Timing of human immunodeficiency virus type 1 (HIV-1) transmission from mother to child: bayesian estimation using a mixture

Association between viral suppression during the third trimester of pregnancy and unintended pregnancy among women on antiretroviral therapy: Results from the 2019 antenatal HIV Sentinel Survey, South Africa

Objectives

About half of the pregnancies among women living with HIV (WLWH) receiving antiretroviral therapy (ART) in sub-Saharan African countries are reported to be unintended. Unintended pregnancy is associated with late initiation of antenatal care (ANC), and may delay provision of viral load monitoring services, antenatal adherence counselling and support, and other services that promote sustained viral suppression throughout pregnancy. This study examines the association between unsuppressed viral load during the third trimester of pregnancy and unintended pregnancy among women who initiated ART before pregnancy.

Methods

This was an analysis of data from a national antenatal survey conducted at 1 589 public health facilities in South Africa between 1 October and 15 November 2019. Consenting pregnant women aged 15–49 years attending ANC during the survey period were enrolled. Demographic and clinical data were collected through interview and medical record review. Pregnancy intention was assessed using two questions from the London Measure of Unplanned Pregnancy, and responses were categorized as “unintended,” “undecided,” and “intended.” Blood specimens were collected from all women and tested for HIV; and if positive, a viral load test was performed. A survey domain-based poisson regression model examined the association between unsuppressed viral load during the third trimester of pregnancy and unintended pregnancy among women who initiated ART before pregnancy. Viral suppression was defined as viral load <50 copies/mL.

Results

Of 10 901 WLWH with viral load data available, 63.3% (95% confidence interval (CI): 62.4%-64.1%) were virally suppressed. Among the 2 681 women (representing 24.1% of all WLWH with viral load data) who initiated ART before pregnancy and were in their third trimester at the time of enrolment, 74.4% (95% CI: 73.0%-75.8%) were virally suppressed. In the same population, the proportion virally suppressed was lower among women whose current pregnancies were unintended (72.1%, 95% CI: 70.1%-74.1%) compared to women whose pregnancies were intended (78.3%, 95% CI: 75.9%-80.5%). In multivariable analyses adjusted for age, gravity, marital status, education, location of facility and syphilis status, unintended pregnancy was associated with unsuppressed viral load during the third trimester (adjusted relative risk: 1.3, 95% CI: 1.1–1.4) among women who initiated ART before pregnancy.

Conclusion

The identified association between unsuppressed viral load and unintended pregnancy among pregnant women who initiated ART before pregnancy highlights the need to strengthen routine assessment of fertility preferences and provision of contraceptive services to reproductive age WLWH receiving ART.

Understanding Viral and Immune Interplay During Vertical Transmission of HIV: Implications for Cure

Despite the significant progress that has been made to eliminate vertical HIV infection, more than 150,000 children were infected with HIV in 2019, emphasizing the continued need for sustainable HIV treatment strategies and ideally a cure for children. Mother-to-child-transmission (MTCT) remains the most important route of pediatric HIV acquisition and, in absence of prevention measures, transmission rates range from 15% to 45% via three distinct routes: in utero, intrapartum, and in the postnatal period through breastfeeding. The exact mechanisms and biological basis of these different routes of transmission are not yet fully understood. Some infants escape infection despite significant virus exposure, while others do not, suggesting possible maternal or fetal immune protective factors including the presence of HIV-specific antibodies. Here we summarize the unique aspects of HIV MTCT including the immunopathogenesis of the different routes of transmission, and how transmission in the antenatal or postnatal periods may affect early life immune responses and HIV persistence. A more refined understanding of the complex interaction between viral, maternal, and fetal/infant factors may enhance the pursuit of strategies to achieve an HIV cure for pediatric populations.

Mother-to-child transmission of HIV: a global perspective

HIV-1 infection is a significant global source of childhood morbidity and mortality, and mother-to-child transmission (MTCT) is the major mode of infection. Research over the past two decades has improved our understanding of the pathogenesis of MTCT and pediatric HIV-1 infection, lending to the development of effective preventive and therapeutic strategies. However, successful implementation of these strategies has been limited in resource-constrained settings, where the majority of new pediatric HIV infections now occur. Continued efforts are necessary to better understand MTCT and to refine preventive and therapeutic strategies to allow their successful implementation in the most needed places.

Placental immunopathology in the FIV-infected cat: a role for inflammation in compromised pregnancy?

In utero transmission of feline immunodeficiency virus (FIV) occurs frequently in queens experimentally infected with FIV-B-2542 and other FIV isolates. Fetal infection has been detected as early as 3-4 weeks gestation, and the incidence of fetal infection increases with progressing gestation. Reproductive failure occurs commonly, including fetal resorptions and developmentally-arrested fetuses, demonstrating that fetal demise occurs early in gestation. Precise, temporal immunomodulation within the placenta is essential for successful pregnancy. Placental Th1 and Th2 cytokines must be appropriately balanced, typically favoring Th2 cytokines at the maternal-fetal interface. Abnormal inflammatory cytokine expression often accompanies miscarriage. Regulatory T cells (Tregs) play an essential role in maternal tolerance of the semi-allogeneic fetus by suppressing inflammation. We are using the FIV-infected cat to examine the relationship between lentivirus-induced placental immunopathology and reproductive outcome. Using TaqMan real time reverse transcriptase (RT)-PCR, we measured relative expression of key immunomodulators in the placentas of FIV-B-2542-infected and control cats, including placentas from both viable and nonviable pregnancies. Our data associate significantly-increased expression of inflammatory cytokines with failed pregnancies, identify Treg markers in the placentas, and provide preliminary evidence that Tregs or other cells bearing similar activation markers may be involved in pregnancy maintenance. Our data suggest that placental inflammation in the FIV-infected cat may compromise pregnancy.

Maternal hematological and virological characteristics during early feline immunodeficiency virus (FIV) infection of cats as predictors of fetal infection and reproductive outcome at early gestation

The FIV-infected cat is a small animal model for HIV mother-to-child transmission (MTCT) because the two lentiviruses are biologically related and produce similar clinical syndromes. Both viruses are vertically transmissible and may negatively impact reproductive outcome. Maternal hematological and virological parameters are predictors of MTCT in HIV-infected women. Our purpose was to determine whether similar maternal characteristics during early pregnancy in FIV-infected cats influence pregnancy outcome. We inoculated 10 cats with FIV-B-2542; 10 cats were uninoculated. We quantified longitudinal CD4:CD8 T cell ratios, proviral load, and plasma viremia, monitored longitudinal serostatus, and documented clinical and reproductive outcome during early pregnancy. Inoculated queens were seropositive and provirus positive by week 4 post-infection (p.i.). CD4:CD8 ratios were depressed in the infected group by month 3.5 p.i. Proviral load was variable in the animals throughout the course of infection; plasma viremia was below the level of detection in all animals. Reduced litter sizes and increased fetal demise occurred in infected queens. Viral RNA, but not proviral DNA, was detected in representative placentas (14 of 14; 100%) and fetuses (12 of 14; 86%) collected from infected queens. However, maternal virological and hematological characteristics did not correlate either positively or negatively with reproductive outcome.

Obstetric nurses' attitudes and nursing care intentions regarding care of HIV-positive pregnant women

OBJECTIVE

To define attitudes toward pregnant women with HIV and how these attitudes correlate with and affect prejudice and nursing care intentions.

DESIGN

Cross-sectional descriptive correlational study of obstetric nurses.

SETTING

Eight hundred (800) mailed surveys in the United States (N = 350).

PARTICIPANTS

A random sample of nurses certified in inpatient obstetrics.

MAIN OUTCOME MEASURES

Background information tool, the Pregnant Women with HIV Attitude Scale, the Prejudice Interaction Scale in response to four vignettes, and the Marlowe-Crowne Social Desirability Scale-Form C.

RESULTS

Obstetric nurses had more positive Mothering-Choice attitudes than Sympathy-Rights attitudes (p= .000). Nurses who knew more than four people affected by HIV/AIDS had more positive attitudes (p<or= .05). Nurses with more positive attitudes were less prejudiced and more willing to care for pregnant women with HIV (p= .05). Nurses were significantly more prejudiced and less willing to care for women with than without HIV (p<or= .0001).

CONCLUSIONS

Nurses' clinical care may be influenced by their attitudes and prejudice toward pregnant women with HIV. Nursing education should include how prejudice can affect our clinical decision making and behaviors. Research is needed to explicate the effects on patient outcomes.

International perspectives, progress, and future challenges of paediatric HIV infection

Paediatric HIV infection is a growing health challenge worldwide, with an estimated 1500 new infections every day. In developed countries, well established prevention programmes keep mother-to-child transmission rates at less than 2%. However, in developing countries, where transmission rates are 25-40%, interventions are available to only 5-10% of women. Children with untreated natural infection progress rapidly to disease, especially in resource-poor settings where mortality is greater than 50% by 2 years of age. As in adult infection, antiretroviral therapy has the potential to rewrite the natural history of HIV, but is accessible only to a small number of children needing therapy. We focus on the clinical and immunological features of HIV that are specific to paediatric infection, and the formidable challenges ahead to ensure that all children worldwide have access to interventions that have proved successful in developed countries.

Bayesian statistics in medicine: a 25 year review

This review examines the state of Bayesian thinking as Statistics in Medicine was launched in 1982, reflecting particularly on its applicability and uses in medical research. It then looks at each subsequent five-year epoch, with a focus on papers appearing in Statistics in Medicine, putting these in the context of major developments in Bayesian thinking and computation with reference to important books, landmark meetings and seminal papers. It charts the growth of Bayesian statistics as it is applied to medicine and makes predictions for the future. From sparse beginnings, where Bayesian statistics was barely mentioned, Bayesian statistics has now permeated all the major areas of medical statistics, including clinical trials, epidemiology, meta-analyses and evidence synthesis, spatial modelling, longitudinal modelling, survival modelling, molecular genetics and decision-making in respect of new technologies.

HIV prevalence, sociodemographic, and behavioral correlates and recruitment methods among injection drug users in St. Petersburg, Russia

OBJECTIVE

In St. Petersburg, Russia, we sought to describe the characteristics of active high-risk injection drug users (IDUs) to evaluate the associations between behavioral and demographic characteristics and HIV-1 infection and to describe 3 discrete recruitment methods.

METHODS

Active high-risk IDUs were recruited in 3 ways: through street outreach, at facilities serving IDUs, and by network-based chain referral. Recruits were screened, counseled, and tested for HIV-1. Sociodemographic and behavioral data were collected. HIV-1 prevalence was analyzed as a function of sociodemographic and behavioral variables.

RESULTS

During the 10-month recruitment period, data from 900 participants were collected: median age was 24 years, and in the previous month, 96% used heroin and 75% shared needles with others. The baseline HIV prevalence was 30% (95% confidence interval [CI]: 27 to 33). Recruitment through social networks was the most productive strategy. HIV-positive individuals were younger, but none of the other sociodemographic or behavioral characteristics differed significantly by HIV status.

CONCLUSIONS

The estimated HIV prevalence of 30% places St. Petersburg among the worst IDU-concentrated epidemics in Europe. Recruitment through network-based chain referral is a useful method for recruiting active IDUs. Sociodemographic and behavioral links to prevalent HIV infection remain to be elucidated.

The Feline Immunodeficiency Virus-Infected Cat: A Model for Lentivirus-induced Placental Immunopathology and Reproductive Failure (Mini-Review)

PROBLEM

Pediatric human immunodeficiency virus (HIV) infection is largely a result of transplacental transmission, and pregnancy perturbation is more frequent in HIV-infected women. Dysregulation of placental immunology may occur during HIV infection, possibly facilitating HIV vertical transfer and miscarriage. The (FIV)-infected cat is a useful small-animal model for HIV pathogenesis because the viruses share common biological and clinical features. Transplacental transmission is readily achieved experimentally, resulting in a high proportion of infected offspring and frequent reproductive failure.

METHOD OF STUDY

We are using this model to examine lentivirus-induced placental immunopathology to determine the role aberrant immunology plays in intrauterine transmission and pregnancy perturbation.

RESULTS

Kittens were cesarean delivered from FIV-B-2542-infected and control queens at week 8 gestation (1 week short of term), and placental and fetal specimens were collected. On average, control queens delivered 3.8 kittens/litter, and 1 of 31 kittens (3.2%) was non-viable. FIV-infected queens produced 2.7 kittens/litter with 15 of 25 fetuses (60%) non-viable. The virus was detected in 14 of 15 placentas (93%) and 21 of 22 fetuses (95%) using polymerase chain reaction (PCR). Using a one-step, real time reverse transcriptase (RT)-PCR, we measured expression of representative placental T helper 1 (Th1) cytokines, interleukin (IL)-1beta and interferon (IFN)-gamma, a Th2 cytokine, IL-10, and chemokine receptor CXCR4. A comparison of placental cytokine expression between infected and control queens did not reveal differences between the two groups. However, elevated expression of Th1 cytokines and increased Th1/Th2 ratios (IL-1beta/IL-10) occurred in placentas from resorptions, indicating that increased placental Th1 cytokine expression was associated with pregnancy failure in the FIV-infected cat.

CONCLUSION

The potential to establish efficient FIV in utero transmission, coupled with the parallels in immunopathology between FIV-infected cats and HIV-infected humans, suggests the usefulness of the FIV-infected cat as a cost-effective, small-animal model to study lentivirus-induced immunopathology, transplacental infection, and reproductive failure.

Seven items were identified for inclusion when reporting a Bayesian analysis of a clinical study

OBJECTIVE

(1) To generate a list of items that experts consider most important when reporting a Bayesian analysis of a clinical study, (2) to report on the extent to which we found these items in the literature, and (3) to identify factors related to the number of items in a report.

STUDY DESIGN AND SETTING

Based on opinions from 23 international experts, we determined the items considered most important when publishing a Bayesian analysis. We then performed a literature search to identify articles in which a Bayesian analysis was performed and determined the extent to which we found these items in each report. Finally, we examined the relationship between the number of items in a report and journal- and article-specific attributes.

RESULTS

Our final set of seven items described the prior distribution (specification, justification, and sensitivity analysis), analysis (statistical model and analytic technique), and presentation of results (central tendency and variance). There was >99% probability that more items were reported in studies with a noncontrolled study design and in journals with a methodological focus, lower impact factor, and absence of a word count limit.

CONCLUSION

We developed a set of seven items that experts believe to be most important when reporting a Bayesian analysis.

Placental immunopathology and pregnancy failure in the FIV-infected cat

Placental HIV infections frequently result in infected babies or miscarriage. Aberrant placental cytokine expression during HIV infections may facilitate transplacental viral transmission or pregnancy perturbation. The feline immunodeficiency virus (FIV)-infected cat is a model for HIV infections due to similarities in biology and clinical disease. The purpose of this study was to evaluate placental immunomodulator expression and reproductive outcome using the FIV-infected cat model. Kittens were cesarean delivered from FIV-B-2542-infected and control queens near term; placental and fetal tissues were collected. Real-time RT-PCR was used to measure expression of representative placental Th1 cytokines, interleukin-1beta (IL-1beta) and interferon-gamma (IFN-gamma), a Th2 cytokine, IL-10, and chemokine receptor CXCR4. On average, control queens delivered 3.8 kittens/litter; 1 of 31 kittens (3.2%) was non-viable. FIV-infected queens produced 2.7 kittens/litter; 15 of 25 concepti (60%) were non-viable. FIV was detected in 14 of 15 placentas (93%) and 21 of 22 fetuses (95%) using PCR. Placental immunomodulator expression did not differ significantly when placentas from infected cats were compared to those of control cats. However, elevated expression of Th1 cytokines and increased Th1/Th2 ratios (IL-1beta/IL-10) occurred in placentas from resorptions. Therefore, increased placental Th1 cytokine expression was associated with pregnancy failure in the FIV-infected cat.

Covert vertical transmission of feline immunodeficiency virus

Covert vertical transmission of feline immunodeficiency virus (FIV), the feline counterpart of human immunodeficiency virus type 1 (HIV-1), was identified in kittens born to FIV-infected cats. DNA PCR detected FIV gag and env sequences in tissues from kittens nonviable at birth, and in viable kittens monitored postnatally and necropsied at either 11 weeks or 1 year of age. Although FIV DNA was detected in initial blood samples from all 16 viable kittens, viral DNA became increasingly difficult to detect over time and infectious virus could rarely be demonstrated. Only maternal FIV antibody was detected in kitten plasma during the entire postnatal observation period, and kittens remained healthy, with normal CD4:CD8 T cell ratios at >14 months of age. Thus, mother-to-offspring FIV exposure, occurring in utero and postnatally, can result in covert infection in kittens with virus sequestered and contained in tissue sites. These findings appear directly relevant to suspected transient HIV infections and reports of HIV-specific cellular immune responses in highly exposed seronegative adults and uninfected infants born to HIV-positive women.

Quantification of fibrosis progression in patients with chronic hepatitis C using a Markov model

The knowledge of fibrosis progression in chronic hepatitis C and the impact of new treatments on progression is limited by the number of available liver biopsies per patient. Moreover, liver biopsies identify a patient's stage of fibrosis at a given point in time, but cannot quantify the time spent in that stage nor the date of transition to that stage. This paper assesses the potential of Markov modelling to overcome these difficulties. The data from interferon-treated (n=185) and untreated patients (n=102) are analysed to illustrate the power of this technique. The model accurately reproduced the distributions of patients in the different fibrosis stages at two subsequent biopsies. A quantification of the role of cofactors in the progression of the disease, and the impact of interferon treatment are given. In subjects who are 40 years old and have been infected for 10 years, the model predicted that 274 of 1000 untreated patients, but only 42 of 1000 treated patients, would progress from F0 or F1 to F3 or F4 fibrosis over the next 5 years. The model also confirms that as age and duration of infection increase, the risk of fibrosis progression increases, while the impact of treatment with interferon decreases. Hence Markov modelling is an accurate tool in the analysis of fibrosis progression in chronic hepatitis C. It will be valuable for the quantification of the effect of new treatments on fibrosis progression in hepatitis C.

Disease surveillance and data collection issues in epidemic modelling

This paper is founded on a tutorial session given to the School on Modern Statistical Methods in Medical Research which was held at the International Centre for Theoretical Physics, Trieste in September 1999. We review the aims, scope and purposes of infectious disease surveillance including determining transmission information to underpin model structure and parameterization in epidemic modelling. The practical problems inherent in collecting surveillance data are illustrated by a study of HIV/AIDS in Cambodia. We also review the basic elements of mathematical models developed to represent the transmission dynamics of infectious diseases, and discuss reasons for the gap between mathematical epidemic models and available data.