Exophiala mesophila spec. nov

Serum samples from 2000 cows, 3311 sheep and 638 goats from Iran were examined for antibodies to Toxoplasma gondii by use of the latex agglutination (LAT) and indirect hemagglutination tests (IHAT). Antibodies to T. gondii were found in 24.50% sheep and 19.25% of goats. Antibodies to T. gondii were not detected in cow sera by LAT and IHAT in 1:8 and 1:64 dilutions of bovine sera, respectively. Toxoplasma gondii was not found in tissues of 300 aborted fetuses from cows by direct microscopy and bioassay in mice.     

Protozoan infections (Toxoplasma gondii, Neospora caninum and Sarcocystis spp.) in sheep and goats: recent advances

The protozoan parasite Toxoplasma gondii is a serious cause of fetal mortality in sheep and goats. Oocysts, the parasite stage responsible for initiating infection, are produced following a primary infection in cats. A primary infection in pregnant sheep and goats can establish a placental and fetal infection which may result in fetal death and resorption, abortion or stillbirth. Diagnosis is aided by the clinical picture, the presence of characteristic small white necrotic foci in placental cotyledons, the possible presence of a mummified fetus and on fetal serology and histopathology. Development of the polymerase chain reaction (PCR) specific for T. gondii may also provide a valuable diagnostic tool. Measures to control abortion include improved management of farm cats, fodder and water. Vaccination of sheep with the live vaccine is an effective preventive measure and the use of decoquinate in feed may be useful in some situations. Neospora caninum is related to T. gondii and while its asexual life cycle is similar to that of the latter it is currently not known whether it has a similar sexual life cycle in a definitive host. Neospora is an important cause of fetal loss in cattle and parallels that of T. gondii infection in sheep and goats. While it does not appear to cause frequent losses in these latter animals, experimental infection is readily induced in them and if initiated during pregnancy provides a very good model of the bovine infection. Furthermore clinical signs and pathological lesions in sheep and goats are similar to those induced in them by T. gondii, although there are subtle histopathological differences. These changes will aid possible diagnosis as will specific serological tests such as the indirect immunofluorescent antibody test and the enzyme linked immunosorbent assay and the PCR. Sarcocystis, which exists as numerous species, undergoes a coccidian-like life cycle with each having a distinctive definitive (usually carnivore) host which excretes sporocysts into the environment. Clinical sarcocystiosis is much less commonly diagnosed than toxoplasmosis and neither is it normally associated with fetal infection or abortion in either sheep or goats. However, infection is extremely common throughout the world and follows ingestion of food or water contaminated with sporocysts. Clinical signs, when seen, include fever, anaemia, inappetance and weight loss or reduced weight gain. Central nervous signs (hind limb weakness, ataxia, paresis), acute myopathy and death may occur. Diagnosis is difficult as infection is so common and clinical signs absent, mild or non-specific. Serology may be useful in some situations and histopathology/immunohistochemistry is valuable for confirming the cause of death. Control relies on preventing contamination of pasture and water with faeces of dogs, foxes and cats or by controlling access of young susceptible stock to contaminated land. Relatively little is known of the immunity induced by infection with Sarcocystis spp. but research indicates that protective immunity does develop and that cell-mediated mechanisms are probably important. It is likely that sarcocystiosis is underdiagnosed as a problem and that better diagnostic methods are needed to show the true extent of the losses caused. Neosporosis on the other hand would appear not to be so common in sheep and goats. The value of experimental infections in these animals may be to provide a comparative model of the infection in cattle in the same way that our understanding of toxoplasmosis in sheep provides a superior model of human toxoplasmosis.     

Antibody responses measured by various serologic tests in pigs orally inoculated with low numbers of Toxoplasma gondii oocysts

OBJECTIVE: To follow antibody responses measured by various serologic tests in pigs orally inoculated with low (< or = 10 oocysts) numbers of Toxoplasma gondii oocysts. ANIMALS: 24, 2- to 3-month-old pigs. PROCEDURE: Pigs (n = 42) were inoculated orally with 10 (14 pigs) or 1 (28 pigs) infective oocysts, and 6 pigs served as uninoculated controls. Blood (serum) samples were obtained at 1- to 3-week intervals until euthanasia. At necropsy, the brain, heart, and tongue of pigs were bioassayed in mice and cats for isolation of T gondii. Modified agglutination test (MAT), using whole, fixed tachyzoites and mercaptoethanol; latex agglutination test (LAT); indirect hemagglutination test (IHAT); Sabin-Feldman dye test (DT); and ELISA were used to evaluate serologic responses to T gondii. RESULTS: T gondii was isolated from tissues of 13 of 14 pigs each fed 10 oocysts, 17 of 28 pigs each fed 1 oocyst, and 0 of 6 control pigs. 29 of 30 T gondii-infected pigs developed antibodies when measured by MAT, DT, and ELISA; the 1 seronegative-infected pig had been fed 10 oocysts and was euthanatized 69 days after inoculation. LAT detected antibodies in 26 of 30 T gondii-infected pigs. IHAT detected antibodies in 11 T gondii-infected pigs. CONCLUSION: MAT, DT, and ELISA were more sensitive serologic assays than LAT and IHAT for detecting antibodies induced by low numbers of T gondii in pigs.     

Seroprevalence of Bartonella henselae and Toxoplasma gondii infections among pet cats in Kanagawa and Saitama Prefectures

Seroprevalence of Bartonella henselae and Toxoplasma gondii was investigated among 471 pet cats obtained from seven private animal hospitals in Kanagawa and Saitama Prefectures during the period from May 1994 to June 1995. 'Furthermore, 67 randomly selected from the 471 serum samples were examined for the feline immunodeficiency virus (FIV) antibody and feline leukemia virus (FeLV) antigen. The antibody to B. henselae was examined by an indirect immunofluorescent antibody test. T. gondii, FIV and FeLV infections in cats were detected with respective commercial kits. Of the cat serum samples tested, 43 (9.1%) were found to be seropositive for B. henselae and 41 (8.7%) for T. gondii. The B. henselae-positive rate (12.9%) of male cats was significantly higher than that (5.2%) of female cats. On the other hand, T. gondii-positive rate was 9.1% in male and 8.7% in female cats and there was no significant difference in the positivity between sexes. The positive rate in each hospital varied from 0 to 19.5% for B. henselae and 4.9 to 18.8% for T. gondii. The ages of B. henselae- and T. gondii-positive cats were distributed from < 1-year-old to 14-year-old and the seropositivity increased with age of cats. Of the 67 cat serum samples, 16 and 6 cases were positive for FIV and FeLV, respectively. There was no relationship between these viral and B. henselae infections in cats.     

Role of Chylamydia in the pathology of pregnancy and chronic gynecological diseases

For the elucidation of the role of chlamydial infection in pathological pregnancies, serological examination by the CFT with group-specific and species ornithosis antigen was carried out on 723 blood serum specimens from women with obstetrical pathology, 124 specimens from patients with various chronic gynecological diseases and 124 control blood serum specimens from women with nromal pregnancy and favourable obstetrical anamnesis. The complement-fixing antibody (CF) was detected in 72 (9.9%) serum specimens from women with obstetrical pathology and chronic gynecological diseases. No CF antibody was found in control sera. Negative results of the CFT were obtained with species ornithosis antigen in all sera. In parallel examinations of the blood serum specimens from women with obstetrical and gynecological pathology by the CFT and intradermal test, correlation of positive results was demonstrated in 62.5% of the patients. Among the women with positive reactions for chlamydial infection, in 52.8% thee pregnancy was pathological. Among 52 sero-positive pregnant women the death of the fetus was observed in the perinatal period in 21.2%. Among 111 babies born alive after previous pregnancies 55 babies (49.5%) died at the age under 1 year. Thus, chlamydial infection may possibly have causative relation to pathological pregnancy, death of the fetus in the perinatal period, and death of the babies under 1 year.     

Anti-toxoplasma antibodies in butchers and slaughtered sheep and goats in Jeddah Municipal abattoir, Saudi Arabia

Toxoplasma gondii is a zoonotic parasite of world-wide distribution. It is more or less endemic in all countries of the Middle East. In Jeddah Municipal abattoir, anti-Toxoplasma IgG was found to be 39% in sheep and 28% in goats as indicated by IHAT. On the other hand, anti-Toxoplasma IgG and IgM in butchers were 80% and 20% respectively, as indicated by the micro-ELISA. The risk of Toxoplasma transmission particularly, from meat inadequately cooked was discussed.     

Sensitized lymphocytes and CD40 ligation augment interleukin-12 production by human dendritic cells in response to Toxoplasma gondii

Dendritic cells (DC) are potent antigen-presenting cells that can stimulate T cell responses by secreting cytokines. During Toxoplasma gondii infection, host immunity is mediated by interferon-gamma, which is induced by interleukin-12 (IL-12). Whether T. gondii infection would stimulate human DC to produce IL-12 was determined. DC were generated from human peripheral blood mononuclear cells cultured with recombinant human granulocyte-macrophage colony-stimulating factor and recombinant human IL-4. DC secreted high levels of IL-12 in response to lipopolysaccharide but not to either live T. gondii tachyzoites or soluble antigen. However, IL-12 production in response to T. gondii was observed when DC were cocultured in contact with lymphocytes isolated from seropositive donors. Ligation of CD40:CD154 was partially essential for IL-12 secretion. These data demonstrate that signals obtained from contact with sensitized lymphocytes are critical for human DC to secrete IL-12 in response to T. gondii.     

End-tidal estimates of arterial PCO2 for cardiac output measurement by CO2 rebreathing: a study in patients with cystic fibrosis and healthy controls

Based on seroprevalence studies, approximately 30% of the cats in the United States have been infected by T gondii. Cats are the only species that pass the environmentally resistant oocyst in feces. Sporulated oocysts are infectious to humans and the organism can cause significant disease in immunocompromised people and transplacentally-infected babies. Clinical illness including liver disease, lung disease, central nervous system disease, fever, and uveitis occur in some infected cats. Veterinarians need to be able to identify T gondii infection in cats because of potential public health risks and during the workup of clinical diseased cats. Oocyst shedding by cats is of short duration, but can be detected by fecal examination. There are currently no serological tests that can accurately determine when a cat has shed oocysts in the past. The combination of serological test findings, clinical signs of disease, exclusion of other causes, and response to anti-Toxoplasma drugs is required to make the diagnosis of antemortem++ clinical toxoplasmosis in cats.     

Multicenter evaluation of a new commercial assay for detection of immunoglobulin M antibodies to Toxoplasma gondii. Multicenter Study Group

A new commercial assay for detection of IgM-specific antibodies to Toxoplasma gondii (IMx Toxo IgM, Abbott, USA), based on microparticle enzyme immunoassay technology, was evaluated at 15 clinical sites in Europe and the USA. Performance characteristics were established by testing clinical specimens collected randomly from pregnant women, blood donors, individuals with suspected Toxoplasma gondii infection and individuals confirmed HIV positive. Reference testing was performed using Toxo-M EIA (Abbott). Specimens evaluated at European sites yielding discordant results between the new assay and the reference EIA were further tested with an immunosorbent agglutination assay; at sites in the USA, discordant results were resolved using Platelia Toxo IgM (Sanofi, France) and Vidas Toxo IgM (bioMérieux, France) assays. In addition, matched plasma and serum, heat-treated and non-heat-treated specimens, and fresh and frozen specimens were evaluated at the USA sites. At European sites the new commercial assay had a sensitivity of 95.6% (196/205), a specificity of 99.8% (3,137/3,143) and an agreement of 99.6% (3,333/3,348) following resolution of discordant results; sensitivity in the USA was 97.4% (184/189), specificity was 99.8% (1,204/1,207) and agreement was 99.4% (1,388/1,396) following resolution. The new IMx Toxo IgM is a sensitive and specific assay for measurement of IgM antibodies to Toxoplasma gondii in human serum and plasma.     

Low seroprevalence of Toxoplasma gondii in feral pigs from a remote island lacking cats

Serum samples from 1,264 feral pigs from Ossabaw Island, Georgia were initially screened for antibodies to Toxoplasma gondii by the modified agglutination test (MAT) using whole-formalinized tachyzoites and mercaptoethanol. Seropositive samples were also tested by the Sabin-Feldman dye test, the latex agglutination test (LAT), and the indirect hemagglutination test (IHAT). Ossabaw Island is a remote, barrier island located southeast of Savannah, Georgia. Antibodies to T. gondii were found in 11 (0.9%) of 1,264 pigs. The antibody titers were 1:20 (1 pig), 1:80 (2 pigs), 1:160 (2 pigs), 1:320 (4 pigs), and 1:640 (2 pigs) by the MAT, and 1:8 (2 pigs), 1:16 (3 pigs), 1:32 (1 pig), 1:64 (2 pigs), 1:128 (1 pig), and > or = 1:256 (2 pigs) by the Sabin-Feldman dye test. By the LAT, 5 pigs had a titer of > or = 1:64 and by the IHAT all 11 pigs had a titer of < 1:64. Antibodies (MAT titer, > or = 1:25) were found in 31 (18.2%) of 170 feral pigs from mainland Georgia. This seroprevalence on the mainland was significantly higher (P < 0.0001) as compared on Ossabaw Island. The markedly low prevalence of T. gondii on Ossabaw Island was attributed to the virtual absence of cats on the Island; only 1 domestic cat was known to be present.     

Experimental toxoplasmosis in broiler chicks

To evaluate chicken toxoplasmosis both as an economic and a public health subject, 84 broiler chicks of a commercial strain, 30 days old, were distributed into seven groups of 12 birds (three replications of four chicks) experimentally infected with three developing T. gondii stages of the P strain as follows: tachyzoites, intravenous (two groups: 5.0 x 10(5) and 5.0 x 10(6)), cysts, per os (two groups: 1.0 x 10(2) and 1.0 x 10(3)) and oocysts, per os (three groups: 5.0 x 10(2), 5.0 x 10(3) and 5.0 x 10(4)). Twelve chicks received only a placebo (control group). During the next 30 days the following parameters were estimated: productivity (weight gain and feed conversion), clinical signs, including rectal temperature and parasitemia (bioassay). No clinical signs suggesting toxoplasmosis were seen and no statistical differences on productivity standards were found in comparison between inoculated and control chicks. However, fowls inoculated with tachyzoites and oocysts occasionally showed hyperthermia. Some haematological changes were detected in fowls inoculated with T. gondii. Anatomo-histopathological changes were not observed. From 14 parasitemias detected, 35.7% appeared on the 5th day after inoculation and 57.1% of them resulted from oocysts inoculation. After 30-35 days all birds were slaughtered: fragments from 12 organs or tissues from each of them were subjected to artificial peptic digestion and after that injected into T. gondii antibody-free mice (IIFR). T. gondii was detected in brain (12), pancreas (five), spleen (five), retina (five), kidney (two), heart (four), proventriculus (three), liver (two), intestine (two), lung (one), and skeletal muscle (one). Similar to observations with parasitemia, from 42 T. gondii isolations, 59.5% came from chicks which had received oocysts. It can thus be inferred that the developing form, expelled by cats, is the most important for T. gondii chicken infection and that brain is the most infected organ in birds. Attention must be paid to the potential importance of chicken meat in public health, since T. gondii was isolated from skeletal and heart muscles.     

Sex, Task, and Behavioral Flexibility Effects on Leadership Perceptions

We critically review and summarize information on the prevalence of Toxoplasma gondii infections in rats, mainly Rattus norvegicus, and their possible role as a source of infection for larger carnivores and omnivores. We also review information on immunology and natural resistance, contributing to the model value of rats in the analysis of human infection. Rats can be successfully infected with oocysts (sporozoites), tissue cysts (bradyzoites), and tachyzoites. Even adult rats, that are resistant to clinical toxoplasmosis, can be infected orally with a few oocysts or tissue cysts. Infections with tachyzoites of the RH strain are highly variable. Congenital transmission of T. gondii occurs at a high rate when rats are infected during pregnancy. Congenitally infected rats can harbor viable T. gondii in the absence of detectable antibodies to T. gondii and rats with low antibody titers may harbor few or no organisms. The isolation of viable T. gondii by bioassay is the only reliable means to determine persistence of chronic T. gondii infection in feral rats. No evidence was found for maintenance of T. gondii in rats by vertical transmission in the absence of cats.     

Caprine toxoplasmosis: abortion, clinical signs, and distribution of Toxoplasma in tissues of goats fed Toxoplasma gondii oocysts

Thirteen goats (9 does and 4 bucks) were each inoculated orally with 10,000 infective Toxoplasma gondii oocysts. Three does and one buck were used as noninoculated controls. In 2 to 4 days after inoculation (DAI), inoculated goats became dull, pyrectic (40 to 41 C), and anorectic. Three goats died (10, 10, and 14 DAI) and two goats were killed (7 and 32 DAI) because they were moribund; also, 3 does aborted, 2 had weak kids, and 2 had dead fetuses. Toxoplasma was isolated from the placenta of three goats, and the fetal tissues of four goats. The control goats remained asymptomatic. The distribution of T gondii in blood and other tissues was studied by inoculation of mice with caprine tissues. Parasitemia was detected in 7 of 7 goats--beginning 4 DAI in 1 goat, 5 DAI in 5 goats, and 8 DAI in 1 goat. The parasitemia lasted 3 to 10 days. Toxoplasma was isolated from the milk of 2 goats at 12 and 14 DAI. Toxoplasma was isolated from 15 or more tissues of 5 goats killed 7 to 35 DAI and from 10 tissues of 2 goats killed 69 and 95 DAI.     

SAMSON: a software package for the biopolymer primary structure analysis

One hundred and twenty seven patients belonging to Neurosurgery (49), Neuromedicine (48), Cardiac medicine (30) wards and Blood donors (30) as healthy controls were investigated for the prevalence of Toxoplasmosis by means of detecting specific IgM antibody against Toxoplasma gondii (T. gondii) employing Enzyme Immuno Assay (EIA). The detection rate of specific IgM antibody against T.gondii was found to be 32.7% (16/49) among Neurosurgery patients, 20.8% (10/48) among Neuromedical patients and 20% (6/30) among Cardiac medical patients. None of the voluntary blood donors tested was found to have T. gondii IgM antibody. Maximum prevalence rate was found among female patients undergoing Neurosurgery (42.3%) followed by Neuromedical patients (40%). There is an increasing rate of prevalence of Toxoplasmosis from the lower age group upto thirty years and a declining prevalence rate among the higher age groups. The present study revealed high prevalence rate of Toxoplasmosis in Neurosurgery patients (32.7%) and in particular among female (35.2%) than male (17.8%) patients.     

Elevated interleukin-10-to-interleukin-12 ratio in feline immunodeficiency virus-infected cats predicts loss of type 1 immunity to Toxoplasma gondii

Similar to human immunodeficiency virus, feline immunodeficiency virus (FIV) induces immunodeficiency and enhanced susceptibility to secondary pathogens. To explore cytokine alterations in lentivirus immunodeficiency, constitutive mRNA expression was measured in lymph nodes of healthy and FIV-infected cats before and after challenge with Toxoplasma gondii. Cytokine mRNA expression was similar in control and FIV-infected cats during the first 10 weeks after infection. At 16 weeks, interferon (IFN)-gamma, tumor necrosis factor-alpha, and interleukin (IL)-10 mRNA were increased in FIV-infected cats. Challenge with T. gondii induced an increase in IL-2, IFN-gamma, and IL-12 in the lymph nodes of control cats, whereas IFN-gamma and IL-10 but not IL-2 or IL-12 increased in the lymph nodes of FIV-T. gondii coinfected cats. These results indicate that FIV immunodeficiency may derive from a failure to generate an IL-12-dependent type 1 response and that an elevated level of IL-10 mRNA expression is a predictor of lentivirus immunodeficiency.     

Isolation and experimental transmission of Sarcocystis moulei Neveu-Lemaire, 1912

Of 44 several years old goats slaughtered in Kabul/Afghanistan 16 proved to be infected ith Sarcocystis moulei. The large white cysts measuring 2-16 x 1-9 mm were found exclusively in oesophageal muscle tissues of the animals. A total of 4 million sporocysts were harvested from mucosal scrapings of the small intestines of two young cats which had been killed 11 or 14 days after being fed with S. moulei-containing oesophagi of those goats. For transmission experiments in Berlin 11 kids from a S. moulei-free goat breeding as well as 5 Sarcocystis-free cats were used. In a preliminary experiment 3 young goats were orally inoculated with 200 or 2000 sporocysts from Kabul. In further consecutive trials each of the 8 remaining kids received 1000 sporocysts, which were isolated from the intestines of cats after feeding them S. moulei-cysts from successfully infected goats of the first experiment in Berlin. No cysts could be detected in oesophageal muscle tissues of two goats which were slaughtered 4 or 6 months after sporocyst application. Also no sporocysts were excreted by two cats which were fed with the oesophagi of those two animals. In oesophageal muscle tissues of the 9 remaining goats, which were slaughtered 19, 25, 43, 44, 59 or 86 months after infection, 17 to 140 macroscopically visible cysts of S. moulei were found. A definite correlation between age and size of cysts was observed. 19 months p.i. cysts measured 1-2 x 0.5-1 mm, at 43 or 44 months p.i. they were already 1-8 x 1-4 mm, and finally 86 months p.i. they reached a size of 7-13 x 5-8 mm. In H.E. stained histological sections cysts appeared to be subdivided into honeycomb like chambers by very prominent septae. In smaller cysts all chambers were filled with sickle shaped cystozoites, whereas in larger cysts only the chambers at the periphery contained cystozoites. Groups of metrocytes were seen within the cyst groundsubstance at the periphery of cysts indicating further growth, even of very large cysts. Cyst walls measured up to 10 microns in thickness and were composed of a primary and a secondary cyst wall. The thin primary cyst wall was folded irregularly to give cauliflower like protrusions, which were up to 4.4 microns high. The parasitized host cell formed a thick surrounding layer of 6 to 7.5 microns, which was covered by a 2 to 2.5 microns thick layer of connective tissue. All three cats which were fed with S. moulei-cysts in Berlin excreted S. moulei-sporocysts with their faeces. Prepatency was 10 days. A total of 100 sporocysts measured 11.6-13.1 x 8.7-9.4 microns.     

Laboratory test differences associated with HTLV-I and HTLV-II infection. Retrovirus Epidemiology Donor Study Investigators

Toxoplasmosis is caused by the protozoan organism, Toxoplasma gondii. Infection with this organism primarily results from contact with infected cats and from ingestion of improperly cooked meat. Most adults with toxoplasmosis are asymptomatic. When symptoms are present, they typically resemble a mononucleosis or flulike illness. The diagnosis of toxoplasmosis in the pregnant adult is best made using serological techniques to detect IgM antibody and to document significant changes in the IgG antibody titer. Congenital toxoplasmosis usually occurs as a result of primary maternal infection. The most useful tests for confirmation of fetal infection are ultrasound examination, cordocentesis for detection of IgM-specific antibody, and amniocentesis for detection of toxoplasma DNA in amniotic fluid. Congenital toxoplasmosis can be treated with reasonable success by administration of antibiotics (spiramycin, sulfadiazine, and pyrimethamine) to the mother. In an effort to prevent acquisition of infection, pregnant women should be counseled to avoid contact with cat litter and improperly cooked beef, pork, or lamb.     

Young people in transition: the relationship between homesickness and self-disclosure

To assess cell-mediated immunity to Toxoplasma gondii, we evaluated the expression of the activation antigens CD69, CD71, and CD25 on T lymphocytes by flow cytometry after specific in vitro stimulation of whole blood from 127 T. gondii-positive and 63 T. gondii-negative patients. T lymphocytes from many seropositive individuals did not express CD69 at 24 h after T. gondii antigen stimulation, but CD71 and CD25 were easily detectable on T cells from seropositive individuals 7 days after specific activation. CD25 was mainly expressed by stimulated CD4(+) T cells, and its detection on total T cells was both a sensitive (98%) and a specific (97%) indicator of prior T. gondii infection. These results make flow cytometric detection of CD25 an excellent candidate for screening cell-mediated immunity to T. gondii in vitro and an interesting tool for the diagnosis of congenital infection.     

Changes in the leukocyte phenotype profile of goats infected with the caprine arthritis encephalitis virus

The proportions of different sub-populations of leukocytes in five healthy goats and five goats infected with the caprine arthritis encephalitis virus (CAEV) were examined using immunofluorescence and flow cytometry. A panel of monoclonal antibodies that identified a monocytegranulocyte marker (GMI); the CD4, CD8, IgM, MHC Class I, MHC Class II and T19 antigens, and the gamma delta (gamma delta) T cell receptor was used. We observed a significant (P = 0.016) reduction in the proportion of monocytes in the peripheral blood of infected (5.98%) compared with healthy control goats (9.92%). There was also a decrease in the proportion of CD4+ T lymphocytes that approached significance (P = 0.076) accompanied by a slight increase in the proportion of CD8+ T lymphocytes, in infected compared with uninfected animals. Consequently, three of the five infected animals had lower CD4:CD8 ratios than any of the healthy animals and two of these three ratios were inverted. Approximately 14% of T cells in the peripheral blood of healthy goats was identified as gamma delta T cells and all expressed the T19 antigen. A significantly elevated level of gamma delta T cells (P = 0.030) and an elevated level of T19 cells were observed in infected, compared with healthy animals. The proportion of leukocytes expressing surface IgM (B cells) was also elevated, although not significantly, in CAEV-infected compared to healthy controls. The changes in peripheral blood leukocyte subsets in infected goats suggest that immune responses to the infection are probably altered in these animals with eventual progression to severe disease and death.