Varicella: historical perspective and clinical overview.

In immunocompetent children in Europe and the United States, varicella is usually a benign disease. However, infants born to women who acquire varicella during or shortly after pregnancy are at high risk of infection. For unknown reasons, the disease is more severe in adolescents and adults, with pneumonia the most common cause of death. Varicella may also be lethal in patients of any age in the presence of biologic or iatrogenic immunosuppression. It is now well documented that varicella-zoster virus remains latent in the dorsal root and cranial ganglia following an attack of varicella. Viral reactivation appears with advancing age as cellular immunity wanes. The contemporary relative aging of the population will enhance the social significance of zoster. The immigration of nonimmune adults in temperate climates poses a major problem in terms of protection of high-risk children. A vaccination program is indicated.

Varicella and herpes zoster: a perspective and overview.

The events leading to the isolation of varicella-zoster virus (VZV) are described beginning with the pioneering contributions of Ernest Tyzzer and Ernest Goodpasture and the early epidemiologic observations that indicated a relationship between varicella and zoster. Isolation, propagation, and immunologic proof of the coidentity of the viruses from the two clinical entities evolved from the introduction of human cell culture systems, a development that revolutionized virus research. Now the social significance of VZV is increasing. This reflects an aging population, increasing use of immunosuppressive therapeutic procedures, and the advent of a biologic immunosuppressive agent, the virus that causes AIDS. Currently there are unsolved problems: For unknown reasons varicella is often an adult disease in the tropics, and cell cultures fail to demonstrate VZV in throat washings from cases. These peculiarities warrant elucidation.

A nine year prospective study of Chagas' disease in a defined rural population in northeast Brazil.

The association between infection with Trypanosoma cruzi and the development of electrocardiographic alterations and mortality was studied longitudinally for 9 years in a population residing in an endemic area in Castro Alves, Bahia, Brazil. Annual censuses were begun in 1973. At 3 year intervals from 1974 to 1983, the population was examined serologically and subjected to electrocardiography using standardized techniques. Of 1,751 individuals registered during the 10 censuses, 1,541 (88%) were examined serologically at least once. Of 747 individuals in constant residence and originally seronegative, 24 were seropositive upon subsequent evaluation, giving a seroconversion rate of 4.92/1,000 person-years (PY). The overall rate of development of an abnormal ECG was 25.7/1,000 PY for seropositive individuals and 12.5/1,000 PY for seronegative individuals, a relative risk of 2. The 10-14-year-old seropositive group had the highest risk of developing ECG abnormalities (24.1/1,000 PY, relative risk = 3.5). The age-adjusted mortality rate of seropositive individuals was slightly higher than for seronegative individuals (8.9 vs. 7.8/1,000 PY). In sero-positive individuals, mortality was strongly associated with the presence of ventricular conduction defects and arrhythmias. Ventricular conduction defects appeared most frequently in younger individuals. Older individuals presented the highest risk of development of frequent and multifocal extrasystoles.

Lessons for the control of AIDS.

PIP: A balanced perspective that places acquired immunodeficiency syndrome (AIDS) in the context of the social needs of a global society is needed to overcome the hysteria and stigmatizing that presently surrounds this public health issue. The migration of poor, rural, sexually active young people to urban centers in the Third World has clearly played a role in the dissemination of AIDS and other infectious diseases. It is necessary, however, to examine the major cause of such population movement--private enterprise. Migrant workers are used to perform menial jobs in the urban labor force. Another cause of population movements is war and political repression. The fact that young people are becoming increasingly mobile has serious implications for the control of AIDS, and this phenomenon cannot be addressed without looking at its causes. Similarly, the disproportionate mortality of minorities- -seen in the AIDS epidemic as well--calls for discrimination. To prevent and control AIDS, the 1st step is to increase understanding of its natural history and epidemiology. Then, lessons must be learned from successful public health programs rooted in a primary health care system, including the Expanded Program on Immunization and oral rehydration campaigns. Although funds should not be diverted from such programs to combat AIDS, their logistic structure should be studied. Above all, however, it must be kept in mind that the constructive influence of health education will be thwarted as long as social inequities remain.^ieng

Cardiac morbidity and mortality due to Chagas' disease: prospective electrocardiographic study of a Brazilian community.

The evolution of Chagas' cardiomyopathy is poorly understood. We therefore examined the development of cardiac lesions in a rural Brazilian community for a period of 7 years. Initially, 42% of 1017 residents were seropositive for infection with Trypanosoma cruzi. Age-specific infection rates indicated that most had become infected before the age of 20 years. On follow-up, it appeared that those persons who developed cardiac lesions did so soon after infection, since the incidence of right bundle branch block and other ventricular conduction defects (VCDs) was also highest before age 20 years. The progressive nature of these lesions was demonstrated by frequent development of additional electrocardiographic abnormalities and high mortality among infected adults with VCDs. In contrast, mortality was low and approximately the same for seropositive and seronegative adults under 60 years who had normal electrocardiograms. Electrocardiography during the early asymptomatic stage of infection was able to distinguish persons with potentially lethal cardiac lesions from those with a benign prognosis.

Inoculation of guinea pigs with varicella-zoster virus via the respiratory route.

Guinea pigs were inoculated by the respiratory route with wild-type (Cyr) or vaccine (Oka) strain varicella zoster virus (VZV). Wild-type cell-free virus obtained by sonication produced neutralizing antibody responses in steroid-treated animals when given via the intratracheal route, and induced neutralizing antibody as well as a pneumonitis in normal animals when given via the intrabronchial (i.b.) route. A humoral response also followed i.b. instillation of cell-associated wild-type or vaccine strain VZV. Prior i.b. administration of thioglycollate or exposure to hyperoxia altered the number and function of pulmonary macrophages, respectively, but viral susceptibility of the guinea pigs was not enhanced. Both strains of VZV could be isolated from bronchial washings up to 48 hours after i.b. instillation of cell-associated virus, but neither strain was isolated thereafter from cultures of bronchial washings or explanted lung tissues.

Association between household triatomine density and incidence of Trypanosoma cruzi infection during a nine-year study in Castro Alves, Bahia, Brazil.

We studied the association between human incidence of Trypanosoma cruzi infection and household infestation density of Panstrongylus megistus in Castro Alves, Bahia, Brazil. During a 9-year period, 19 persons seroconverted; 17 were children, 17 lived in nonplastered houses, and 13 lived in houses infested with triatomines. Although 6 seroconverting persons lived in houses where triatomines could not be found, the risk of seroconversion was significantly greater in infested houses and 16 times greater in densely infested houses (greater than 15 bugs/person-hour of search). The highest rate of seroconversion (6/100 person-years exposure) occurred in houses containing the greatest number of bugs infected with T. cruzi (greater than 6 infected bugs/person-hour). These observations suggest that vector control measures could have a dramatic impact on transmission of T. cruzi by P. megistus.

Three-year prospective study of the evolution of Manson's schistosomiasis in north-east Brazil.

A cross-sectional study of morbidity associated with Schistosoma mansoni infection in an area in North-East Brazil where the disease is endemic was carried out in 1974. The survey was repeated in 1977, before mass treatment with oxamniquine, providing a cohort of 210 individuals who had both examinations. The high prevalence of hepatomegaly (over 80%) and of splenomegaly (over 15%) contrasted with rates of 10% and 1%, respectively, in a non-endemic area. Over the 3-year period hepatomegaly spontaneously regressed in 13% of patients, and splenomegaly regressed in 56%, a phenomenon most common in older individuals with light infections. Those with heavy infections--ie, 500 or more eggs per g faeces, had an excess risk of splenomegaly of 19.6% and, of its persistence, of 61.5%. Thus, intensity of infection was a critical factor in liver and spleen involvement, and programmes of chemotherapy that reduce infection should mitigate the risk of schistosomal morbidity.