Breast Cancer Screening: Knowledge, Attitudes, and Practices among Female University Students in The Gambia.

Background: Breast cancer is the second most prevalent form of cancer in The Gambia, with an incidence rate of approximately 15% and a mortality rate exceeding 50% in 2020. The all-age prevalence stands at 11.25 per 100,000 population. In light of this, we conducted a study to assess the knowledge, attitude, and practice of breast cancer screening among female university students. Method: We conducted an institutional cross-sectional study involving 361 randomly sampled female university students. Data collection was done using a pretested, self-administered questionnaire. We utilized descriptive statistics to describe the prevalence and burden of breast cancer screening among the participants. Results: Our study revealed good knowledge regarding breast cancer screening among female university students, yet 82.8% had a negative attitude about the disease. More than three-quarters (76.6%) of the respondents had never practiced any form of breast cancer screening. Notably, there was a significant association between knowledge of breast cancer screening and attitude (p = 0.027), and factors such as level of study (p = 0.041), ethnicity (p = 0.026), parity (p = 0.018), and faculty of study (p = <0.001) influenced the participants' knowledge. Conclusion: It is crucial to implement comprehensive awareness campaigns to address the negative attitude and poor screening practices among female university students regarding breast cancer. Additionally, providing free and widespread breast cancer screening services to students should be considered as a means to combat this disease.

Prevalence and factors associated with unplanned pregnancy in The Gambia: findings from 2018 population-based survey.

BACKGROUND: Unplanned pregnancy is a public health issue that has detrimental implications for the mother and baby alike. However, few studies have been conducted in The Gambia on this subject. As a result, the prevalence of unplanned pregnancy among women of reproductive age in The Gambia was investigated, as well as the factors associated with it. METHODS: The Gambia's Multiple Indicators Cluster Survey (MICS) was used to evaluate the 2018 results. Data was obtained from 3790 women aged 15 to 49 who had also given birth. The univariate analysis was conducted using percentage. The adjusted odds ratios (AOR) were determined using a multivariable logistic regression model (with corresponding 95% confidence interval (CI)). The degree of statistical significance was set at 5%. RESULTS: Approximately 25.3% (95% CI: 23.1%-27.6%) of the women reported unplanned pregnancy. Women aged 30-34 years had 45% reduction in unplanned pregnancy, when compared with those aged 15-19 years (AOR = 0.55; 95% CI: 0.32-0.94). The Fula and non-Gambian women had 30% and 45% reduction in unplanned pregnancy respectively, when compared with Mandinka women. Those who had no functional difficulties had 47% reduction in unplanned pregnancy, when compared with women who had functional difficulties (AOR = 0.53; 95% CI: 0.30, 0.91). Respondents who had given births to 3-4 and 5 + children were 1.79 and 3.02 times as likely to have unplanned pregnancy, when compared with women who had given birth to 1-2 children. Single/unmarried women were 11.38 times as likely to have unplanned pregnancy, when compared with women currently married/in union (AOR = 11.38; 95% CI: 6.38, 20.29). Local Government Area of residence was significantly associated with unplanned pregnancy. Furthermore, women who were neither happy nor unhappy and 18 + at sexual debut were 1.39 and 1.34 times as likely to have unplanned pregnancy, when compared with the very happy women and those < 18 at sexual debut respectively. CONCLUSION: The rate of unintended pregnancies was large (25.3%). Several causes have been linked to unplanned pregnancies. These results suggest that further efforts are required to enhance women's sex education, expand access to family planning services, and provide affordable health care to high-risk women in order to minimize unintended pregnancies.

Childhood vaccination uptake and associated factors among children 12-23 months in rural settings of the Gambia: a community-based cross-sectional study.

BACKGROUND: Globally, immunization prevents 2-3 million deaths annually from vaccine-preventable diseases such as diphtheria, tetanus, pertussis, influenza, and measles. In developing countries, several immunization programs have made progress, but the coverage remains a standstill in some areas. In order to inform policies and practices, the present study aimed at assessing vaccination uptake and contextual-associated factors among children aged 12-23 months in rural Gambia. METHODS: A community-based triangulated cross-sectional design was conducted in January 2020, with 200 caregivers with children aged 12-23 months in selected households in rural communities across Upper River Region of the Gambia using multistage sampling technique were recruited. A structured interview questionnaire was developed and Infant Welfare Cards were assessed to elicit information regarding contextual household characteristics towards childhood immunization uptake. Percentages, chi-square/fisher exact test for variables with p-value ≤0.15 were considered for inclusion into logistic regression model. The significance level was set at p < 0.05. The adjusted Odds Ratio (aOR) with 95% Confidence Interval (CI) were reported to declare significance. RESULTS: The proportion of children who received all the required vaccines was 66%. At the level of antigen-specific coverage, about 88.5% received BCG, 71% received OPV 3, 82.5% received Penta 3, while 72 and 71% received Measles-Rubella and yellow fever, respectively. Caregivers who had primary education level 88.8% (aOR = 0.112; 95% CI = 0.029-0.434), secondary & above 87.2% (aOR = 0.128; 95% CI = 0.029, 0. 561) and arabic/madrassa 95.7% (aOR = 0.043; 95% CI = 0.008-1.227) were less likely to be fully vaccinated when compared to those who have never been to school. Farmers are less likely by 88.9% (aOR = 0.111; 95% CI 0.020, 0.635) while children from family size of more than 20 members had reduced odds (aOR = 0.420; 95% CI = 0.197, 0.894) for their children to complete their vaccination schedule as compared to those with at most 20 household members. CONCLUSION: There is moderately a burden of incomplete vaccination in rural Gambia. Vaccination programs should be constantly monitored and evaluated by the Ministry of Health, especially in rural areas. To increase societal awareness and vaccine acceptance, a robust community-based health education efforts are desperately needed as part of initiatives to increase vaccine service utilization for these high-risk classes.

Knowledge, Attitude, and Practice of Provincial Dwellers on Prevention and Control of Schistosomiasis: Evidence from a Community-Based Cross-Sectional Study in the Gambia.

BACKGROUND: Socioeconomically disadvantaged and neglected communities were found to be the most affected groups for schistosomiasis as a result of inadequate safe water and sanitation facilities. In order to inform policies and practices, the present study examined the influence of sociodemographic factors and attitudes on the knowledge and practice in the prevention and control of schistosomiasis in eighteen endemic rural communities in the Gambia. METHODS: In January 2019, a community-based cross-sectional study was conducted in which 383 household heads in rural communities across Kuntaur and Janjanbureh Local Government Areas (LGAs) in Central River Region were recruited. A structured interview questionnaire was developed to elicit information regarding residents' knowledge, attitude, and practice on schistosomiasis prevention and control measures. Percentages, chi-square test, and binary and multiple logistic regression models were used to identify sociodemographic factors associated with the KAP variables. The significance level was set at p < 0.05. RESULTS: Among the 383 participants, only 14.9% had good knowledge, while 54.3% had poor knowledge, 96.9% had positive attitude, and 57.7% had good practice towards prevention and control of schistosomiasis. Older age (≥40 years), compared with residents aged 30-39 years (AOR = 0.331; 95% CI: 0.133, 0.825); ever heard of bilharziasis (AOR = 11.911; 95% CI: 3.452, 41.099); and risks of contact with the polluted river (AOR = 0.101; 95% CI: 0.042, 0.242) were more likely to have good knowledge on schistosomiasis prevention and control in the rural Gambia. Conversely, young people (≤30 years), compared with residents aged ≥40 years (AOR = 2.503; 95% CI = 1.539, 4.071); residents aged 30-39 years (AOR = 2.880; 95% CI = 1.559, 5.320); and male residents (AOR = 2.631; 95% CI = 1.703, 4.067) were more likely to have good practice towards schistosomiasis prevention and control in the rural Gambia. CONCLUSION: Despite the low knowledge, rural dwellers' attitudes were found to be positive with slightly good practice towards schistosomiasis prevention and control measures. Thus, while maintaining health system improvement strategies, disease control efforts should focus on these factors as they may influence the knowledge and practices of rural dwellers in a given setting. The findings could prompt appropriate policy responses towards improving the knowledge and practices on schistosomiasis prevention and control in the Gambia.

Enhancement of cytokine-driven NK cell IFN-γ production after vaccination of HCMV infected Africans.

Human cytomegalovirus (HCMV) infection drives the phenotypic and functional differentiation of NK cells, thereby influencing the responses of these cells after vaccination. NK cell functional differentiation is particularly advanced in African populations with universal exposure to HCMV. To investigate the impact of advanced differentiation on vaccine-induced responses, we studied NK-cell function before and after vaccination with Trivalent Influenza Vaccine (TIV) or diphtheria, tetanus, pertussis, inactivated poliovirus vaccine (DTPiP) in Africans with universal, lifelong HCMV exposure. In contrast to populations with lower prevalence of HCMV infection, no significant enhancement of NK-cell responses (IFN-γ, CD107a, CD25) occurred after in vitro re-stimulation of post-vaccination NK cells with TIV or DTPiP antigens compared to pre-vaccination baseline cells. However, both vaccinations resulted in higher frequencies of NK cells producing IFN-γ in response to exogenous IL-12 with IL-18, which persisted for up to 6 months. Enhanced cytokine responsiveness was restricted to less differentiated NK cells, with increased frequencies of IFN-γ+ cells observed within CD56bright CD57- , CD56dim CD57- NKG2C- and CD56dim CD57- NKG2C+ NK-cell subsets. These data suggest a common mechanism whereby different vaccines enhance NK cell IFN-γ function in HCMV infected donors and raise the potential for further exploitation of NK cell "pre-activation" to improve vaccine effectiveness.

Immunological impact of an additional early measles vaccine in Gambian children: responses to a boost at 3 years.

BACKGROUND: Measles vaccine in early infancy followed by a dose at 9 months of age protects against measles and enhances child survival through non-specific effects. Little is known of immune responses in the short or long term after booster doses. METHODS: Infants were randomized to receive measles vaccine at 9 months of age (group 1) or 4 and 9 months of age (group 2). Both groups received a boost at 36 months of age. T-cell effector and memory responses using IFN-γ ELIspot and cytokine assays and antibody titres using a haemagglutination-inhibition assay were compared at various times. RESULTS: Vaccination at 4 months of age elicited antibody and CD4 T-cell mediated immune responses .Two weeks after vaccination at 9 months of age group 2 had much higher antibody titres than group1 infants; cell-mediated effector responses were similar. At 36 months of age group 2 antibody titres exceeded protective levels but were 4-fold lower than group 1; effector and cytokine responses were similar. Re-vaccination resulted in similar rapid and high antibody titres in both groups (median 512); cellular immunity changed little. At 48 months of age group 2 antibody concentrations remained well above protective levels though 2-fold lower than group 1; T-cell memory was readily detectable and similar in both groups. CONCLUSIONS: An additional early measles vaccine given to children at 4 months of age induced a predominant CD4 T-cell response at 9 months and rapid development of high antibody concentrations after booster doses. However, antibody decayed faster in these children than in the group given primary vaccination at 9 months of age. Cellular responses after 9 months were generally insignificantly different.

Placental malaria is associated with attenuated CD4 T-cell responses to tuberculin PPD 12 months after BCG vaccination.

BACKGROUND: Placental malaria (PM) is associated with prenatal malaise, but many PM+ infants are born without symptoms. As malaria has powerful immunomodulatory effects, we tested the hypothesis that PM predicts reduced T-cell responses to vaccine challenge. METHODS: We recruited healthy PM+ and PM- infants at birth. At six and 12 months, we stimulated PBMCs with tuberculin purified protein derivative (PPD) and compared expression of CD154, IL-2 and IFNγ by CD4 T-cells to a negative control using flow cytometry.We measured the length, weight and head circumference at birth and 12 months. RESULTS: IL-2 and CD154 expression were low in both groups at both timepoints, without discernable differences. Expression of IFNγ was similarly low at 6 months but by 12 months, the median response was higher in PM- than PM + infants (p = 0.026). The PM+ infants also had a lower weight (p = 0.032) and head circumference (p = 0.041) at 12 months, indicating lower growth rates.At birth, the size and weight of the PM+ and PM- infants were equivalent. By 12 months, the PM+ infants had a lower weight and head circumference than the PM- infants. CONCLUSIONS: Placental malaria was associated with reduced immune responses 12 months after immune challenge in infants apparently healthy at birth.

Age-dependent maturation of Toll-like receptor-mediated cytokine responses in Gambian infants.

The global burden of neonatal and infant mortality due to infection is staggering, particularly in resource-poor settings. Early childhood vaccination is one of the major interventions that can reduce this burden, but there are specific limitations to inducing effective immunity in early life, including impaired neonatal leukocyte production of Th1-polarizing cytokines to many stimuli. Characterizing the ontogeny of Toll-like receptor (TLR)-mediated innate immune responses in infants may shed light on susceptibility to infection in this vulnerable age group, and provide insights into TLR agonists as candidate adjuvants for improved neonatal vaccines. As little is known about the leukocyte responses of infants in resource-poor settings, we characterized production of Th1-, Th2-, and anti-inflammatory-cytokines in response to agonists of TLRs 1-9 in whole blood from 120 Gambian infants ranging from newborns (cord blood) to 12 months of age. Most of the TLR agonists induced TNFα, IL-1ß, IL-6, and IL-10 in cord blood. The greatest TNFα responses were observed for TLR4, -5, and -8 agonists, the highest being the thiazoloquinoline CLO75 (TLR7/8) that also uniquely induced cord blood IFNγ production. For most agonists, TLR-mediated TNFα and IFNγ responses increased from birth to 1 month of age. TLR8 agonists also induced the greatest production of the Th1-polarizing cytokines TNFα and IFNγ throughout the first year of life, although the relative responses to the single TLR8 agonist and the combined TLR7/8 agonist changed with age. In contrast, IL-1ß, IL-6, and IL-10 responses to most agonists were robust at birth and remained stable through 12 months of age. These observations provide fresh insights into the ontogeny of innate immunity in African children, and may inform development of age-specific adjuvanted vaccine formulations important for global health.

Epstein-Barr virus but not cytomegalovirus is associated with reduced vaccine antibody responses in Gambian infants.

BACKGROUND: Epstein-Barr virus (EBV) and cytomegalovirus (CMV) are persistent herpesviruses that have various immunomodulatory effects on their hosts. Both viruses are usually acquired in infancy in Sub-Saharan Africa, a region where childhood vaccines are less effective than in high income settings. To establish whether there is an association between these two observations, we tested the hypothesis that infection with one or both viruses modulate antibody responses to the T-cell independent meningococcal polysaccharide vaccine and the T-cell dependent measles vaccines. METHODOLOGY/PRINCIPAL FINDINGS: Infection with EBV and CMV was diagnosed by the presence of virus-specific IgM in the peripheral blood or by the presence of IgG at higher levels than that found in umbilical cord blood. Anti-meningococcus IgG and IgM were quantified by ELISA. Anti-measles antibody responses were quantified by haemagglutinin antibody inhibition assay. Infants infected with EBV had reduced IgG and IgM antibody responses to meningococcal polysaccharides and to measles vaccine. Infection with CMV alone predicted no changes in the response to meningococcal polysaccharide. While CMV alone had no discernable effect on the antibody response to measles, the response of infants infected with both CMV and EBV was similar to that of infants infected with neither, suggesting that the effects of CMV infection countered the effects of EBV on measles antibody responses. CONCLUSIONS: The results of this exploratory study indicate that infection with EBV is associated with reduced antibody responses to polysaccharides and to measles vaccine, but suggest that the response to T-cell dependent antigens such as measles haemagglutinin may be restored by infection with CMV.

The tuberculin skin test (TST) is affected by recent BCG vaccination but not by exposure to non-tuberculosis mycobacteria (NTM) during early life.

The tuberculin skin test (TST) is widely used in TB clinics to aid Mycobacterium tuberculosis (M.tb) diagnosis, but the definition and the significance of a positive test in very young children is still unclear. This study compared the TST in Gambian children at 4(1/2) months of age who either received BCG vaccination at birth (Group 1) or were BCG naïve (Group 2) in order to examine the role of BCG vaccination and/or exposure to environmental mycobacteria in TST reactivity at this age. Nearly half of the BCG vaccinated children had a positive TST (>or=5 mm) whereas all the BCG naïve children were non-reactive, confirming that recent BCG vaccination affects TST reactivity. The BCG naïve children demonstrated in vitro PPD responses in peripheral blood in the absence of TST reactivity, supporting exposure to and priming by environmental mycobacterial antigens. Group 2 were then vaccinated at 4(1/2) months of age and a repeat TST was performed at 20-28 months of age. Positive reactivity (>or=5 mm) was evident in 11.1% and 12.5% infants from Group 1 and Group 2 respectively suggesting that the timing of BCG vaccination had little effect by this age. We further assessed for immune correlates in peripheral blood at 4(1/2) months of age. Mycobacterial specific IFNgamma responses were greater in TST responders than in non-responders, although the size of induration did not correlate with IFNgamma. However the IFNgamma: IL-10 ratio positively correlated with TST induration suggesting that the relationship between PPD induced IFNgamma and IL-10 in the peripheral blood may be important in controlling TST reactivity. Collectively these data provide further insights into how the TST is regulated in early life, and how a positive response might be interpreted.

Delaying bacillus Calmette-Guérin vaccination from birth to 4 1/2 months of age reduces postvaccination Th1 and IL-17 responses but leads to comparable mycobacterial responses at 9 months of age.

Bacillus Camette-Guérin (BCG) vaccine is the only licensed vaccine against tuberculosis, yet its protective efficacy is highly variable between different geographical regions. We hypothesized that exposure to nontuberculous mycobacteria attenuates BCG immunogenicity by inducing mycobacterial-specific regulatory T cells (Tregs). Gambian neonates were recruited at birth and randomized to receive BCG vaccination either at birth or at 4 1/2 mo. Mycobacterial immune responses were assessed at birth, 4 1/2, and 9 mo of age. At 4 1/2 mo of age the BCG naive individuals had detectable mycobacterial responses, including increased IL-10 production suggesting environmental priming. Vaccination at birth significantly enhanced Th1, Th2, IL-6, IL-17, and Treg responses in mycobacterial cultures at 4 1/2 mo compared with the BCG naive group. Analyzing results at 4 1/2 mo postvaccination revealed lower IFN-gamma, IL-6, and IL-17 responses in the delayed BCG vaccine group compared with those vaccinated at birth, but this did not relate to Treg levels prevaccination. When comparing responses pre- and post-BCG vaccination in the delayed vaccine group, there was no priming of mycobacterial IL-17. Mycobacterial responses waned over 9 mo in those vaccinated at birth, leading to comparable mycobacterial immunity in both groups at 9 mo of age. Overall, these data suggest that vaccination at birth induces a broad Th1/Th2/IL-17/Treg mycobacterial response but the Th1/Th-17 response was reduced when delaying the vaccine. The evidence did not suggest that mycobacterial specific naturally occurring Tregs accounted for this attenuated immunogenicity.

Placental malaria is associated with reduced early life weight development of affected children independent of low birth weight.

BACKGROUND: Infection with Plasmodium falciparum during pregnancy contributes substantially to the disease burden in both mothers and offspring. Placental malaria may lead to intrauterine growth restriction or preterm delivery resulting in low birth weight (LBW), which, in general, is associated with increased infant morbidity and mortality. However, little is known about the possible direct impact of the specific disease processes occurring in PM on longer term outcomes such as subsequent retarded growth development independent of LBW. METHODS: In an existing West-African cohort, 783 healthy infants with a birth weight of at least 2,000 g were followed up during their first year of life. The aim of the study was to investigate if Plasmodium falciparum infection of the placenta, assessed by placental histology, has an impact on several anthropometric parameters, measured at birth and after three, six and 12 months using generalized estimating equations models adjusting for moderate low birth weight. RESULTS: Independent of LBW, first to third born infants who were exposed to either past, chronic or acute placental malaria during pregnancy had significantly lower weight-for-age (-0.43, 95% CI: -0.80;-0.07), weight-for-length (-0.47, 95% CI: -0.84; -0.10) and BMI-for-age z-scores (-0.57, 95% CI: -0.84; -0.10) compared to infants born to mothers who were not diagnosed with placental malaria (p = 0.019, 0.013, and 0.012, respectively). Interestingly, the longitudinal data on histology-based diagnosis of PM also document a sharp decline of PM prevalence in the Sukuta cohort from 16.5% in 2002 to 5.4% in 2004. CONCLUSIONS: It was demonstrated that PM has a negative impact on the infant's subsequent weight development that is independent of LBW, suggesting that the longer term effects of PM have been underestimated, even in areas where malaria transmission is declining.

Maintenance of large subpopulations of differentiated CD8 T-cells two years after cytomegalovirus infection in Gambian infants.

BACKGROUND: In a previously published study, we found that large differentiated subpopulations of CD8 T-cells emerged rapidly after CMV infection in young infants and persisted throughout the following year. Here we describe a follow-up study conducted on the same infants to establish whether the differentiated subpopulations continued through the second year post-infection. METHODOLOGY / PRINCIPAL FINDINGS: CMV-specific cells identified using tetramers remained more activated and differentiated than the overall CD8 population. The large subpopulation of differentiated cytotoxic (CD28(-)CD62L(-)Bcl-2(low)CD95(+)perforin(+)) cells that emerged rapidly after infection remained stable after two years. No similar subpopulation was found in CMV-uninfected infants indicating that two years after infection, CMV remained a major factor in driving CD8 T-cell differentiation. Although markers of activation (CD45R0 and HLA-D) declined throughout the first year, HLA-D expression continued to decline during the second year and CD45R0 expression increased slightly. The age-related increase in IFNgamma response observed during the first year continued but was non-significant during the second year, indicating that the rate of functional improvement had slowed substantially. CONCLUSIONS / SIGNIFICANCE: The large differentiated subpopulations of CD8 T-cells that had emerged immediately after CMV infection persisted through the second year post-infection, while levels of activation and functional capacity remained fairly constant.

Effects of antenatal and postnatal environments on CD4 T-cell responses to Mycobacterium bovis BCG in healthy infants in the Gambia.

The Mycobacterium bovis BCG vaccine has a poor record of efficacy in low-income tropical settings. Against this background, we evaluated the immune response of infants to mycobacterial antigens over the 2 years following BCG vaccination at birth by measuring the gamma interferon (IFN-gamma), interleukin-2 (IL-2), and CD154 responses of CD4 T cells. Similar numbers of cells expressed IFN-gamma in infants, 4- to 5-year-old children, and adults, while CD154 was not expressed at comparable levels until the second year of infancy. The IL-2 response remained relatively low in infants, children, and adults but correlated negatively with mother's body mass index and was highest among infants born to Mandinka mothers. Similarly, infants born in the wet season had a stronger CD154 response than those born in the dry season throughout the 2 years of the study. We conclude that the prenatal and perinatal environments have a lasting effect on the response of infants to the BCG vaccine.

CD4(+) T cell responses to cytomegalovirus in early life: a prospective birth cohort study.

We compared cytomegalovirus (CMV)-specific interferon-gamma (IFN-gamma), interleukin 2 (IL-2), and CD154 CD4(+) T cell responses of infants to those from chronically infected adults and from children aged 4-5 years. Magnitudes of the responses were similar, although coexpression of IFN-gamma plus CD154 occurred more than coexpression of IFN-gamma plus IL-2 or IL-2 plus CD154. Responses remained constant during infancy, although the proportion of IFN-gamma-producing cells increased from infancy to adulthood. Most responding cells in infants were undifferentiated (i.e., CD27(+)CD28(+)), although IFN-gamma-producing cells were disproportionately CD27(-). By 12 months after diagnosis, viremia was rarely detectable, indicating that CMV was controlled despite the slow development of CMV-specific CD4(+) T cell responses.

Cytomegalovirus infection induces T-cell differentiation without impairing antigen-specific responses in Gambian infants.

Cytomegalovirus (CMV) infection induces profound differentiation of T cells, and is associated with impaired responses to other immune challenges. We therefore considered whether CMV infection and the consequent T-cell differentiation in Gambian infants was associated with impaired specific responses to measles vaccination or polyclonal responses to the superantigen staphylococcal enterotoxin B (SEB). While the concentration of undifferentiated (CD27(+) CD28(+) CCR7(+)) T-cells in peripheral blood was unaffected by CMV, there was a large increase in differentiated (CD28(-) CD57(+)) CD8 T-cells and a smaller increase in differentiated CD4 cells. One week post-vaccination, the CD4 cell interferon-gamma (IFN-gamma) response to measles was lower among CMV-infected infants, but there were no other differences between the cytokine responses, or between the cytokine or proliferative responses 4 months post-vaccination. However, the CD8 T cells of CMV-infected infants proliferated more in response to SEB and the antibody response to measles correlated with the IFN-gamma response to CMV, indicating that CMV infection actually enhances some immune responses in infancy.

Cytomegalovirus infection in Gambian infants leads to profound CD8 T-cell differentiation.

Cytomegalovirus (CMV) infection is endemic in Gambian infants, with 62% infected by 3 months and 85% by 12 months of age. We studied the CD8 T-cell responses of infants to CMV following primary infection. CMV-specific CD8 T cells, identified with tetramers, showed a fully differentiated phenotype (CD28(-) CD62L(-) CD95(+) perforin(+) granzyme A(+) Bcl-2(low)). Strikingly, the overall CD8 T-cell population developed a similar phenotype following CMV infection, which persisted for at least 12 months. In contrast, primary infection was accompanied by up-regulation of markers of activation (CD45R0 and HLA-D) on both CMV-specific cells and the overall CD8 T-cell population and division (Ki-67) of specific cells, but neither pattern persisted. At 12 months of age, the CD8 T-cell population of CMV-infected infants was more differentiated than that of uninfected infants. Although the subpopulation of CMV-specific cells remained constant, the CMV peptide-specific gamma interferon response was lower in younger infants and increased with age. As the CD8 T-cell phenotype induced by CMV is indicative of immune dysfunction in the elderly, the existence of a similar phenotype in large numbers of Gambian infants raises the question of whether CMV induces a similarly deleterious effect.