Journal of Hygiene最新文献

In an attempt to determine the frequency of virus infections of the gastrointestinal tract, the duration of virus shedding in faeces and its relation to outbreaks of illness of any kind, faecal samples were collected from children attending a day nursery at a Lisbon institution. In this study, ten children were surveyed from their enrollment at the nursery, weekly specimens of faeces being collected over a period of 1 year. A total of 459 samples were obtained. In addition four of these children were also followed-up from their first week of life to their enrollment at the nursery, 79 samples being collected during this period. Viruses were detected in a high percentage (44.4%) of these stools, including strains of oral vaccine polioviruses together with viruses isolated in routine cell cultures and by electron microscopy (EM). These viruses were detected in both healthy and ill babies. The possible association between viruses isolated in cell cultures or detected by EM and illness was examined and the results show that the asymptomatic excretion of viruses is frequent, particularly in children within this age group.

A cross-sectional study of 447 laying hens (age range 0-65 weeks) and a longitudinal study of 164 similar birds showed that Campylobacter jejuni was not present in the faeces of newly hatched chicks, but that colonization arose after 5-9 weeks. A survey of 250 broilers obtained from four breeders showed that all were negative for C. jejuni before and after slaughter at the age of 5 weeks. Once C. jejuni had appeared in a flock, it rapidly spread to virtually all birds, but at the age of 42 weeks only 20-46% of birds remained colonized, possibly as a result of having developed immunity. Birds housed in the protective environment of a laboratory still became colonized (after 9 weeks). The mode of infection is unknown, but water and food were bacteriologically negative and were deemed to be unlikely sources. Transmission via attendants, flies or other insects remain possibilities. It is concluded that prevention of colonization might be possible within the life-span of broiler chickens (5-7 weeks), but that it would be difficult to extend this period. There is a need to define how colonization arises so that the feasibility and cost of possible preventive measures can be assessed.

The eradication of smallpox was achieved by surveillance and containment vaccination after the failure of mass immunization campaigns. The reasons for this failure are considered in this paper. Comparison of population densities in the Indian subcontinent and Africa show that in highly populated areas even an 80% vaccine coverage will still leave a density of susceptibles high enough to maintain the disease, a finding with important implications for other vaccine campaigns.

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 relative efficiencies of three commercially available dehydrated Rappaport-Vassiliadis media have been compared with a similar medium prepared from individual constituents in our own laboratory. An inoculation ratio of 1:100 was found to be optimal for each of the media tested. Laboratory produced RV-medium was significantly better than the three commercial preparations after 24 h incubation. However, when the duration of incubation was extended to 48 h, there was no significant difference in the number of salmonella isolates obtained when using our own RV medium and that produced by Oxoid Ltd and Difco Ltd (P greater than 0.05). All of these three media were, however, significantly more effective than the medium produced by Lab.M. (P less than 0.01).

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 micrograms of the Merck Institute vaccine (HB-VAX). Compared with the 20 micrograms dose, vaccination with the 10 micrograms 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 micrograms dose. We conclude that (1) hospital staff working in high endemic areas should be vaccinated on recruitment and (2) the 10 micrograms dose of HB-VAX can replace the recommended 20 micrograms dose for adults, being cheaper and as efficacious.

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 greater than or equal to 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.

This report presents the parasitological, bacteriological, mycological and physicochemical data obtained from both surface water and beach sand of a lake used for water sports. These show that the lake is contaminated in both winter and spring by water which overflows from the River Maine, and is self-purified by a mechanism of 'lagunage'. In summer signs of pollution are at their lowest level although use of the complex is at its peak. Conversely, the amoebic flora, which is independent of the usual criteria of pollution, predominates in summer, and serves as a marker for the need for increased surveillance. The sand of the beaches does not appear to show any infectious hazard. Environmental pressure will doubtless change these data over a period of time, and it is planned to monitor this.

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.

The sera of healthy blood donors from the Wellington area of New Zealand, collected between 1976 and 1980, were analysed by the complement fixation test for antibody to Mycoplasma pneumoniae. A high prevalence of antibody to this organism was demonstrated and the occurrence of an M. pneumoniae epidemic in New Zealand within the survey period was shown to be reflected in the immune status of this healthy adult population. This would suggest that during an epidemic many people within the Wellington community may have M. pneumoniae infections involving little overt illness.