Age-dependent acquisition of IgG antibodies to Shigella serotypes-a retrospective analysis of seroprevalence in Kenyan children with implications for infant vaccination.

Background: Shigellosis mainly affects children under 5 years of age living in low- and middle-income countries, who are the target population for vaccination. There are, however, limited data available to define the appropriate timing for vaccine administration in this age group. Information on antibody responses following natural infection, proxy for exposure, could help guide vaccination strategies. Methods: We undertook a retrospective analysis of antibodies to five of the most prevalent Shigella serotypes among children aged <5 years in Kenya. Serum samples from a cross-sectional serosurvey in three Kenyan sites (Nairobi, Siaya, and Kilifi) were analyzed by standardized ELISA to measure IgG against Shigella sonnei and Shigella flexneri 1b, 2a, 3a, and 6. We identified factors associated with seropositivity to each Shigella serotype, including seropositivity to other Shigella serotypes. Results: A total of 474 samples, one for each participant, were analyzed: Nairobi (n = 169), Siaya (n = 185), and Kilifi (n = 120). The median age of the participants was 13.4 months (IQR 7.0-35.6), and the male:female ratio was 1:1. Geometric mean concentrations (GMCs) for each serotype increased with age, mostly in the second year of life. The overall seroprevalence of IgG antibodies increased with age except for S. flexneri 6 which was high across all age subgroups. In the second year of life, there was a statistically significant increase of antibody GMCs against all five serotypes (p = 0.01-0.0001) and a significant increase of seroprevalence for S. flexneri 2a (p = 0.006), S. flexneri 3a (p = 0.006), and S. sonnei (p = 0.05) compared with the second part of the first year of life. Among all possible pairwise comparisons of antibody seropositivity, there was a significant association between S. flexneri 1b and 2a (OR = 6.75, 95% CI 3-14, p < 0.001) and between S. flexneri 1b and 3a (OR = 23.85, 95% CI 11-54, p < 0.001). Conclusion: Children living in low- and middle-income settings such as Kenya are exposed to Shigella infection starting from the first year of life and acquire serotype-specific antibodies against multiple serotypes. The data from this study suggest that Shigella vaccination should be targeted to infants, ideally at 6 or at least 9 months of age, to ensure children are protected in the second year of life when exposure significantly increases.

Assessing the acceptability, reliability, and validity of the EORTC Quality of Life Questionnaire (QLQ-C30) in Kenyan cancer patients: a cross-sectional study.

BACKGROUND: In oncology practice, eliciting the patient's perspective on their quality of life (QOL) adds important information and value to their treatment and care. The European Organization for Research and Treatment of Cancer QOL questionnaire (EORTC QLQ-C30) is the most commonly used tool for this purpose but has not been validated in Kenya. The present study aimed to conduct a preliminary assessment of the QOL among Kenyan cancer patients and examine the psychometric properties of the tool in this population. One hundred patients with heterogeneous types of cancer were enrolled in this cross-sectional study between July and August 2019. The EORTC QLQ-C30 questionnaire was administered to patients using either the English or Kiswahili official version. Descriptive statistics were used to assess patient demographics and clinical characteristics. The psychometric properties of the EORTC QLQ-C30 were evaluated in terms of acceptability, internal consistency, and construct validity using statistical software packages, STATA and SPSS. RESULTS: The EORTC QLQ-C30 was found to be acceptable for use in our patient population as indicated by high compliance and low missing responses. Of the 100 patients, 66 were able to self-administer the questionnaire. The average time for completion was 13 min. Preliminary QOL assessment indicated an average QOL in Kenyan cancer patients (53 ± 27). Among the function scales, participants scored the lowest on the social function scale (51 ± 36) whereas among the symptom scales, participants scored the highest on the financial difficulties scale (79 ± 31). Cronbach's alpha coefficient values ranged from 0.72-0.95, illustrating the reliability of the scales measured. Interscale correlations were statistically significant (p < 0.05), indicating clinical validity of the data collected. The magnitudes of the correlations between the physical functioning scale and the role functioning, pain, and fatigue scales were consistent with the values published in other studies across different geographical populations, further cross-validating the results from our study. CONCLUSION: The results from this study provide important first insights into using EORTC QLQ-C30 in the Kenyan population. We conclude that the questionnaire is an acceptable, reliable, and valid instrument for measuring the QOL in cancer patients in Kenya and recommend its use in clinical practice.