The minor role of pigs in outbreaks of foot-and-mouth disease of northern Thailand

SUMMARY: A study was undertaken in northern Thailand to examine the involvement of pigs in outbreaks of foot-and-mouth disease (FMD). Data were collected by surveying selected villages, by serological monitoring of pigs and by investigating outbreaks. Fifty-three of 58 villages (91%) surveyed reported that pigs did not develop FMD during the most recent outbreak. The source of 49/60 (82%) outbreaks was attributed to either recent purchases of infected cattle and buffalo or commingling of cattle and buffalo with stock from an infected neighbouring village. One of 60 villages (1.7%) reported that the source was introduced infected pigs. There was no association between the various hypothesised risk factors relating to the management of pigs and the frequency of FMD outbreaks in the survey. The percentage of seropositive pigs during 3 rounds of serological monitoring conducted at 6-monthly intervals in selected villages was 3.5%, 2.6% and 0%, respectively. No clinically affected pigs were observed in 11 outbreak investigations. It was concluded that pigs did not commonly become infected when there were outbreaks of FMD in village cattle and buffalo in northern Thailand. This was probably due to the pig feeding and housing practices employed by villagers that protected pigs from exposure to virus from infected cattle or buffalo, or their products.     

Investigation of an outbreak of foot-and-mouth disease in vaccinated dairy cattle in Thailand

SUMMARY An outbreak of foot-and-mouth disease that spread between two related vaccinated dairy herds was investigated. Although the cattle were of similar vaccination status, in one herd there was high morbidity, whereas in the other there was considerably lower morbidity. The relationship between the vaccine virus and the outbreak virus was expressed as an r value determined by the two-dimensional neutralisation test. Bovine serum homologous to the vaccine virus indicated a close antigenic relationship between the vaccine virus and the outbreak virus (r = 0.61). The source of the outbreak virus was not determined. The investigation suggested a requirement for close contact between stock for foot-and-mouth disease to spread in a tropical environment, in contrast to the capacity of the disease to spread considerable distances by aerosol transmission in temperate climates.     

Transplacental Transfer of Iron in the Water Buffalo (Bubalus bubalis): Uteroferrin and Erythrophagocytosis

The objectives of this investigation were to understand transplacental transport of iron by secreted uteroferrin (UF) and haemophagous areas of water buffalo placenta and clarify the role(s) of blood extravasation at the placental‐maternal interface. Placentomes and interplacentomal region of 51 placentae at various stages of gestation were fixed, processed for light and transmission electron microscopy, histochemistry and immunohistochemistry. Haemophagous areas were present in placentomes collected between 4 and 10 months of pregnancy. Perl’s reaction for ferric iron was negative in placentomes, but positive in endometrial glands. Positive staining for UF indicated areas in which it was being taken up by phagocytosis and/or fluid phase pinocytosis in areolae of the interplacentomal mesenchyme, with little staining in endometrial stroma. Imunohistochemistry detected UF in trophectoderm of haemophagous regions of placentomes and in other parts of the foetal villous tree, but the strongest immunostaining was in the epithelial cells and lumen of uterine glands. Ultrastructural analyses indicated that erythrophagocytosis was occurring and that erythrocytes were present inside cells of the chorion that also contained endocytic vesicles and caveolae. Results of this study indicate that both the haemophagous areas of placentomes and the areolae at the interface between chorion and endometrial glands are important sites for iron transfer from mother to foetal‐placental tissues in buffalo throughout pregnancy.     

Giardia infection in budgerigars

Budgerigars ( Melopsittacus undulatus ) from two different breeding colonies were found to have Giardia infection. Light microscopy, scanning electron microscopy and in-vitro and in-vivo studies confirmed the species was G psittaci . Chicks were clinically affected and showed signs of retarded growth, dehydration and diarrhoea. The faeces of adult birds treated with metronidazole in drinking water were negative for Giardia 5 days after treatment. Megabacteria were also found in adult birds but were not treated. This study extends the known host range for Giardia in Australia to include budgerigars.     

注射用头孢呋辛钠的安全性试验研究

通过试验研究对注射用头孢呋辛钠的安全性进行评价。采用豚鼠和家兔分别进行本品的全身用药过敏性、血管和肌肉局部刺激性及家兔红细胞体外溶血性试验研究。结果显示本品对豚鼠无明显全身过敏性、静脉注射对家兔耳缘静脉无明显局部刺激性、对家兔肌肉注射给药无明显局部刺激性、对家兔红细胞无明显体外溶血性。表明本品的各项安全性均良好,为实际应用提供了有力依据。     

Leptospira interrogans serovar hardjo is not a major cause of bovine abortion in Victoria

The aim of this study was to determine whether evidence could be obtained of foetal infection with Leptospira interrogans serovar hardjo in aborted foetuses collected from dairy farms. Material from 197 abortions occurring over a wide area of Victoria was collected over 3 years. None of 195 foetal kidney cultures or 7 cultures from membranes was positive for leptospiral organisms. Immunogold silver staining for leptospires was performed on sections of kidneys, lungs or heart from 156 foetuses, with negative results. Evidence of transient leptospiral infection in 11 of 123 foetuses was obtained by foetal heart blood serology. Two isolates of L. interrogans serovar hardjo were obtained from the urine of milking cows. These strains were examined by restriction endonuclease analysis and both were shown to be of the genotype Hardjobovis, as have been all Australian isolates studied so far. It appears that foetal infection with serovar hardjo is not associated with any substantial proportion of bovine abortions in Victoria, in contrast to the situation in Northern Ireland. The apparent absence from Victoria of the pathogenic genotype Hardjoprajitno is a possible explanation.