Prototheca zopfii mastitis in a herd of dairy cows

Mastitis caused by the colourless alga Prototheca zopfii was diagnosed in 17 of 120 cows in a dairy herd. Infection occurred in animals varying from 3-14 years old and was present in one to four quarters of each cow. Nine cases were associated with clinical mastitis characterised by the presence in milk of flakes or small clots. Somatic cell counts consistent with subclinical mastitis (>500 x 10(3) cells/ml) were recorded in five of the eight remaining cows. Histological examination of udder tissue showed the presence of granulomatous lesions associated with the presence of Prototheca. The problem was identified and controlled by repeated microbiological examination of milk samples from all lactating cows and immediate culling of infected animals. P. zopfii was also recovered from environmental water samples on this farm. It is suggested that infection may have occurred as a result of teat sores caused by trauma from a milking machine, and the tendency for cows to lay down on a race, the surface of which was sometimes flooded by drain water in which Prototheca were present.     

Colostral transfer of anti-nematode antibodies in cattle and its significance for protection

The transfer via colostrum of antibodies against Cooperia oncophora was demonstrated in 180 cow-calf pairs. Subsequently, at the age of 2.5 to 4 months, 47 calves were challenged with 100, 000 C. oncophora larvae. Previous acquisition of antibodies from colostrum did not influence the course of infection in these calves.     

Transmission and control of caprine arthritis-encephalitis virus

Caprine arthritis-encephalitis virus was isolated from goat milk and transmitted most efficiently to kids through both milk and colostrum. In addition, it appeared that transmissions through other secretions of the doe occurred, but were less important than transmission in milk and colostrum. Intrauterine infection may have occurred in 2 of 32 cesarean-derived goats, but postpartum horizontal transmission could not be ruled out. Transmission by the aerosol route was not demonstrated, and even short-term direct contact between virus-infected bucks and virus-free does during breeding did not result in transmission. Prolonged direct contact for over 12 months between weaned cesarean-derived goats and virus-infected goats was necessary before horizontal transmission could be demonstrated under nondairy conditions. However, when uninfected does were milked with infected does, a high percentage became infected in less than 10 months. Heat inactivation (56 C) reduced approximately 10(5) median tissue culture infective doses of caprine arthritis-encephalitis virus to below titratable levels, and virus was not transmitted to kids fed virus-infected colostrum that had been heated at 56 C for 1 hour. A program of eradication is discussed in which kids are removed from their dams at birth, fed safe sources of colostrum and milk, and isolated from other goats until weaning.     

Development of cell content and shedding of Prototheca spp. in milk from infected udder quarters of cows

It was the objective of this study to analyse shedding patterns and somatic cell counts in cows and quarters infected with Prototheca spp. and to evaluate two approaches to identify infected animals by somatic cell count (SCC) or by bacteriological analysis of pooled milk samples. Five lactating dairy cows, chronically infected with Prototheca spp. in at least one quarter were studied over 11 weeks to 13 months. Quarter milk samples and a pooled milk sample from 4 quarters were collected aseptically from all quarters of the cows on a weekly basis. Culture results of quarter milk and pooled samples were compared using cross tabulation. SCC of quarter milk samples and of pooled samples were related to the probability of detection in the infected quarters and cows, respectively. Shedding of Prototheca spp. was continuous in 2 of 8 quarters. In the other quarters negative samples were obtained sporadically or over a longer period (1 quarter). Overall, Prototheca spp. were isolated from 83.6% of quarter milk samples and 77.0% of pooled milk samples of infected quarters and cows. Somatic cell counts were higher in those samples from infected quarters that contained the algae than in negative samples (p < 0.0001). The same applied for composite samples from infected cows. Positive samples had higher SCC than negative samples. However, Prototheca spp. were also isolated from quarter milk and pooled samples with physiological SCC (i.e. < 10(5)/ml). Infected quarters that were dried off did not develop acute mastitis. However, drying off had no effect on the infection, i.e. samples collected at calving or 8 weeks after dry off still contained Prototheca spp. Results indicate that pre-selection of cows to be sampled for Prototheca spp. by SCC and the use of composite samples are probably inadequate in attempts to eradicate the disease. However, due to intermittent shedding of the algae in some cows, single herd sampling using quarter milk samples probably also fails to detect all infected cases. Therefore, continuous monitoring of problem cows with clinical mastitis or increased SCC in herds during eradication programs is recommended.     

Prototheca zopfii mastitis in a herd of dairy cows

Mastitis caused by the colourless alga Prototheca zopfii was diagnosed in 17 of 120 cows in a dairy herd. Infection occurred in animals varying from 3–14 years old and was present in one to four quarters of each cow.

Nine cases were associated with clinical mastitis characterised by the presence in milk of flakes or small clots. Somatic cell counts consistent with subclinical mastitis (>500 × 10³ cells/ml) were recorded in five of the eight remaining cows.

Histological examination of udder tissue showed the presence of granulomatous lesions associated with the presence of Prototheca.

The problem was identified and controlled by repeated microbiological examination of milk samples from all lactating cows and immediate culling of infected animals.

P. zopfii was also recovered from environmental water samples on this farm. It is suggested that infection may have occurred as a result of teat sores caused by trauma from a milking machine, and the tendency for cows to lay down on a race, the surface of which was sometimes flooded by drain water in which Prototheca were present.     

猪流行性腹泻IgA、IgG抗体与PEDV抗原相关性研究

为了研究仔猪所吮乳汁中IgA抗体水平与乳汁中PEDV感染情况,探讨母猪免疫猪流行性腹泻疫苗后乳汁与血清中IgA、IgG抗体水平的相关性,临床采集多家规模化猪场母猪群乳汁、血清样品以及发病仔猪所吮母猪乳汁样品。采用实验室已经建立的IgA、IgG抗体ELISA方法,检测临床上猪流行性腹泻疫苗免疫后IgA抗体与IgG抗体的相关性,同时采用RT-PCR方法检测发病仔猪所吮乳汁中PEDV感染情况。结果表明,免疫猪流行性腹泻活疫苗后母猪乳汁中IgA抗体水平与血清中IgA、IgG抗体水平呈现很好的正相关性;当发病仔猪所吮母猪乳汁IgA抗体检测结果为阴性时,其PEDV抗原检测结果为阳性;乳汁IgA抗体检测结果趋于阳性样品临界值时,其PEDV抗原检测结果亦为阳性。结论:乳汁中低水平的IgA抗体很难有效地保护仔猪抵御PEDV感染;乳汁中IgA抗体与血清IgA、IgG抗体呈现很好的相关性,且乳汁中IgA抗体水平远远高于血清;通过IgG抗体水平可以间接反映乳汁中的IgA抗体水平,在初乳样品采集难度较大的情况下,可用于间接评估猪流行性腹泻免疫保护水平。     

Passive immunity and serological immune response in dairy calves associated with natural Giardia duodenalis infections

In a previous study, Giardia infection patterns were studied in newborn dairy calves over a 4-month period. Chronic Giardia infections were observed in all calves with initial cyst excretion occurring at approximately 1 month of age. In the work presented here, the passive immunity and serological immune response associated with these Giardia infections were examined. Colostrum and milk samples were collected from the dams of these calves, and monthly serum samples were collected from each calf. The colostrum, milk and sera samples were analyzed by ELISA and Western blot for the presence of anti-Giardia IgG antibodies. In addition, the in vitro anti-Giardia activity of milk and colostrum was examined using a miniculture adherence assay. When examined by ELISA, mean anti-Giardia antibody titres were found to be significantly higher in colostrum compared to milk. The monthly mean serum antibody titres in the calves were not found to differ significantly at any time point during the study. Western blot analysis revealed that colostrum from the dams reacted strongly with many different Giardia antigens between 205 and 7.5kDa, while milk reacted with few antigens in the same size range. Sera collected from the calves when 30 and 60 days of age reacted with few Giardia antigens, but as the calves aged, IgG antibodies in their sera began to react with antigens of 21, 50, 65, 73 and 79kDa. The miniculture adherence assay demonstrated that colostrum had significantly more anti-Giardia activity in vitro compared to milk. These results suggest that the calves in this dairy did not mount a significant humoral immune response against Giardia following infection. However, colostrum contained a high level of anti-Giardia antibodies and exhibited anti-Giardia activity in vitro. Therefore, colostrum may have the potential to provide initial protection against Giardia infections in calves, but the lack of a strong, specific humoral immune response by these calves could account for the high prevalence and chronic duration of the infections.     

Infection of the Bovine Udder with Bovine Herpesvirus

Infectious bovine rhinotracheitis — infectious pustular vulvovaginitis (bovine herpesvirus) grown in tissue culture was used as inoculum in trials to infect the lactating bovine udder. Six experiments were undertaken in which one or more quarters were infused with 1 ml. of tissue culture fluids containing 10⁶ to 10⁷ tissue culture infectious doses (TCID) of virus. In four of the experiments the inoculated quarters showed marked evidence of infection in the form of acute inflammation, swelling, reduced milk secretion and profound changes in the physical appearance of the milk. In each case virus was recovered in high titres in the milk from about the second until the tenth to fifteenth days following exposure. Uninfected quarters remained normal in appearance and virus could not be recovered from the milk.

In three of the experiments it was shown that serum and milk antibodies appeared shortly after the disappearance of virus from the milk. One experiment involving two animals showed that about 1000 TCID of virus were required to produce infection. In one experiment a cow having a pre-inoculation serum titre for bovine herpesvirus proved resistant to infection.

The experiments indicate that the bovine udder is readily susceptible to bovine herpesvirus in non-immune animals, and that the virus produces an acute, limited infection leading to a temporary disfunction of the gland. It appears that natural invasion of the udder through the teat canal is not readily accomplished by the virus.

     

Immunity to Escherichia coli in Pigs. The Role of Milk in Protective Immunity to E. coli Enteritis

Milk whey from immunized sows increased the survival time of gnotobiotic piglets infected with Escherichia coli. The survival time of infected piglets fed milk whey from non-vaccinated sow's was the same as that of similar pigs fed condensed cow milk.

The significance of milk antibodies in immune protection against E. coli enteritis is discussed and compared with that of absorbed colostral antibodies. From calculations presented it would appear that seven day old piglets receive approximately 1 g of gamma globulin daily from milk and that this is equal to the piglets total serum gamma globulin content. After seven days of age the gamma globulin content of piglet serum falls, whereas that of milk remains constant; milk is, therefore, potentially a major source of immunoglobulins with protective activity against E. coli associated enteritides.

     

Variations in the immune response to natural Schistosoma mattheei infections in calves born to infected mothers

During previous work Schistosoma antibodies and circulating antigens were detected at birth in the serum from some calves born to Schistosoma mattheei infected mothers. The objectives of the present survey were: (1) to investigate the proportion of calves, born to cows infected with S. mattheei, which have specific antibodies and circulating schistosome antigens present in their serum at birth and (2) to investigate whether the presence or absence of these specific antibodies and/or circulating antigens at birth may affect the pattern of a natural S. mattheei infection in calves from 4 to 5 months of age, when the colostral antibodies are thought to be of negligible importance. A total of 28 calves born to infected mothers were randomly selected. Faeces, serum and colostrum samples were collected from the cows at calving, serum samples were collected from the calves at birth (day 0), after intake of colostrum (day 1) and monthly thereafter up to the age of 10 months. Both serum and colostrum samples were analysed for IgG(H+L) against SWAP mattheei and schistosome circulating anodic antigen (CAA) levels. The calves were exposed to a natural challenge from the age of 4-5 months. Faecal samples were collected from the calves monthly, starting at an age of 5 months up to 10 months, and were examined for faecal egg counts. Nine (group 1) out of the 28 calves were found to have specific antibodies in their serum at birth, in 5 of them CAA levels were also detected. In the other 19 calves (group 2) no IgG(H+L) or CAA were detected. At the end of the study faecal egg counts and CAA levels were significantly lower in calves from group 1 compared to group 2. Results confirm earlier work that specific antibodies and circulating antigens may be present in serum from calves at birth, and show that these calves have lower faecal egg counts and CAA levels after exposure to a natural challenge.     

A survey of Prototheca bovis infection in dairy farms of the Hubei province,China

Bovine mastitis, caused by Prototheca bovis, has received much attention worldwide. To investigate the status of P. bovis infection in dairy farms of Hubei, we collected 1,158 milk samples and 90 environmental samples from 14 dairy farms of Hubei, China. The isolates were identified with traditional biological methods and molecular biological techniques, and their pathogenicity was tested through mice infection experiments. Isolates from 57 milk and 20 environmental samples were identified as P. bovis. The mice infection tests proved that the isolated P. bovis could cause mastitis in mice, manifesting as severe red swelling of the mammary glands. Histopathological analysis of tissue sections showed necrosis and nodules lesions formed in the infected mice mammary tissue, accompanied by macrophage and neutrophil infiltration. These results suggested the existence of pathogenic P. bovis in dairy farms of the Hubei province, China, with brewer’s grains and fresh feces possibly playing important roles in the spread of this disease.     

Studies on transmission of maedi virus to lambs

Lambs born to 5 ewes in 3 successive years were studied for presence of maedi virus and its antibodies. In the middle of the first-year pregnancies the ewes and the only ram of the colony were inoculated with maedi virus. No antibodies or viraemia could be detected in the lambs at birth. After sucking colostrum, antibodies appeared in the lambs of the ewes which themselves were seropositive, and reached their peak in a few days. Maternal antibodies disappeared within 12 weeks in all the lambs. Neutralizing antibodies were demonstrated in the colostrum and their content declined rapidly after lambing. Virus was isolated from the milk of 2 ewes in the third year of the studyIn the first year the spread of maedi virus was demonstrated to only 1 of the lambs, but in the other 2 years maedi virus was detected in tissues of half of the lambs sacrificed at 3–12 weeks of age. It was concluded that lambs born to chronically infected ewes are readily infected, indicating excretion of virus by ewes. The study yielded no information on the specific routes of transmission, except for the finding of the virus in milk of 2 ewes in the third year of the study. No evidence was obtained of transplacental transmission of maedi.     

Persistent shedding of Salmonella enteritidis from the udder of a cow

Salmonella enteritidis phagetype 8 was isolated from ill humans, milk-line filters, milk from a bulk tank, and milk from the right hind quarter of a five-year-old Holstein cow on a dairy farm in southern Alberta. The affected animal was removed from the herd and continued to shed S. enteritidis from this quarter during a seven-month interval in an isolation facility. Milk from the affected quarter was visually normal, and no other pathogen was isolated from the udder during the investigation. After removal of the infected cow from the herd, milk from the bulk tank was culturally negative for Salmonella sp. during the succeeding 15 months.     

Systemic and local immune response of cows to intramammary infection with Staphylococcus aureus

The association between Staphylococcus aureus chronic mammary gland infection and the resulting immune response expressed by the production of specific IgG and IgA antibodies in blood and milk was studied in Israeli Holstein cows. Specific antibodies of the IgG class were detected in sera of 82.6 per cent of the cows chronically infected by S aureus, while in 17.4 per cent no such antibodies could be detected. Specific IgG antibodies to S aureus were neither detected in sera of cows free of mammary infection nor in those infected with different coagulase-negative staphylococci (CNS) such as S intermedius, S chromogenes or S haemolyticus. In milk, specific IgG antibodies to S aureus were detected only in cows with positive serology. The end point dilutions in the milk were 5 to 30 per cent of that of blood from the same cow. No significant difference in IgG titres was found in the same cow if the quarter was infected with S aureus or not. Specific antibodies to S aureus of the IgA class could not be detected in the sera of any of the cows included in this study. In milk, a specific IgA antibody was detected only in the samples from the S aureus infected quarters in which S aureus was isolated at the time of the experiment. In the same cow, quarters infected by S aureus were found to have a significantly higher IgA titre (P < 0.0001) than that of the non-infected ones.     

Humoral immune response of water buffalo monitored with three different antigens of Toxocara vitulorum

Humoral immune response of water buffalo naturally infected with Toxocara vitulorum was monitored using three different antigens of this parasite in serum and colostrum of buffalo cows and calves. Soluble extract (Ex) and excretory/secretory (ES) larval antigens and perienteric fluid antigen (Pe) of adult T. vitulorum were used to measure the antibody levels by an indirect ELISA. Serum of 7-12 buffalo cows for the first 365 days and colostrum of the same number of buffalo cows for the first 60 days of parturition, and serum of 8-10 buffalo calves for the first 365 days after birth were assayed. The ELISA detected antibodies against all three T. vitulorum antigens in the colostrum and serum of 100% of buffalo cows and calves examined. The highest antibody levels against Ex, ES and Pe antigens were detected in the buffalo cow sera during the perinatal period and were maintained at high levels through 300 days after parturition. On the other hand, colostrum antibody concentrations of all three antigens were highest on the first day post-parturition, but decreased sharply during the first 15 days. Concomitantly to the monitoring of immune response, the parasitic status of the calves was also evaluated. In calves, antibodies passively acquired were at the highest concentrations 24 h after birth and remained at high levels until 45 days coincidentally with the peak of T. vitulorum infection. The rejection of the worms by the calves occurred simultaneously with the decline of antibody levels, which reached their lowest levels between 76 and 150 days. Thereafter, probably because of the presence of adults/larvae stimulation, the calves acquired active immunity and the antibodies started to increase slightly in the serum and plateaued between the days 211 and 365. All three antigens were detected by the serum antibodies of buffalo calves; however, the concentration of anti-Pe antibody was higher than anti-EX and anti-ES, particularly after 90 days of age. By conclusion, the buffalo cows develop immunity and keep high levels of antibodies against T. vitulorum-Ex, ES and Pe antigens and these antibodies are transferred to their calves through the colostrum. This passively acquired immunity does not protect the calves against the acquisition of the infection, but these antibodies, passively or actively acquired, may have an important role during worm rejection by the calves and prevention of intestinal reinfection.     

Effect of passive immunity on the development of a protective immune response against bovine viral diarrhea virus in calves

OBJECTIVE: To determine whether passively acquired antibodies prevent development of a protective immune response to live virus in calves. ANIMALS: 18 calves. PROCEDURES: Calves were caught immediately after birth and tested free of bovine viral diarrhea virus (BVDV) and serum antibodies against BVDV. Within 48 hours, 12 calves were fed colostrum that contained antibodies against BVDV and 6 calves received BVDV antibody free milk replacer. Three milk replacer fed and 6 colostrum fed calves were exposed to virulent BVDV2-1373 at 2 to 5 weeks of life when passively acquired serum antibody titers were high. After serum antibody titers against BVDV had decayed to undetectable concentrations (at 7 to 9 months of age), the 3 remaining milk replacer fed calves, 6 colostrum fed calves previously exposed to BVDV2-1373, and 6 colostrum fed calves that had not been exposed to the virus were inoculated with BVDV2-1373. RESULTS: Passively acquired antibodies prevented clinical disease in inoculated colostrum fed calves at 2 to 5 weeks of life. Serum antibody titers did not increase in these calves following virus inoculation, and serum antibody titers decayed at the same rate as in noninoculated colostrum fed calves. Inoculated colostrum fed calves were still protected from clinical disease after serum antibody titers had decayed to nondetectable concentrations. Same age colostrum fed calves that had not been previously exposed to the virus were not protected. CONCLUSIONS AND CLINICAL RELEVANCE: A protective immune response was mounted in calves with passive immunity, but was not reflected by serum antibodies titers. This finding has implications for evaluating vaccine efficacy and immune status.     

Rotaviral antibodies in cow's milk.

In the past, it has been reported that neonatal diets made from unheated cow's milk were superior to those made from heated cow's milk. It was observed that piglets were equally protected from rotaviral diarrhea when they were fed diets made from either unheated milk that came from a cow immunized against porcine rotavirus or from a cow that was not immunized. Because of this observation, we examined four pools of "normal" cows' colostrum and 58 samples of "normal" cow's milk for the presence of antibody to rotavirus. All pools of colostrum, collected in four different years, had immunofluorescent antibody titers of 1:100 to rotavirus. Seventy-two percent of the samples of milk were also positive--titer no higher than 1:10. Antibodies to rotavirus were found in cow's milk at a creamery prior to but not after pasteurization. Rotaviral antibodies were detected in one out of eight brands of milk bought at the market--perhaps indicating inadequate pasteurization for this brand. These results support the proposition that, at least in part, unheated milk is superior to heated milk because unheated milk contains antibody to an ubiquitous enteropathogen like rotavirus.     

Trypsin Inhibitor and Immunoglobulins in Porcine Colostrum

The specific trypsin inhibitor in porcine colostrum first described by Laskowski et al. (1957) is assumed to protect maternal antibodies in colostrum during absorption from the gut of the neonatal piglets (Baintner 1973). Investigations of Jensen & Pedersen have shown that the serum levels of IgG and IgA in newborn suckling piglets depend on both the immunoglobulin and the trypsin inhibitor levels in the colostrum of their mothers. Accordingly, the sow colostrum trypsin inhibitor (SCTI) is essential in order to ensure optimal systemic antibody protection to the newborn and young piglets. The secretory IgA in colostrum and milk, which gives local passive immunity to the gastro-intestinal tract of the piglets (Bourne 1973), is assumed in itself to be relatively resistant against proteolytic degradation (Tomasi & Bienenstock 1968).     

Bovine mycoplasma mastitis from intramammary inoculation of small numbers of Mycoplasma bovis. I. Microbiology and pathology

Intrammary inoculation of 70 colony forming units (cfu) of Mycoplasma bovis into one quarter of four previously non-infected cows resulted in severe mastitis in inoculated and uninoculated quarters. Hematogenous spread of the infection was most likely, as mycoplasma was isolated from the peripheral blood of three of four cows and the milking machine was designed to prevent quarter to quarter communication of milk and air. The presence of large numbers of mycoplasma exceeding 10⁶ cfu/ml of milk preceded the onset of overt sero-purulent mastitis by 1–3 days. In general, the severity, duration of the infection and within cow spread of mastitis to adjacent quarters after the inoculation of 70 cfu was indistinguishable from naturally occurring mycoplasma mastitis.The pathology of the chronically infected quarters consisted of alveolar involution and moderate to severe mononuclear infiltration and an increase in interalveolar and loose connective tissue. The quarters of one cow resolving the infections at the time of slaughter were not as severely affected and contained numerous milk-producing alveoli and many alveoli with hyperplasia of the alveolar cells.