Impact of Option B+ Combination Antiretroviral Therapy on Mother-to-Child Transmission of HIV-1, Maternal and Infant Virologic Responses to Combination Antiretroviral Therapy, and Maternal and Infant Mortality Rates: A 24-Month Prospective Follow-Up Study at a Primary Health Care Clinic, in Harare, Zimbabwe

We conducted a 24-month prospective follow-up study, at a primary health care clinic in Harare, Zimbabwe, to determine cumulative mother-to-child transmission of HIV-1 (MTCT) rate and the contributions of intrauterine (IU), intrapartum (IP), and postpartum (PP) to MTCT, as well as maternal and infant mortality rates in the era of Option B⁺ combination antiretroviral therapy (cART). Plasma for viral load (VL) quantitation was obtained from 475 mothers enrolled into the study. VL was quantified at enrolment and every 6 months thereafter up to 24 months using the Cepheid GeneXpert HIV-1 Quantitative test. Dried blood spots were collected from 453 infants at birth, 4–6 weeks, 3 months, and every 3 months thereafter up to 24 months. HIV-1 infant diagnosis was conducted using the Cepheid GeneXpert HIV-1 Qualitative test. Absolute, cumulative MTCT rates and mortality rate were calculated. Seven mothers (1.55%) transmitted HIV-1 infection to their infants by 24 months. Four infants (0.88%; 95% CI 0.26–2.33%), one infant (0.22%; 95% CI 0–1.4%), and two infants (0.44%; 95% CI 0.01–1.7%) were infected IU, IP, and PP, respectively. By 24 months, 88.94% of the mothers and 80% of the infants had undetectable VL. The maternal and infant mortality rates were 0.21% and 1.78%, respectively. In the first 24 months of life, IU transmission is the major route of MTCT. The cumulative MTCT rate of 1.55% and low maternal and infant mortality rates of 0.21% and 1.78%, respectively, contribute to growing evidence that Option B⁺ cART not only drastically reduces MTCT but also maternal and infant mortality.

Mother-to-child transmission of HIV-1 and infant mortality in the first six months of life, in the era of Option B Plus combination antiretroviral therapy

OBJECTIVES

The aim of this study was to determine the contributions of intrauterine (IU), intrapartum (IP), and postpartum (PP) transmission to mother-to-child transmission of HIV-1 (MTCT) and infant mortality in the first 6 months of life, in the era of Option B Plus combination antiretroviral therapy.

METHODS

Plasma for virus load (VL) quantitation was obtained from 451 women enrolled into the study. VL was quantified using the Cepheid GeneXpert HIV-1 quantitative test. Dried blood spots were collected from 453 infants at birth, 4-6 weeks, 3 months, and 6 months. HIV-1 infant diagnosis was conducted using the Cepheid GeneXpert HIV-1 qualitative test. Absolute and cumulative MTCT rates, and the mortality rate by 6 months were calculated.

RESULTS

Seven mothers (1.55%) had transmitted HIV-1 infection to their infants by 6 months. Four infants (0.88%, 95% confidence interval (CI) 0.26-2.33%) were infected IU, one infant (0.22%, 95% CI 0-1.4%) was infected IP, and two infants (0.44%, 95% CI 0.01-1.7%) were infected PP. The infant mortality rate was 0.88% (95% CI 0.26-2.33%).

CONCLUSIONS

In the first 6 months of life, in the era of Option B Plus combination antiretroviral therapy, IU transmission is the major route of MTCT. The cumulative MTCT rate of 1.55% in a breastfeeding population contributes to growing evidence that complete elimination of MTCT is possible.

Higher serum 25-hydroxyvitamin D concentrations are associated with active pulmonary tuberculosis in hospitalised HIV infected patients in a low income tropical setting: a cross sectional study

Background

The inherent risk of developing tuberculosis (TB) in HIV- infected individuals is further enhanced by hypovitaminosis D. Interventions that offset HIV-associated immune deterioration potentially arrest disease progression and incidence of opportunistic infections including TB. Despite conflicting reports on association between vitamin D deficiency (VDD) and risk of TB, vitamin D (VD) supplementation remains a promising intervention.

Methods

We conducted a comparative cross-sectional study on 145 HIV⁺/pulmonary TB⁺ (PTB) and 139 HIV⁺/PTB⁻ hospitalised patients to investigate association of vitamin D status and risk of PTB. Stratified random sampling was used to select archived serum specimens from participants enrolled in a randomised controlled trial (RCT) conducted to investigate the impact of using a point-of-care urine lipoarabinomannan strip test for TB diagnosis. PTB status was confirmed using sputum smear microscopy, culture or GeneXpert MTB/RIF. Serum 25-hydroxyvitamin D [25(OH) D] concentrations were assayed by competitive chemiluminescent immunoassay prior to commencement of anti-TB treatment. Effect of VD status on duration of hospital stay and patient outcomes on follow up at 8 weeks were also investigated. Median serum 25(OH) D concentrations were compared using Mann-Whitney test and covariates of serum VD status were assessed using logistic regression analysis.

Results

Overall VDD prevalence in the cohort was 40.9% (95% CI: 35.1–46.8). Median serum 25(OH)D concentrations were significantly higher in HIV⁺/PTB⁺ group (25.3 ng/ml, IQR:18.0–33.7) compared to the HIV⁺/PTB⁻ group (20.4 ng/ml, IQR:14.6–26.9), p = 0.0003. Patients with serum 25(OH) D concentration ≥ 30 ng/ml were 1.9 times more likely to be PTB⁺ compared to those with serum 25(OH) D concentrations < 30 ng/ml (odds ratio (OR) 1.91; 95% CI 1.1–3.2). PTB-related death was associated with higher odds of having 25(OH) D levels≥30 ng/ml. Age, gender, CD4⁺ count, combination antiretroviral therapy (cART) status, efavirenz based cART regimen and length of hospital stay were not associated with vitamin D status.

Conclusions

The finding of an association between higher serum 25(OH) D concentrations and active PTB and TB-related mortality among hospitalised HIV-infected patients in the present study is at variance with the commonly reported association of hypovitaminosis and susceptibility to TB. Our findings though, are in concordance with a small pool of reports from other settings.

Association of high serum vitamin D concentrations with active pulmonary TB in an HIV co-endemic setting, Harare, Zimbabwe

Background

There is paucity data on the association of vitamin D deficiency (VDD) and active tuberculosis (TB) in southern Africa where the human immunodeficiency virus (HIV) is co-endemic. We examined the association of serum vitamin D concentrations with active pulmonary tuberculosis (PTB) in HIV-infected (n = 284) and uninfected (n = 267) Black Zimbabweans, in Harare, Zimbabwe.

Methods

We conducted a cross-sectional study of 551 participants comprising 145 HIV⁺/PTB ⁺, 139 HIV⁺/PTB⁻, 134 HIV⁻/PTB⁺ and 133 HIV⁻/PTB⁻. PTB status was confirmed using sputum by culture, or smear microscopy, or GeneXpert MTB/RIF. Serum 25-hydroxyvitamin D (25(OH)D) concentrations were measured using a competitive chemiluminescent immunoassay prior to commencement of anti-TB treatment.

Results

In all four groups, the median vitamin D concentrations were above the 20 ng/ml cut off for VDD. However, the median vitamin D concentrations in all the four groups were below the cut off for vitamin D sufficiency ≥30 ng/ml. The median vitamin D concentrations were significantly higher in PTB⁺ cases; 24.2 ng/ml (IQR: 18.8–32.0) compared to PTB⁻ controls 20.9 ng/ml (IQR: 17.1–26.9), p < 0.0001 regardless of HIV status. The HIV⁺/PTB⁺ group had the highest median vitamin D concentration (25.3 (IQR: 18.0–33.7 ng/ml) whilst the HIV⁺/PTB⁻ group had the lowest; 20.4 ng/ml (IQR: 14.6–26.9), p = 0.0003. Vitamin D concentration <30 ng/ml was associated with 43% lower odds of being PTB⁺ OR 0.57 (95% CI 0.35–0.89).

Conclusions

Our results are not in agreement with the generally accepted hypothesis that VDD is associated with active PTB. To the contrary our results showed an association of higher vitamin D concentrations with active TB irrespective of HIV status. Although findings from the available pool of case control studies remain inconsistent, the results from the current study provide further rationale for larger-scale, prospectively designed studies to evaluate whether sufficient vitamin D concentrations do indeed precede the development of active PTB in our setting.

Comparative performance characteristics of the urine lipoarabinomannan strip test and sputum smear microscopy in hospitalized HIV-infected patients with suspected tuberculosis in Harare, Zimbabwe

Background

In Zimbabwe, sputum smear microscopy (SSM) is the routinely used TB diagnostic tool in hospitalised HIV-infected patients. However, SSM has poor sensitivity in HIV-infected patients. We compared performance of urine lipoarabinomannan strip test (LAM) and SSM among hospitalized HIV-infected patients with suspected TB.

Methods

Hospitalized HIV-infected patients with suspected TB were randomized to LAM plus SSM or SSM alone groups as part of a larger multi-country parent study. Here we present a comparison of LAM versus SSM performance from the Zimbabwe study site. LAM analyses (grade 2 cut-off) were conducted using (i) a microbiological reference standard (MRS; culture positivity for M.tb and designated definite TB) and (ii) a composite reference standard (CRS; definite TB plus probable TB i.e. patients with clinical TB excluded from the culture negative group). CRS constituted the primary analysis.

Results

82/457 (18 %) of the patients randomized to the LAM group were M.tuberculosis culture positive. Using CRS, sensitivity (%, 95 % CI) of LAM was significantly higher than SSM [49.2 (42.1-56.4) versus 29.4(23.2-36.3); p < 0.001]. Specificity and PPV were 98.1 %, and 95.8 %, respectively. By contrast, using MRS, LAM sensitivity was similar to SSM and specificity was significantly lower, however, the combined sensitivity of LAM and SSM was significantly higher than that of SSM alone, p = 0.009. Using CRS, LAM sensitivity (%, CI) was CD4 count dependent [60.6(50.7-69.8) at ≤50 cells/μL; 40.0(22.7-59.4) at 51-100 cells/μL, and 32.8(21.0-46.3) at >100 cells/μL. The combined sensitivity of LAM and SSM was higher than SSM alone being highest at CD4 counts <50 cells/μL [67.6(57.9-76.3); p = <0.001]. Specificity of LAM or SSM alone, or of combined LAM and SSM was >97 % in all the 3 CD4 strata.

Conclusion

Among hospitalized HIV-infected patients with suspected TB, the sensitivity of LAM is significantly higher than that of SSM, especially at low CD4 counts. LAM and SSM are complimentary tests for diagnosis of TB in HIV-infected patients. We recommend a combination of LAM and SSM for TB diagnosis in HIV-infected patients with low CD4 counts in HIV/TB co-endemic countries, where alternative methods are unavailable.