The survival of various faecal bacteria used as indicators of the faecal contamination of water supplies has been investigated in a tropical environment (Sierra Leone). Isolates representing the thermotolerant coliform (TtC) and faecal streptococcus (FS) groups, Clostridium perfringens and Salmonella spp. were studied over a 48 h period of immersion in water from three different sources. Survival patterns varied according to source type, but some general observations were made: a portion of the TtC group was apparently capable of substantial regrowth; FS organisms died off at a faster rate than TtC organisms initially, but survived longer; vegetative cells of C. perfringens died off rapidly; and Salmonella spp. could survive for as long as the other faecal organisms tested. The implications of results for the analysis of tropical waters for faecal contamination are discussed.

Epidem. Inf. 102 (1989), 78

D. J. Hampson, J. R. L. Mhoma, B. Combs and J. R. Buddle

Proposed revisions to the serologieal typing system for Treponema hyodysenteriae

Table 2. Positive reactions shown between LPS from WAT. WA8 and WA12 and antiserum against B234 should have been with antiserum against B204 (i.e. in the adjacent column to the right).

Epidem. Inf. 102 (1989), 328

J. R. Davies and E. A. Grilli

Natural or vaccine-induced antibody as a predictor of immunity in the face of natural challenge with influenza viruses

The indirect haemagglutination (IHA) test was compared with the complement-fixation (CF) test for the measurement of antibodies to Mycoplasma pneumoniae. A modification of the IHA was used to measure M. pneumoniae IgM antibodies. Sera were obtained from various groups of patients who were either culture or antigen positive for M. pneumoniae in nasopharyngeal aspirates or who had fourfold or greater increase in CF antibody or a titre ≥ 320.

The cell-mediated immune response (CMI) to E6 and E4 fusion proteins of human papillomavirus type 16 (HPV-16), E6 fusion protein of HPV-18, and to control proteins similarly produced, was analysed in 29 patients with cervical intraepithelial neoplasia (CIN) and in 15 age-matched laboratory personnel using a lymphocyte proliferation assay (LPA).

This study assessed the influence of influenza on mortality from heart and lung diseases in people over 70 years of age. The data used were obtained from the Dutch Bureau of Statistics. With a regression model, the observed monthly mortality from heart and lung diseases (influenza not included) in people over 70 years is explained with a yearly variable, a monthly variable and the overall monthly number of influenza mortality cases, assuming that monthly mortality has a Poisson distribution. The monthly excess mortality from heart and lung diseases (influenza not included) due to influenza among elderly people (> 70 years) is estimated.

Virus-specific antibody responses were studied in 12 children with cancer in whom rubella was diagnosed by seroconversion or a rising titre (≥ fourfold) of haemagglutination inhibiting (HI) antibody. Our results confirmed the difficulties of making a diagnosis of rubella infection in immunocompromised children using criteria for interpreting antibody assays established in immunocompetent patients. Specific IgM antibody persisted for more than 2 months in 7 of 10 children with probable primary rubella, 3 of whom had high concentrations of such antibody 6, 7 and 11 months after the rash. Radial haemolysis and specific IgG1 and IgG3 antibody responses were low in 4, 2, and 4 patients, respectively. One child apparently had a rubella reinfection and, in another, rubella antibody passively acquired from blood transfusions was probably responsible for the HI seroconversion. Nonetheless, the benign clinical course of rubella in immunocompromised children was confirmed.

The classical time series decomposition method was used to compare the temporal pattern of rabies in Chile before and after the implementation of the control programme. In the years 1950–60, a period without control measures, rabies showed an increasing trend, a seasonal excess of cases in November and December and a cyclic behaviour with outbreaks occurring every 5 years. During 1961–1970 and 1971–86, a 26-year period that includes two different phases of the rabies programme which started in 1961, there was a general decline in the incidence of rabies. The seasonality disappeared when the disease reached a low frequency level and the cyclical component was not evident.

The specific humoral immune response of 17 volunteers to infection with human rhinovirus type 2 (HRV-2) has been measured both by neutralization and by ELISA. Six volunteers who had HRV-2-specific antibodies in either serum or nasal secretions before HRV-2 inoculation were resistant to infection and illness. Of the remaining 11 volunteers who had little pre-existing HRV-2-specific antibody, one was immune but 10 became infected and displayed increases in HRV-2-specific antibodies. These antibodies first increased 1–2 weeks after infection and reached a maximum at 5 weeks. All six resistant volunteers who had high pre-existing antibody and eight of the volunteers who became infected maintained their HRV-2-specific antibody for at least 1 year. At this time they were protected against reinfection. Two volunteers showed decreases in HRV-2-specific antibodies from either serum or nasal secretions. They became infected but not ill after HRV-2 inoculation 1 year later.

The outbreak of poliomyelitis in Finland in 1984 was caused by a wild strain of poliovirus 3 with uncommon molecular and antigenic properties. We prepared a synthetic oligonucleotide probe complementary to nucleotides 494–510 in the 5′-noncoding part of the genome of a representative strain of the outbreak. This short nucleotide stretch was found to be relatively well conserved within the outbreak and uncommon among 82 independent poliovirus isolates. It may thus be a useful marker for screening isolates to identify those requiring more detailed genetic comparison. The sequences of the corresponding region of the genome are known for 32 separate poliovirus strains and 3 coxsackie B virus strains and show 6 fully conserved nucleotides that could assume a constant hairpin-loop position in a hypothetical secondary structure of the RNA. This could explain the persistence of a particular 17 nucleotide sequence for 40 years in nature in this highly variable region of the poliovirus genome.

A 5-year Integrated Vector Management (IVM) project was implemented in Pondicherry, South India, for the control of Bancroftian filariasis. The efficacy of the IVM strategy was compared with routine control strategy under the national programme. The present paper describes the pre-control epidemiological features of filariasis as determined by a mass blood survey in 1981. Of 24946 persons examined 8·41%; were microfilaraemic. Microfilaraemia prevalence was homogeneous throughout the study area. The prevalence and intensity of microfilaraemia were age dependent, and increased monotonically until about 20 years, following which there was a decline until about 40 years to become relatively stable in older age classes. The gender profiles of both prevalence and intensity of microfilaraemia showed no difference between the sexes until about 15 years of age, following which both were higher in males compared to females. The distribution of microfilarial counts was overdispersed, indicating aggregation of adult worms.

This article examines the evaluation of a bancroftian filariasis control programme undertaken in Pondicherry from 1981–5. Integrated vector management was applied in one half of the town, and routine operations under the national programme (larviciding and chemotherapy) continued in the comparison area. The programme was evaluated by monitoring relative change in the epidemiological statistics of both populations. The results indicate that there was significant reduction in prevalence of microfilaraemia in juveniles in the controlled area. An apparent reduction in intensity of microfilaraemia was also observed but this was a consequence of the reduction in prevalence, since the density of microfilariae remained unchanged. The results suggest that primary constraints on the epidemiological evaluation of the vector control of filariasis are the longevity and the population characteristics of the parasite.

An outbreak of waterborne cryptosporidiosis affecting 27 persons, diagnosed stool positive, occurred in Ayrshire in April 1988. Twenty-one of the 27 confirmed cases required some form of fluid replacement therapy. Local general practitioners indicated a two- to fivefold increase in diarrhoeal disease during the outbreak, and following enquiries made by Environmental Health Officers it became apparent that many hundreds of people had suffered a diarrhoeal illness at that time. Cryptosporidium spp. oocysts were detected in the treated chlorinated water supply system, in the absence of faecal bacterial indicators. Oocyst contamination of a break-pressure tank containing final water for distribution was the cause of this waterborne outbreak. An irregular seepage of oocyst-containing water, which increased during heavy rains, was the cause of the break-pressure tank contamination, rather than a failure of the water-treatment processes. The waterborne route should be considered when clusters of cryptosporidiosis associated with potable water occur. Waterborne cryptosporidiosis can occur in the absence of other faecal indicators of contamination.