IgM antibody response to Crimean-Congo haemorrhagic fever (CCHF) virus was monitored in experimentally infected sheep and cattle by an IgM capture enzyme-linked immunoassay (ELISA). Specific binding of antigen was detected by a rabbit anti-CCHF horseradish peroxidase conjugate or a sandwich technique with hyperimmune mouse anti-CCHF ascitic fluid and commercially available anti-mouse immunoglobulin peroxidase conjugate. The persistence of IgM antibody activity was found to be of shorter duration than in humans, and this may be a function of the relative lack of susceptibility of these animals to infection with CCHF virus. IgG antibody responses in the sheep could be monitoried by sandwich ELISA using commercially available anti-sheep immunoglobulin peroxidase conjugates. Total antibody activity in the sera of experimentally infected sheep, cattle and small mammals could be monitored in a competitive ELISA (CELISA) using rabbit anti-CCHF peroxidase conjugate. The CELISA was applied to the sera of 960 wild vertebrates from a nature reserve in South Africa, and the prevalence of antibody was found to be greatest in large mammals such as rhinoceros, giraffe and buffalo, which are known to be the preferred hosts of the adult tick (Hyalomma) vectors of the virus.

Intranasal inoculation of 12 young adult mice (strain TO) with Mycoplasma pulmonis protected all of them against vaginal colonization when they were challenged intravaginally 60 days later with the same mycoplasmal strain. In contrast, all 15 mice without a respiratory infection became colonized vaginally (geometric mean titre [GMT] 4·6 × 106 colour-changing units [c.c.u.]) when challenged in the same way. The GMT of serum antibody, measured by a micro-immunofluorescence technique, prior to challenge was 200 and 8 for the oropharyngeally infected and unexposed mice, respectively. The GMT of antibody in vaginal washings from the two groups was 6 and 3, respectively. All four nude BALB/c mice were susceptible to vaginal colonization (GMT 5·6 × 106 c.c.u.) after oropharyngeal infection (GMT 5·1 × 104 c.c.u.) resulting from intranasal inoculation, as were all six nude mice (vaginal GMT 1·4 × 107 c.c.u.) that had not been inoculated intranasally. In contrast, all ten of their immunocompetent counterparts were resistant to vaginal colonization after oropharyngeal infection (GMT 1·3 × 103 c.c.u.), whereas all nine such mice that had not been infected oropharyngeally were susceptible to vaginal colonization (GMT 7·6 × 106 c.c.u.). These results show the important role that a respiratory infection has in protecting the vagina against colonization and that protection is dependent on a functioning T-lymphocyte system.

Between 1989 and 1992, 7970 wild ungulates, comprising 14 different species, were tested for antibodies to types SAT 1, SAT 2 and SAT 3 foot-and-mouth disease (FMD) virus. Of these 1·2% were found to be positive and these included impala (Aepyceros melampus), eland (Taurotragus oryx), waterbuck (Kobus ellipsiprymnus) and sable (Hippotragus niger). All the positive animals were either from the wildlife areas where buffalo (Syncerus caffer) occur or from ranches where clinical FMD had occurred in cattle. The role of these animal species in the current epidemiology of FMD in Zimbabwe is discussed.

Influenza A (H1N1) viruses when initially isolated in mammalian cell cultures (MDCK cells) had different agglutination reactions with chicken and guinea-pig erythrocytes compared to the same viruses after passage. On first isolation the virus HA resembled the ‘O’ phase viruses described originally by Burnet and Bull and agglutinated mammalian but not avian erythrocytes. After passage, the virus HA resembled a classical ‘D’ phase virus and agglutinated both avian and mammalian erythrocytes. Monoclonal and polyclonal antisera detected antigenic differences between the HAs of the viruses in the ‘O’ and ‘D’ phases. The ‘O’ phase virus HA reacted preferentially with antibodies in post infection human antisera. Viruses in the ‘O’ phase replicated poorly in the allantoic cavity of embryonated hens' eggs whilst ‘D’ phase virus replicated in both MDCK cells and in embryonated hens' eggs. At least three distinguishable subpopulations of influenza A (H1N1) viruses may co-exist in clinical throat swab material, including viruses possessing HAs in the ‘O’ and ‘D’ phases and other ‘D’ phase viruses cultivable in embryonated hens' eggs but antigenically distinguishable from the corresponding ‘D’ phase virus in MDCK cells.

In order to study the effect of antichlamydial antibodies in ocular secretions on resistance to ocular chlamydial infection and clearance of this infection, we have performed linked longitudinal studies in a Gambian village in which trachoma is endemic. We have measured IgG and IgA antibody levels to a local serotype B isolate of Chlamydia trachomatis by amplified enzyme immunoassay, and chlamydial antigen levels in conjunctival swabs using a commercially available immunoassay which detects chlamydial glycolipid. Having previously demonstrated that sharing a bedroom with a case of active trachoma is a risk factor for acquisition of the disease, we have analysed the effect of IgG and IgA antibody on the acquisition and persistance of clinical trachoma after controlling for age, sex, exposure to infection and for the presence of chlamydial antigen using a Poisson regression model. We have found that the presence of antichlamydial IgG in ocular secretions of disease-free subjects is associated with an increased incidence of trachoma. IgA antibody shows an opposite trend, but this is not statistically significant. One possible explanation of these findings is that antichlamydial IgG antibodies enhance the infectivity of C. trachomatis for the human eye; this could have major implications for the development of a chlamydial vaccine.

The patterns of disease caused by five common viruses which infect the respiratory tract are described. The viruses were strains of rhinovirus types 2, 9, and 14, a strain of coronavirus type 229E and of respiratory syncytial virus. Volunteers were given nasal drops containing a low infections dose of one of the viruses, quarantined from 2 days before to 5 days after inoculation, and examined daily by a clinician using a standard checklist of respiratory signs and symptoms. Only subjects who developed clinical illness accompanied by viral shedding and/or specific antibody production were analysed [n = 116]. The results confirm indication from earlier studies that the main difference between colds induced by different viruses is in duration of the incubation period. Patterens of symptom development were not substantially different with different viruses. Analyses of signs and symptoms in different categories, e.g. nasal symptoms v. coughing, justify treatment with different drugs either successively or simultaneously.

A study was undertaken to examine the feasibility of using naturally-occurring bacteriophages to assess the impact of re-laying on levels of viral contamination in Crassostrea gigas, the Pacific oyster. Two phages were chosen. One, male-specific (F+), was enumerated using Salmonella typhimurium. The other, a somatic phage, was detected using an, as yet, uncharacterized Escherichia coli. Investigations, using a variety of re-laying sites, demonstrated that numbers of F+ phage in oyster tissue declined more rapidly than those of somatic phage. For example, in oysters placed in commercially-used sea water ponds, F+ phage reached undetectable levels within 2–3 weeks, whereas somatic phage could still be detected 5 weeks after re-laying. The studies suggest that F+ phage may not be a suitable indicator for virus removal and that somatic phage may be better suited to this role.

This study investigated the morbidity associated with respiratory virus infections in patients with well-documented chest disease, and the risk of transmission between close contacts. Patients informed the study team if they were exposed to a family member or colleague with a cold. Patients and symptomatic index cases recorded respiratory symptoms during the study period. Acute nasopharyngeal swabs and paired sera were obtained for viral diagnosis.

Twenty-five (43%) of 58 recorded exposures resulted in a symptomatic illness and 16 (28%) patients developed lower respiratory tract symptoms. Sixteen (64%) of the 25 symptomatic patients contacted their general practitioner, 14 (56%) received antibiotics and 4 (16%) were hospitalized. Mean duration of illness was 10·6 days in symptomatic patients and 5·7 days in their corresponding index cases (P < 0·005). Mean symptom scores were 100·6 in symptomatic patients and 62.2 in index cases (P < 0·01). Respiratory viruses were identified in 19 (33%) episodes. Rhinovirus, coronavirus and respiratory syncytial virus infections were all associated with lower respiratory tract exacerbations.

Respiratory tract symptoms following exposure to a cold were comparatively severe in these patients with chronic chest disease. This group of patients might gain particular benefit from the introduction of effective vaccines or antiviral therapy.

In an outbreak of small round structured virus (SRSV) gastroenteritis at an international AIDS conference 67 people were ill with diarrhoea or vomiting, one requiring admission to hospital. Epidemiological investigations demonstrated that the vehicle of infection was food prepared by a foodhandler who was recovering from a mild gastrointestinal illness. The food most strongly associated with illness, coronation chicken, was prepared by the food handler on the second day after symptoms ceased.

The investigation confirms the view that foodhandlers may contaminate food with SRSV after cessation of symptoms and should remain off work until at least 48 h after recovery.

The epidemic cycle of Chlamydia pneumoniae infection in eastern Finland, 1972–1987 Fig 2. For the top right-hand graph of the four shown, the legend should show: urban. … rural, –––; all, ——. The legend for the remaining three graphs is correct.

During 1990 and 1991, dengue fever was detected in the State of Rio de Janeiro, Brazil. It occurred in two epidemic waves; one, from January to August 1990, caused predominantly by dengue virus type 1 (DEN-1) the other from October 1990 to May 1991 caused by type 2 virus (DEN-2). Dengue was confirmed by virus isolation and/or IgM capture enzyme-linked immunosorbent assay (MAC-ELISA) in 2109/5964 (35·4%) of the cases. DEN-2 virus was isolated from 180 patients. HAI tests indicated that of these previous infection with DEN-1 had occurred in 130 (72%). The epidemic was classified as dengue fever, but severe and even fatal cases occurred in association with secondary infection.

Current levels of influenza vaccine uptake in patients considered to be at high risk have been determined by means of a questionnaire survey. During March–April 1992, information was sought from 624 patients in Leicestershire, UK with either chronic cardiovascular or respiratory disease, or diabetes; questions related to current health status and the request, offer and receipt of influenza vaccine in the current and three previous seasons. Ninety-eight percent of all offers of immunization were made in the primary care setting, and vaccine was well tolerated as judged by the fact that 86% of vaccinees between 1988/9–1990/1 returned for immunization in the following year. However in the 1991/2 season the overall level of vaccine uptake was only about 41% which is at variance with the stated policies and practices of general practitioners. Opportunities were missed, in both hospitals and general practices, to publicise and offer immunization to individuals with vaccine indications. Future attempts to improve vaccine uptake should focus on increasing the role of hospital staff in influenza prevention, in addition to promoting better vaccine delivery through primary care.

The signs and symptoms exhibited by 29 patients with an acute illness in whom antibodies to hantavirus were detected are described. In the severe cases the most striking signs and symptoms were the persistence for 2 or 3 weeks of a severe sore throat with pyrexia that developed early in the illness, followed by swelling of the face, neck and extremities, with arthropathy and prolonged malaise that lasted for months. A macular erythematous rash, hepatomegaly with abnormal liver function tests, and a tendency to haemorrhage was a later feature of the severe cases. Mild cases presented with a variety of signs and symptoms that were very difficult to link together as a syndrome.

Nine years accumulated laboratory data derived from the culture of the cerebrospinal fluid of 11 360 aseptic meningitis cases were retrospectively reviewed to establish the epidemiology of viral meningitis in Cape Town. Virus was isolated from 3406 of the cases (91% enteroviruses and 9% mumps).

Five major summer viral meningitis episodes were documented: two of echovirus 4 (706 and 445 cases), echovirus 9 (223), coxsackie A9 (104) and one of unidentified enterovirus (324 cases – probably echo 9). Although coxsackie B was endemic, clusters of one or other type were dominant at any one time. Mumps was endemic. Sixty-two percent of all viral cases were <5 years old. The median ages of 4 and 5 years in echoviruses 9 and 4 (the epidemic strains) contrasted with that of 1 year in coxsackie B (with many cases <3 months old). Mumps peaked at 3–4 years of age. Males dominated overall, particularly in mumps.

Cases of western equine encephalitis in horses in 1987 in western USA and Manitoba, Canada were examined by backward trajectory analysis of winds. Culex tarsalis mosquitoes infected with western equine encephalitis virus could have been carried on southerly winds from Texas and Oklahoma to northern LTSA and from there to Manitoba. The presence of the Polar front over North Dakota and Minnesota at the end of July would have led to the landing of Cx. tarsalis in Montana and Wisconsin and prevented further carriage into Manitoba. Temperatures in southern Texas during the winter months (average daily maximum temperatures 19.7 °C and higher) would have permitted continuous transmission of western equine encephalitis virus by Cx. tarsalis in this area.

Weather factors involved in outbreaks from 1975–88 were analysed to see if epidemics in Manitoba (23 or more cases in horses) could be predicted. The conditions for epidemics could be defined as follows: (a) the number of cases in horses in LTSA was 98 or more, (b) winds were southerly with speeds 45 kmh-1 or higher, and (c) counts of Cx. tarsalis females/light trap per day were 3·2 or higher. There were 3 or fewer cases in Manitoba, when the number of cases in USA was 27 or less, even when Cx. tarsalis counts were higher than 3·2. With Cx. tarsalis counts below 3 and/or unsuitable winds, or the Polar front further south, the number of cases in Manitoba was between 0 and 17, even when the number of cases in USA was from 38–172. Without information on the extent of infection further south, the weather variables would probably be more useful in excluding the possibility of an epidemic in Manitoba than in predicting one.