We describe an outbreak of Q fever affecting 16 of 32 employees at a truck repair plant. None of the cases were exposed to cattle, sheep or goats. the traditional reservoirs of Q fever. The cases did not work, live on, or visit farms or attend livestock auctions. One of the employees had a cat which gave birth to kittens 2 weeks prior to the first case of Q fever in the plant. The cat owner fed the kittens every day before coming to work as the cat would not let the kittens suckle. Serum from the cat had high antibody titres to phase I and phase II Coxiella burnetii antigens. The attack rate among the employees where the cat owner worked. 13 of 19 (68%), was higher than that of employees elsewhere, 3 of 13 (28%) [P <0·01]. The cat owner's wife and son also developed Q fever. None of the family members of the other employees with Q fever was so affected.

We conclude that this outbreak of Q fever probably resulted from exposure to the contaminated clothing of the cat owner.

A simultaneous study of cockroach (Supella supellectilium) distribution and of associated carried bacterial flora has been made in the main hospital in Rennes (France).

Wild cockroaches carry a high number of bacterial species that can be related to the normal environmental flora and a contaminant flora acquired from particular environments. The diversity of carried bacterial species reveals a proximity factor between continguous floors of the building which leads us to suppose that cockroaches are able to forage from one floor to the other.

From December 1982 to March 1986 a group of 80 children between 0 and 3 years old who lived in the peripheral area of Belém, Brazil, were followed up for episodes of diarrhoea. A total of 441 diarrhoeal episodes were recorded and 36 (8·2%) were associated with rotavirus. This agent was the only pathogen in 50% of rotavirus-related episodes of acute diarrhoea, and strains were characterized by analysis of RNA in polyacrylamide gels. Forty-one belonged to subgroup II (long pattern) and five to subgroup I. Reinfections by rotavirus were noted in 12 children involving either the same or different subgroups. Ten distinct electrophoretypes were detected in the study period and the predominant one had the ‘1N2L’ profile. The cumulative age-specific attack rate for diarrhoea reached 2–8 by the end of the first year of life; a frequency of 2–3 episodes of diarrhoea per child per year was observed throughout the complete investigation. In comparing the age-specific attack rates for diarrhoea between breast-fed and bottle-fed children, a peak at 6 months of age was noted in the former, and at 1 month in the latter. A comparison by Fischer's exact test (P = 0·21) provided no evidence for protection against clinical rotavirus disease by maternal milk. By the same test, however (P = 0·021), we found significant evidence that early rotavirus infections were more likely to be asymptomatic and that infections after 4 months were more likely to be symptomatic. The clinical picture in children with rotavirus-related diarrhoea was more severe than in those suffering from acute diarrhoea due to another agent.

The chemical disinfection of virus-contaminated non-porous inanimate surfaces was investigated using coxsackievirus B3, adenovirus type 5, parainfluenzavirus type 3 and coronavirus 229E as representatives of important nosocomial viral pathogens. A 10 µl amount of the test virus, suspended in either faeces or mucin, was placed onto each stainless steel disk (about 1 cm in diameter) and the inoculum allowed to dry for 1 h under ambient conditions. Sixteen disinfectant formulations were selected for this study based on the findings of an earlier investigation with a human rotavirus.After 1 min exposure to 20 µl of the disinfectant, the virus from the disks was immediately eluted into tryptose phosphate broth and plaque assayed. Using an efficacy criterion of a 3 log10 or greater reduction in virus infectivity titre and irrespective of the virus suspending medium, only the following five disinfectants proved to be effective against all the four viruses tested: (1) 2% glutaraldehyde normally used as an instrument soak.(2) a strongly alkaline mixture of 0·5% sodium o-benzyl-p-chlorophenate and 0·6% sodium lauryl sulphate, generally used as a domestic disinfectant cleaner for hard surfaces, (3) a 0·04% solution of a quaternary ammonium compound containing 7% hydrochloric acid, which is the basis of many toilet bowl cleaners. (4) chloraminc T at a minimum free chlorine level of 3000 p.p.m. and (5) sodium hypochlorite at a minimum free chlorine concentration of 5000 p.p.m. Of those chemicals suitable for use as topical antiseptics, 70% ethanol alone or products containing at least 70% ethanol were ineffective only against coxsackievirus B3. These results emphasize the care needed in selecting chemical disinfectants for routine use in infection control.

The seroepidemiology of chlamydial infections in the Finnish population was studied by analysing the prevalence of chlamydial complement fixing (CF) antibodies in patients sera sent for virus serological screening tests over 17 years from 1971 to 1987. The total number of sera studied was over 160 000. In the early 1970s, the prevalence of chlamydial CF antibodies (CF titres ≥8) was low (less than 2%), but later the proportion of seropositive cases rose, and in 1976, 18% of sera contained antibodies. In 1984, the seropositivity rate was over 31%. The prevalence of high chlamydial CF titres (titres ≥64) also showed annual variation. In general, under 1% of sera contained chlamydial CF antibodies in high titre, but in 1979 and 1984, distinct peaks occurred when 1·3% and 1·4% of sera, respectively, had titres ≥64 The age-related antibody positivity rate showed a decline during early infancy, an increase in childhood and adolescence, and a stable level in adulthood when approximately 20% of the sera contained antibodies. The chlamydial antigen used in this survey was genus-specific, i.e. it detects antibodies against, all chlamydial species. Epidemiological data support the hypothesis that infections due to a novel chlamydial species, TWAR chlamydia, are the most likely explanation for the relatively frequent occurrence of chlamydial CF antibodies and for the variation in CF antibody prevalence.

A detailed study was made in 1983–5 in three villages in Mehinji district in the African swine fever (ASF) enzootic area of Malawi, following an outbreak of ASF which affected all three villages.

Ticks of the Ornithodoros moubata complex were collected from both pig sties and houses shortly after the outbreak, and approximately 24% contained ASF virus. The proportion of ticks infected did not differ significantly in the three villages, or more surprisingly in different types of premises, and was equivalent in all stages of ticks. The proportion infected decreased with the passage of time, but infected ticks were still present in all three villages 8 months after the outbreak,some with high titres of virus.

The proportion of seropositive pigs in the three villages approached 100% following the outbreak, with many apparently healthy pigs being seropositive. It is suggested that Malawian isolates of ASF virus may be less virulent in African than European breeds of domestic pig.

Three enzyme immunoassays were used for the serodiagnosis of Trypanosoma evansi in camels in the Sudan in order to evaluate their ability to discriminate between infected and non-infected animals. Two assays were used for the detection of trypanosomal antibodies, one using specific anti-camel IgG conjugate and another using a non-specific Protein A conjugate. The third assay detected the presence of trypanosomal antigens using anti-T. evansi antibodies in a double antibody sandwich assay. Inspection of the frequency distribution of assay results suggested that the ELISA for circulating trypanosomal antibodies using specific antisera and the ELISA for circulating antigens can distinguish between non-infected camels and infected camels exhibiting patent infections or not. The ELISA using Protein A conjugate to bind non-specifically to camel immunoglobulin did not appear to discriminate between infected and non-infected animals.

A seroepidemiological study of the prevalence of mumps virus specific antibodies reveals a pattern of endemic peristence on the island of St Lucia in the West Indies. In the unvaccinated population the proportion seropositive rose rapidly in the child age classes to attain a stable plateau close to unity in value in the teenage and adult age groups. The average age at infection was estimated to be between 3 and 4 years of age and the average duration of detectable levels of maternally derived antibodies was approximately 3 months. Analyses based on mathematical models of the transmission dynamics of the virus suggest that in excess of 75% of each cohort of 1-to 2-year-old children must be effectively immunized to eliminate mumps virus transmission. A mumps radial haemolysis test, developed for quantitative measurements of antibody, is discussed.

Monoclonal antibodies specific for rotavirus subgroup 1 (SG1) and subgroup 2 (SG2) were used to analyse by enzyme immunoassay (EIA) the subgroups of human rotavirus isolates obtained from three different parts of India during the period September 1985 to July 1987. We identified one isolate which failed to react with either SG1 or SG2 specific monoclonal antibodies, although it reacted well with a monoclonal antibody specific for group A rotaviruses. This finding suggests that it belongs to a new rotavirus subgroup. Further, another isolate was found to belong to SG1 although it had a ‘long’ electropherotype.

The food and water hygiene in two Liberian communities was studied in a house-to-house diarrhoea survey. The level of contamination with enterobacteria of drinking water stored in the households was significantly higher than at the water sources. Food hygiene standards were low, particularly in the urban slum where storage of cooked food for long periods led to bacterial multiplication at high levels. Infant foods were particularly heavily contaminated. It is concluded that when water supply programmes are planned, the presence of other risk factors for water-related diseases should be investigated. To ensure maximum health benefits, water projects should as a rule be accompanied by other interventions.

The finding that there had been multiple isolations of Palyam serogroup orbiviruses from aborted cattle fetuses in neighbouring Zimbabwe, suggested that there was a need to investigate the possible occurrence of the viruses in South Africa. Unidentified viruses isolated in South Africa, which had been in storage, were examined. Four viruses which had been isolated from Culicoides midges collected at various sites in the years from 1969 to 1977, were identified as three strains of Gweru virus and one of the Nyabira virus (Palyam group serotypes originally described from Zimbabwe) A fifth virus, isolated in 1967 from the blood of a cow with mild fever, was found to be a distinct new member of the Vellore antigenic complex of the Palyam serogroup and was named Apies River virus. Sera from 476 cattle, 150 sheep, 24 goats and 78 humans from 10 farms were tested for neutralizing antibodies to the above three serotypes of virus plus Abadina and Marondera serotypes. Only 1 of 100 cattle sera from two farms in the southern coastal area had antibody, but elsewhere there was a high prevalence of antibody with 254 (53%) of all cattle exhibiting activity for one or more of the five serotypes of virus tested. Only 6 (4%) sheep, 3 (12–5%) goats and 11 (14%) humans had antibody.

We have analysed data on respiratory syneytial (RS) and parainfiuenza type 3 (PF3) viruses reported to the Communicable Disease Surveillance Centre. London, over the period 1978–87. These confirm the annual winter epidemic of RS virus and show that, in England and Wales, PF3 is a summer infection with regular yearly epidemics.

A study of influenza in residential schools provided the opportunity to assess the significance of antibody as a predictor of immunity. Five hundred and fifty-six pupils from 8 schools were included in the investigations, and the outcome for these children in 27 naturally occurring outbreaks of influenza was analysed. The outbreaks comprised 5 caused by strains of influenza A H3N2, 10 caused by strains of influenza A H1N1, and 12 caused by strains of influenza B. On 8 occasions a second outbreak of the same serotype occurred in a school.

There was a general correlation between the presence of antibody to the outbreak strain and protection from infection. For each of the three influenza virus serotypes the infection rate in those with no detectable antibody was approximately 80%. Those with past experience of the virus but no antibody to the outbreak strain experienced lower infection rates (62% overall) but the infection rates were lowest in those with intermediate and high level antibody to the challenge strain (18% overall).

Vaccine was used by three of the schools. The effect of antibody derived from recent experience, either natural or vaccine-induced, on subsequent challenge with a drifted strain i.e. one showing antigenic drift away from the previous strain, was compared. Intermediate or high level antibody to the challenge strain in those who had experienced a recent natural infection was associated with a low infection rate (9%). A similar level of antibody produced in response to vaccination was associated with a significantly higher infection rate (23%:P 0-025). Among the vaccinees who had produced such antibody the infection rate was highest (32%) in those who had responded to vaccine in the presence of antibody to the vaccine strain.

The evidence from this study indicates that whilst antibody surveys of populations may provide some information about susceptibility to challenge with new strains of influenza viruses, the cirucumstances of the induction of the antibody affect its value as a predictor of immunity.

Cryptosporidium oocysts were observed in the stools of 9 (7·2%) of 124 Italian children with diarrhoea, examined during the period 1 January—31 December 1984. In two children, the parasite was associated with other enteric pathogens. The duration of diarrhoea was 2–30 days, with a median of 6 days. In all cases the infection was self limiting. The mean age of the Cryptosporidium-positive children was 34 months, and all cases occurred in the warm season. Cryptosporidium was found to be the third most common enteric pathogen after rotavirus and Salmonella spp.

Epidem. Inf. 102 (1989), 33

N. Bornstein. Marmet. M. Surgot, M. Nowicki, A. Arslan, J. Esteve and J. Fleurette

Exposure to Legionellaceae at a hot spring spa: a prospective clinical and serological study

Table 1. penultimate line: ‘≤ L. pneumophila’ should read

‘≥ 128 L. pneumophila’

line 14:‘ 103–105 colony forming units (c.f.u.).’ should read ‘ 103–105 colony forming units/1.’

Isolates of capripoxvirus collected from sub-Saharan Africa were compared in sheep, goats and cattle and by restriction endonuclease digestion of their purified DNA. Biochemical techniques were used to precisely identify strains of capripoxvirus for epidemiological investigations. Strains of capripoxvirus infecting cattle have remained very stable over a 30-year period and are closely related to strains recovered from sheep in Africa.