Management of gastrointestinal disorders in children with HIV infection

The presence of enteropathy in HIV infected children on antiretroviral therapy in Malawi

BACKGROUND

Undernutrition and malnutrition in children in low- and middle-income countries contribute to high mortality rates. Stunting, a prevalent form of malnutrition, is associated with educational and productivity losses. Environmental enteric dysfunction (EED) and human immunodeficiency virus (HIV) infection worsen these conditions. This study seeks to investigate the presence of enteropathy using EED fecal biomarkers in HIV-infected children who are stable on antiretroviral therapy (ART) across various nutritional statuses. By understanding the interplay between EED, HIV, and nutritional status, this study aims to provide insights that can inform targeted interventions to optimize nutritional outcomes in HIV infected children.

METHODS/PRINCIPAL FINDINGS

This study evaluated the levels of alpha-1-antitrypsin, calprotectin and myeloperoxidase in frozen fecal samples from 61 HIV infected (mean age 9.16 ±3.08 years) and 31 HIV uninfected (6.65 ±3.41 years) children in Malawi. Anthropometric measurements and clinical data were collected. The height-for-age z-score (-1.66 vs -1.27, p = 0.040) and BMI-for-age z-score (-0.36 vs 0.01, p = 0.037) were lower in HIV infected children. Enzyme-linked immunosorbent assays were used to measure biomarker concentrations. Statistical tests were applied to compare biomarker levels based on HIV status and anthropometric parameters. Myeloperoxidase, alpha-1-antitrypsin, and calprotectin concentrations did not differ between HIV infected and HIV uninfected children of different age groups. In HIV infected children from 5-15 years, there is no difference in biomarker concentration between the stunted and non-stunted groups.

CONCLUSION/SIGNIFICANCE

Our study found a higher prevalence of stunting in HIV infected children compared to uninfected children, but no significant differences in biomarker concentrations. This suggests no causal relationship between enteropathy and stunting in HIV infected children. These results contribute to the understanding of growth impairment in HIV infected children and emphasize the need for further research, particularly a longitudinal, biopsy-controlled study.

Gastrointestinal Diseases in Children Living with HIV

Thanks to the advances in antiretroviral therapies (ART) and early diagnosis, pediatric HIV has turned into a chronic infection that requires the collaboration of all pediatric subspecialists for holistic patient management. Gastrointestinal complaints are a frequent reason for seeking access to medical care in all pediatric patients worldwide. Intestinal involvement is present in virtually all children with HIV infections. In high-prevalence settings, up to 25% of children accessing the hospital for diarrhea are diagnosed with HIV. More than half of patients with advanced disease present with gastrointestinal symptoms, from mild infectious diarrhea to severe gastrointestinal impairment, malabsorption and failure to thrive. Gastrointestinal disorders do not spare children on ART, particularly in the initial months of therapy. ART-associated pancreatitis and hepatitis are rare but potentially severe adverse events, whereas lower abdominal symptoms have been reported in more than a third of patients. The latter are usually mild and transient, but may limit ART adherence; a correct framing of the problem is necessary to minimize therapy switches while optimizing the quality of life of children on ART. This review aims to provide state-of-the-art guidance for the initial approach to gastrointestinal diseases in children living with HIV.

Development of a Pediatric Relative Bioavailability/Bioequivalence Database and Identification of Putative Risk Factors Associated With Evaluation of Pediatric Oral Products

Generally, bioequivalence (BE) studies of drug products for pediatric patients are conducted in adults due to ethical reasons. Given the lack of direct BE assessment in pediatric populations, the aim of this work is to develop a database of BE and relative bioavailability (relative BA) studies conducted in pediatric populations and to enable the identification of risk factors associated with certain drug substances or products that may lead to failed BE or different pharmacokinetic (PK) parameters in relative BA studies in pediatrics. A literature search from 1965 to 2020 was conducted in PubMed, Cochrane Library, and Google Scholar to identify BE studies conducted in pediatric populations and relative BA studies conducted in pediatric populations. Overall, 79 studies covering 37 active pharmaceutical ingredients (APIs) were included in the database: 4 bioequivalence studies with data that passed BE evaluations; 2 studies showed bioinequivalence results; 34 relative BA studies showing comparable PK parameters, and 39 relative BA studies showing differences in PK parameters between test and reference products. Based on the above studies, common putative risk factors associated with differences in relative bioavailability (DRBA) in pediatric populations include age-related absorption effects, high inter-individual variability, and poor study design. A database containing 79 clinical studies on BE or relative BA in pediatrics has been developed. Putative risk factors associated with DRBA in pediatric populations are summarized.

Mitochondrial Impairment in Well-Suppressed Children with Perinatal HIV-Infection on Antiretroviral Therapy

Mitochondrial impairment is reported in HIV-infected children receiving antiretroviral therapy (ART), as well as those naive to ART. Whether mitochondrial function recovers with early initiation of ART and sustained viral suppression on long-term ART is unclear. In this study, we evaluate mitochondrial markers in well-suppressed perinatally HIV-infected children initiated on ART early in life. We selected a cross-sectional sample of 120 HIV-infected children with viral load <400 copies/mL and 60 age-matched uninfected children (22 HIV-exposed uninfected) enrolled in a cohort study in Johannesburg, South Africa. Complex IV (CIV) and citrate synthase (CS) activity were measured by spectrophotometry. Mitochondrial DNA (mtDNA) content relative to nuclear DNA (nDNA) was measured by quantitative real-time polymerase chain reaction and expressed as copies/nDNA. Mitochondrial markers were impaired in HIV-infected children, including lower mean CIV activities [1.76 vs. 1.40 optical densities (OD)/min], higher risk of a CIV/CS ratio ≤0.22 (third quartile; odds ratio = 3.03, 95% confidence interval: 1.38-6.66), and lower mtDNA content. Children with shorter versus longer ART duration (<6.3 vs. ≥6.3 years) had lower means of CIV activity (1.22-1.58 OD/min) and mtDNA content (386-907 copies/nDNA). There were no differences in mitochondrial markers between children who started ART earlier (<6 months) or later (6-24 months). CIV activity was impaired in children with lower height-for-age Z-scores (HAZs). Despite early treatment and prolonged viral suppression, HIV-infected children had detectable mitochondrial impairment, particularly among those with stunted growth. Further study is required to determine if continued treatment will lead to full recovery of mitochondrial function in HIV-infected children.

Treatment interventions for diarrhoea in HIV-infected and HIV-exposed children: a systematic review

INTRODUCTION

Seventy percent of an estimated 10 million children less than five years of age in developing countries die each year of acute respiratory infections, diarrhoea, measles, malaria, malnutrition or a combination of these conditions. Children living with Human immunodeficiency virus (HIV) are at risk of diarrhoea because of drug interactions with antiretroviral therapy and bottle feeding. This may be aggravated by malnutrition and other infectious diseases which are frequent in children living with HIV. Objective: to evaluate treatment interventions for diarrhoea in HIV infected and exposed children.

METHODS

A comprehensive search was conducted on 02 June 2016 to identify relevant studies for inclusion. We included randomised controlled trials of HIV infected or exposed children under 15 years of age with diarrhoea. Two authors independently selected studies for inclusion, assessed risk of bias (RoB) and extracted data using a pre-designed data extraction form.

RESULTS

We included two studies (Amadi 2002 and Mda 2010) that each enrolled 50 participants. The RoB was assessed as low-risk for both included studies. There was no difference in clinical cure and all-cause mortality between nitazoxanide and placebo for cryptosporidial diarrhoea in Amadi 2002. In Mda 2010, there was a reduction in duration of hospitalisation in the micronutrient supplement group (P < 0.005) although there was no difference in all-cause mortality.

CONCLUSION

There is low certainty evidence on the effectiveness of nitazoxanide for treating cryptosporidial diarrhoea and micronutrient supplementation in children with diarrhoea. Adequately powered trials are needed to assess micronutrients and nitazoxanide, as well as other interventions, for diarrhoea in HIV-infected and-exposed children.

Mechanisms of antidiarrhoeal effects by diosmectite in human intestinal cells

Background

Rotavirus (RV) induces diarrhoea through a sequence of enterotoxic and cytotoxic effects. The former are NSP4-dependent, induce calcium-dependent chloride secretion and involve oxidative stress. Diosmectite (DS) is a natural clay that has been recommended as an active therapy for diarrhoea, but the mechanism of its effect is not clear. Electrical parameters may be used to measure the direct enterotoxic and cytotoxic effects in polar epithelial intestinal cells. To investigate the effects of DS on RV-induced enterotoxic and cytotoxic damage. Caco-2 cells were used as a model of RV infection to evaluate chloride secretion, epithelial integrity, oxidative stress and viral infectivity in Ussing chambers.

Results

Diosmectite reduced the expression of NSP4 and oxidative stress, resulting in a strong inhibition of chloride secretion. Preincubating RV with DS reduced the cytotoxic effect. Finally, the viral load was reduced by DS but not by control clay. This result suggests that DS specifically affects the early events of RV infection protecting the enterocyte, whereas it does not restore already-established cell damage.

Conclusion

These findings indicate that DS exerts an anti-diarrhoeal effect by inhibiting viral replication and the expression of NSP4. Both ion secretion and cell damage induced by RV are strongly inhibited consequent to the antiviral effect, which explains its clinical efficacy.

Improving feeding and growth of HIV-positive children through nutrition training of frontline health workers in Tanga, Tanzania

Background

Nutrition training can boost competence of health workers to improve children’s feeding practices. In this way, child undernutrition can be ameliorated in general populations. However, evidence is lacking on efficacy of such interventions among Human Immunodeficiency Virus (HIV)-positive children. We aimed to examine the efficacy of a nutrition training intervention to improve midlevel providers’ (MLPs) nutrition knowledge and feeding practices and the nutrition statuses of HIV-positive children in Tanga, Tanzania.

Methods

This cluster-randomized controlled trial was conducted in 16 out of 32 care and treatment centers (CTCs) in Tanga. Eight CTCs were assigned to the intervention arm and a total of 16 MLPs received nutrition training and provided nutrition counseling and care to caregivers of HIV-positive children. A total of 776 pairs of HIV-positive children and their caregivers were recruited, of whom 397 were in the intervention arm. Data were analyzed using instrumental variable random effects regression with panel data to examine the efficacy of the intervention on nutrition status through feeding practices.

Results

Mean nutrition knowledge scores were higher post-training compared to pre-training among MLPs (37.1 vs. 23.5, p < 0.001). A mean increment weight gain of 300 g was also observed at follow-up compared to baseline among children of the intervention arm. Feeding frequency and dietary diversity improved following the intervention and a 6 months follow-up (p < 0.001). An increase in each unit of feeding frequency and dietary diversity were associated with a 0.15-unit and a 0.16-unit respectively decrease in the child underweight (p < 0.001).

Conclusions

Nutrition training improved nutrition knowledge among MLPs caring for HIV-positive children attending CTCs in Tanga, Tanzania. Caregivers’ feeding practices also improved, which in turn led to a modest weight gain among HIV-positive children. To sustain weight gain, efforts should be made to also improve households’ food security and caregivers’ education in addition to inservice nutrition trainings. The protocol was registered on 15/02/2013, before the recruitment at ISRCTN trial registry with the trial registration number: ISRCTN65346364.

Nutritional Care of the Child with Human Immunodeficiency Virus Infection in the United States

In well-resourced settings, early infant diagnosis and administration of life-saving antiretrovirals (ARVs) have significantly improved clinical outcomes in pediatric human immunodeficiency virus (HIV) infection. The dramatic increase in survival rates is associated with enhancements in overall quality of life, which reflect a multidisciplinary, holistic approach to care. Current optimism starkly contrasts with the outlook and prognosis two decades ago, when failure to thrive and wasting syndrome from uncontrolled pediatric HIV infection resulted from poor oral intake, malabsorption, chronic diarrhea, and a persistently catabolic state. The tenets of care developed from that era still hold true in that all infants, children, and adolescents with HIV require comprehensive nutritional services in addition to effective combination antiretroviral therapy (cART). This chapter will review the principles of nutrition in the pre- and post-cART eras and discuss the etiologic factors associated with malnutrition, with an emphasis on interventions that have favorably impacted the growth and body composition of infants, children and adolescents with HIV.

Growth failure and nutrition considerations in chronic childhood wasting diseases

Growth failure is a common problem in many children with chronic diseases. This article is an overview of the most common causes of growth failure/growth retardation that affect children with a number of chronic diseases. We also briefly review the nutrition considerations and treatment goals. Growth failure is multifactorial in children with chronic conditions, including patients with cystic fibrosis, chronic kidney disease, chronic liver disease, congenital heart disease, human immunodeficiency virus, inflammatory bowel disease, short bowel syndrome, and muscular dystrophies. Important contributory factors to growth failure include increased energy needs, increased energy loss, malabsorption, decreased energy intake, anorexia, pain, vomiting, intestinal obstruction, and inflammatory cytokines. Various metabolic and pathologic abnormalities that are characteristic of chronic diseases further lead to significant malnutrition and growth failure. In addition to treating disease-specific abnormalities, treatment should address the energy and protein deficits, including vitamin and mineral supplements to correct deficiencies, correct metabolic and endocrinologic abnormalities, and include long-term monitoring of weight and growth. Individualized, age-appropriate nutrition intervention will minimize the malnutrition and growth failure seen in children with chronic diseases.

Understanding the contribution of common childhood illnesses and opportunistic infections to morbidity and mortality in children living with HIV in resource-limited settings

OBJECTIVE

Although antiretroviral treatment (ART) has reduced the incidence of HIV-related opportunistic infections among children living with HIV, access to ART remains limited for children, especially in resource-limited settings. This paper reviews current knowledge on the contribution of opportunistic infections and common childhood illnesses to morbidity and mortality in children living with HIV, highlights interventions known to improve the health of children, and identifies research gaps for further exploration.

DESIGN AND METHODS

Literature review of peer-reviewed articles and abstracts combined with expert opinion and operational experience.

RESULTS

Morbidity and mortality due to opportunistic infections has decreased in both developed and resource-limited countries. However, the burden of HIV-related infections remains high, especially in sub-Saharan Africa, where the majority of HIV-infected children live. Limitations in diagnostic capacity in resource-limited settings have resulted in a relative paucity of data on opportunistic infections in children. Additionally, the reliance on clinical diagnosis means that opportunistic infections are often confused with common childhood illnesseswhich also contribute to excess morbidity and mortality in these children. Although several preventive interventions have been shown to decrease opportunistic infection-related mortality, implementation of many of these interventions remains inconsistent.

CONCLUSIONS

In order to reduce opportunistic infection-related mortality, early ART must be expanded, training for front-line clinicians must be improved, and additional research is needed to improve screening and diagnostic algorithms.

Protective effects of alanyl-glutamine supplementation against nelfinavir-induced epithelial impairment in IEC-6 cells and in mouse intestinal mucosa

PURPOSE

Human Immunodeficiency Virus (HIV) protease inhibitors (PI) remain a crucial component of highly active therapy (HAART) and recently have been demonstrated to have potent antitumor effect on a wide variety of tumor cell lines. However, discontinuation of therapy is an important issue, which may be related to various side-effects, especially diarrhea. The aim of this study was to evaluate the effects of nelfinavir (NFV), an HIV PI, and of alanyl-glutamine (AQ) supplementation, on intestinal cell migration, proliferation, apoptosis and necrosis, using IEC-6 cells and on intestinal crypt depth, villus length, villus area, mitotic index and apoptosis in Swiss mice.

METHODS

Migration was evaluated at 12 and 24 h after injury using a wound healing assay. Cellular proliferation was measured indirectly at 24 and 48 h using tetrazolium salt WST-1. Apoptosis and necrosis were measured by flow cytometry using the Annexin V assay. Intestinal morphometry and mitotic index in vivo were assessed following a seven-day treatment with 100 mg/kg of NFV, given orally. In vivo proliferation and apoptosis were evaluated by intestinal crypt mitotic index and immunohistochemistry, respectively.

RESULTS

In vitro, AQ supplementation enhanced IEC-6 cell migration and proliferation, following challenge with NFV. In vivo, AQ increased intestinal villus length, villus area, crypt depth and cell proliferation and cell migration, following treatment with NFV. AQ did not decrease cell death induced by NFV both in vivo and in vitro.

CONCLUSIONS

AQ supplementation is potentially beneficial in preventing the effects of PIs, such as NFV, in the intestinal tract.

Undernutrition among HIV-positive children in Dar es Salaam, Tanzania: antiretroviral therapy alone is not enough

Background

The prevalence of HIV/AIDS has exacerbated the impact of childhood undernutrition in many developing countries, including Tanzania. Even with the provision of antiretroviral therapy, undernutrition among HIV-positive children remains a serious problem. Most studies to examine risk factors for undernutrition have been limited to the general population and ART-naive HIV-positive children, making it difficult to generalize findings to ART-treated HIV-positive children. The objectives of this study were thus to compare the proportions of undernutrition among ART-treated HIV-positive and HIV-negative children and to examine factors associated with undernutrition among ART-treated HIV-positive children in Dar es Salaam, Tanzania.

Methods

From September to October 2010, we conducted a cross-sectional survey among 213 ART-treated HIV-positive and 202 HIV-negative children in Dar es Salaam, Tanzania. We measured the children's anthropometrics, socio-demographic factors, food security, dietary habits, diarrhea episodes, economic status, and HIV clinical stage. Data were analyzed using both univariate and multivariate methods.

Results

ART-treated HIV-positive children had higher rates of undernutrition than their HIV-negative counterparts. Among the ART-treated HIV-positive children, 78 (36.6%) were stunted, 47 (22.1%) were underweight, and 29 (13.6%) were wasted. Households of ART-treated HIV-positive children exhibited lower economic status, lower levels of education, and higher percentages of unmarried caregivers with higher unemployment rates. Food insecurity was prevalent in over half of ART-treated HIV-positive children's households. Furthermore, ART-treated HIV-positive children were more likely to be orphaned, to be fed less frequently, and to have lower body weight at birth compared to HIV-negative children.

In the multivariate analysis, child's HIV-positive status was associated with being underweight (AOR = 4.61, 95% CI 1.38-15.36 P = 0.013) and wasting (AOR = 9.62, 95% CI 1.72-54.02, P = 0.010) but not with stunting (AOR = 0.68, 95% CI 0.26-1.77, P = 0.428). Important factors associated with underweight status among ART-treated HIV-positive children included hunger (AOR = 9.90, P = 0.022), feeding frequency (AOR = 0.02, p < 0.001), and low birth weight (AOR = 5.13, P = 0.039). Factors associated with wasting among ART-treated HIV-positive children were diarrhea (AOR = 22.49, P = 0.001) and feeding frequency (AOR = 0.03, p < 0.001).

Conclusion

HIV/AIDS is associated with an increased burden of child underweight status and wasting, even among ART-treated children, in Dar es Salaam, Tanzania. In addition to increasing coverage of ART among HIV-positive children, interventions to ameliorate poor nutrition status may be necessary in this and similar settings. Such interventions should aim at promoting adequate feeding patterns, as well as preventing and treating diarrhea.

Evaluation of HIV protease and nucleoside reverse transcriptase inhibitors on proliferation, necrosis, apoptosis in intestinal epithelial cells and electrolyte and water transport and epithelial barrier function in mice

Background

Protease inhibitors (PI's) and reverse transcriptase drugs are important components of highly active antiretroviral therapy (HAART) for treating human acquired immunodeficiency syndrome (AIDS). Long-term clinical therapeutic efficacy and treatment compliance of these agents have been limited by undesirable side-effects, such as diarrhea. This study aims to investigate the effects of selected antiretroviral agents on intestinal histopathology and function in vivo and on cell proliferation and death in vitro.

Methods

Selected antiretroviral drugs were given orally over 7 days, to Swiss mice, as follows: 100 mg/kg of nelfinavir (NFV), indinavir (IDV), didanosine (DDI) or 50 mg/kg of zidovudine (AZT). Intestinal permeability measured by lactulose and mannitol assays; net water and electrolyte transport, in perfused intestinal segments; and small intestinal morphology and cell apoptosis were assessed in treated and control mice. In vitro cell proliferation was evaluated using the WST-1 reagent and apoptosis and necrosis by flow cytometry analysis.

Results

NFV, IDV, AZT and DDI caused significant reductions in duodenal and in jejunal villus length (p < 0.05). IDV and AZT increased crypt depth in the duodenum and AZT increased crypt depth in the jejunum. NFV, AZT and DDI significantly decreased ileal crypt depth. All selected antiretroviral drugs significantly increased net water secretion and electrolyte secretion, except for DDI, which did not alter water or chloride secretion. Additionally, only NFV significantly increased mannitol and lactulose absorption. NFV and IDV caused a significant reduction in cell proliferation in vitro at both 24 h and 48 h. DDI and AZT did not alter cell proliferation. There was a significant increase in apoptosis rates in IEC-6 cells after 24 h with 70 ug/mL of NFV (control: 4.7% vs NFV: 22%) while IDV, AZT and DDI did not show any significant changes in apoptosis compared to the control group. In jejunal sections, IDV and NFV significantly increased the number of TUNEL positive cells.

Conclusion

The PI's, NFV and IDV, increased cell apoptosis in vivo, water and electrolyte secretion and intestinal permeability and decreased villus length and cell proliferation. NFV was the only drug tested that increased cell apoptosis in vitro. The nucleoside reverse transcriptase inhibitors, AZT and DDI, did not affect cell apoptosis or proliferation. These findings may partly explain the intestinal side-effects associated with PI's.

Prevention of diarrhoea in children with HIV infection or exposure to maternal HIV infection

BACKGROUND

Diarrhoea is a major cause of morbidity and mortality among infants and children worldwide, especially in low- and middle-income countries. Human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) is a condition that similarly disproportionately affects low- and middle-income countries; of the nearly 2.1 million children under age 15 years living with HIV/AIDS, the large majority reside in sub-Saharan Africa. Infants and children with HIV infection have more frequent and more severe diarrhoea than children without HIV. Interventions including vitamin A, zinc and cotrimoxazole may contribute substantially to preventing diarrhoea in children with HIV infection or exposure to HIV.

OBJECTIVES

We perform a systematic review of randomised controlled trials and nonrandomised studies that examine the effectiveness of vitamin A, zinc and cotrimoxazole on mortality and morbidity from diarrhoea in HIV-infected and -exposed infants and children.

SEARCH STRATEGY

Electronic databases including Pubmed, Central and EMBASE were searched without limits to language from 1980 to April 2010. Conference database searches were performed, experts were contacted and bibliographies were handsearched.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and nonrandomised studies (NRSs) that examined the effectiveness of the three interventions were included.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed citations for eligibility and double-extracted included studies. Assessment of bias of individual studies was performed independently by both reviewers. Only two summary estimates were performed due to heterogeneity in study design and interventions.

MAIN RESULTS

Four RCTs were identified for vitamin A. One RCT was identified for zinc. One RCT and two NRSs were identified for cotrimoxazole. Vitamin A reduced mortality overall in children with HIV infection (four studies). A pooled estimate of three studies for reduction in mortality from vitamin A compared to placebo had a relative risk (DerSimonian and Laird method, random effects) of 0.50 (95% confidence interval (CI): 0.31 to 0.79) in 267 patients. Diarrheoa-specific mortality did not reach statistical significance and diarrhoeal morbidity outcomes were variable in three trials. Zinc supplementation reduced the number of physician visits for watery diarrhoea in one trial. Cotrimoxazole reduced mortality and hospitalisations compared to placebo in one RCT, although diarrhoea-specific morbidities were not significant.

AUTHORS' CONCLUSIONS

Vitamin A shows benefits in reduction of mortality in HIV-infected children. The effect of vitamin A on children with HIV exposure is not clear and needs further review. Zinc and combination vitamin A, zinc and micronutrient supplementation did not show an effect compared to vitamin A alone in children with HIV infection. Cotrimoxazole reduced mortality and some morbidity in children with HIV infection. Further research may clarify the effects of these interventions on morbidity from diarrhoea and in the population of children with HIV exposure.

Estimating the burden of disease attributable to four selected environmental risk factors in South Africa

INTRODUCTION

The first South African National Burden of Disease study quantified the underlying causes of premature mortality and morbidity experienced in South Africa in the year 2000. This was followed by a Comparative Risk Assessment to estimate the contributions of 17 selected risk factors to burden of disease in South Africa. This paper describes the health impact of exposure to four selected environmental risk factors: unsafe water, sanitation and hygiene; indoor air pollution from household use of solid fuels; urban outdoor air pollution and lead exposure.

METHODS

The study followed World Health Organization comparative risk assessment methodology. Population-attributable fractions were calculated and applied to revised burden of disease estimates (deaths and disability adjusted life years, [DALYs]) from the South African Burden of Disease study to obtain the attributable burden for each selected risk factor. The burden attributable to the joint effect of the four environmental risk factors was also estimated taking into account competing risks and common pathways. Monte Carlo simulation-modeling techniques were used to quantify sampling, uncertainty.

RESULTS

Almost 24 000 deaths were attributable to the joint effect of these four environmental risk factors, accounting for 4.6% (95% uncertainty interval 3.8-5.3%) of all deaths in South Africa in 2000. Overall the burden due to these environmental risks was equivalent to 3.7% (95% uncertainty interval 3.4-4.0%) of the total disease burden for South Africa, with unsafe water sanitation and hygiene the main contributor to joint burden. The joint attributable burden was especially high in children under 5 years of age, accounting for 10.8% of total deaths in this age group and 9.7% of burden of disease.

CONCLUSION

This study highlights the public health impact of exposure to environmental risks and the significant burden of preventable disease attributable to exposure to these four major environmental risk factors in South Africa. Evidence-based policies and programs must be developed and implemented to address these risk factors at individual, household, and community levels.

Diarrhea in children less than two years of age with known HIV status in Kisumu, Kenya

OBJECTIVE

To compare the frequency and etiology of diarrhea in children aged less than 2 years with known HIV status.

METHODS

This was a nested cohort study, whereby children were followed during monthly routine and unscheduled visits. The HIV status of children was determined with PCR. A stool culture was obtained from children with diarrhea. A subset of stool samples was examined for parasites and tested for rotavirus.

RESULTS

Between 1997 and 2001, 682 children (51.0% male) contributed observation periods with a mean of 47 weeks. Overall there were 198 episodes of diarrhea per 100 child-years of observation (CYO); diarrhea was more common among HIV-positive children than among HIV-negative children (321 vs. 183 episodes/100 CYO, respectively, p<0.01) and was not statistically different for HIV-negative children born to HIV-positive compared with HIV-negative mothers (182 vs. 187 episodes/100 CYO, respectively, p=0.36). For 66.5% of the acute episodes a stool culture was obtained; 27.8% of stool cultures yielded a bacterial pathogen. A positive stool culture was less likely among HIV-positive children compared to children of HIV-negative mothers (20.5% vs. 34.3%, p=0.01). Susceptibility of Salmonella and Shigella to commonly used antibiotics was low. Rotavirus was detected in 13.9% of 202 examined stool samples, and a stool parasite in 3.8% of 394 samples. Diarrhea was associated with 37.8% of child deaths.

CONCLUSIONS

Diarrhea was more common among HIV-infected children, but was not associated with specific bacterial pathogens. Measures that reduce diarrhea will benefit all children, but may benefit HIV-infected children in particular.

Patterns of postnatal growth in HIV-infected and HIV-exposed children

HIV infection can contribute to disturbances in both linear growth and weight gain in early childhood, with disturbances often apparent as early as 3 months of age. There is little evidence for a difference in the early growth of HIV-exposed but uninfected children compared to healthy controls. Owing to the close association of growth with immune function and clinical progression, an understanding of growth patterns may be an important tool to ensure the provision of appropriate care to HIV-infected and exposed children. Timely growth monitoring may be used to improve the clinical course and quality of life of these children.

Effect of pre-existing malnutrition on growth parameters in HIV-infected children commencing antiretroviral therapy

BACKGROUND

Growth in HIV-infected children generally improves with antiretroviral therapy (ART). Little is known about the effect of pre-existing malnutrition on response to treatment.

AIM

To evaluate prospectively the effect of pre-existing malnutrition on growth of HIV-infected children commenced on ART compared with those without pre-existing malnutrition.

METHODS

Inclusion criteria were children (2 months to 8.5 years) who were commenced on ART. Exclusion criteria were pre-treatment with ART, virological non-responders and co-existing tuberculous infection. Weight-for-age (WAZ) and height-for-age Z scores (HAZ) < or =-2 at the initiation of treatment were the criteria for malnutrition. Monthly height and weight measurements were made for 18 months (2007-2008) after initiation of ART. Z scores were used to express changes in standard deviation (SD) units for each of the children at 0 and 18 months of the study using WHO height and weight reference curves for age and gender. The changes in Z score were compared within the groups by paired t-test and in both groups by the Mann-Whitney U test.

RESULTS

The subjects were grouped as malnourished (G1) and not malnourished (G2) before initiation of treatment. There was a significant increase in HAZ score (mean -0.15, p=0.006) and WAZ score (mean -0.09, p=0.034) in G1 and also HAZ score (mean -0.29, p<0.001) and WAZ score (mean -0.30, p=0.001) in G2. There was a trend toward a significantly greater Z-score change in G2 than in G1 for height (p=0.027) and weight (p=0.046).

CONCLUSION

In HIV-infected children, pre-existing malnutrition may impair nutritional response to ART.

Novel non-active site inhibitor of Cryptosporidium hominis TS-DHFR identified by a virtual screen

The essential enzyme thymidylate synthase-dihydrofolate reductase (TS-DHFR) is a validated drug target for many pathogens, but has been elusive in Cryptosporidium hominis, as active site inhibitors of the enzymes from related parasitic protozoa show decreased potency and lack of species specificity over the human enzymes. As a rational approach to discover novel inhibitors, we conducted a virtual screen of a non-active site pocket in the DHFR linker region. From this screen, we have identified and characterized a noncompetitive inhibitor, flavin mononucleotide (FMN), with micromolar potency that is selective for ChTS-DHFR versus the human enzymes. These results describe a novel allosteric pocket amenable to inhibitor targeting, and a lead compound with which to move towards potent, selective inhibitors of ChTS-DHFR.

Antimotility agents for chronic diarrhoea in people with HIV/AIDS

BACKGROUND

AIDS-related diarrhoea is a common cause of morbidity and mortality in HIV positive individuals, especially in the sub-Saharan Africa where 70% of deaths from HIV occur. It often compromises quality of life both in those receiving antiretroviral therapy (ART) and the ART naive. Empirical antidiarrhoeal treatment may be required in about 50% of cases which are non-pathogenic or idiopathic and in cases resulting from antiretroviral therapy. Antimotility agents (Loperamide, Diphenoxylate, Codeine) and adsorbents (Bismuth Subsalicylate, Kaolin/Pectin, Attapulgite) are readily available, and have been found to be useful in this condition and so, are often used. Antimotilitics are opioids, decreasing stool output by reducing bowel activity thereby increasing fecal transit time in the gut, promoting fluid and electrolyte retention while adsorbents act by binding to fluids, toxins and other substances to improve stool consistency and eliminate the toxins. Due to its potential impact on the management of chronic diarrhoea in persons with HIV/AIDS, we reviewed the effectiveness of antimotility agents in controlling chronic diarrhoea in immunocompromised states caused by HIV/AIDS.

OBJECTIVES

To assess the effectiveness of antimotility agents in controlling chronic diarrhoea in people with HIV/AIDS.

SEARCH STRATEGY

We searched Medline, EMBASE, the Cochrane Controlled Trials Register, the Cochrane HIV/AIDS Register and AIDSearch databases in November 2006. We also contacted WHO, CDC, pharmaceutical companies and experts in the field for information on previous or on-going trials and checked reference list from retrieved studies, irrespective of language and publication status.

SELECTION CRITERIA

Randomised controlled trials comparing an antimotility agent or an adsorbent with another antimotility agent, placebo, an adsorbent or no treatment in children and adults diagnosed with HIV and presenting with diarrhoea of three or more weeks duration.

DATA COLLECTION AND ANALYSIS

Two authors independently undertook study selection and examined full articles of potentially eligible studies.

MAIN RESULTS

One trial was found assessing the use of an adsorbent (attapulgite) compared to a placebo for chronic diarrhoea in people with HIV/AIDS. It included 91 adults (Aged 18 to 60), diagnosed with AIDS and experiencing diarrhoea for at least 7 days. There was no evidence that attapulgite is superior to placebo in controlling diarrhoea by reducing stool frequency and normalising stool consistency on days 1 (0.34 (95% CI 0.01 - 8.15)), 3 (1.35 (95% CI 0.51 - 3.62)) and 5 (1.74 (95% CI 0.89 - 3.38)). This was a small trial and may not have had enough power to show evidence of effects. Five deaths were reported which was not classified according to the arms of the study.Studies assessing the use of antimotility agents were not found.

AUTHORS' CONCLUSIONS

This review highlights the absence of evidence for the use of antimotility agents and adsorbents in controlling diarrhoea in people with HIV/AIDS. While no trials assessing the use of Antimotilitics were found, the retrieved study showed that attapulgite was not better than placebo in controlling diarrhoea in HIV/AIDS patients . For optimum patient care, these agents can still be used, with greater emphasis placed on adjunct therapies like massive fluid replacement while evidence for practice is awaited from further studies and reviews.

CCAAT/enhancer binding protein beta is a major mediator of inflammation and viral replication in the gastrointestinal tract of simian immunodeficiency virus-infected rhesus macaques

The gastrointestinal tract (GIT) is a major target of infection with human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV). Chronic GIT disease and inflammation are common sequelae to HIV/SIV infection. Nonetheless, the molecular mechanisms that cause and maintain GIT dysfunction remain unclear. We investigated the contribution of CCAAT/enhancer-binding protein beta (C/EBPbeta) to GIT disease and viral replication in jejunum and colon collected at necropsy from 12 SIV-infected (group 1), or 10 uninfected macaques with chronic diarrhea (group 2), and 9 uninfected control macaques (group 3). All group 1 and 2 macaques had chronic diarrhea, wasting, and colitis, but group 1 animals had more severe lesions in the jejunum. C/EBPbeta gene expression increased significantly in colon of groups 1 and 2 and in jejunum of only group 1 macaques compared with controls. In group 1 animals, CEBPbeta expression was localized predominantly to macrophages and occasionally lymphocytes. Chromatin immunoprecipitation assays confirmed the binding of C/EBPbeta and p65 to the SIV long terminal repeat region in colonic lamina propria cells, suggesting a mechanistic link between inflammation and activation of viral replication in vivo. This is the first in vivo study describing the transcriptional changes and immunophenotypic localization of C/EBPbeta in the GIT of SIV-infected macaques. More importantly, these data provide a molecular mechanism for persistent inflammation and immune activation leading to increased SIV burden and GIT pathology in SIV-infected macaques and perhaps HIV-infected individuals.

Gastrointestinal disease in simian immunodeficiency virus-infected rhesus macaques is characterized by proinflammatory dysregulation of the interleukin-6-Janus kinase/signal transducer and activator of transcription3 pathway

Gastrointestinal disease and inflammation are common sequelae of human and simian immunodeficiency virus (SIV) infection. Nevertheless, the molecular mechanisms that lead to gastrointestinal dysfunction remain unclear. We investigated regulation of the interleukin (IL)-6-JAK-STAT3 pathway in jejunum and colon, collected at necropsy, from 10 SIV-infected macaques with diarrhea (group 1), 10 non-SIV-infected macaques with diarrhea (group 2), and 7 control uninfected macaques (group 3). All group 1 and 2 macaques had chronic diarrhea, wasting, and colitis, but group 1 animals had more frequent and severe lesions in the jejunum. A significant increase in IL-6 and SOCS-3 gene expression along with constitutive STAT3 activation was observed in the colon of all group 1 and 2 macaques and in the jejunum of only group 1 macaques compared to controls. Further, in colon, histopathology severity scores correlated significantly with IL-6 (groups 1 and 2) and SOCS-3 (group 2) gene expression. In jejunum, a similar correlation was observed only in group 1 animals. Phosphorylated STAT3 (p-STAT3) was localized to lymphocytes (CD3+) and macrophages (CD68+), with fewer CD3+ lymphocytes expressing p-STAT3 in group 1 macaques. Despite high SOCS-3 expression, STAT3 remained constitutively active, providing a possible explanation for persistent intestinal inflammation and immune activation that may favor viral replication and disease pro-gression.

Inhibitory effect of HIV-1 Tat protein on the sodium-D-glucose symporter of human intestinal epithelial cells

OBJECTIVE

The pathophysiology of HIV-1-related intestinal dysfunction is largely unknown. We previously found that the transactivator factor peptide (Tat) produced by HIV-1 induces ion secretion and inhibits cell proliferation in human enterocytes. Because sugar malabsorption is a frequent feature in AIDS patients, we evaluated whether Tat inhibits intestinal glucose absorption.

DESIGN AND METHODS

We measured Na-D-glucose symporter (SGLT-1) activity and determined its phenotypic expression in Caco-2 cells, in the presence and absence of Tat, in uptake experiments using a non-metabolized radiolabelled glucose analogue, and by western blot analysis, respectively. alpha-Tubulin staining was used to study the effects exerted by Tat on cell structure.

RESULTS

Tat dose dependently inhibited glucose uptake by human enterocytes. This effect was prevented by anti-Tat polyclonal antibodies and by L-type Ca channels agonist Bay K8644. Western blot analysis of cellular lysates and brush-border membrane preparations showed that Tat induced SGLT-1 missorting. Tat also caused a dramatic decrease in alpha-tubulin staining, which indicates dysruption of the cytoskeleton organization.

CONCLUSIONS

Tat acutely impairs intestinal glucose absorption through SGLT-1 missorting. This result indicates that Tat is directly involved in AIDS-associated intestinal dysfunction.

Gastrointestinal parasites in the immunocompromised

PURPOSE OF REVIEW

Parasites and other infections have many effects on the gastrointestinal tract of individuals who are immunocompromised. Few reviews focus on parasitic infections, which are covered here.

RECENT FINDINGS

The review first examines recent advances in our understanding of the taxonomy, diagnosis and treatment of pathogens such as cryptosporidia, cyclospora, isospora and microsporidia, which are recognized causes of diarrhoea in the immunocompromised, and discusses possible links between amoebiasis and HIV. The complex interactions of both intact and abnormal immune systems with helminth infections such as hookworm and strongyloidiasis, and with trematode infections such as schistosomiasis, are receiving increasing attention. These are discussed, together with the novel concept of using live helminths to treat inflammatory bowel disease.

SUMMARY

Parasitic infections remain a significant problem for immunocompromised individuals in resource-poor settings, and further work is needed to develop accessible diagnostic tests and to improve our understanding and management of their pathogenic effects. New concepts about the interactions of helminths with host immunity suggest the need for collection of further epidemiological and clinical data to unravel the complexities of such immunological interactions.