Vivian H. Alfonso

Ebola Virus Neutralizing Antibodies Detectable in Survivors of theYambuku, Zaire Outbreak 40 Years after Infection

Duration of immunity against Ebola virus among survivors remains unclear. We assessed serological immune profiles and retention of Ebola virus neutralizing antibodies in 14 survivors of the 1976 Yambuku outbreak 40 years postinfection, providing the longest documentation of such measures reported.

Evidence of Mumps Infection Among Children in the Democratic Republic of Congo

Background: Mumps is an acute viral infection and while the infection is usually mild, complications can lead to permanent sequelae including brain damage and deafness. The burden of mumps is currently unknown the Democratic Republic of Congo (DRC), we therefore assessed susceptibility to mumps infection among children 6–59 months of age. Methods: In collaboration with the 2013–2014 DRC Demographic and Health Survey, we conducted a serosurvey to assess population immunity to vaccine preventable diseases. Dried blood spot samples were collected from children 6 to 59 months of age and processed at the UCLA-DRC laboratory in Kinshasa, DRC using the Dynex Technologies Multiplier FLEX chemiluminescent immunoassay platform (Dynex multiplex assay, Chantilly, VA). Logistic multivariate analyses were used to determine risk factors for mumps seropositivity. Results: Serologic and survey data were matched for 7195, 6–59 month-old children, among whom 22% were positive and 3% indeterminate for mumps antibodies in weighted analyses. In multivariate analyses, the odds of seropositivity increased with increasing age, female gender, number of children in household, increasing socioeconomic status and province (Kinshasa with the highest odds of positive test result compared with all other provinces). Conclusion: These data suggest that mumps virus is circulating in DRC and risk of exposure increases with age. At present, the introduction of a combined measles–mumps–rubella vaccine remains unlikely, as the capacity to maintain adequate vaccine coverage levels for routine immunization must be improved before additional antigens can be considered for the routine immunization schedule.

Predictors of measles vaccination coverage among children 6–59 months of age in the Democratic Republic of the Congo

Highlights • DRC’s overall measles vaccination coverage level of 70% is too low to halt the spread of measles.• Socioeconomic variables and residence are associated with vaccination coverage disparities.• Vaccination coverage and data quality are linked, and as such, dated records must be increased.

Serologic Evidence of Ebolavirus Infection in a Population With No History of Outbreaks in the Democratic Republic of the Congo

Background Previous studies suggest that cases of Ebola virus disease (EVD) may go unreported because they are asymptomatic or unrecognized, but evidence is limited by study designs and sample size. Methods A large population-based survey was conducted (n = 3415) to assess animal exposures and behaviors associated with Ebolavirus antibody prevalence in rural Kasai Oriental province of the Democratic Republic of Congo (DRC). Fourteen villages were randomly selected and all healthy individuals ≥1 year of age were eligible. Results Overall, 11% of subjects tested positive for Zaire Ebolavirus (EBOV) immunoglobulin G antibodies. Odds of seropositivity were higher for study participants older than 15 years of age and for males. Those residing in Kole (closer to the outbreak site) tested positive at a rate 1.6× higher than Lomela, with seropositivity peaking at a site located between Kole and Lomela. Multivariate analyses of behaviors and animal exposures showed that visits to the forest or hunting and exposure to rodents or duikers predicted a higher likelihood of EBOV seropositivity. Conclusions These results provide serologic evidence of Ebolavirus exposure in a population residing in non-EBOV outbreak locations in the DRC and define statistically significant activities and animal exposures that associate with EBOV seropositivity.

Detecting Ebola with limited laboratory access in the Democratic Republic of Congo: evaluation of a clinical passive surveillance reporting system

Ebola virus disease (EVD) can be clinically severe and highly fatal, making surveillance efforts for early disease detection of paramount importance. In areas with limited access to laboratory testing, the Integrated Disease Surveillance and Response (IDSR) strategy in the Democratic Republic of Congo (DRC) may be a vital tool in improving outbreak response.

The Influence of Pre-natal Supplement Initiation on Preterm Birth Among Majority Hispanic Women in Los Angeles County: The Role of Nativity.

Objectives Despite being encouraged to take pre-natal supplements, suboptimal micronutrient intake is common in pregnancy, especially among Hispanic women. In this study, we assessed whether initiation and timing of pre-natal vitamin use influences the risk of preterm birth. Methods Women who gave birth to singletons in 2003 in Los Angeles County, California, were enrolled into a population-based case–control study. Focusing on non-Hispanic white and Hispanic women, associations between timing of pre-natal supplement use and preterm birth were assessed using logistic regression. Results Among Hispanic mothers, the odds of preterm birth increased the later a woman initiated pre-natal supplement use in pregnancy. The magnitude of this association was larger in US-born compared to foreign-born Hispanic women. Conclusions These findings suggest that nativity may modify the relationship between pre-natal supplement use and preterm birth possibly due to underlying differences in diet composition of Hispanic women by place of birth.

Serologic Markers for Ebolavirus Among Healthcare Workers in the Democratic Republic of the Congo.

Healthcare workers in an area with a previous Ebola outbreak in the Democratic Republic of the Congo exhibited both antibody response and neutralizing capacity to at least 1 Ebola protein, despite never having been diagnosed with Ebola virus disease.

Association of Previous Measles Infection With Markers of Acute Infectious Disease Among 9- to 59-Month-Old Children in the Democratic Republic of the Congo

Abstract Background Transient immunosuppression and increased susceptibility to other infections after measles infection is well known, but recent studies have suggested the occurrence of an “immune amnesia” that could have long-term immunosuppressive effects. Methods We examined the association between past measles infection and acute episodes of fever, cough, and diarrhea among 2350 children aged 9 to 59 months whose mothers were selected for interview in the 2013–2014 Democratic Republic of the Congo (DRC) Demographic and Health Survey (DHS). Classification of children who had had measles was completed using maternal recall and measles immunoglobulin G serostatus obtained via dried-blood-spot analysis with a multiplex immunoassay. The association with time since measles infection and fever, cough, and diarrhea outcomes was also examined. Results The odds of fever in the previous 2 weeks were 1.80 (95% confidence interval [CI], 1.25–2.60) among children for whom measles was reported compared to children with no history of measles. Measles vaccination demonstrated a protective association against selected clinical markers of acute infectious diseases. Conclusion Our results suggest that measles might have a long-term effect on selected clinical markers of acute infectious diseases among children aged 9 to 59 months in the DRC. These findings support the immune-amnesia hypothesis suggested by others and underscore the need for continued evaluation and improvement of the DRC’s measles vaccination program.

Polio immunity and the impact of mass immunization campaigns in the Democratic Republic of the Congo

Background In order to prevent outbreaks from wild and vaccine-derived poliovirus, maintenance of population immunity in non-endemic countries is critical. Methods We estimated population seroprevalence using dried blood spots collected from 4893 children 6–59 months olds in the 2013–2014 Demographic and Health Survey in the Democratic Republic of the Congo (DRC). Results Population immunity was 81%, 90%, and 70% for poliovirus types 1, 2, and 3, respectively. Among 6–59-month-old children, 78% reported at least one dose of polio in routine immunization, while only 15% had three doses documented on vaccination cards. All children in the study had been eligible for at least two trivalent oral polio vaccine campaigns at the time of enrollment; additional immunization campaigns seroconverted 5.0%, 14%, and 5.5% of non-immune children per-campaign for types 1, 2, and 3, respectively, averaged over relevant campaigns for each serotype. Conclusions Overall polio immunity was high at the time of the study, though pockets of low immunity cannot be ruled out. The DRC still relies on supplementary immunization campaigns, and this report stresses the importance of the quality and coverage of those campaigns over their quantity, as well as the importance of routine immunization.

Prevalence of Rubella Antibodies Among Children in the Democratic Republic of the Congo

Background: While generally mild in children, rubella infection in early pregnancy can lead to miscarriage, fetal death or congenital rubella syndrome. Rubella vaccination is not yet available as a part of routine immunization in the Democratic Republic of the Congo (DRC), and the burden of infection is unknown. Methods: In collaboration with the 2013–2014 DRC Demographic and Health Survey, a serosurvey was carried out to assess population immunity to vaccine-preventable diseases. Dry blood spot samples collected from children 6–59 months of age were processed using the Dynex Technologies Multiplier FLEX chemiluminescent immunoassay platform (Dynex Technologies, Chantilly, VA). Results: Among the 7195 6- to 59-month-old children, 33% were positive and <1% indeterminate for rubella antibodies in weighted analyses. Seroprevalence was positively associated with age of the child and province, with seropositivity highest in Bandundu (53%) and lowest in Kasai-Oriental (20%). In multivariate analyses, serologic evidence of infection was associated with age of the mother and child, socioeconomic status and geographic location. Conclusions: Rubella infection is prevalent among children in the DRC, and while most seroconversion occurs in young children, a significant proportion of children remain at risk and may enter reproductive age susceptible to rubella infection. While not currently in place, implementation of a surveillance program will provide improved estimates of both rubella virus circulation and the burden of congenital rubella syndrome. Such information will play an important role in future policy decisions, vaccine delivery strategies and may provide a basis upon which the effectiveness of rubella antigen introduction may be assessed.