Improving the quality of data entry in a low-budget head injury database.

BACKGROUND: To assess the efficacy of a centralised review of a voluntary low-budget head injury database with a retrospective analysis of data before and after a centralised review. METHOD: A computerised data collection (Neurolink) on traumatic brain injury cases admitted to three neuro-intensive care units in Milan (Italy): analysis of a three-year period (1999-2001). Data from 499 patients (epidemiology, type of lesion, clinical course, monitoring, treatment, complications and outcome). The audit involved a review of forms relating to patients enrolled in the three-year period, with the aim of improving the quality of data entry. Missing data in all empty fields were identified; evident errors and contradictory data were identified and corrected; missing and final data were analysed to test the efficacy of the review. FINDINGS: The total post-review missing data rate was significantly lower than the paired pre-review missing data rate (p = 0.001). The same was confirmed for each of the 3 years (p = 0.001 for each year). The missing data rate significantly improved over the three-year period (p = 0.001). Data for the pre-hospitalisation period had the highest missing rates; data regarding the ICU stay showed the greatest improvement after the review. A total of 407 items (0.44%) were identified as errors. CONCLUSIONS: Data quality is fundamental to avoid information bias in database analysis. This study indicates that it is possible to generate a serious data collection without significant resources. Audit seems to be an important tool before the final data is used for scientific projects.

A study of some pathogenetic aspects of bovine viral diarrhea virus infection.

The cytopathic (CP) strain TVM-2 of bovine virus diarrhea virus (BVDV) induced in calves a severe disease, whereas the calves inoculated with the non-cytopathic (NCP) New York-1 strain, remained clinically normal. When calves were immunosuppressed with dexamethasone (DMS) they underwent an overt, generally fatal disease. This result was obtained with either the CP and the NCP strain of BVDV. It was speculated that the immunosuppressive activity of BVDV could be a property peculiar to certain isolates of the virus.

A further study on relationships between herpes simplex virus and Bovid herpesvirus-2.

Calves exposed by intravenous or intradermal inoculation with Herpes simplex virus (HSV), types 1 and 2, remained clinically normal and HSV was not recovered from nasal secretion nor blood samples. However, the clinical response of calves pre-inoculated with HSV, to Bovid herpesvirus-2 (BH-2) challenge infection was much milder than that in the challenge control calves, and the titer of BHV-2 by skin titration underwent a significant (2-2.5 log units) reduction in the HSV pre-inoculated calves. Inoculation of calves with live HSV provided a much greater protection against BHV-2 challenge infection compared with the results of previous experiments in which a Triton X100-inactivated HSV antigen was used. It was speculated that the possibility of HSV replicating in cattle must still be considered an open question.

A study of some pathogenetic aspects of bovine viral diarrhea virus infection.

The cytopathic (CP) TVM-2 strain of bovine viral diarrhea virus (BVDV) induced in calves a severe disease, characterized by the clinical picture which is usually reported for the acute primary infection observed under natural conditions. In contrast, the calves inoculated with a different biotype of BVDV, the non-cytopathic (NCP) New York-1 strain, remained clinically normal with the only evidence of virus replication in these calves being the recovery of the virus from their pharyngeal swabbings and blood and also the detection of specific neutralizing antibody in their serums. When calves were immunosuppressed with dexamethasone (DMS), they underwent an overt systemic disease of such a severity that in most of the cases it ended with the death of the animals. This result was obtained with either the CP and the NCP strain of BVDV. Finally, the mixed infection that was obtained in the calves with the CP and the NCP BVDV did not result in any particular unexpected pathological situation. It was speculated that the immunosuppressive activity of BVDV could be a property peculiar to certain isolates of the virus.

Immunization against bovine rotaviral infection.

Calves fed with colostrum from cows vaccinated with an inactivated rotavirus vaccine were refractory to experimental infection with strain 81/36F of bovine rotavirus. In the field study, 458 pregnant cows from 26 herds were involved. In each herd, cows were selected and randomly subdivided in two groups. Cows in one group (248 head in total) were vaccinated, whereas cows in the other group (210 head in total) were left as unvaccinated controls. At calving, colostrum was collected from each cow and stored at -30 degrees C until used for feeding calves. The newborn calves, beginning the second day of life and for the next 7-10 days, were each fed a daily supplement of 400 ml of colostrum from its dam. The diarrhea occurred in 86 (40.9%) calves that had received colostrum from unvaccinated dams (normal colostrum), and in 7 (2.8%) calves which were fed colostrum from vaccinated dams (immune colostrum). The disease was very severe in the normal colostrum-fed calves and 52 of them died. By contrast, the 7 immune colostrum-fed calves displayed a rather mild enteric condition, and all recovered without any sequela being observed.

Further studies on passive immunization of newborn calves against rotaviral infection.

An inactivated rotavirus vaccine was prepared with an adjuvant which gives a water-in-oil emulsion. The vaccine when injected into cows in their last month of pregnancy, proved to be as effective as the traditional vaccine, prepared with the Freud's incomplete adjuvant, in enhancing the lactogenic immunity. Thus, feeding experimentally infected calves with colostrum and first milk from vaccinated cows prevented diarrhea and reduced significantly rotavirus shedding. Because of its low grade viscosity the water-in-oil emulsifier facilitates inoculation of the vaccine and is therefore recommended as an adjuvant in the preparation of inactivated rotavirus vaccine.

The protection of newborn calves against experimental rotavirus infection by feeding mammary secretions from vaccinated cows.

Pregnant cows were given the first injection of an inactivated bovine rotavirus vaccine approximately 4 weeks before calving and a second injection just before calving. This led to the enhancement of rotavirus antibody titers in their colostrum as well as in the milk for at least 5 days after parturition. Thus, when newborn calves were fed with the mammary secretions obtained from the vaccinated cows daily for 5 consecutive days they were fully refractory to experimental infection with 81/36F bovine rotavirus. By contrast, the calves which were given the mammary secretions from unvaccinated cows, had clinical signs consistent with rotavirus infection and viral shedding. Based on these results it is suggested that vaccination of cows according to the scheme followed in this experiment, i.e., two injections within the last month of pregnancy, might be a valid approach which depending on confirmation under field conditions, could help reduce the incidence of rotavirus-induced diarrhea in newborn calves.

Neonatal calf diarrhea induced by rotavirus.

This presentation summarizes the results of a comprehensive study on rotaviruses isolated in Italy from calves and rabbits affected by neonatal diarrhea. The results clearly indicated that rotavirus infection is widespread and supported the evidence for an etiologic role of these viruses in neonatal diarrhea. The evidence of differences in virulence among bovine rotaviruses appeared also to be confirmed. Conventionally reared calves were fully susceptible to the experimental infection induced by three rotaviruses originating from heterologous hosts, i.e. monkeys, pigs and rabbits, respectively. When rotavirus strains of bovine, simian, porcine and rabbit origin were compared by cross neutralization tests, it was found the simian and porcine strains were indistinguishable and both appeared to relate antigenically to the bovine strain. On the other hand, a reciprocal antigenic correlation was found between bovine and rabbit isolates. Finally, it was proven that feeding newborn calves with colostrum of their dams, previously vaccinated with an inactivated rotavirus vaccine, could prevent the neonatal diarrhea from occurring.

Comparative study of two strains of Bovid herpesvirus-4.

Two strains of Bovid herpesvirus-4 (BHV-4), i.e. the prototype strain DN-599, obtained from a steer suffering of a respiratory disease, and the strain 85/BH 16TV, originated from a cow with vulvovaginitis, were compared in studies which included restriction endonuclease analysis, experimental infection and reciprocal cross protection tests. The restriction endonuclease analysis revealed that the resultant DNA patterns of the isolates were generally similar with only a difference in one fragment. The two strains were capable of causing respiratory tract infection in calves, even if they displayed a different level of virulence: the strain 85/BH 16TV being the most virulent while the strain DN-599 the least. The two viral strains were mutually protective in that the calves were generally found to be refractory to challenge inoculation with either the homologous or the heterologous virus. Finally, both viral strains failed to evoke the production of neutralizing antibody in the experimental calves.

Field trial evaluation of an inactivated rotavirus vaccine against neonatal diarrhea of calves.

Field trials were conducted using an inactivated rotavirus vaccine for prevention of calf neonatal diarrhea. For the trials, 458 pregnant cows from 26 herds were involved. In each herd, cows which had been inseminated within a period of two months were selected and randomly subdivided in two groups. Cows in one group (248 head in total) were vaccinated 6 weeks before calving and again 4 weeks later; cows in the other group (210 head in total) were left as unvaccinated controls. At calving, colostrum was collected from each cow and stored at -30 degrees C until used for feeding calves. The newborn calves, beginning the second day of life and for the next 7-10 consecutive days, each was fed a daily supplement of 400 ml of colostrum from its dam. The diarrhea occurred in 86 (40.9%) calves that had received colostrum from unvaccinated dams (normal colostrum), and in 7 (2.8%) calves which were fed colostrum from vaccinated dams (immune colostrum). The disease was very severe in the normal colostrum-fed calves and 52 of them died. Those calves which survived the disease underwent a significant loss of condition. By contrast, the 7 immune colostrum-fed calves displayed a rather mild enteric condition, and all recovered without any sequela being observed.

Reactivation in calves of latent infection by Bovid herpesvirus-4.

Nine calves, six of which had been infected with strain 85/BH 16TV and three with strain 85/BH 232TN of Bovid herpesvirus-4 (BHV-4), were treated with dexamethasone (DMS) three months after infection. DMS administration did not induce any clinical signs of disease, but BHV-4 was isolated from the nasal swabbings of all calves for a maximum of 8 days after the start of DMS treatment. The virus was also isolated from the nerve tissues, nasal mucosa, lymph nodes, lung and spleen of 4 calves that were killed at different stages (3, 5, 7 days) of the DMS treatment. Intranuclear inclusions associated with cellular shrinkage were found in the neural tissues of calves killed either 3 or 5 days after the start of DMS treatment. Unexpectedly, a latent infection by infectious bovine rhinotracheitis (IBR) virus was reactivated. The virus was isolated from the nasal swabbings of two calves and also from the brain, cerebellum and nasal mucosa of one calf killed 5 days after the start of DMS treatment.

Experimental infection of calves with strains of Bovid herpesvirus-4.

Fourteen calves were inoculated intranasally (i.n.) with the viral isolates as follows: 5 with 85/BH 16TV, 1 with 85/BH 17TV, 1 with 85/BH 18TV, 2 with 85/BH 231TN and 5 with 85/BH 232TN. Strain 85/BH 16TV was the only one which caused overt respiratory-like disease in all inoculated calves. Onset of the disease was observed after 7-8 days of incubation and was characterized by fever, depression, nasal discharge and coughing. Virus was isolated from the nasal swabbings of calves obtained from post-infection day (PID) 2-10. The other viral strains did not cause any sign of disease although virus was isolated regularly from the nasal swabbings of the inoculated calves. Virus was recovered from central nervous system tissues of calves that were infected with 85/BH 16TV or 85/BH 232TN strains and were killed on PID 4 or 8. Virus was also isolated from other tissues, such as lymph node, nasal mucosa (PID 8), or lung (PID 4). It was speculated that the nervous system could be one of the target areas of the virus of the naturally occurring infection by BHV-4. This might indicate a possible role of the nervous system (site of latency?) in the pathogenesis of BHV-4 as is the case in certain herpesviral infections of man and the lower animals.

A comparison of rotavirus strains of bovine, simian and porcine origin.

Three rotavirus strains of bovine, simian and porcine origin, respectively, were compared. The 3 viruses induced a classic rotaviral infection in newborn, conventionally reared calves. The cross neutralization tests revealed an antigenic identity of simian and porcine rotaviruses and a slight serologic correlation of these two viruses with the bovine rotavirus strain. However, in reciprocal cross protection tests carried out in calves, the simian rotavirus antiserum afforded weak protection to challenge infection with either the porcine or the bovine viruses. By contrast, the protective level of the bovine and the porcine rotavirus antisera was relatively high. It was speculated that the 81/36F bovine rotavirus could be considered, tentatively, as an antigenic reassortant rotavirus strain.

Response of calves previously inoculated with inactivated herpes simplex virus to challenge exposure with Bovid herpesvirus 2.

Concentrated antigen of Herpes simplex virus (HSV) types 1 and 2, previously inactivated with Triton 100X, were inoculated into calves. Thirty-two days later the calves were challenge exposed either by the intradermal or the intravenous route with Bovid herpesvirus 2 (BHV 2). The HSV-immune calves responded to BHV 2 infection with clinical signs which were much less severe that those observed in the challenge control calves. The skin lesions in the calves exposed to intravenous inoculation of BHV 2, were fewer in the calves in the HSV-immune group, whereas they were heavily disseminated, covering the skin of the entire body, in the control calves. In the case of calves which received BHV 2 intradermally, the titer of the virus underwent a reduction of more than one log unit in the pre-immunized calves. The most significant serologic finding was that the HSV-preimmunized calves produced antibody to the BHV 2 challenge virus at an earlier time than did the control calves. The immunologic relationship between BHV 2 and HSV was confirmed by the results of this study.

Comparative studies of strains of infectious bovine rhinotracheitis virus isolated from latently infected calves.

Three strains (479 C, 778 TL, 982 LE) of infectious bovine rhinotracheitis (IBR) virus isolated from latently infected calves were compared with the prototype strain of IBR virus (LA strain) in studies which included restriction endonuclease analysis, experimental infection, and reciprocal cross protection tests in cattle. From the restriction endonuclease analysis it appeared that the 3 "latent" viruses were derived from the same isolate, and that it differed slightly from the LA strain. However, latency does not seem to have affected the pathogenicity or the immunogenicity of the virus. This is demonstrated by the identical clinical and virologic response of calves subjected to experimental infection with the various strains under study, and by the finding that when the LA strain and a "latent" strain (982 LE) were tested in cross protection tests in cattle, they proved to be mutually protective.

The efficacy of colostrum from cows vaccinated with rotavirus in protecting calves to experimentally induced rotavirus infection.

Calves which were continuously fed colostrum from vaccinated cows for the first ten days of life, were fully refractory to experimental infection with strain 81/36 F of bovine rotavirus. By contrast, the response to virus exposure of calves which were treated with normal colostrum was identical to that of the control calves, in that they underwent severe diarrhea and a significant slowing of the growth rate. The antibody titer in the milk of vaccinated cows tends to decline rapidly so that it no longer provides any protective effect. Two alternatives were considered feasible in improving prophylaxis for rotavirus infections: (a) the continuous feeding of calves with 1st day colostrum as part of the ration throughout the period of greatest risk (first week of life), or (b) enhancing the efficacy of the vaccine in pregnant cows to the point where antibody concentration in the milk would remain at a protective level.

Comparative study of rotavirus strains of bovine and rabbit origin.

Newborn calves were susceptible to infection with a rotavirus strain isolated from rabbits and, conversely, rabbits 4-5 weeks of age became ill and some died when inoculated with the rotavirus strain of bovine origin. However, the latter isolate appeared to be more virulent than the rabbit isolate in either calves or rabbits. Moreover, in reciprocal cross protection tests, carried out in calves and in rabbits, the rabbit rotavirus antiserum afforded only weak protection to challenge infection with either the homologous or the heterologous virus. By contrast, the protective level of the bovine rotavirus antiserum was relatively high.

Experimental infection and cross protection tests in calves with cytopathic strains of bovine rotavirus.

Four cytopathic strains (81/32F, 81/36F, 81/40F, 82/80F) of bovine rotavirus were shown to be pathogenic for conventionally reared newborn calves. Calves were infected orally, using 3 calves for each isolate. All became febrile, were depressed and diarrhoeic. Two calves, one of which in the group of those infected with 81/36F isolate, and the other infected with strain 81/40F, were killed when moribund. A 3rd calf from the 81/36F infected group, died. At necropsy localized lesions of the small intestines, which are considered to be typical of rotavirus infection, were found. Virus was consistently isolated from the fecal samples of the inoculated calves up to 13 days post-inoculation. It was speculated that some differences existed in the virulence of the bovine rotaviruses tested. The cross protection tests revealed that 1 strain (81/36F) might be antigenically more complex than the others.