verhalten und bis zu einem gewissen Grad seiner geographischen Verbreitung, eine Spezies, die eng mitT. brucei verwandt ist und warscheinlich von dieser Spezies abstammt. Die Verbreitung vonT. evansi ist sowohl in der alten als auch der Neuen Welt weit, und seine Übertragung erfolgt durch beissende Fliegen und blutleckende Fledermäuse. In befallenen Regionen ist die Verbreitung ungleichmässig und neue Infektionsfoci sind häufig. Eine Diagnose wird durch Nachweis der Trypanosomen, biochemische Teste, durch Nachweis einer Erhöhung von Serumproteinen und mit spezifischen serologischen Verfahren durchgeführt. Klinische Erscheinungen variieren mit der Heftigkeit des Auftretens des Syndroms und sind häufig charakterisiert durch einen chronischen Verlauf ohne pathognomonische Erscheinungen. Nur wenig ist bekannt über die Pathologie der Erkrankungen bei den verschiedenen Spezies. Die Veränderungen scheinen jedoch denen ähnlich zu sein, die durch Intektionen mitT. brucei verursacht werden und sind mit der Verbreitung von Trypanosomen in Geweben vergesellschaftet. Immunologische Untersuchungen sind bisher nur begrenzt im Rahmen der serologischen Diagnostikverfahren durchgeführt worden. Versuche mit Infektionsmodellen ergaben Erkrankungen, die ähnlich denen waren, die durchT. brucei induziert werden konnten. Die Erfahrungen mit einer Chemotherapie sind variabel und Erfolge sind bis zu einem gewissen Grad wirtsabhängig. Weitere Informationen über das Vorkommen und die Schwere der Erkrankungen sind notwendig, um Prioritäten für zukünftige Forschungen zu ermitteln.

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Resume La littérature sur les maladies causées parT. evansi est passée en revue et le manque d'informations sur certains points est souligné.T. evansi est très proche deT. brucei (morphologie, comportement biologique, épidémiologie) et peut être même issue de ce type.T. evansi est très largement répandu dans le nouveau et l'ancien monde, transmis par les insectes piqueurs et les vampires suceurs de sang. Dans chaque région sa distribution se fait par foyers où sa fréquence est très élevée. Le diagnostic de la trypanosomiase est basé sur la mise en évidence du parasite, d'une hyperprotéinémie et sur des épreuves sérologiques spécifiques. Les symptômes varient en fonetion du type d'évolution mais ont surtout une allure chronique qui n'a rien de caractéristique. Il y a très peu d'informations disponibles sur les lésions correspondant aux différentes espèces mais elles sont certainement voisines de celles provoquées parT. brucei et en relation avec la distribution des parasites dans les différents organes. Les études immunologiques sont pour l'instant limitées à celles pouvant avoir une incidence sur le diagnostic sérologique. Des modèles expérimentaux ont été étudiés provoquant des syndromes voisins de ceux liés à l'infection parT. brucei. La chimiothérapie est variée en fonction de l'animal parasité. Davantage d'informations sur la fréquence et la sévérité de la maladie sont souhaitées afin de préciser les priorités en matière de recherches futures.

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Riassunto Viene esaminata la letteratura sulle malattie causate daTrypanosoma evansi e vengono sottolineate le lacune esistenti nei dati conoscitivi disponibili.T. evansi, sulla base di una combinazione di somiglianze, di comportamento biologico e, sino a un certo punto, sulla base della distribuzione geografica, è una specie strettamente correlata conT. brucei e probabilmente da esso derivante. La distribuzione diT. evansi è molto vasta nel Vecchio e nel Nuovo Mondo e la trasmissione avviene attraverso la puntura di mosche e il morso di vampiri. In tutte le regioni il parassita presenta una distribuzione a chiazze e i nuovi focolai di infezione hanno un'alta incidenza. La diagnosi viene emessa con la dimostrazione dei tripanosomi, mediante test biochimici che mettono in luce un aumento delle proteine seriche, nonché con prove sierologiche specifiche. La sintomatologia clinica varia a seconda dell'acuzie della sindrome, ed è spesso caratterizzata da un decorso cronico con assenza di sintomi patognomonici. Ben poco si sa sulla patologia delle malattie nelle varie specie animali, ma le lesioni appaiono essere simili a quelle sostenute daT. brucei e sono provocate dalla distribuzione dei tripanosomi nei tessuti solidi. Gli studi immunologici si sono sopratutto limitati agli aspetti sierologici relativi alle tecniche diagnostiche. Sono stati anche studiati modelli di laboratorio e le sindromi evocate sono state analoghe a quelle prodotte daT. brucei. La chemioterapia è varia e dipende in una certa misura dalla specie dell'ospite. Sono necessari maggiori informazioni sulla incidenza e gravità delle forme morbose al fine di identificare i punti prioritari per ulteriori ricerche.

     

The viability ofCampylobacter jenuni on refrigerated chicken drumsticks

Radappertized chicken drumsticks were experimentally contaminated with suspensions ofCampylobacter jejuni in two trials. Qualitative analysis on drumsticks with an initial level of contamination of 4.8×10³ CFU/cm² showed that viability was retained for at least 10 days of storage at either 9° or –12°C.In a second quantitative trial, the level of contamination declined from 9.9×10² CFU/cm² to 4.5×10¹ CFU/cm² after 7 days at –20°C. Thereafter,C. jejuni persisted at levels ranging from 1.8×10¹ to 0.2×10¹ CFU/cm² through the 26th week of storage. Drumsticks held at 4°C showed a significant decline in count from 9.9×10² CFU/cm² to 1.8×10² CFU/cm² on day 7.It is concluded that the viability ofC. jejuni on chicken parts is maintained under both refrigerated and freezing conditions which approximate commercial storage. This is of significance to the meat industry and consumers.     

Passive transfer of immunity to Trichostrongyle species infections in sheep. Investigations of specificity and limitations of ‘transfer factor’ activity withTrichostrongylus axei infections

The ability of transfer factor (TF) preparations to transfer resistance to challenge withTrichostrongylus axei in sheep and to correct partially the immune immaturity of young lambs was confirmed. Non-dialysed TF consistently transferred resistance but dialysed TF frequently failed, perhaps demonstrating a loss of activity during TF preparation procedures. Specificity of transfer was demonstrated whenT. axei TF transferred resistance toT. axei challenge butHaemonchus contortus TF failed to do so.     

Pharmacokinetic behaviour and anthelmintic efficacy of 1-n-butyl carbamoyl oxfendazole given by intramuscular injection

Oxfendazole (OFZ) was chemically modified to 1-n-butyl carbamoyl OFZ (C₄-OFZ) in an attempt to improve the solubility of OFZ and enable it to be administered by injection. After intramuscular injection to sheep and cattle, C₄-OFZ was metabolised to OFZ which resulted in higher plasma OFZ concentrations that persisted for a considerably longer period than those observed following administration of OFZ orally. The anthelmintic efficacy of injected C₄-OFZ was tested, in sheep, against strains ofTrichostrongylus colubriformis,Haemonchus contortus andOstertagia circumcincta, which were highly resistant to benzimidazoles. In all cases, the C₄-OFZ treatment showed a significant improvement in efficacy over the conventional oral OFZ drench.     

Effects of dexamethasone on selected parameters of the bovine immune system

The synthetic glucocorticoid, dexamethasone, has been used by investigators studying bovine immune mechanisms to either exacerbate infectious processes or simulate stress-induced steroid-influenced immunosuppression. Considerable differences exist in the literature concerning the effect of dexamethasone on the bovine immune response.The purpose of our study was to clarify the reported effects of dexamethasone on bovine T-lymphocyte function. Therefore, we designed experiments to evaluate cellular and humoral aspects of the bovine immune response under the influence of dexamethasone. The experiments took into consideration the pharmacokinetics of dexamethasone and optimal and suboptimal doses of selected mitogens. The data suggest little variation in hematological parameters that occurred with the administration of dexamethasone. Leukocyte counts were slightly elevated at two observations, and this was believed to be the result of an increase in peripheral blood neutrophils. T-lymphocytes (erythrocyte rosetting) were not selectively depleted. However, suppression of T-lymphocyte function was noted, particularly in response to suboptimum doses of phytohaemagglutinin (PHA) and Concanavalin A (Con A). Antibody production to the T-dependent antigen, KLH, was suppressed in those animals receiving dexamethasone. These data suggest that the immunosuppressive effect of dexamethasone in the bovine is dependent upon the dose of dexamethasone administered, the pharmacological level of dexamethasone in vivo, physiological adaptation of the host, mitogen dose used in evaluation, and the time of evaluation post drug administration. The study points out the importance of considering these variables when interpreting the effects of dexamethasone on the bovine immune response.     

Attachment ofNematospiroides dubius in the murine intestine

The mechanism of attachment ofNematospiroides dubius to its murine host was seen to involve primary longitudinal striae which embed into the intestinal villi.