Forty-six gnotobiotic calves aged less than 16 days or 42–116 days were infected with three strains of bovine rotavirus designated C3–160, CP-1 and PP-1. Each virus was passaged and cloned in cell culture (cloned viruses) but CP-1 and PP-1 Were also used before culture (faecal viruses).

Infection of calves aged less than 16 days with faecal or cloned CP-1 caused disease whereas cloned C3–160 and faecal or cloned PP-1 caused subclinical infections. The clinical signs of disease were change in faecal colour to pale yellow or cream, increase of 2- to 7-fold in the volume of faecal output and, usually, anorexia. With the virulent CP-1 virus and the avirulent C3–160, similar amounts of virus were excreted in the faeces for 4–6 days.

Infection of calves aged 56–116days with faecal CP-1 produced disease of similar severity to that seen in calves aged 7–10 days infected with the same virus. No differences in clinical signs, virus excretion or levels of convalescent antibody were seen between the two groups. With cloned CP-1, 5 of 8 older calves developed disease but 3 showed only mild signs of infection.

It was concluded that two strains of rotavirus caused sub-clinical infections in young calves while a third was virulent in calves up to at least 116 days of age.

The anticoagulant rodenticide flocoumafen was evaluated against Rattus rattus and Bandicota bengalensis, In no-choice 24 h feeding tests 100% mortality occurred at 0·00125% concentration of the poison in the bait in the case of B. bengalensis and at 0·00375% in R. rattus. Feeding of 0·0025% poison bait in 1-day, no-choice and 2-day choice tests resulted in 60% and 75% mortality of R. rattus, respectively, and 100% of B. bengalensis. The differences between the consumption of plain food in the pretreatment period and of poison bait in no-choice tests were non-significant, except in one case. The rodents consumed significantly more (P < 0·01) poison bait than the plain alternative in the choice trials. Median period of survival and its 95% confidence limits of R. rattus and B. bengalensis, at the 100% mortality dose levels of the poison, were 6·3 (5·04–7·88) and 6·2 (4·92–7·81) days respectively.

A serological survey carried out on 1379 school-children from Skye and Mallaig in the N.W. of Scotland failed to show evidence of subclinical cases of hydatidosis. There appeared to be a relatively low level of exposure to the parasite, as judged by ELISA and IHA tests. Thirty-one children reacted positively in the ELISA; only one child had a transient positive result in the IHA test. Surveillance of these children will be continued for the present but the duration required is uncertain. The local population appeared to be well aware of the mode of spread of the parasite and the methods for its control.

In order to study the serological status of the Northern Greek population to poliovirus, 881 sera from healthy people were examined for neutralizing antibody by the micrometabolic inhibition test. The people under examination were aged from 1 day to 70 years old. Overall, of the 881 sera examined, 704 (80%) had antibodies (titre ≥ 4) to poliovirus 1, 742 (84%) had antibodies to poliovirus 2 and 715 (81%) had antibodies to poliovirus 3. Fifty-five per cent of the sera had antibodies to all three polioviruses while 3·3% had no poliovirus antibody at all. There was no statistically significant difference in the rates of seropositivity to the various poliovirus types or between males and females. However the rates of seropositivity did vary with age.

The epidemiology of human rotavirus (HRV) in north-east Scotland was investigated between 1982 and 1984. During this period 708 HRV infections were recorded. The majority (83%) of the infections were in children less than 5 years of age although some were recorded in adults. The peak incidence occurred in the winter months although a high number of HRV infections was reported during the summer of 1983. A total of 840 faecal specimens containing rotavirus were screened for HRV genome RNA by polyacrylamide gel electrophoresis. Seven hundred (83%) specimens gave RNA profiles suitable for establishing the HRV electrophoretype. Twenty-five different electrophoretypes were identified, of which 21 had ‘long’ RNA profiles and four had ‘short’ RNA profiles. There was extensive co-circulation of distinct electrophoretypes although during any one epidemic period the majority of viruses belonged to a relatively small number of types. Comparison of viruses collected from hospitalized and non-hospitalized Patients showed no differences in electrophoretype distribution. HRV was identified in faecal specimens from a wide age group and no correlation was demonstrated between age of patient and electrophoretype of the infecting virus.

Neutralizing antibody responses to conventional rabies post-exposure regimens of human diploid cell strain vaccine (HDCSV) and the new purified Vero cell rabies vaccine (PVRV) were compared in 58 healthy Thai veterinary students. The geometric mean titres (GMTs) of the group given HDCSV were slightly higher than those given PVRV, but on day 28 the peak GMTs of the two groups were statistically similar. The early antibody response to PVRV was unaffected by the addition of passive immunization, whereas the level of HDCSV response was reduced on day 14, so that there was no difference on that day between the GMTs of the two vaccine groups given HRIG. However, by day 91 the GMT of those given PVRV and HRIG was lower than in those given HDCSV alone or with HRIG. The appearance of antibody was less rapid than was observed in previous studies using multiple-site intradermal vaccination. Side effects were trivial. Our results confirm the promise of this new, potentially more economical tissue culture vaccine, but they suggest that the regimen could be improved.

The epidemiology of hydatid disease in man in England and Wales, based on the data collected between 1981 and 1983 at the Hydatid Reference Laboratory of the Public Health Laboratory Service, is presented. The incidence of hydatid disease was 42 cases per annum, with 2 cases per million population occurring in Wales and 0·2 per million in England. The highest prevalence was in London amongst the immigrant population. The incidence in the indigenous population was 15·5 cases per annum, with 5·6 cases per million occurring in South Powys, parts of South Wales and Herefordshire. The population most at risk is the rural, farming community in that area, but the West Midlands is also an apparent focus of the disease.

To assess the potential of fomites and environmental surfaces as vehicles in the transmission of rotaviral diarrhoea, disks (1 cm diameter) of various porous and non-porous materials were contaminated with about 105 plaque-forming units of the Wa strain of human rotavirus (HRV) suspended in faecal matter. The contaminated disks were then held for 10 days at either room temperature (22±2 °C) or 4°C with the relative humidity (RH) at the high (85±5%), medium (50±5%) or low (25±5%) level. Survival was longer on non-porous surfaces at the lower temperature and at lower humidity. In contrast, survival on porous surfaces was very variable; better on cotton-polyester than on poster card or paper currency on which HRV survived very poorly. These results suggest that under the right environmental conditions, HRV-contaminated objects could play a role in the transmission of rotavirus infections in hospitals, nursing homes and day-care centres.

Four thousand and one hospital staff were screened for hepatitis B virus (HBV) markers in a vaccination programme in Hong Kong. The seropositivity rate for HBsAg, anti-HBs and anti-HBc were significantly higher in the 3160 existing hospital staff than in 841 new recruits. Of the subjects negative for HBV markers, 605 were randomized to receive three doses of either 10 or 20 μg of the Merck Institute vaccine (HB-VAX). Compared with the 20 μg dose, vaccination with the 10 μg dose results in equal immunogenicity and efficacy at the completion of the three injections but induced a slower response rate and lower anti-HBs titres with the first two doses. The commonest side-effect of local soreness was less with the 10 μg dose. We conclude that (1) hospital staff working in high endemic areas should be vaccinated on recruitment and (2) the 10 μg dose of HB-VAX can replace the recommended 20 μg dose for adults, being cheaper and as efficacious.

Analyses of data collected in a large survey (sample size > 3000) of rubella antibody in South East England, finely stratified according to age, reveal age-dependent changes in the pattern of virus transmission. The rate or force of infection changes from low in the young children to high in the 5 - to 15-year-olds and back to low again in the adult age classes (there is a 50% reduction between the 5- to 15-year-olds and the 20+-year-olds). Raised levels of immunity are recorded in the teenage and young adult female segments of the population as a consequence of the UK rubella immunization programme. Mean antibody concentrations show a decline with age and are, on average, lower in vaccinated females when compared with unvaccinated males of the same age. The interpretation of horizontal cross-sectional serological data and future research needs are discussed.

The paper examines predictions of the impact of various one-, two- and three-stage vaccination policies on the incidence of congenital rubella syndrome (CRS) in the United Kingdom with the aid of a mathematical model of the transmission dynamics of rubella virus. Parameter estimates for the model are derived from either serological data or case notifications, and special attention is given to the significance of age-related changes in the rate of exposure to rubella infection and heterogeneous mixing between age groups. Where possible, model predictions are compared with observed epidemiological trends.

The principal conclusion of the analyses is that benefit is to be gained in the UK, both in the short and long term, by the introduction of a multiple-stage vaccination policy involving high levels of vaccination coverage of young male and female children (at around two years of age) and teenage girls (between the ages of 10–15 years), plus continued surveillance and vaccination of adult women in the child-bearing age classes. Model predictions suggest that to reduce the incidence of CRS in future years, below the level generated by a continuation of the current UK policy (the vaccination of teenage girls), would require high rates of vaccination > 60%) of both boys and girls at around two years of age. Numerical studies also suggest that uniform vaccination coverage levels of greater than 80–85% of young male and female children could, in the long term (40 years or more), eradicate rubella virus from the population. The robustness of these conclusions with respect to the accuracy of parameter estimates and various assumptions concerning the pattern of age-related change in exposure to infections and ‘who acquires infection from whom’ is discussed.

Four groups of sows were inoculated, either once or twice, with O1BFS 1860 foot and mouth disease oil-emulsion vaccine during pregnancy and samples of serum. for analysis, were collected at intervals for > 300 days.

The pregnant sows responded well to vaccination regardless of their state of gestation. Single vaccination produced protective levels of antibody (> 1·53 log10SN50) in 3 out of 4 sows while double vaccination produced protective levels in all 6 sows tested. Anti-FMD IgM antibodies could be detected for 40–60 days after vaccination or revaccination. Anti-FMD IgG antibodies appeared within 10 days of vaccination and persisted, in each sow, for the duration of the study. The anti-FMD IgA response observed was less easy to characterize due to significant animal to animal variation. Although there was no evidence of a fall in the neutralizing antibody titres over one year post vaccination the anti-FMD IgG antibody population did show signs of a change in its heterogenity and avidity.

Three outbreaks of influenza caused by influenza A H1N1 occurred in a boys' boarding school in 1978, 1979 and 1983. The serological response to infection with variants of the H1N1 virus was studied by radial haemolysis and haemagglutination inhibition after primary infection and reinfection. The persistence of this antibody was also studied. Infection in 1978 resulted in the production of persistent antibody to both the haemagglutinin and neuraminidase of the homotypic strain. Antibody which cross-reacted with later variants of the virus was less frequently produced, the peak response was delayed and such antibody persisted less well. Infection in 1979 resulted in a similar response to that observed in 1978 after primary infection. Reinfection resulted in a broad response in all cases. In 1983 all infected boys produced antibody which reacted with the homotypic strain but only approximately one-third of primary infections produced antibody which reacted with the A/USSR/92/77 strain. The neuraminidase of the A/USSR strain failed to detect one third of the primary infections. Reinfection again resulted in a broad response.

Fifty volunteers, treated with an inactivated trivalent influenza vaccine containing A/Bangkok/1/79 (H3N2), A/Brazil/11/78 (H1N1) and B/Singapore/222/79 virus, were subdivided according to the estimated first exposure to influenza in their lifetime (priming) and the presence of antibodies against the vaccine components in the pre-vaccination sera. The isotypic antibody response (IgG, IgA, IgM) was determined by means of an antibody capture haemadsorption immunosorbent technique. For all three vaccine components, previously seropositive subjects produced antibodies of the IgG- and IgA-class more frequently than previously seronegative persons. Subjects primed to one of the influenza A subtypes showed more IgG and IgA responses in comparison with those unprimed (prime-effect). In contrast, IgM antibodies occurred in only 19 and 11% of primed, but in 59 and 54% of unprimed subjects, for A (H3N2) and A (HlNl), respectively. The incidence of IgM titre rises was not influenced by the prevaccination state. However, the mean magnitude of anti-A(H1N1)-IgM titre rises was greater in those previously seronegative. The concepts of primary and reinfection and of ‘original antigenic sin’ are discussed, and it is suggested that age and, if possible, serological state prior to antigen-exposure should be taken into account when studying isotypic antibody responses after influenza infection or vaccination.

Enzyme immunoassays (ELISA) have been developed for the detection of BK virus IgG- and IgM-antibodies. Specific IgG is detected by an antigen-coated solid phase test; IgM by an antibody capture method.

These methods have been used to study the age-distribution of BK virus antibodies in Troms county in Northern Norway. The serum panels tested were: (a) 60 sera from paediatric patients aged 0–1 year; (b) 220 sera from healthy persons aged 1–82 years; (c) 74 sera from healthy blood donors; (d) 107 sera from healthy pregnant women.

The age-distribution of BKV-IgG antibodies showed that primary infections took place predominantly between the ages of 1 and 6 years, and that there were no sex differences, either in the age-specific prevalence or in the level of BKV-IgG.

We found no significant differences in the prevalence of BKV-IgM antibodies in healthy children and adults and pregnant women. BKV-IgM was detected in 26 of the 461 sera tested (5·6%).

Following its reintroduction in 1978 influenza A H1N1 spread widely in the child population. By the autumn of 1979, 75% of 11-year olds entering a boys' boarding school had detectable antibody. The protective effect of previous experience could be assessed during two outbreaks in the school. In the first outbreak in 1979, 90% of those known to have been infected in the previous year were protected against reinfection. In 1983 after strains of the H1N1 subtype had undergone antigenic drift a large outbreak occurred. It was estimated that past infection conferred protection against clinical influenza in 55%. Where past infection resulted in the presence of antibody which reacted with the outbreak strain the attack rate was further reduced. A large number of sub-clinical infections was detected in all groups.

Virus of the bluetongue (BT) serogroup was recovered from 11% of cattle sera collected from apparently healthy animals in Khartoum Province for the sole purpose of screening for BT antibodies. Since these sera did not contain BT antibodies, the donor cattle could have been scored as BT free in the serological survey.

Virus was initially isolated in chicken embryos inoculated intravascularly, and was further adapted to Vero cell cultures. Isolates were identified as belonging to the BT serogroup using the agar gel immunodiffusion (AGID) and complement fixation (CF) tests.

The results indicated that cattle in the Sudan could harbour BT virus without showing symptoms of the disease. Such an observation necessitates further work to clarify the role of cattle in the epidemiology of BT in the Sudan.

Evidence for influenza-associated excess mortality in the three centuries before the 20th has been sought from parish burial registers in Cumbria, Devon, Dyfed, East Anglia, Gloucestershire and Northumbria, compared with inter-epidemic years. Most of the registers showed excess of burials concordant with eight historic influenza epidemics.

Comparison of the dates of these epidemics, deduced from the burials data in different areas, showed a rate of spread difficult to reconcile with direct personto-person spread of influenza from the sick. An alternative explanation based on development of latency of the virus in the sick person and subsequent seasonal reactivation is discussed.