CHICAGO—High levels of thyroid hormone in pregnant women can have a direct toxic effect on fetal development, according to a study in the August 10 issue of JAMA, the Journal of the American Medical Association.

According to background information in the article, thyroid hormone (TH) plays an important role in the development of the embryo and maturation of the fetus. Maternal hypothyroidism (an underactive thyroid gland) and hyperthyroidism (an overactive thyroid gland) have deleterious effects on the outcome of pregnancy. While the effects of TH deprivation on the fetus, independently from that on the mother, can be studied in infants with congenital hypothyroidism, this is not the case in those with fetal thyrotoxicosis (an overactive thyroid gland).

João Anselmo, M.D., of Hospital Divino Espírito Santo, Ponta Delgada, Azores-Portugal, and colleagues from the University of Chicago Hospitals studied the effects of TH excess on fetuses carried by mothers who, because of their resistance to TH (RTH) are normal despite high TH levels but who carry normal fetuses that have been exposed to high maternal hormone levels. The study included 167 members of an Azorean family with RTH. Affected individuals had the RTH phenotype.

Thirty-six couples with complete information belonged to 1 of 3 groups: affected mothers (n=9), affected fathers (n=9), and unaffected relatives (n=18). "Mean miscarriage rates were 22.9 percent, 2.0 percent, and 4.4 percent, respectively. Affected mothers had an increased rate of miscarriage. They had marginally higher than expected numbers of affected offspring, i.e., 20 affected and 11 unaffected children, while affected fathers had 15 affected and 12 unaffected children. Unaffected infants born to affected mothers were significantly smaller than affected infants...," the authors write. "Our data show a 3- to 4-fold increase in the rate of miscarriage in affected mothers compared with that of spouses of affected fathers or unaffected first-degree relatives..."

CHICAGO—Children and adolescents who have received the varicella (chickenpox) vaccine and contract varicella are about half as contagious as those who have not been vaccinated, according to a study in the August 10 issue of JAMA, the Journal of the American Medical Association.

According to background information in the article, varicella is a highly infectious disease caused by the varicella zoster virus, which is spread by droplet or airborne transmission. Before the varicella vaccination program in the United States, approximately 4 million varicella cases occurred each year, resulting in 10,600 hospitalizations and 100 deaths. The majority of cases occurred in children, which reflects the highly contagious nature of the disease. Limited data are available on the contagiousness of vaccinated varicella cases.

Jane F. Seward, M.B., B.S., M.P.H., of the Centers for Disease Control and Prevention, Atlanta, and colleagues examined varicella transmission within households according to the varicella history and vaccination status of both the primary case and exposed household member(s) and estimated vaccine effectiveness from household secondary attack rates. The study consisted of a population-based, active varicella surveillance project in a community of approximately 320,000 in Los Angeles County during 1997 and 2001. Varicella cases were reported by child care centers, private and public schools, and health care clinicians and were investigated to collect demographic, clinical, medical, and vaccination data. Information on household contacts' age, varicella history, and vaccination status was collected.

During the study period, 6,316 cases of varicella were reported. The researchers found that among children and adolescents aged 1 to 14 years, secondary attack rates varied according to age and by disease and vaccination status of the primary case and exposed household contacts. "Among contacts aged 1 to 14 years exposed to unvaccinated cases, the secondary attack rate was 71.5 percent if they were unvaccinated and 15.1 percent if they were vaccinated. Overall, vaccinated cases were half as contagious as unvaccinated cases. However, vaccinated cases with 50 lesions or more were similarly contagious as unvaccinated cases whereas those with fewer than 50 lesions were only one-third as contagious."

CHICAGO—Preliminary results from a trial for a streptococcal vaccine indicate the vaccine appears likely to offer protection against streptococcal infections, according to a study in the August 10 issue of JAMA, the Journal of the American Medical Association.

Efforts to develop a vaccine to prevent group A streptococcal (a type of bacteria that commonly causes illness) infections have been ongoing for more than 70 years, according to background information in the article. Recent advances have allowed previous obstacles associated with group A streptococcal vaccine development to be overcome. Group A streptococcal infections and their sequelae represent a global health problem.

Karen L. Kotloff, M.D., of the University of Maryland School of Medicine, Baltimore, and colleagues report on a preliminary study evaluating the safety and immune reactivity of a group A streptococcal vaccine in healthy volunteers. The phase 1 vaccine trial included 28 adult volunteers aged 18 to 50 years recruited from the metropolitan area of Baltimore between October 1999 and February 2003. Each volunteer received 3 spaced intramuscular injections of either 50 micrograms (n=8), 100 micrograms (n=10), or 200 micrograms (n=10) of group A streptococcal vaccine formulated with aluminum hydroxide into the deltoid muscle of alternating arms.

CHICKEN POX VACCINE HIGHLY EFFECTIVE AT PREVENTING SEVERE DISEASE-BREAKTHROUGH CASES OCCUR BUT ARE MILD AND LESS CONTAGIOUS