Dorothy M. Horstmann

Rubella: Reinfection of Vaccinated and Naturally Immune Persons Exposed in an Epidemic

Abstract The protective efficacy of vaccine-induced and naturally acquired immunity was compared in a prospective study of a rubella epidemic among military recruits. The population consisted of 190 men in the following categories with respect to immunity to rubella: 26 who were susceptible, 15 vaccinees who had been immunized two to three months previously and 149 who were naturally immune. As a result of the epidemic all 26 susceptible men were infected; rubella virus was recovered from the throats of 11. On the basis of hemagglutination-inhibiting and complement-fixing antibody responses, 80 per cent of those vaccinated and 3.4 per cent of those who were naturally immune were reinfected. Virus was recovered from the throat of one vaccinee, but from none of the reinfected naturally immune men. If precipitin antibody results are included, 100 per cent of vaccinees responded serologically. None of those reinfected became ill; among the susceptible men the ratio of inapparent to apparent infections was app...

Diffuse Polyclonal B-Cell Lymphoma during Primary Infection with Epstein–Barr Virus

ALTHOUGH most primary infections with Epstein–Barr virus (EBV) in childhood are silent or associated with mild nonspecific illness, a few are recognized as infectious mononucleosis, a lymphoprolife...

Poliomyelitis Virus in Blood of Orally Infected Monkeys and Chimpanzees.

Summary Seven of 10 cynomolgus monkeys and 3 of 4 chimpanzees have been found to have viremia early in the incubation period following oral infection with poliomyelitis virus. Viremia was present in animals infected with a Brunhilde type (Egypt) as well as a Lansing type (Y-SK), and persisted in some animals over the 4th, 5th, and 6th days after virus ingestion. Virus was not isolated from blood specimens collected during the first 3 days after feeding, nor on the 7th day, in the two instances in which it was tested. The interval between viremia and the appearance of paralysis varied between 3 and 7 days in the cynomolgus monkeys.

Poliomyelitis: severity and type of disease in different age groups.

Because of the changing age incidence of poliomyelitis in certain parts of the world, considerable attention has been drawn recently to differences in host responses associated with age. The problems involved are of concern both to the epidemiologist and to the clinician, and they have practical implications in both fields. That age f~er se, in addition to other host factors, such as genetic constitution, plays an important role in natural and experimental virus infections in animals is well recognized. Theiler’s virus, the Coxsackie group, various other neurotropic viruses, and the tumor viruses have been studied experimentally in this respect. Marked differences in susceptibility to infection by different routes and, in some instances, marked differences in the character of the response have been observed.’ The age problem in relation to poliomyelitis in the human population is complicated by several factors, including the prevalence of mild or inapparent infection which cannot be recognized clinically, and the difficulties encountered in defining and reporting of nonparalytic cases. About one aspect, namely severity, there is perhaps less confusion, a t least if one considers mortality statistics as an index. In Connecticut, since 1916, the shape of the curve for case fatality per cent by age group has been relatively constant, with the lowest per cent of deaths in young children (except those under one year), the incidence rising steadily with each age group (FIGURE 1).t This pattern has been maintained in Connecticut, as elsewhere, despite marked shifts in age incidence of the disease, and a marked reduction in case fatality rates. The higher mortality in 1916 and in 1925 to 1929 is explained in part by the fact that in, general, only paralytic cases were reported during this time, the practice of reporting nonparalytic cases not having become widespread until the 1930’s. The question arises: Is the greater mortality in older age groups due to age alone, or to some extrinsic factor or factors? This query cannot be answered with finality. There is, however, some evidence to suggest that the greater severity-and therefore mortality-in older age groups is perhaps enhanced by the ill effects of exercise or continued activity, often carried out under stress, after the onset of symptoms of the major illness phase of the clinical disease. This is a far more common occurrence in adults than in children?’ Another contributing factor to the higher mortality in adults is probably associated with the relatively high incidence of the bulbar form of the disease in older age groups in some outbreaks. This is, however, a variable occurrence and, in some large series, the incidence of bulbar cases has not differed markedly in

POLIOMYELITIS VIRUS IN FLY-CONTAMINATED FOOD COLLECTED AT AN EPIDEMIC

Poliomyelitis virus has been detected in food exposed to flies at homes of poliomyelitis patients within an epidemic area. This was achieved by feeding such exposed food to chimpanzees which developed subclinical infections or asymptomatic carrier states ascertained by positive stool tests in rhesus monkeys.

Clinical, virologic, and serologic evidence of Epstein-Barr virus infection in association with childhood pneumonia

To explore the association of Epstein-Barr virus infection with childhood pneumonia we studied two patients whose mononucleosis-like illnesses were accompanied by pneumonia; both had virologic and serologic evidence of current or recent EBV infection. We then analyzed the sera of 71 children (age range, 14 months to 9 years) with pulmonary infiltrates for the presence of four classes of antibody to EBV. Antibody responses consistent with current or recent EB virus infection were found in 15. Two children had IgM antibodies to the EBV viral antigen at titers ≥1:160, indicating current infection, and all 15 patients had antibody to components of the early antigen complex, suggesting recent infection. A fourfold rise or drop in one or more EBV-specific antibody classes was noted in eight patients within 30 days following onset of clinical illness. Few patients had clinical features suggesting infectious mononucleosis. Eight of the 15 with serologic evidence of current or recent EBV infection also had clinical or serologic evidence of infection with another pathogen-bacterial, viral, or mycoplasmal. Thus, in childhood pneumonia, EBV may be a primary, co-primary, or secondary pathogen; it may be reactivated in the course of infection with another agent, or possibly, by suppressing immune function, it may precipitate infection with some other organism.

Infectious hepatitis in childhood

Summary Two institutional outbreaks of infectious hepatitis among children werestudies. In all of the ninety-six junvenile patients the disease was mild and of relatively short duration as compared with statistics on the adult disease. The mildness of infectious hepatitis in children has tended to belittle thedisease. There is no evidence that such mild cases are less dangerous to the community from the infectious standpoint than are the more severe adult cases.

Replication of Rubella Virus in a Continuous Line of African Green Monkey Kidney Cells (Vero).

Summary Rubella virus has been found to grow to high titer in a continuous line of green monkey kidney cells (Vero), with the production of CPE and plaques. Infectivity titrations can be read within 2 weeks and are somewhat higher than comparable titers measured by echovirus 11 interference in pGMK. Primary isolation rates of 56% were obtained in Vero cultures as compared to 12% with the same specimens tested in pGMK cultures. Complement fixing antigen can be produced in satisfactory titer in Vero cultures, and the system is suitable for the direct measurement of neutralizing antibody.

Primary atypical pneumonia: An epidemic caused by Mycoplasma pneumoniae

The clinical epidemiology of Mycoplasma pneumoniae infections was investigated by serological means during the course of an outbreak of pneumonia in an institution for retarded children. The epidemic worked its way slowly through the population over a period of several months. By means of the tetrazolium reduction inhibition (TRI) and direct hemagglutination tests, it was found that among those exposed infection rates were 90 per cent in the 5 to 18 age group, and 64 per cent in adults. The highest incidence of pneumonia was in the youngest age group (28 per cent); children with Downs syndrome proved particularly susceptible to this manifestation.

A NATURAL EPIDEMIC OF RUBELLA IN A CLOSED POPULATION: VIROLOGICAL AND EPIDEMIOLOGICAL OBSERVATIONS.

We have recently had the opportuni ty of fo l lo~ng the course of a rubella epidemic in a closed population, using virus isolations and serologic tests to determine the spread of infection among susceptibles. The epidemic occurred in an institution for retarded children in which the residents are housed in cottages, each with a population of approximately 30 to 40. The clinical a t tack rates in the four cottages in which the majori ty of cases occurred are shown in Table 1. The average ages of the children ranged from abont 12 to 18, and the a t tack rates for clinical rubella were 19 to 37% in the different units. Fig. 1 indicates the t ime sequence of cases in the four cottages. The pat tern in each was remarkably regular. At first, several cases occurred over a two to three day period; then, sixteen days after the first case, a second wave began. An exception was cottage 20 in which the interval was only thirteen days between the first case and the beginning of the second group of cases. Throat swabs and blood specimens were collected from all children in each cottage several days after the first case was recognized, and again approximately two to three months later, when the epidemic was over. During the interim, all the children were examined regularly, particular at tention being paid to post-auricular lymph node enlargement and rash. Specimens were collected repeatedly from all children with suspicious findings and from those who developed frank rubella. In addition to throat swabs and blood samples, a few urine specimens were obtained from children seen on the first day of rash.