Continuation of emtricitabine/lamivudine within combination antiretroviral therapy following detection of the M184V/I HIV-1 resistance mutation

OBJECTIVES

The aim of the study was to investigate whether lamivudine (3TC) or emtricitabine (FTC) use following detection of M184V/I is associated with better virological outcomes.

METHODS

We identified people with viruses harbouring the M184V/I mutation in UK multicentre data sets who had treatment change/initiation within 1 year. We analysed outcomes of viral suppression (< 200 HIV-1 RNA copies/mL) and appearance of new major drug resistance mutations (DRMs) using Cox and Poisson models, with stratification by new drug regimen (excluding 3TC/FTC) and Bayesian implementation, and estimated the effect of 3TC/FTC adjusted for individual and viral characteristics.

RESULTS

We included 2597 people with the M184V/I resistance mutation, of whom 665 (25.6%) were on 3TC and 458 (17.6%) on FTC. We found a negative adjusted association between 3TC/FTC use and viral suppression [hazard ratio (HR) 0.84; 95% credibility interval (CrI) 0.71-0.98]. On subgroup analysis of individual drugs, there was no evidence of an association with viral suppression for 3TC (n = 184; HR 0.94; 95% CrI 0.73-1.15) or FTC (n = 454; HR 0.99; 95% CrI 0.80-1.19) amongst those on tenofovir-containing regimens, but we estimated a reduced rate of viral suppression for people on 3TC amongst those without tenofovir use (n = 481; HR 0.71; 95% CrI 0.54-0.90). We found no association between 3TC/FTC and detection of any new DRM (overall HR 0.92; 95% CrI 0.64-1.18), but found inconclusive evidence of a lower incidence rate of new DRMs (overall incidence rate ratio 0.69; 95% CrI 0.34-1.11).

CONCLUSIONS

We did not find evidence that 3TC or FTC use is associated with an increase in viral suppression, but it may reduce the appearance of additional DRMs in people with M184V/I. 3TC was associated with reduced viral suppression amongst people on regimens without tenofovir.

HIV self-testing intervention experiences and kit usability: results from a qualitative study among men who have sex with men in the SELPHI (Self-Testing Public Health Intervention) randomized controlled trial in England and Wales

Objectives

SELPHI (HIV Self‐Testing Public Health Intervention) is the largest randomized controlled trial (RCT) of HIV self‐testing (HIVST) in a high‐income setting to date, and has recruited 10 000 men who have sex with men (cis‐ and transgender) and transgender women who have sex with men. This qualitative substudy aimed to explore how those utilizing self‐tests experience HIVST and the implications for further intervention development and scale‐up. This is the first qualitative study in Europe investigating experiences of HIVST among intervention users, and the first globally examining the experience of using blood‐based HIVST.

Methods

Thirty‐seven cisgender MSM SELPHI participants from across England and Wales were purposively recruited to the substudy, in which semi‐structured interviews were used to explore testing history, HIVST experiences and intervention preferences. Interviews were audio‐recorded, transcribed and analysed through a framework analysis.

Results

Men accessed the intervention because HIVST reduced barriers related to convenience, stigma and privacy concerns. Emotional responses had direct links to acceptability. Supportive intervention components increased engagement with testing and addressed supportive concerns. HIVST facilitated more frequent testing, with the potential to reduce sexually transmitted infection (STI) screening frequency. Substudy participants with an HIV‐positive result (n = 2) linked to care promptly and reported very high acceptability. Minor adverse outcomes (n = 2; relationship discord and fainting) did not reduce acceptability. Ease of use difficulties were with the lancet and the test processing stage.

Conclusions

Intervention components shaped acceptability, particularly in relation to overcoming a perceived lack of support. The intervention was broadly acceptable and usable; participants expressed an unexpected degree of enthusiasm for HIVST, including those with HIV‐positive results and individuals with minor adverse outcomes.

Phenotypic and genotypic analyses to guide selection of reverse transcriptase inhibitors in second-line HIV therapy following extended virological failure in Uganda

Objectives

We investigated phenotypic and genotypic resistance after 2 years of first-line therapy with two HIV treatment regimens in the absence of virological monitoring.

Methods

NORA [Nevirapine OR Abacavir study, a sub-study of the Development of AntiRetroviral Therapy in Africa (DART) trial] randomized 600 symptomatic HIV-infected Ugandan adults (CD4 cell count <200 cells/mm³) to receive zidovudine/lamivudine plus abacavir (cABC arm) or nevirapine (cNVP arm). All virological tests were performed retrospectively, including resistance tests on week 96 plasma samples with HIV RNA levels ≥1000 copies/mL. Phenotypic resistance was expressed as fold-change in IC₅₀ (FC) relative to wild-type virus.

Results

HIV-1 RNA viral load ≥1000 copies/mL at week 96 was seen in 58/204 (28.4%) cABC participants and 21/159 (13.2%) cNVP participants. Resistance results were available in 35 cABC and 17 cNVP participants; 31 (89%) cABC and 16 (94%) cNVP isolates had a week 96 FC below the biological cut-off for tenofovir (2.2). In the cNVP arm, 16/17 participants had resistance mutations synonymous with high-level resistance to nevirapine and efavirenz; FC values for etravirine were above the biological cut-off in 9 (53%) isolates. In multivariate regression models, K65R, Y115F and the presence of thymidine analogue-associated mutations were associated with increased susceptibility to etravirine in the cABC arm.

Conclusions

Our data support the use of tenofovir following failure of a first-line zidovudine-containing regimen and shed further light on non-nucleoside reverse transcriptase inhibitor hypersusceptibility.

Modelling the association between patient characteristics and the change over time in a disease measure using observational cohort data

In observational cohort studies we may wish to examine the associations between fixed patient characteristics and the longitudinal changes from baseline in a repeated outcome measure. Many biological and other outcome measures are known to be subject to measurement error and biological variation. In an initial analysis we may fit a regression model to all outcome measurements, accounting for all the identified sources of variability, and see how the characteristics are linked to the change for typical patients. However, the characteristics may also be linked to different distributions of the underlying outcome value at baseline, which itself may be correlated with the change over time. Therefore, if we wish to examine the change over time for patients of different characteristics but with the same underlying baseline value then the initial approach is confounded by the baseline values. Furthermore, if we attempt to remove this confounding by including the observed baseline measure as a covariate in a model for later measurements, then this may provide an approximate solution but is likely to introduce some bias. We propose a method based on first following the initial approach but then, applying a correction to the parameter estimates. This allows the predicted trajectories to be plotted and valid significance tests of association with characteristics. Our approach is compared with other methods and illustrated through a simulation study and an analysis of the association between HIV-1 subtype and immunological response after starting antiretroviral therapy.

Patterns and predictors of the use of different antiretroviral drug regimens at treatment initiation in the UK

BACKGROUND

We describe the patterns of antiretroviral drug use at treatment initiation from 1996 to 2005 in a large UK multicentre cohort.

METHODS

We examined trends over time and across 10 clinical sites in stage of disease and type of antiretroviral therapy (ART). Multivariable regression was used to identify factors associated with the CD4 cell count at ART initiation, and with the choice of a protease inhibitor (PI) over a nonnucleoside reverse transcriptase inhibitor (NNRTI), and use of nevirapine over efavirenz.

RESULTS

A total of 14 252 patients initiated ART, of whom 54% had a CD4 count <200 cells/microL. The most important predictors of starting ART at a lower CD4 cell count were being male, nonwhite, and heterosexual or an injecting drug user (P<0.0001). Among those starting ART, the use of highly active ART increased from 23% in 1996 to >96% from 2000 onwards. There were differences over time and across the clinics in the use of PIs vs. NNRTIs, in the choice of specific PIs, NNRTIs and nucleoside reverse transcriptase inhibitor (NRTI) backbone, and in the rate at which prescribing practices changed.

CONCLUSIONS

Clinic site and calendar year were important determinants of choice of drug at ART initiation, whereas clinical and demographic characteristics were more important in influencing the CD4 cell count at initiation of ART.

Emergence of the H208Y mutation in the reverse transcriptase (RT) of HIV-1 in association with nucleoside RT inhibitor therapy

OBJECTIVES

The aim of the study was to determine whether mutations at RT codon 208 are associated with nucleoside RT inhibitor (NRTI) exposure, NRTI resistance patterns and HIV-1 subtype.

METHODS

Six thousand three hundred and fifty two genotypic resistance tests linked to a clinical database were analysed.

RESULTS

The prevalence of mutations at codon 208 was 6/2347 (0.3%) in treatment-naive and 165/4005 (4.1%) in treatment-experienced persons. H208Y was the most common mutation in both groups (0.2% and 3.8%, respectively) and occurred in 4.5% of treatment-experienced persons with Subtype B, 1.7% of those with Subtype C and 0.7% of those with other non-B subtypes (P=0.001). The association with subtypes was independent of treatment experience. H208Y showed a strong association with NRTI experience, which persisted after adjusting for subtype [odds ratio (OR) 19.34; 95% confidence interval (CI) 7.87-47.54; P=0.0001]. The prevalence of H208Y was highest in genotypes harbouring M184V and the thymidine analogue mutations (TAMs) M41L, D67N, L210W and T215Y. The median number of TAMs was 4 and 0 in genotypes with and without H208Y, respectively (P=0.0001). The prevalence of H208Y declined over time, being highest in 1998 (9.9%) and lowest in 2003 (0.9%) (P=0.0001).

CONCLUSIONS

There is a strong association between H208Y and NRTI experience, particularly in persons with Subtype B harbouring multiple NRTI resistance mutations. These findings indicate an accessory role for H208Y in NRTI resistance.

A randomized controlled trial of the value of phenotypic testing in addition to genotypic testing for HIV drug resistance: evaluation of resistance assays (ERA) trial investigators

OBJECTIVES

To assess the clinical utility of phenotypic resistance testing in addition to genotypic resistance testing among HIV-1-infected patients experiencing virologic failure and with limited therapeutic options.

DESIGN

Multicenter randomized trial.

METHODS

Patients were eligible if a decision had been made to switch antiretroviral therapy, the most recent HIV-1 RNA plasma viral load (VL) exceeded 2000 copies/mL, and the clinician was unable to select a potent regimen of 3 or more drugs without access to a resistance test. Subjects were randomized to genotypic resistance testing alone (G arm) or to genotypic plus phenotypic testing (G + P arm). Patients had access to resistance testing at any time during follow-up (minimum of 1 year) according to the original allocation. The primary end point was change in plasma VL from baseline at 12 months.

RESULTS

Three hundred eleven patients were recruited between February 2000 and July 2001. At baseline, mean VL and CD4 count were 4.23 log10 copies/mL and 275 cells/mm, respectively, and subjects had previous exposure to a mean of 7.7 antiretroviral drugs. There was no appreciable difference between the study arms in the drug regimens prescribed after randomization. Mean reduction in VL load at 12 months was similar in the 2 arms (G: 1.37 log10 reduction, G + P: 1.28 log10 reduction; P = 0.77), as was the proportion of subjects with VL <50 copies/mL (G: 35%, G + P: 27%).

CONCLUSION

The study did not demonstrate added value of phenotypic resistance testing in conjunction with genotypic resistance testing in patients with limited therapeutic options.

A prospective multicentre study of discontinuing prophylaxis for opportunistic infections after effective antiretroviral therapy

OBJECTIVE

To assess the medium-term safety of discontinuing prophylaxis (primary or secondary) for opportunistic infections following an effective response to antiretroviral therapy.

METHODS

Participating clinical sites prospectively identified patients in whom the discontinuation of prophylaxis for any opportunistic infection was considered to be clinically indicated, although CD4 levels were not predefined. A follow-up report was subsequently sent every 6 months requesting information on changes in prophylaxis, antiretroviral drugs, new AIDS-defining events, and CD4 cell count results.

RESULTS

Prophylaxis for Pneumocystis carinii pneumonia (PCP) was withdrawn in 524 patients (426 primary and 98 secondary prophylaxis), prophylaxis for Mycobacterium avium complex (MAC) was withdrawn in 28 patients (13 primary and 15 secondary), and prophylaxis for cytomegalovirus (CMV) retinitis was withdrawn in 10 patients. CD4 counts were generally maintained above accepted prophylaxis threshold levels during the period of follow up (95-98% of the time). Total follow up to last report or re-continuation of prophylaxis was 680 and 144 person-years for patients discontinuing primary and secondary PCP prophylaxis, respectively. No cases of PCP were reported, giving incidence rates of 0.0 (upper 95% confidence limit 0.4) and 0.0 (2.1) per 100 person-years. No cases of MAC were reported, but one patient had a recurrence of CMV retinitis. PCP prophylaxis was restarted in 30 patients; no patients restarted MAC or CMV prophylaxis.

CONCLUSIONS

Previous studies have demonstrated a low risk of PCP in the short term following the withdrawal of prophylaxis in patients who have responded well to antiretroviral therapy. The present study suggests a continuing low level of risk with extended follow up, provided adequate CD4 count levels are maintained. The case of recurrent CMV retinitis in a patient with impressive immunological and virological response indicates the need for close monitoring of patients previously diagnosed with this condition.

Decline in mortality, AIDS, and hospital admissions in perinatally HIV-1 infected children in the United Kingdom and Ireland

OBJECTIVE

To describe changes in demographic factors, disease progression, hospital admissions, and use of antiretroviral therapy in children with HIV.

DESIGN

Active surveillance through the national study of HIV in pregnancy and childhood (NSHPC) and additional data from a subset of children in the collaborative HIV paediatric study (CHIPS).

SETTING

United Kingdom and Ireland.

PARTICIPANTS

944 children with perinatally acquired HIV-1 under clinical care.

MAIN OUTCOME MEASURES

Changes over time in progression to AIDS and death, hospital admission rates, and use of antiretroviral therapy.

RESULTS

944 children with perinatally acquired HIV were reported in the United Kingdom and Ireland by October 2002; 628 (67%) were black African, 205 (22%) were aged > or = 10 years at last follow up, 193 (20%) are known to have died. The proportion of children presenting who were born abroad increased from 20% in 1994-5 to 60% during 2000-2. Mortality was stable before 1997 at 9.3 per 100 child years at risk but fell to 2.0 in 2001-2 (trend P < 0.001). Progression to AIDS also declined (P < 0.001). From 1997 onwards the proportion of children on three or four drug antiretroviral therapy increased. Hospital admission rates declined by 80%, but with more children in follow up the absolute number of admissions fell by only 26%.

CONCLUSION

In children with HIV infection, mortality, AIDS, and hospital admission rates have declined substantially since the introduction of three or four drug antiretroviral therapy in 1997. As infected children in the United Kingdom and Ireland are living longer, there is an increasing need to address their medical, social, and psychological needs as they enter adolescence and adult life.

Observations of HIV-1 Genotypic Drug Resistance in a Trial of Four Reverse Transcriptase Inhibitors (Quattro Trial)

The Quattro Trial compared the use of four HIV-1 reverse transcriptase (RT) inhibitors (zidovudine, lamivudine, loviride and zalcitabine), given either as four-drug combination therapy or monotherapy, with 8-week cycles of each drug, with zidovudine/lamivudine dual therapy. Observations of resistance associated and other mutations in the RT gene were made to determine whether therapy failure could be explained by acquisition of these mutations and whether novel mutation patterns developed. As in the intent-to-treat analysis, the use of cyclical monotherapy gave a smaller reduction in plasma virus load at 64 weeks (0.4 log10 copies/ml below baseline) than the quadruple or dual therapy arms (1.3 and 0.8 log10 copies/ml below baseline). Cyclical therapy appeared to generate less genotypic resistance to zidovudine, loviride or zalcitabine than the other arms. Resistance to lamivudine (mutation M184V) developed rapidly in all three arms. Resistance to zidovudine was acquired by a larger proportion of subjects on dual therapy than on quadruple therapy. Resistance to loviride or zalcitabine was rarely observed. During lamivudine monotherapy the M184V mutation was rapidly acquired and viral load rebounded. Zalcitabine monotherapy initially selected M184V mutants, but these were lost as therapy continued. Novel mutations that may have been associated with combination or cyclical quadruple therapy were observed infrequently. There was no clear correlation between changes in response to therapy and the development of previously described resistance mutations or with novel mutations in the RT gene.

Effect of prenatal treatment on the risk of intracranial and ocular lesions in children with congenital toxoplasmosis

BACKGROUND

Hydrocephalus, intracranial calcification and retinochoroiditis are the most common manifestations of tissue damage due to congenital toxoplasmosis, but the effect of prenatal treatment on these outcomes is unclear. We aimed to determine the effect of prenatal treatment for toxoplasmosis on the risk of intracranial and ocular lesions in congenitally infected children at 3 years of age.

METHODS

A cohort of mothers identified during pregnancy with toxoplasma infection and their 181 liveborn children with confirmed congenital toxoplasmosis was retrospectively analysed to determine the presence of intracranial and ocular lesions. As few women are not treated, we compared the effects of the treatment potency (pyrimethamine-sulfadiazine versus spiramycin or no treatment), and the timing of treatment, on the risks of intracranial lesions, time to detection of ocular lesions, and detection of any lesions (intracranial or ocular) by 3 years of age. Analyses took account of the gestation at maternal seroconversion.

RESULTS

There was no evidence for an effect of pyrimethamine-sulfadiazine on intracranial, ocular or any lesions by 3 years: odds ratio (OR) for any lesions 0.89 (95% CI : 0.41, 1.88). There was no evidence of an effect of delayed treatment on ocular lesions (hazard ratio = 0.69, 95% CI : 0.28, 1.68) or any lesions by 3 years of age (OR = 0.44, 95% CI : 0.16, 1.19).

CONCLUSIONS

Our study failed to detect a beneficial effect of early or more potent anti toxoplasma treatment on the risks of intracranial or ocular lesions in children with congenital toxoplasmosis. However, larger, prospective studies, which determine the effect of prenatal treatment on long-term developmental outcomes are required to justify changes in clinical practice.

Effect of prenatal treatment on mother to child transmission of Toxoplasma gondii: retrospective cohort study of 554 mother-child pairs in Lyon, France

BACKGROUND

The aim of prenatal serological screening for toxoplasmosis is to identify and treat maternal infection as soon as possible in order to prevent transmission of the parasite to the fetus. However, despite widespread provision of prenatal toxoplasma screening across Europe, the effectiveness of prenatal treatment is uncertain. The study aimed to determine the effect of the timing and type of prenatal treatment on mother to child transmission of Toxoplasma gondii.

METHOD

A cohort of 554 infected pregnant women were identified in Lyon, France between 1987 and 1995 and their children were followed to determine congenital infection status. We determined the effect of prenatal treatment on transmission by examining the effect of the delay between maternal seroconversion and start of treatment. We also compared the effect of the type of treatment and no treatment on the risk of mother to child transmission. Analyses were adjusted for gestation at maternal seroconversion.

RESULTS

Compared to treatment within 4 weeks from seroconversion, the adjusted odds ratios (OR) for mother to child transmission after a treatment delay of 4-7 weeks was 1.29 (95% CI : 0.61, 2.73) and after more than 8 weeks, 1.44 (95% CI : 0.60, 3.31). The adjusted OR associated with spiramycin alone compared with pyrimethamine-sulfadiazine treatment was 0.91 (95% CI : 0.45, 1.84) and the OR for no treatment compared with pyrimethamine-sulfadiazine treatment was 1.06 (95% CI : 0.37, 3.03).

CONCLUSIONS

The authors hypothesize that the absence of an effect of prenatal treatment is due to transmission before the start of treatment.

Timing and interpretation of tests for diagnosing perinatally acquired hepatitis C virus infection

The diagnosis of hepatitis C virus (HCV) infection in children born to HCV-infected women is based on serologic assays and HCV RNA measurement by PCR. Interpretation of the results of these tests is hampered by uncertainty about the age distribution of loss of maternal antibody and the sensitivity and specificity of PCR at different ages. On the basis of findings from a recent vertical transmission study, we estimated the posttest probability of a child's being infected or uninfected under several test result scenarios. These estimates may assist clinicians in assessing the likelihood of infection in an individual child and in using the currently available assays cost effectively.

Mother-to-child transmission of hepatitis C virus: evidence for preventable peripartum transmission

BACKGROUND

Little information is available about the timing of mother-to-child transmission of hepatitis C virus (HCV), and no interventions to decrease transmission rates have been identified. We examined the effect of risk factors, including mode of delivery, on the vertical transmission rate.

METHODS

Data from HCV-infected women and their infants from three hospitals in Ireland and from a British Paediatric Surveillance Unit study of infants born to HCV-infected mothers were used to estimate the vertical transmission rate and risk factors for transmission. We used a probabilistic model using methods that simultaneously estimated the time to HCV-antibody loss in uninfected infants and the diagnostic accuracy of PCR tests for HCV RNA.

FINDINGS

441 mother-child pairs from the UK (227) and Ireland (214) were included. 50% of uninfected children became HCV-antibody negative by 8 months and 95% by 13 months. The estimated specificity of PCR for HCV RNA was 97% (95% CI 96-99) and was unrelated to age; sensitivity was only 22% (7-46) in the first month but rose sharply to 97% (85-100) thereafter. The vertical transmission rate was 6.7% (4.1-10.2) overall, and 3.8 times higher in HIV coinfected (n=22) than in HIV-negative women after adjustment for other factors (p=0.06). No effect of breastfeeding on transmission was observed, although only 59 women breastfed. However, delivery by elective caesarean section before membrane rupture was associated with a lower transmission risk than vaginal or emergency caesarean-section delivery (odds ratio 0 [0-0.87], p=0.04, after adjustment for other factors).

INTERPRETATION

The low sensitivity of HCV RNA soon after birth and the finding of a lower transmission rate after delivery by elective caesarean section suggest that HCV transmission occurs predominantly around the time of delivery. If the findings on elective caesarean section are confirmed in other studies, the case for antenatal HCV testing should be reconsidered.

Sources of toxoplasma infection in pregnant women: European multicentre case-control study. European Research Network on Congenital Toxoplasmosis

OBJECTIVE

To determine the odds ratio and population attributable fraction associated with food and environmental risk factors for acute toxoplasmosis in pregnancy.

DESIGN

Case-control study.

SETTING

Six large European cities.

PARTICIPANTS

Pregnant women with acute infection (cases) detected by seroconversion or positive for anti-Toxoplasma gondii IgM were compared with pregnant women seronegative for toxoplasma (controls).

MAIN OUTCOME MEASURES

Odds ratios for acute infection adjusted for confounding variables; the population attributable fraction for risk factors.

RESULTS

Risk factors most strongly predictive of acute infection in pregnant women were eating undercooked lamb, beef, or game, contact with soil, and travel outside Europe and the United States and Canada. Contact with cats was not a risk factor. Between 30% and 63% of infections in different centres were attributed to consumption of undercooked or cured meat products and 6% to 17% to soil contact.

CONCLUSIONS

Inadequately cooked or cured meat is the main risk factor for infection with toxoplasma in all centres. Preventive strategies should aim to reduce prevalence of infection in meat, improve labelling of meat according to farming and processing methods, and improve the quality and consistency of health information given to pregnant women.

Interventions to prevent vertical transmission of HIV-1: effect on viral detection rate in early infant samples

OBJECTIVE

To determine whether mode of delivery or the use of maternal or neonatal antiretroviral prophylaxis influence the age when HIV-1 can first be detected in infected infants, particularly the probability of detection at birth.

METHODS

In a collaboration between four multicentre studies, data on 422 HIV-1 infected infants who were assessed by HIV-1 DNA PCR or cell culture before 14 days of age were analysed. Weibull mixture models were used to estimate the cumulative proportion of infants with detectable levels of HIV-1 according to use of maternal/neonatal antiretroviral therapy (mainly zidovudine monotherapy) and mode of delivery.

RESULTS

HIV-1 was detected in 162 infants (38%) when they were first tested, at a median age of 2 days. At birth, it was estimated that 36% [95% confidence interval (CI), 31-41%] of infants have levels of virus that can be detected by DNA PCR or cell culture. This percentage was not associated with either mode of delivery (35% for vaginal delivery versus 40% for cesarean section delivery; P = 0.4) or the use of maternal or neonatal antiretroviral prophylaxis. Among infants with undetectable levels of HIV-1 at birth, the median time to viral detectability was estimated to be 14.8 days (95% CI, 12.9-16.8 days). This time was increased by 15% (95% CI, -11 to 48%; P = 0.3) among infants who were exposed to antiretroviral therapy postnatally compared with infants who were not exposed. No effect was observed for mode of delivery.

CONCLUSIONS

The outcome of an early virological test for HIV-1 is thought to be related directly to the timing of transmission and cesarean section delivery primarily reduces the risk of intrapartum transmission. The absence of an association between mode of delivery and viral detectability at birth was therefore unexpected. There was no evidence that foetal or neonatal exposure to prophylactic zidovudine delays substantially the diagnosis of infection, although this cannot be inferred for combination antiretroviral therapy.

Incidence of symptomatic toxoplasma eye disease: aetiology and public health implications

Ocular disease is the commonest disabling consequence of toxoplasma infection. Incidence and lifetime risk of ocular symptoms were determined by ascertaining affected patients in a population-based, active reporting study involving ophthalmologists serving a population of 7.4 million. Eighty-seven symptomatic episodes were attributed to toxoplasma infection. Bilateral visual acuity of 6/12 or less was found in seven episodes (8%) and was likely to have been transient in most cases. Black people born in West Africa had a 100-fold higher incidence of symptoms than white people born in Britain. Only two patients reported symptoms before 10 years of age. The estimated lifetime risk of symptoms in British born individuals (52% of all episodes) was 18/100000 (95% confidence interval: 10.8-25.2). The low risk and mild symptoms in an unscreened British population indicate limited potential benefits of prenatal or postnatal screening. The late age at presentation suggests a mixed aetiology of postnatally acquired and congenital infection for which primary prevention may be appropriate, particularly among West Africans.

A review of statistical methods for estimating the risk of vertical human immunodeficiency virus transmission

BACKGROUND

Estimation of the risk of vertical transmission of human immunodeficiency virus (HIV) has been complicated by the lack of a reliable diagnostic test for paediatric HIV infection.

METHODS

A literature search was conducted to identify all statistical methods that have been used to estimate HIV vertical transmission risk. Although the focus of this article is the analysis of birth cohort studies, ad hoc studies are also reviewed.

CONCLUSIONS

The standard method for estimating HIV vertical transmission risk is biased and inefficient. Various alternative analytical approaches have been proposed but all involve simplifying assumptions and some are difficult to implement. However, early diagnosis/exclusion of infection is now possible because of improvements in polymerase chain reaction technology and complex estimation methods should no longer be required. The best way to analyse studies conducted in breastfeeding populations is still unclear and deserves attention in view of the many intervention studies being planned or conducted in developing countries.

Mother-to-child transmission of HIV: implications of variation in maternal infectivity

OBJECTIVES

To examine the implications of variation in maternal infectivity on the timing of mother-to-child HIV transmission through breastfeeding.

DESIGN AND METHODS

A mathematical model of mother-to-child HIV transmission was developed that incorporates two main features: (i) the fetus/child potentially experiences a series of exposures (in utero, intrapartum, and via breastmilk) to HIV; and (ii) variation in maternal infectivity. The model was estimated from different sources of epidemiological data: a retrospective cohort study of children born to HIV-1-infected women in Sao Paulo State, Brazil, the International Registry of HIV-Exposed Twins, and the AIDS Clinical Trials Group 076 trial, which assessed the effectiveness of zidovudine in preventing mother-to-child HIV transmission.

RESULTS

Variation in maternal infectivity results in higher average risk of breastfeeding-related transmission in the early stages of breastfeeding than in the late stages, even in the absence of a direct relationship between transmission risk and the age of the child. However, the available data were unable to resolve the quantitative importance of this mechanism.

CONCLUSIONS

Our model has helped identify a previously unrecognized determinant of the timing of breastfeeding-related HIV transmission, which may have adverse implications for the effectiveness of certain interventions to reduce mother-to-child HIV transmission such as maternal antiretroviral therapy in breastfeeding populations and the early cessation of breastfeeding.

Infant feeding and risk of mother-to-child transmission of HIV-1 in São Paulo State, Brazil. São Paulo Collaborative Study for Vertical Transmission of HIV-1

Although vertical transmission of HIV-1 can occur through breast-feeding, little is known about the effect of colostrum, duration of breast-feeding, mixing feeding, and nipple pathology. We used retrospective cohort data to examine the association between breast-feeding-related factors and transmission of HIV-1 from mother to child in São Paulo State, Brazil. Information on maternal and postnatal factors was collected by medical record review and interview. Infection status was determined for 434 children by anti-HIV-1 tests performed beyond 18 months of age or diagnosis of AIDS at any age. Among 168 breast-fed children, the risk of transmission of HIV-1 was 21%, compared with 13% (p = .01) among 264 children artificially fed. Breast-feeding was independently and significantly associated with mother-to-child transmission of HIV-1 after controlling for stage of maternal HIV-1 disease (odds ratio [OR] = 2.2; 95% confidence interval [CI], 1.3-3.8). A trend was shown toward an increased risk of transmission with longer duration of breast-feeding, a history of bleeding nipples, and introduction of other liquid food before weaning, but these associations were not statistically significant. History of colostrum intake or cracked nipples without bleeding were not associated with transmission. Most of the women who breast-fed were unaware of their HIV-1 infection status at the time of delivery. Avoidance of mixed feeding and withholding of breast-feeding in the presence of bleeding nipples should be considered in further research as strategies to reduce postnatal transmission of HIV-1 in settings in which safe and sustainable alternatives for breast-feeding are not yet available.

Routine vaccination and vaccine-preventable infections in children born to human immunodeficiency virus-infected mothers. European Collaborative Study

Information on vaccinations and vaccine-preventable infections collected in a prospective study of children born to human immunodeficiency virus (HIV)-infected mothers was analysed for reports of adverse reactions and to estimate the clinical efficacy of vaccines. No vaccinated, HIV-infected child developed measles (56 child-years' follow-up), mumps (33), rubella (33) or pertussis (239), and only one adverse reaction - to Bacillus Calmette-Guerin (BCG) - was reported. These findings provide limited evidence of the safety and efficacy of routine vaccination of HIV-infected children.

Breastfeeding, genetic, obstetric and other risk factors associated with mother-to-child transmission of HIV-1 in Sao Paulo State, Brazil. Sao Paulo Collaborative Study for Vertical Transmission of HIV-1

OBJECTIVES

To evaluate the effect of maternal, obstetric, neonatal and post-natal factors on the risk of vertical transmission of HIV-1.

DESIGN

Multicentre retrospective cohort study.

SETTING

Obstetric and paediatric clinics in four cities in Sao Paulo State, Brazil.

MAIN OUTCOME

Child's HIV-1 infection status.

METHODS

Data were collected by standardized record abstraction and interview on 553 children born to women identified as HIV-1-infected before or at delivery. Paediatric infection was determined by immunoglobulin G anti-HIV-1 tests at age 18 months or by AIDS diagnosis at any age. Multivariate logistic regression was used to assess the effect of potential risk factors on vertical transmission of HIV-1.

RESULTS

HIV-1 infection status was determined for 434 children (follow-up rate of 78%); 69 were classified as HIV-1-infected [transmission risk, 16%; 95% confidence interval (CI), 13-20%]. In multivariate analysis, advanced maternal HIV-1 disease [odds ratio (OR), 4.5; 95% CI, 2.1-9.5], ever breastfed (OR, 2.2; 95% CI, 1.2-4.2), child's negative Rhesus blood group (OR, 2.5; 95% CI, 1.2-5.5), third trimester amniocentesis (OR, 4.1; 95% CI, 1.2-13.5) and black racial group (OR, 0.3; 95% CI, 0.1-0.9) were independently and significantly associated with mother-to-child transmission of HIV-1. Transmission was increased marginally with prematurity, more than 10 lifetime sexual partners and prolonged duration of membrane rupture. No association was found between child's HIV-1 infection and mode of delivery or serological evidence of syphilis during pregnancy.

CONCLUSION

These findings support the importance of severity of maternal HIV-1 disease in the risk of vertical transmission of HIV-1, indicate measures to reduce transmission by avoiding amniocentesis and breastfeeding and suggest that race and Rhesus blood type may be markers for genetic susceptibility to infection.

Maternal viral load, CD4 cell count and vertical transmission of HIV-1

HIV load and CD4 cell numbers were measured among 95 HIV infected women during pregnancy in order to determine their value as prognostic markers for transmission of virus from mother to infant. Among the 94 live births, 13 children were infected with HIV, 69 were uninfected and 12 were of unknown infection status. HIV RNA levels, as measured by nucleic acid sequence based amplification, were significantly higher (P < 0.001) in women who transmitted virus than among those who did not transmit and maternal viral load was a stronger predictor of transmission than CD4 cell number. The predicted rate of transmission relative to maternal HIV RNA was 2% at 1,000 copies, 11% at 10,000 copies and 40% at 100,000 copies/ml. Little variation in viral load occurred during pregnancy and there was an association between viral load and prematurity, the mean gestation at delivery decreasing by 1.3 weeks for every 10-fold increase in maternal HIV RNA (P = 0.007). This study demonstrates that a high level of maternal HIV RNA is a risk factor for transmission of virus to the infant and maternal viral load is of more value as a prognostic marker for transmission risk than CD4 cell number. High viral load is also associated with premature delivery. Maternal viral load is therefore a useful marker on which to base management decisions during pregnancy.

Morbidity and mortality in European children vertically infected by HIV-1. The French Pediatric HIV Infection Study Group and European Collaborative Study

Based on 392 infected children enrolled in two European prospective studies of infants born to HIV-infected women, with similar standard protocols, HIV disease progression in the first 6 years of life is described, using the 1994 CDC paediatric HIV classification. Most children had developed minor (A) or moderately severe (B) illness in the first 4 years of life, although usually it was transient in nature. Progression to U.S. Centers for Disease Control and Prevention (CDC) group C disease or HIV-related death is an estimated 20% (95% confidence interval 16-24%) during the first year of life, and 4.7% (3.3-6.5%) per year thereafter, giving a cumulative incidence of 36% (30-43%) by 6 years. The mortality rate at 6 years is 26% (20-32%). Two thirds of the children alive at 6 years had only minor symptoms, and one third had a CD4+ cell distribution of > 25% despite previous clinical manifestations and a transient period of moderate immune deficiency. Differences in zidovudine monotherapy between the two cohorts were not associated with the mortality rate. However, the risk of severe bacterial infections was lower in the French cohort, in which the use of antibacterial prophylaxis was more common. The early, severe form of HIV disease affects approximately 20% of infants, and after 6 years 75% of infected children are still alive. This has important implications for health-care planning.

Vertical transmission of HIV-1: maternal immune status and obstetric factors. The European Collaborative Study

OBJECTIVE

To estimate the effect of maternal factors and events around the time of delivery on HIV-1 vertical transmission risk.

DESIGN

Prospective study.

SETTING

Twenty-two obstetric and paediatric clinics in seven European countries.

PATIENTS OR OTHER PARTICIPANTS

Mothers identified as HIV-infected before or at delivery and their children.

MAIN OUTCOME MEASURE

Paediatric HIV infection.

RESULTS

By November 1995, 1846 mothers with 1945 children had been enrolled. The vertical transmission rate was 16.4% (95% confidence interval, 14.5-18.3). Parity, maternal age, race, mode of HIV acquisition, injecting drug use and sex of infant were not statistically significantly associated with risk of transmission. Children delivered vaginally were more likely to be infected than those delivered by Caesarean section. However, in vaginal deliveries the procedures used, duration of ruptured membranes or length of second-stage labour were not related to transmission. Transmission increased almost linearly with decreasing CD4 cell count, but there was no such trend for CD8 cell count. Women with CD4 cell counts below 200 x 10(6)/l were significantly more likely to deliver early (chi 2 for trend, 14.02; P < 0.001). Very premature infants were at increased risk of infection, but after about 35 weeks gestation the transmission rate remained stable, with no increase in late pregnancy. This trend was confirmed after allowing for maternal CD4 cell count.

CONCLUSIONS

The rate of vertical transmission increases linearly with decreasing maternal CD4 cell count. Women with fewer than 200 x 10(6) CD4 cells/l have an increased risk of premature delivery, which would affect timing of interventions. The stable transmission rate after 35 weeks gestation suggests little acquisition of infection during late pregnancy.

Salivary testing for human immunodeficiency virus type 1 infection in children born to infected mothers in Sao Paulo, Brazil. The Sao Paulo Collaborative Study for Vertical Transmission of HIV-1

OBJECTIVE

To validate a method for salivary testing for HIV infection in children older than 12 months.

METHODS

Oral fluid samples were collected via sponge foam swabs from children born to HIV-positive mothers and were tested for antibodies to HIV-1 and HIV-2 with an IgG antibody capture enzyme-linked immunosorbent assay and a modified Western blot for confirmation. In each child serum antibody status was the standard used to validate the salivary antibody test.

RESULTS

We obtained 331 oral fluid samples from children born to HIV-positive mothers. The specificity and sensitivity of salivary testing compared with results on sera were both 100% (297 of 297 (95% confidence interval 98.8 to 100%) and 34 of 34 (95% confidence interval 89.7 to 100%), respectively). Compliance in the study population increased from 91% to 97% when mothers were offered the opportunity to provide oral fluid from their children instead of blood specimens.

CONCLUSION

Salivary testing provides an accurate and acceptable noninvasive method for assessing the HIV infection status of children born to infected mothers by using IgG antibody capture enzyme-linked immunosorbent assay alone with a strategy of duplicate retesting of reactive specimens.

The sensitivity of HIV-1 DNA polymerase chain reaction in the neonatal period and the relative contributions of intra-uterine and intra-partum transmission

OBJECTIVE

To derive reliable estimates of the sensitivity of HIV-1 DNA polymerase chain reaction (PCR) in the neonatal period and to quantify the relative contributions of intra-uterine and intra-partum transmission.

METHODS

After reviewing studies on the early diagnosis of HIV-1 infection, investigators were asked to provide published and unpublished PCR test results on prospectively followed, non-breastfed, vertically infected children. Age-specific estimates of the sensitivity of PCR were derived using distribution-free methods for interval-censored data.

RESULTS

Data on 271 infected children were combined for analysis. PCR detected HIV-1 DNA in an estimated 38% [90% confidence interval (CI), 29-46] of HIV-infected children tested on the day of, or day after, birth. Sensitivity was observed to rise rapidly in the second week of life, reaching 93% (90% CI, 76-97) by 14 days of age.

CONCLUSION

The sensitivity of PCR in the neonatal period is higher than previously reported. This affects the clinical interpretation of an early negative test result and encourages the use of PCR as an endpoint for trials to evaluate interventions to reduce vertical transmission in non-breastfed populations. Approximately one-third of vertically acquired HIV-1 infection could be attributable to intra-uterine transmission.

How much paediatric HIV infection could be prevented by antenatal HIV testing?

OBJECTIVE

To estimate the reduction in the number of children infected with HIV that might be achieved by extending the provision of voluntary antenatal HIV testing. This effect would be mediated by increased numbers of women infected with HIV who receive an intervention to reduce the risk of vertical transmission (for example, zidovudine or caesarean section delivery), who use an alternative to breast feeding, or whose pregnancy is terminated.

SETTING

London, United Kingdom.

METHODS

Relevant data were derived from neonatal seroprevalence studies, obstetric and paediatric reporting schemes, and review of external information. Sensitivity analyses were performed for certain parameters.

RESULTS

Of 106,000 births annually in London, an estimated 169 are to women infected with HIV whose infection is not currently recognised before pregnancy. An estimated 28-33 children born to these women will be infected. Precise prediction of the number of paediatric HIV infections that could be prevented is difficult because of uncertainty in certain factors, particularly the uptake of antenatal testing and the efficacy and acceptability of interventions to reduce prenatal or perinatal transmission. If a testing programme detected 70% of infected women, none of whom opted for a termination but all of whom exclusively bottle fed and received an intervention which halved the risk of transmission, about 12-16 (42-46%) paediatric HIV infections would be prevented annually.

CONCLUSIONS

The estimated cost of preventing each paediatric infection is high, but this should be seen in the context of the lifetime health and social care costs for a child infected with HIV. The feasibility of selective testing should be considered when formulating policies on antenatal HIV testing. Programmes that are introduced should be audited to obtain better estimates of costs and benefits.

Haematological risk factors for pregnancy outcome in Jamaican women with homozygous sickle cell disease

OBJECTIVE

To examine the association between fetal outcome and the steady state haematology of mothers with homozygous sickle cell disease.

DESIGN

A retrospective observational study. The data were taken from dockets kept at the Sickle Cell Clinic and verified by interview with 45% of the patients.

SETTING

The Sickle Cell Clinic at the University Hospital of the West Indies or two peripheral clinics operated by the staff of the MRC Laboratories.

SUBJECTS

All women aged 14 years or older with homozygous sickle cell disease who had experienced at least one pregnancy in the period 1977 to 1986.

MAIN OUTCOME MEASURES

Three fetal outcomes including miscarriages, perinatal deaths, and birthweight.

RESULTS

There were 270 singleton pregnancies in 175 women with an overall fetal wastage of 32.2%. There was a significant increased risk of perinatal death with low maternal fetal haemoglobin level, but there were no haematological associations with miscarriages or birthweight.

CONCLUSIONS

These data suggest that maternal steady-state haematology has little influence on fetal outcome, with the exception that mothers with high HbF levels are less prone to perinatal deaths. Further study is required to investigate acute haematological changes associated with pregnancy.

The effect of human immunodeficiency virus type-1 on the infectiousness of tuberculosis

SETTING

Developing country tertiary referral hospital plus catchment community.

OBJECTIVE

To determine the infectiousness of culture-confirmed pulmonary tuberculosis in patients infected with Human Immunodeficiency Virus type-1 (HIV-1).

DESIGN

Comparison of the incidence of tuberculosis and the prevalence of tuberculin skin test positivity among the household contacts of both HIV-1 positive and negative cases with pulmonary tuberculosis.

RESULTS

Of 255 contacts of HIV-1 negative index cases, 2 were HIV-1 positive and of 102 contacts of HIV-1 positive index cases, 14 were HIV-1 positive (odds ratio (OR) = 20.0 95% Confidence Interval (CI) 4.4-193). 21 cases of tuberculosis were diagnosed among contacts, of whom 3 were HIV-1 positive. The overall unadjusted OR for tuberculosis among contacts of HIV-1 positive index cases was 1.6 (95% CI 0.6-4.3) compared to contacts of HIV-1 negative index cases. Amongst HIV-1 negative contacts alone the OR was 1.5 (95% CI 0.4-4.4). In this group the best predictors of tuberculosis among contacts were female sex of the index case (OR = 3.4 95% CI 1.1-12), sharing the same bed as the index case (OR = 2.6 95% CI 0.9-7.4), and contact's age less than 5 years (OR = 3.3 95% CI 1.1-9.5). HIV-1 positive contacts were more likely to develop tuberculosis than HIV-1 negative contacts (OR = 4.1 95% CI 0.7-17). Tuberculin skin test positivity rates were the same among the HIV-1 negative contacts of HIV-1 positive and negative index cases (OR = 1.1 CI 0.7-1.6).

CONCLUSIONS

HIV-1 associated pulmonary tuberculosis is not more infectious than tuberculosis alone. The presence of HIV-1 in a community does not mandate a change in the management of contacts of patients with pulmonary tuberculosis.

Suppressed peripheral and placental blood lymphoproliferative responses in first pregnancies: relevance to malaria

An understanding of processes that predispose pregnant women, and in particular primigravidae, to malaria infection is essential to improve malaria management in pregnancy. Lymphoproliferative responses to malaria-specific (F32, 190L, and 190N) as well as other antigens (Candida and purified protein derivative [PPD]) were examined in the peripheral and placental blood of 102 Gambian women at the time of delivery. The lymphoproliferative responses of placental cells were poor to all antigens compared with those of peripheral blood (Candida P < 0.001, PPD P < 0.001, F32 P = 0.008, 190L P = 0.003, and 190N P = 0.10). Reduced proliferative capacity of placental mononuclear cells may contribute to heavy parasite colonization of this organ. Proliferation to malarial and PPD but not Candida antigens was selectively suppressed in peripheral and placental blood of primiparae relative to multiparae (F32 P = 0.07, 190L P = 0.09, 190N P = 0.007, PPD P = 0.09). Autologous plasma contained factors that suppressed lymphoproliferative responses to the same series of antigens to which the primiparae responded poorly (F32 P < 0.001, 190L P < 0.001, 190N P < 0.001, PPD P = 0.03). Malarial antibody levels were comparable among women of different parities and between peripheral and placental blood. Primigravidae may be more susceptible to malaria because of unique physiologic factors, such as higher levels of circulating immunosuppressive corticosteroids (P < 0.001), rather than differences in levels of acquired immunity.

Risk of human immunodeficiency virus type 1 transmission through breastfeeding

Detection of human immunodeficiency virus type 1 (HIV-1) in breast milk by culture and polymerase chain reaction does not necessarily mean that breastfeeding is a route of transmission, although evidence from several case-reports points in that direction. We undertook a systematic review of published studies meeting criteria that allowed determination of quantitative risk of transmission via breastfeeding. Based on four studies in which mothers acquired HIV-1 postnatally, the estimated risk of transmission is 29% (95% Cl 16-42%). Analysis of five studies showed that when the mother was infected prenatally, the additional risk of transmission through breastfeeding, over and above transmission in utero or during delivery, is 14% (95% Cl 7-22%). Where there are safe alternatives to breastfeeding, universal named testing of pregnant women would provide an opportunity to advise more infected women not to breastfeed and might thereby reduce the number of vertically infected children. Since breastfeeding protects against infant deaths from infectious diseases, breastfeeding is still recommended where infectious diseases are a common cause of death in childhood, despite the additional risk of HIV transmission.

The impact of medical services on trachoma in a Gambian village: antibiotics alone are not the answer

We have measured the prevalence of active trachoma in children aged less than 15 years in the Gambian village of Keneba, which has had excellent free medical care and a continuous supply of antibiotics since 1974. The prevalence was 13%, with the peak prevalence (20%) occurring in the 2 to 3-year age group. Of 71 cases diagnosed, only 23 (33%) had complained of ocular symptoms in the previous 3 months, in spite of the fact that 66 (94%) had attended the clinic. Only five had been diagnosed as having trachoma by the duty paediatrician (7%). Compliance with treatment was poor, with only 29 subjects returning for continued treatment (41%), and at follow-up 16 months later 22 of 64 subjects still had active disease (34%). We conclude that the widespread use of antimicrobial agents does not preclude the persistence of endemic disease. Socio-economic improvement or behavioural changes appear necessary for the control of trachoma in endemic areas. In the meantime there is a need for greater awareness of the disease both among clinicians in endemic areas and among the communities afflicted.

Risk factors for proliferative sickle retinopathy

The prevalence, incidence, and risk factors associated with proliferative sickle retinopathy (PSR) were investigated in 786 patients with homozygous sickle cell (SS) disease and 533 patients with sickle cell haemoglobin C (SC) disease. PSR was more common in SC disease, in which there was a significant predominance of males, and it increased with age in both genotypes. In SC disease the risk of developing PSR was highest between 15 and 24 years in males, between 20 and 39 years in females, and in SS disease between 25 and 39 years in both sexes. PSR tended to be bilateral, especially in SC disease. There was no evidence of familial clustering of PSR in SC siblings, and insufficient numbers of SS siblings were available to test for clustering. Haematological risk factors associated with PSR in SS disease were a high haemoglobin in males and a low fetal haemoglobin in both sexes and in SC disease, a high mean cell volume, and a low fetal haemoglobin in females.

Abnormal thyroid hormone and thyrotropin levels in homozygous sickle cell disease

Male patients with SS disease had significantly lower T3 and higher TSH levels than a comparison group. Stimulation with TRH in 10 male sibling pairs showed highly significant increases in T3 and TSH in both patients and sibling controls although the increase in TSH was significantly greater in SS disease. The interpretation of these findings is unclear although the thyroid indices indicate an abnormal pituitary-thyroid axis most consistent with a modest primary thyroid failure.

Diabetic maculopathy in a Jamaican population

Maculopathy is the commonest cause of severe visual loss from diabetic retinopathy in Jamaica [5]. Ophthalmic assessment of 158 black Jamaican maturity onset diabetics referred randomly from the primary and secondary health centres, demonstrated maculopathy in 48% of patients. Duration of diabetes was a strong risk factor for maculopathy (p less than 0.001). Poor compliance with diabetic and hypertensive therapy may influence the prevalence of maculopathy.

Fetal haemoglobin and pregnancy in homozygous sickle cell disease

The pregnancy related changes in fetal haemoglobin (HbF) have been observed in 152 pregnancies in 125 women with homozygous sickle cell (SS) disease and related to steady state levels in the same individual. Statistically significant increases in the first and second trimesters, were followed by significant falls below steady state levels in the third trimester and postpartum period. Although these corresponded to a mean increase of 0.7% and a mean decrease of 1.6%, much greater changes occurred in some individuals. Mean levels had not returned to steady state values 1 year after delivery. The hormonal changes in pregnancy appear to have profound effects on HbF level in SS disease, the mechanisms of which require further study.

Gall stones in Jamaican children with homozygous sickle cell disease

Gall stones were detected by ultrasonography in 30 of 226 (13%) children with homozygous sickle cell disease aged 5-13 years participating in a cohort study from birth. Children with gall stones had significantly lower total haemoglobin and fetal haemoglobin and higher bilirubin concentrations, but further analysis showed that the apparent effects of haemoglobin and fetal haemoglobin concentration were secondary to their relationship with bilirubin concentrations. Abdominal pain crises were significantly associated with gall stones but both factors appeared to reflect an increased clinical severity and were probably not causally related. No patients had symptoms specific of gall stones and an association with abdominal pain crisis should not, of itself, be considered an indication for surgery.

Nutritional status and risk of morbidity among young Gambian children allowing for social and environmental factors

A prospective study of the relationship between anthropometric indices and subsequent morbidity was conducted during 2 seasons in young children in an urban Gambian community. Children with low height-for-age at the beginning of the rainy season had a significantly higher prevalence of diarrhoea and fever during the next 4 months, even after controlling for the possible confounding effects of a range of social, economic and environmental factors. The association was weaker in the dry season. This indicates that the increased prevalence of symptoms among stunted children is not solely attributable to environmental factors, and suggests that impaired growth is associated with impaired host response to infection.

The metacarpal index in homozygous sickle-cell disease

The metacarpal index (MCI) was measured in 240 patients with homozygous sickle-cell (SS) disease and in 1082 normal persons constituting a comparison group. The MCI was greater in females than in males, but there appeared to be no significant difference between genotypes. Arachnodactyly may occur in some patients with SS disease, but there is no evidence of a genotype-related increase in metacarpal index.

Sequelae of epidemic meningococcal meningitis in Africa

Audiological and other long-term neurological sequelae were determined in 157 cases and their controls matched for age, sex and village 6 to 12 months after an epidemic of group A meningococcal meningitis in rural West Africa. 19 cases (12.1%) and 3 controls (1.9%) had moderate or severe neurological sequelae of any type (P less than 0.001); 6 cases (3.9%) and no controls had severe or profound sensorineural hearing loss (P = 0.03). There was no difference in conductive hearing loss between cases and controls. Other cranial nerve sequelae (except visual defects) and generalized neurological and motor and co-ordination sequelae were also significantly increased in cases. Sensorineural hearing loss and other cranial nerve sequelae occurred significantly more frequently in males than in females, and co-ordination sequelae more frequently in cases aged 10 years or more than in younger cases. Sensorineural hearing loss and loss of visual acuity were found significantly more frequently in cases whose treatment was delayed for 4 d or more, compared with those who received treatment sooner.

Argon laser trabeculoplasty in primary open-angle glaucoma--results in black Jamaican population

A controlled, randomised, prospective trial of Argon laser trabeculoplasty (ALT) was carried out on 48 eyes of 30 black Jamaican patients with primary open-angle glaucoma. All eyes had uncontrolled intra-ocular pressures (greater than or equal to 22 mm Hg) despite medical therapy. Treatment was successful in controlling intraocular pressure in 68% of eyes after 12 months follow-up (p = 0.004). The average drop in intraocular pressure attributable to ALT was 6.6 mmHg. Argon laser trabeculoplasty is an effective adjunct in managing to control intraocular pressure in black Jamaican glaucoma patients.

Alternative measures of diarrhoeal morbidity and their association with social and environmental factors in urban children in The Gambia

Diarrhoeal morbidity was studied during a 15-week period of the rainy season in 244 children aged 6 to 35 months in an urban Gambian community. The average prevalence of diarrhoea was 12.0% and the mean number of episodes per child varied between 2.4 and 2.9 depending on the definition of an episode. The number of chronic episodes lasting 14 d or more was tripled when 7 rather than one diarrhoea-free days were required to define a new episode. Neither prevalence nor the number of episodes varied significantly with age or sex. There was little association between the social and environmental characteristics of the children and diarrhoeal morbidity. The implications of using differing measures of diarrhoeal morbidity are discussed.

The painful crisis of homozygous sickle cell disease. A study of the risk factors

Some epidemiologic features of the painful crisis in homozygous sickle cell disease were examined in a retrospective study of 995 painful crises. Previously reported associations with cold weather and pregnancy were confirmed. There was a striking increase in painful crises in male patients between the ages of 15 and 25 years, whereas female patients showed little age-related change. The frequency of painful crises correlated positively with hemoglobin levels and reticulocyte counts in both sexes and negatively with mean corpuscular volume in female patients. There was a striking increase in painful crises in male patients with hemoglobin levels above 8.5 g/dL (greater than 85 g/L). High hemoglobin levels appear to be an important risk factor for painful crises.