Increased risk of measles mortality for children with siblings among the Fula Bande, Senegal

Decreasing stochasticity through enhanced seasonality in measles epidemics

Seasonal changes in the environment are known to be important drivers of population dynamics, giving rise to sustained population cycles. However, it is often difficult to measure the strength and shape of seasonal forces affecting populations. In recent years, statistical time-series methods have been applied to the incidence records of childhood infectious diseases in an attempt to estimate seasonal variation in transmission rates, as driven by the pattern of school terms. In turn, school-term forcing was used to show how susceptible influx rates affect the interepidemic period. In this paper, we document the response of measles dynamics to distinct shifts in the parameter regime using previously unexplored records of measles mortality from the early decades of the twentieth century. We describe temporal patterns of measles epidemics using spectral analysis techniques, and point out a marked decrease in birth rates over time. Changes in host demography alone do not, however, suffice to explain epidemiological transitions. By fitting the time-series susceptible-infected-recovered model to measles mortality data, we obtain estimates of seasonal transmission in different eras, and find that seasonality increased over time. This analysis supports theoretical work linking complex population dynamics and the balance between stochastic and deterministic forces as determined by the strength of seasonality.

Comparison of the Vitek Immunodiagnostic Assay System with three immunoassay systems for detection of cytomegalovirus-specific immunoglobulin G

The Vitek Immunodiagnostic Assay System (VIDAS; bioMerieux Vitek Inc., Hazelwood, Mo.) was evaluated for its ability to detect anticytomegalovirus immunoglobulin G (IgG) and was compared with the following assay systems: Abbott IMx Cytomegalovirus IgG antibody assay (Abbott Laboratories, Abbott Park, Ill.), Whittaker Cytomegelisa II IgG assay (Whittaker Bioproducts, Walkersville, Md.), and Whittaker FIAX Cytomegalovirus IgG assay (Whittaker Bioproducts). Samples were considered positive if at least two of three (IMx, Cytomegelisa II, and FIAX) comparative assays gave positive results; a sample was considered negative if at least two of the three assays were negative. Of the 199 clinical serum samples tested, 194 gave concordant results among the three comparative assays (145 were positive and 49 were negative). The VIDAS results with two samples were persistently equivocal and were therefore excluded from the comparison study. The overall agreement between VIDAS and the established standard was 98.5%. The VIDAS assay yielded one false-positive and two false-negative results. The intra- and interassay precision studies indicate that the VIDAS assay is suitable for clinical use. The VIDAS system is rapid, self-contained, and fully automated and would be useful for screening of cytomegalovirus immune status.

Increased risk of death from measles in children with a sibling of opposite sex in Senegal

OBJECTIVE

To examine whether contracting measles from a sibling of the opposite sex affects mortality.

DESIGN

Prospective registration during 15-20 years of all births and deaths, including 243 measles related deaths. Measles infection was not registered; however, as in fatal cases measles was probably contracted from a maternal sibling the risk of dying during measles outbreaks was examined in families with two boys, two girls, or a boy and a girl.

SETTING

31 small villages in two rural areas of eastern Senegal.

SUBJECTS

766 children living in families with two children aged under 10 years during outbreaks of measles, 107 (14%) of whom died of measles.

MAIN OUTCOME MEASURE

Deaths from measles, size of village, age and sex of maternal siblings.

RESULTS

The interval between outbreaks in the same village was greater than 10 years. The risk of dying of measles was significantly related to age, increasing with the age difference between siblings and decreasing with the size of village. In a multiple logistic regression analysis adjusting for these background factors, children in families with a boy and a girl had a significantly higher mortality than children in families with two boys or two girls (odds ratio = 1.81, 95% confidence interval 1.17 to 2.82). The increase in risk was the same for boys and girls in families with two children one of whom was a boy and one a girl.

CONCLUSION

Cross sexual transmission may be an important determinant of severity of measles infection.

Measles virus specific antibody in infants in a highly vaccinated society

Measles virus specific antibody levels were measured in infants from 2 to 12 months of age. The sera were tested by hemagglutination-inhibition (HI), neutralization (NT), and enzyme immunoassay (EIA) methods. The results of this study indicate that in the population examined, infants at an early age have very low or no immunity of maternal origin to measles virus-93% of the infants were without detectable neutralizing antibody (NT titer less than or equal to 10) at 6 months of age, and by the end of the first year of life 100% had no neutralizing antibody.

Vaccine-preventable disease and immunization in the developing world

Vaccines have given health care providers control over a substantial portion of the morbidity and mortality in the developing world. Global efforts have immunized two-thirds of the world's children with DTP and polio vaccines; 72% have received BCG and 59% measles vaccine; but only 29% of pregnant women have received two doses of tetanus toxoid. In addition, vaccines against yellow fever, Japanese encephalitis, hepatitis B, rubella, and mumps and meningococcal polysaccharide vaccine are being used in specific regions of the world. New vaccine candidates will enhance the vaccine armamentarium over the next decade to include the causes of pneumonia, diarrhea, and meningitis: Haemophilus influenzae type b, pneumococcal and meningococcal protein conjugate vaccines, typhoid and rotavirus vaccine. Genetically engineered vaccine vehicles, genetic reassortants, and genetic deletions are being investigated as new vaccine candidates.