Assessment of the influence of ABO blood groups on oral cholera vaccine immunogenicity in a cholera endemic area in Zambia

BACKGROUND

Histo-blood group antigens (HBGAs) which include the ABO and Lewis antigen systems have been known for determining predisposition to infections. For instance, blood group O individuals have a higher risk of severe illness due to V. cholerae compared to those with non-blood group O antigens. We set out to determine the influence that these HBGAs have on oral cholera vaccine immunogenicity and seroconversion in individuals residing within a cholera endemic area in Zambia.

METHODOLOGY

We conducted a longitudinal study nested under a clinical trial in which samples from a cohort of 223 adults who were vaccinated with two doses of Shanchol™ and followed up over 4 years were used. We measured serum vibriocidal geometric mean titers (GMTs) at Baseline, Day 28, Months 6, 12, 24, 30, 36 and 48 in response to the vaccine. Saliva obtained at 1 year post vaccination was tested for HBGA phenotypes and secretor status using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

Of the 133/223 participants included in the final analysis, the majority were above 34 years old (58%) and of these, 90% were males. Seroconversion rates to V. cholerae O1 Inaba with non-O (23%) and O (30%) blood types were comparable. The same pattern was observed against O1 Ogawa serotype between non-O (25%) and O (35%). This trend continued over the four-year follow-up period. Similarly, no significant differences were observed in seroconversion rates between the non-secretors (26%) and secretors (36%) against V. cholerae O1 Inaba. The same was observed for O1 Ogawa in non-secretors (22%) and the secretors (36%).

CONCLUSION

Our results do not support the idea that ABO blood grouping influence vaccine uptake and responses against cholera.

Microbiologic and virulence characteristics of Moraxella catarrhalis isolates from Zambian children presenting with acute pneumonia

BACKGROUND

Moraxella catarrhalis is one of the bacterial pathogens associated with childhood pneumonia, but its clinical importance is not clearly defined.

OBJECTIVE

This study aimed to investigate the microbiologic and virulence characteristics of M. catarrhalis isolates obtained from children with pneumonia in Lusaka, Zambia.

METHODS

This retrospective, cross-sectional study analyzed 91 M. catarrhalis isolates from induced sputum samples of children less than 5 years of age with pneumonia enrolled in the Pneumonia Etiology Research for Child Health study in Lusaka, Zambia between 2011 and 2014. Bacteria identification and virulence genes detection were performed by PCR and DNA sequencing, while antimicrobial susceptibility testing was determined by the Kirby-Bauer method.

RESULTS

All the M. catarrhalis isolates were obtained from good-quality sputum samples and were the predominant bacteria. These isolates harbored virulence genes copB (100%), ompE (69.2%), ompCD (71.4%), uspA1 (92.3%), and uspA2 (69.2%) and were all β-lactamase producers. They showed resistance to ampicillin (100%), amoxicillin (100%), trimethoprim-sulfamethoxazole (92.3%), ciprofloxacin (46.2%), chloramphenicol (45.1%), erythromycin (36.3%), tetracycline (25.3%), cefuroxime (11.0%), and amoxicillin-clavulanate (2.2%), with 71.4% displaying multi-drug resistant phenotype but all susceptible to imipenem (100%).

CONCLUSION

This study showed that M. catarrhalis isolates were the predominant or only bacterial isolates from the sputum samples analyzed. The findings provide supportive evidence for the pathogenic potential role of this bacterium in pediatric pneumonia. High multidrug resistance was also observed amongst the isolates, which can result in affected patients not responding to standard treatment, leading to prolonged illness, increased healthcare costs, and risk of death.

Immunogenicity and waning immunity from the oral cholera vaccine (Shanchol™) in adults residing in Lukanga Swamps of Zambia

Introduction

In cholera endemic areas, the periodicity of cholera outbreaks remains unpredictable, making it difficult to organize preventive efforts. Lack of data on duration of protection conferred by oral cholera vaccines further makes it difficult to determine when to deploy preemptive vaccination. We report on the immunogenicity and waning of immunity to Shanchol^™ in Lukanga Swamps.

Methods

We enrolled a cohort of 223 participants aged between 18 and 65 years old from whom serum samples were collected at baseline, day 28 before administration of the second dose, and consecutively at 6, 12, 24, 30, 36, and 48 months. Vibriocidal antibody titres were measured and expressed as geometric mean titres. Box plots and 95% CI were computed at each visit for both Inaba and Ogawa. Seroconversion was defined as a four fold or greater increase in antibody titres compared to baseline titres.

Results

Overall, seroconversion against V. cholerae Inaba and Ogawa after 1st dose was 35/134 (26%) and 34/134 (25%) respectively. We observed a statistical difference in seroconversion between the two subgroups of baseline titres (low <80 and high ≥80) for both Inaba (p = 0.02) and Ogawa (p<0.0001). From a baseline of 13.58, anti-Ogawa GMT increased to 21.95 after the first dose, but rapidly waned to 14.52, 13.13, and 12.78 at months 6, 12 and 24 respectively, and then increased to 13.21, 18.67 and 23.65 at months 30, 36 and 48 respectively. A similar trend was observed for anti-Inaba GMT across the same time points.

Conclusion

We found that Shanchol^™ was immunogenic in our study population and that vibriocidal antibodies may not be a good marker for long-term immunity. The observed rise in titres after 36 months suggests natural exposure, and this may be a critical time window opening for natural transmission in an endemic areas. We recommend re-vaccination at this time point in high risk areas.

Serum vibriocidal responses when second doses of oral cholera vaccine are delayed 6 months in Zambia

Two-dose killed oral cholera vaccines (OCV) are currently being used widely to control cholera. The standard dose-interval for OCV is 2 weeks; however, during emergency use of the vaccine, it may be more appropriate to use the available doses to quickly give a single dose to more people and give a delayed second dose when more vaccine becomes available. This study is an open label, randomized, phase 2 clinical trial of the vibriocidal response induced by OCV, comparing the responses when the second dose was given either 2 weeks (standard dose interval) or 6 months (extended dose interval) after the first dose. Vaccine was administered to healthy participants > 1 year of age living in the Lukanga Swamps area of Zambia. Three age cohorts (<5 years, 5-14 years, and ≥ 15 years) were randomized to the either dose-interval. The primary outcome was the vibriocidal GMT 14 days after the second dose. 156 of 172 subjects enrolled in the study were included in this analysis. The Inaba vibriocidal titers were not significantly different 14 days post dose two for a standard dose-interval GMT: 45.6 (32-64.9), as compared to the GMT 47.6 (32.6-69.3), for the extended dose-interval, (p = 0.87). However, the Ogawa vibriocidal GMTs were significantly higher 14 days post dose two for the extended-dose interval at 87.6 (58.9-130.4) compared to the standard dose-interval group at 49.7 (34.1-72.3), p = 0.04. Vibriocidal seroconversion rates (a > 4-fold rise in vibriocidal titer) were not significantly different between dose-interval groups. This study demonstrated that vibriocidal titers 14 days after a second dose when given at an extended\ dose interval were similar to the standard dose-interval. The findings suggest that a flexible dosing schedule may be considered when epidemiologically appropriate. The trial was registered at Clinical Trials.gov (NCT03373669).

Predictors of first-line antiretroviral therapy failure among adults and adolescents living with HIV/AIDS in a large prevention and treatment program in Nigeria

Background

A substantial number of persons living with HIV (PLWH) in Nigeria do not experience durable viral suppression on first-line antiretroviral therapy (ART). Understanding risk factors for first-line treatment failure informs patient monitoring practices and distribution of limited resources for second-line regimens. We determined predictors of immunologic and virologic failures in a large ART delivery program in Abuja, Nigeria.

Methods

A retrospective cohort study was conducted at the University of Abuja Teaching Hospital, a tertiary health care facility, using data from February 2005 to December 2014 in Abuja, Nigeria. All PLWH aged ≥ 15 years who initiated ART with at least 6-month follow-up and one CD4 measurement were included. Immunologic failure was defined as a CD4 decrease to or below pre-ART level or persistent CD4 < 100 cells per mm³ after 6 months on ART. Virologic failure (VF) was defined as two consecutive HIV-1 RNA levels > 1000 copies/mL after at least 6 months of ART and enhanced adherence counselling. HIV drug resistance (Sanger sequences) was analyzed using the Stanford HIV database algorithm and scored for resistance to common nucleoside reverse transcriptase inhibitors (NRTIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs). Univariate and multivariate log binomial regression models were used to estimate relative risks (RRs) and 95% confidence intervals (CIs).

Results

Of 12,452 patients followed, a total of 5928 initiated ART with at least 6 months of follow-up and one CD4 measurement. The entry point for 3924 (66.2%) was through the program’s own voluntary counseling and testing (VCT) center, while 1310 (22.1%) were referred from an outside clinic/program, 332 (5.6%) in-patients, and 373 (6.3%) through other entry points including prevention of mother to child transmission (PMTCT) and transferred from other programs. The mean CD4 at enrollment in care was 268 ± 23.7 cells per mm³, and the mean HIV-1 RNA was 3.3 ± 1.3.log₁₀ copies/mL. A total of 3468 (80.5%) received nevirapine (NVP) and 2260 (19.5%) received efavirenz (EFV)—based regimens. A total of 2140 (36.1%) received tenofovir (TDF); 2662 (44.9%) zidovudine (AZT); and 1126 (19.0%) stavudine (d4T). Among those receiving TDF, 45.0% also received emtricitabine (FTC). In a multivariate model, immunologic failure was more common among PLWH with female gender as compared to male [RR (95% CI) 1.22 (1.07–1.40)] and less common among those who entered care at the program’s VCT center as compared to other entry points [0.79 (0.64–0.91)], WHO stage 3/4 as compared to 1/2 [0.19 (0.16–0.22)], or CD4 200 + cells per mm³ as compared to lower [0.19 (0.16–0.22)]. Virologic failure was more common among PLWH who entered care at the program’s VCT center as compared to other entry points [RR (95% CI) 1.45 (1.11–1.91) and those with CD4 < 200 cells per mm³ at entry into care as compared to higher [1.71 (1.36–2.16)]. Of 198 patient-derived samples sequenced during virologic failure, 42 (21%) were wild-type; 145 (73%) carried NNRTI drug resistance mutations; 151 (76.3%) M184I/V; 29 (14.6%) had ≥ 3 TAMs, and 37 (18.7%) had K65R, of whom all were on TDF-containing first-line regimens.

Conclusions

In this cohort of Nigerian PLWH followed for a period of 9 years, immunologic criteria poorly predicted virologic failure. Furthermore, a subset of samples showed that patients failing ART for extended periods of time had HIV-1 strains harboring drug resistance mutations.

Antiretroviral Drugs Alter the Content of Extracellular Vesicles from HIV-1-Infected Cells

To date, the most effective treatment of HIV-1 is a combination antiretroviral therapy (cART), which reduces viral replication and reverses pathology. We investigated the effect of cART (RT and protease inhibitors) on the content of extracellular vesicles (EVs) released from HIV-1-infected cells. We have previously shown that EVs contain non-coding HIV-1 RNA, which can elicit responses in recipient cells. In this manuscript, we show that TAR RNA levels demonstrate little change with the addition of cART treatment in cell lines, primary macrophages, and patient biofluids. We determined possible mechanisms involved in the selective packaging of HIV-1 RNA into EVs, specifically an increase in EV-associated hnRNP A2/B1. More recent experiments have shown that several other FDA-approved drugs have the ability to alter the content of exosomes released from HIV-1-infected cells. These findings on cART-altered EV content can also be applied to general viral inhibitors (interferons) which are used to treat other chronic infections. Additionally, we describe unique mechanisms of ESCRT pathway manipulation by antivirals, specifically the targeting of VPS4. Collectively, these data imply that, despite antiretroviral therapy, EVs containing viral products are continually released and may cause neurocognitive and immunological dysfunction.

Associations between Cognition, Gender and Monocyte Activation among HIV Infected Individuals in Nigeria

The potential role of gender in the occurrence of HIV-related neurocognitive impairment (NCI) and associations with markers of HIV-related immune activity has not been previously examined. In this study 149 antiretroviral-naïve seropositive subjects in Nigeria (SP, 92 women and 57 men) and 58 seronegative (SN, 38 women and 20 men) were administered neuropsychological testing that assessed 7 ability domains. From the neuropsychological test scores was calculated a global deficit score (GDS), a measure of overall NCI. Percentages of circulating monocytes and plasma HIV RNA, soluble CD163 and soluble CD14 levels were also assessed. HIV SP women were found to be younger, more educated and had higher CD4+ T cell counts and borderline higher viral load measures than SP men. On the neuropsychological testing, SP women were more impaired in speed of information processing and verbal fluency and had a higher mean GDS than SN women. Compared to SP men, SP women were also more impaired in speed of information processing and verbal fluency as well as on tests of learning and memory. Numbers of circulating monocytes and plasma sCD14 and sCD163 levels were significantly higher for all SP versus all SN individuals and were also higher for SP women and for SP men versus their SN counterparts. Among SP women, soluble CD14 levels were slightly higher than for SP men, and SP women had higher viral load measurements and were more likely to have detectable virus than SP men. Higher sCD14 levels among SP women correlated with more severe global impairment, and higher viral load measurements correlated with higher monocyte numbers and sCD14 and sCD14 levels, associations that were not observed for SP men. These studies suggest that the risk of developing NCI differ for HIV infected women and men in Nigeria and, for women, may be linked to effects from higher plasma levels of HIV driving activation of circulating monocytes.

Neonatal hyperthermia and thermal stress in low- and middle-income countries: a hidden cause of death in extremely low-birthweight neonates

BACKGROUND

Over 70% of neonatal deaths in Nigeria occur within the first 7 days of life and, despite the millennium development goals, there has been no significant reduction of this figure.

OBJECTIVE

To investigate how rapid changes of temperature outside the physiologically allowable range in extremely low-birthweight infants are associated with increased mortality.

METHODS

Ninety-eight neonatal cases in three Nigerian tertiary-care hospitals were retrospectively recruited; on the basis of birthweight  < 1500 g, this number was reduced to 41 for a two-stage analysis. In the first stage, 34 cases recruited over 24 months were analysed. In the second stage, seven cases recruited over 6 months were analysed; these were neonates managed with a new temperature control technique (the 'handy approach') to enable comparison of outcomes. The mean (SD) birthweight of the infants analysed was 991 g (251), and 28 of them were of extremely low-birthweight (ELBW) [mean (SD) 846 g (128)]. A lifetime temperature plot with a clearly visible reference zone was developed, from which all thermal stresses and their duration associated with mortality were identified and defined on the basis of their characteristics. Methods of quantifying the magnitude and duration of these thermal stresses were devised to enable definition of critical values. This was then applied to calculate a measure of the various thermal stresses which may have contributed to neonatal death.

RESULTS

Hypothermic events were very common in all the infants in the study period, but were not significantly associated with mortality. However, hyperthermic events occurred in 35% of the infants and were more likely to be associated with mortality. Most neonates with prolonged hypothermia culminating in rapid hyperthermia survived. However, all ELBW neonates who experienced prolonged hyperthermia culminating in rapid hypothermia died within 8 hours of the event. There was greater ELBW survival (6/6) in the second stage using the 'handy approach' than in the first stage (2/22).

CONCLUSION

Hyperthermia is a high-risk event in ELBW infants and methods of cooling a high and prolonged temperature must be reviewed.

Challenges and frugal remedies for lowering facility based neonatal mortality and morbidity: a comparative study

Millennium development goal target on infant mortality (MDG4) by 2015 would not be realised in some low-resource countries. This was in part due to unsustainable high-tech ideas that have been poorly executed. Prudent but high impact techniques could have been synthesised in these countries. A collaborative outreach was initiated to devise frugal measures that could reduce neonatal deaths in Nigeria. Prevailing issues of concern that could militate against neonatal survival within care centres were identified and remedies were proffered. These included application of (i) recycled incubator technology (RIT) as a measure of providing affordable incubator sufficiency, (ii) facility-based research groups, (iii) elective training courses for clinicians/nurses, (iv) independent local artisans on spare parts production, (v) power-banking and apnoea-monitoring schemes, and (v) 1/2 yearly failure-preventive maintenance and auditing system. Through a retrospective data analyses 4 outreach centres and one "control" were assessed. Average neonatal mortality of centres reduced from 254/1000 to 114/1000 whilst control remained at 250/1000. There was higher relative influx of incubator-dependent-neonates at outreach centres. It was found that 43% of mortality occurred within 48 hours of presentation (d48) and up to 92% of d48 were of very-low birth parameters. The RIT and associated concerns remedies have demonstrated the vital signs of efficiency that would have guaranteed MDG4 neonatal component in Nigeria.

Stroke risk factors, subtypes, and 30-day case fatality in Abuja, Nigeria

Background:

Stroke is the second leading cause of death and the leading cause of adult disability worldwide. A better understanding of stroke risk factors and outcome may help guide efforts at reducing the community burden of stroke. This study aimed to understand stroke risk factors, imaging subtypes, and 30-day outcomes among adult Nigerians.

Materials and Methods:

We prospectively recruited all patients presenting with acute stroke at the National Hospital Abuja between January 2010 and June 2012. We assessed clinical and laboratory variables, as well as brain computerized tomography, magnetic resonance imaging, and carotid Doppler ultrasound scans. We also assessed case fatality and functional outcome at 30 days after stroke.

Results:

Of 272 patients studied, 168 (61.8%) were males. Age at presentation (mean ± standard deviation) was 56.4 ± 12.7 years in males and 52.9 ± 14.8 years in females (P = 0.039). Neuroimaging was obtained in 96.7% patients, revealing cerebral infarction (61.8%), intracerebral hemorrhage (ICH) (34.8%), and subarachnoid hemorrhage (SAH) (3.4%). Carotid plaques or stenosis ≥50% were detected in 53.2% patients with cerebral infarction. Stroke risk factors included hypertension (82.7%), obesity (32.6%), diabetes (23.5%), hyperlipidemia (18.4%), atrial fibrillation (9.2%), and cigarette smoking (7.7%). At 30 days after stroke, case-fatality rate was 18.8%, whereas modified Rankin Scale (mRS) scores for cerebral infarction, ICH, and SAH were 3.71, 4.21, and 4.56, respectively. Atrial fibrillation, a previous stroke, and age older than 50 years were all associated with worse mRS scores at 30 days.

Conclusion:

Although hypertension, obesity, diabetes mellitus, and atrial fibrillation were important stroke risk factors, in many patients, these were detected only after a stroke. While the commonest stroke subtype was cerebral infarction, observed in almost two-third of patients, SAH was associated with the highest case-fatality rate at 30 days of 44.4%. Larger population-based studies may provide additional data on stroke incidence and outcome among Nigerians.

Prevalence of metabolic syndrome among hypertensive patients in Abuja, Nigeria

BACKGROUND

It is well known that factors like high blood pressure, hyperglycemia, dyslipidemia, obesity and hyperuricemia tend to cluster together giving rise to what is called metabolic syndrome. In spite of the high prevalence of hypertension in Nigeria, there is a dearth of data describing the prevalence of metabolic syndrome in Nigerian hypertensive patients. We therefore set out to look at the prevalence of metabolic syndrome in hypertensive patients presenting to the cardiology clinic of a tertiary institution in Abuja, Nigeria.

METHODS

Metabolic syndrome was defined in patients according to the World Health Organisation's definition.

RESULTS

Of the 362 patients studied, 56.9% were male and 43.1% were female. The mean age was 51.80 +/- 11.63 years, mean duration of hypertension was 8.90 +/- 3.95 years, mean body mass index was 29.36 +/- 6.12 kg/m2 and mean arterial blood pressure was 110.28 +/- 18.17 mm Hg. Overall, 13.0% of the study population had metabolic syndrome; 16.7% of females and 10.2% of males.

CONCLUSION

The prevalence of metabolic syndrome among hypertensive patients in Abuja, Nigeria is comparable to rates observed in some general populations in Europe. This might imply the epidemiological transition in disease pattern already being experienced in many parts of sub-Saharan Africa.

Knowledge and attitudes of secondary school students in Federal Capital Territory (FCT), Abuja, Nigeria towards sickle cell disease

BACKGROUND

This study was conducted among Secondary School Students in Federal Capital Territory (FCT),Abuja Nigeria, between May and June 2010 to determine the knowledge and attitudes of the students towards Sickle Cell Disease (SCD).

METHODS

The study was a cross-sectional study carried out on 600 students from 8 secondary schools located within (FCT). A multistage sampling method was used for selection of the study population. Data was collected with the aid of a pretested self-administered questionnaire and analyzed with EPI-INFO 2008.

RESULTS

The age of respondents ranged from 9 to 26 years with the mean age of 15.16 (SD = 2.13). The modal age of the respondents was 10-19 years (97.8%). The male: female ratio was 1.01:1. A large number of respondents' fathers (80.7%) and mothers (70.2%) respectively, had at least secondary school education. Majority (81.8%) of the respondents claimed to have heard about sickle cell disease (SCD) but only 38.0% of them knew the cause of SCD. Slightly less than half, 292 (48.7%) of the respondents knew their genotype. Of the 292 respondents that knew their genotype, 206 (70.5%) were AA, 50 (17.1%) were AS,14 (4.8%), SS, 11 (3.8%)AC, 5 (1.7%) SC, 4 (1.4%) CC, 2 (0.7%) other types of genotype. Only 46.2% and 36.8% of them respectively, correctly identified that pre-marital genotype testing and avoidance of marriage between two persons with haemoglobin S genotype as means of preventing further spread of SCD. Factors found to be significantly associated with the knowledge of respondents' genotype were; age = 15 years, respondents' mothers' educational status, being taught about SCD in school, ever seeing somebody suffering from SCD complication, losing a relative to SCD, being in senior secondary school class and knowing the cause of SCD.

CONCLUSION

This study shows that majority of the respondents did not know their genotype ,and their knowledge about the cause and prevention of SCD was poor.

Knowledge and Practice of Post-Exposure Prophylaxis (PEP) against HIV Infection among Health Care Providers in a Tertiary Hospital in Nigeria

Objective: To assess the knowledge and practice of post exposure prophylaxis (PEP) against HIV infection among health care providers in University of Abuja Teaching Hospital (UATH). Methods: A cross-sectional survey conducted on 230 health care providers in UATH. Results: Majority (97.0%) of the respondents have heard about PEP, but only a few (30.9%) of them could correctly identify the drugs used and duration of PEP. A third of respondents have had one form of accidental exposure or the other. HIV test was carried out in about two-thirds (64.8%) of the source patients. Thirteen (28.3%) of the source patients were HIV-positive. Of the 13 respondents that were exposed to HIV-positive patients, only 3 (23.1%) received PEP, and these three completed PEP, while majority, 10/13 (76.9%) did not receive PEP in spite of their exposure to HIV-positive sources. Conclusion: The study shows that the knowledge and practice of PEP among health care providers are very poor.