An epidemic of acute respiratory disease in a colony of CFE rats is described, the main laboratory findings are recorded and its aetiology discussed.

The epidemic showed that severe respiratory disease varying from peracute to chronic was associated with infection of the lungs with a mycoplasma but that mycoplasmas could be present in rats, even in the lungs, without signs of disease, thus suggesting that one or more other factors were involved. It is also evident that there are strain differences in the susceptibility of rats to this disease.

The response of wild and domestic rabbits with a degree of genetic resistance to myxomatosis has been shown to be markedly affected by the age at which they were infected with a virulent strain of the virus. The response, in terms of mean survival time and percentage survival, fell with increasing age from 10 to 30 weeks with little change thereafter.

Acute blood samples from 120 children, attending the fever hospital in Alexandria and complaining of fever, were collected and examined for haemagglutination-inhibiting (HAI) and complement-fixing (CF) antibodies against the following arbovirus antigens; Sindbis, West Nile (WN), yellow fever, dengue 1, sandfly fever, Quaranfil, Chenuda and Nyamanini. Positive reactions in the acute sera were only detected against Sindbis (4·3%) and WN (4·3%) antigens. The convalescent sera obtained from 48 of these children showed a pronounced HAI titre against WN antigen in 14·6 % of them. The same sera showed a lower titre against yellow fever antigen (Asibi strain) which is due to cross-reaction between the two viruses. None of the acute or the convalescent sera showed CF antibodies against Quaranfil, Chenuda or Nyamanini antigens. The convalescent sera were not tested against dengue type 1 antigen. It is suggested that of the known arboviruses in Egypt, WN is the most important from the public health point of view.

Nine hundred and seventeen Salmonella infections in 580 households were confirmed during a laboratory study of diarrhoea in general practices in a large urban area during the years 1953–68. This was an annual incidence of about 2/10,000 population. Salmonellas were found in nearly 2% of new cases of diarrhoea investigated. Plural infections were found in 36% of the households studied and 18% of all contacts examined were shown to be infected. Among these contacts the infection rate was higher for children (24%) than for adults (16%). The duration of infection was longer than 2 months in nearly a quarter of the cases followed up, and intermittent excretion was observed in one-fifth. The commonest serotype was Salmonella typhimurium, but its incidence in the district declined especially after 1964. S. typhimurium infection provoked a severer enteritis but less general symptoms than did other salmonellas. Children were more susceptible than adults to salmonella infection, to illness and to prolonged excretion, but symptoms in index cases were as severe in adults as in children.

The isoquinoline compound UK 2054 prevents the uptake of influenza virus by susceptible cells. Pre-incubation of virus particles with 500μg./ml. UK 2054 at 37°C. for 2 hr. does not reduce virus infectivity. Host cells vary in their responsiveness to the inhibitory effect of UK 2054; virus multiplication is inhibited in chick allantoic cells by lower concentrations than those required to inhibit virus growth in chick embryo fibroblasts. The effectiveness of UK 2054 is reduced by the presence of serum.

It is concluded that inhibition of influenza virus multiplication by UK2054 might result from interaction of the inhibitor with both virus and cells. Any direct combination between inhibitor and virus is completely reversible.

The haemagglutinin of influenza virus A 2/Hong Kong/1/68 was shown to be markedly different from that of previously isolated A 2 virus strains. No haemagglutination-inhibiting (HI) antibody to A 2/Hong Kong/1/68 virus was detected in serum specimens collected in 1966 from persons aged 60 years or less. In contrast, HI antibody tests with 270 sera collected in 1968 indicated that 9·6% had demonstrable HI antibody at low titres, and 35·2% of 454 postepidemic (1969) sera had demonstrable HI antibody at relatively high titres. Most sera from persons aged 80 years and more collected in 1968 and 1969 had demonstrable HI anti-body to influenza virus A 2/Hong Kong/1/68. No HI antibody to the Hong Kong virus was detected in pre-epidemic sera from children aged 6 months to 3 years, whereas 32 % of postepidemic sera had HI antibody. The acquisition of HI antibody to A 2/Hong Kong/1/68 was not accompanied by an increase hi the incidence or titres of HI antibody to heterotypic A 2 influenza viruses. For sera from children aged 4–11 years, an increase of HI titre to heterotypic A 2 influenza was found.

Daily observations were made on the excretion of African swine fever (ASF) virus by pigs infected intranasally or by contact. Two strains of virus having mean death times of approximately 3 and 6 days were used, the latter being recently isolated from a warthog.

First excretion usually occurred by the nasopharyngeal route, as early as 1 or 2 days before the onset of fever in many cases. The titres of pharyngeal and nasal swabs rose rapidly to reach mean levels of about 104–106 HAD 50 at 48–72 hr. following the onset of pyrexia. Virus in the secretions of the conjunctiva or lower urogenital tract appeared later and did not attain such high levels. Faecal and urinary excretion was of relatively little significance, except in slower infections caused by the recent warthog virus.

These results are discussed in relation to the known failure of infected pigs to transmit the disease to stallmates during the first 12–24 hr. of pyrexia and also in relation to recent work on the pathogenesis of ASF in domestic swine.

This report summarizes closed, family, and open studies conducted sequentially over a 10 month period with the Cendehill rubella virus vaccine in more than 16,000 children and adolescents. This strain of rubella was attenuated by serial propagation on primary rabbit kidney cell cultures. Inoculation of the Cendehill vaccine produced seroconversion in 97% of the 3589 susceptible (seronegative) vaccinated persons. There was no spread of the virus to susceptible controls living in close contact with those vaccinated. The vaccine was well tolerated. No arthritis or arthralgia occurred in 860 female subjects 13–18 years of age who were included in the study. The Cendehill vaccine would appear to meet the requirements of an acceptable vaccine.

There are situations in which direct observation of the attachment of antibody molecules may be the simplest method of detecting antigen-antibody reactions. Applied to the study of the sex pili determined by a number of transmissible bacterial plasmids, the method has distinguished four serotypes in the F-like class and two in the I-like class. Antibody was usually attached haphazardly to the pili; however, in a few cases a regular periodicity could be observed. When few antibody molecules were attached, they could frequently be individually resolved and in certain antibody-pilus combinations large antibody molecules, tentatively identified as IgM, could be seen to predominate.