Surveillance and modelling of HIV, STI, and risk behaviours in concentrated HIV epidemics

BACKGROUND

HIV epidemics in most countries are highly concentrated among population subgroups such as female sex workers, injecting drug users, men who have sex with men, mobile populations, and their sexual partners. The perception that they are important only when they cause epidemic expansion to general populations has obscured a critical lack of coverage of preventive interventions in these groups, as well as appropriate methods for monitoring epidemic and behavioural risk trends. The difficulties in accessing such groups have likewise often cast doubt on the representativeness of observed disease and behavioural risk estimates and their validity and reliability, particularly those related to sampling and the measurement of risk behaviours.

OBJECTIVES

To review methodological obstacles in conducting surveillance with population subgroups in concentrated HIV epidemics, elaborate on recent advancements that partially overcome these obstacles, and illustrate the importance of modelling integrated HIV, STI, and behavioural surveillance data.

METHODS

Review of published HIV, STI, and behavioural surveillance data, research on epidemic dynamics, and case studies from selected countries.

CONCLUSIONS

The population subgroups that merit regular and systematic surveillance in concentrated epidemics are best determined through extensive assessment and careful definition. Adherence to recently refined chain referral and time location sampling methods can help to ensure more representative samples. Finally, because of the inherent limitations of cross sectional surveys in understanding associations between complex sexual behaviours and HIV and STI transmission, mathematical models using multiple year data offer opportunities for integrated analysis of behavioural change and HIV/STI trends.

Generalização de um modelo linear de impedância eletroquímica

Em geral, a função de um modelo de impedância para processos de eletrodo simples é deduzida de um modelo elétrico equivalente, denominado circuito de Randles. Neste trabalho estudou-se a generalização dessa função, mediante a introdução de um parâmetro não-elétrico, relacionado com a flexibilidade do ângulo de fase e da magnitude. A função foi ajustada às medidas experimentais de impedância obtidas de um sistema constituído de uma liga Ti-10%Al (m/m) em solução de cloreto de sódio 0,9%, variando-se a amplitude de perturbação. Verificou-se que a função generalizada foi adequada para descrever a impedância do sistema analisado, reduzindo as distorções entre a curva experimental e a curva teórica. Além disso, os melhores resultados foram obtidos para sinais de perturbação do sistema com amplitude igual a 10 mV.

Cypress in Italy: landscape and pollen monitoring

In Italy the Cupressaceae pollen has been monitored by the Italian Aeroallergen Network (IAN) in collaboration with the Italian Research Council (CNR) since 1988. The measurements carried out over the last decade show a positive trend of the seasonal emission of the cypress pollen, whose flowering peak occurs in Italy from mid-February to mid-March. During the pollination period the cypress pollen represents 10% to 40% of the total pollen, showing a high variability of its annual production.

Prevention of vaginal stenosis in patients following vaginal brachytherapy

The assessment of patients following intracavitary irradiation administered as part of the treatment of gynaecological malignancy reveals vaginal stenosis in the majority. Vaginal dilators are available for daily insertion in an attempt to prevent the formation of adhesions. However, the design of the dilator neglects the fact that the vagina is the most distensible in the upper third and hence many patients develop stenosis of the upper vagina. Many clinicians have abandoned the use of dilators and instead advise patients to have sexual intercourse to prevent the problem. In 1994, we designed a new vaginal stent, which was given to all patients who had received intracavitary irradiation with full instructions about its use. This stent was designed to suit better the true anatomy of the vagina and hence, with correct use, should prevent vaginal stenosis. A retrospective study was undertaken to look at the incidence of vaginal stenosis and this was compared with the incidence in patients using the new stent. The study revealed that 57% of the patients who were advised to have sexual intercourse had stenosis, whereas 11% of the patients using the stent had evidence of stenosis, which, however, was related to their incorrect use of the stent. In those who used the stent correctly there was no evidence of vaginal stenosis. Details of the design of the stent and the problems relating to those who used the stent incorrectly are presented. The findings of this study strongly support the continued use of this vaginal stent in patients who have undergone intracavitary irradiation as a means of preventing this common complication.

HIV risk behavioral surveillance: a methodology for monitoring behavioral trends

OBJECTIVE

This article summarizes issues and recommendations for conducting HIV risk behavioral surveillance surveys (BSS) based on experiences from ten BSS projects in eight countries in Asia and Africa.

BACKGROUND

BSS consists of systematic and repeated cross-sectional surveys of HIV and sexually transmitted disease-related behaviors, with other knowledge and attitudinal variables added where appropriate. Its major purpose and utility is in detecting trends among selected vulnerable and high-risk population groups whose behavioral change can have the most impact on the epidemic. BSS is also useful for tracking trends in behaviors over time in regions exposed to HIV prevention activities, as a contributing component to the comprehensive monitoring and evaluation of interventions.

RECOMMENDATIONS

(i) implement BSS as an essential adjunct to HIV/STD epidemiological surveillance; (ii) use BSS for evaluation purposes in combination with process data and triangulate results with qualitative research; (iii) choose sentinel groups based on epidemiological considerations, evaluation and monitoring needs, representative sampling frames, and political and cultural considerations; (iv) maintain 1-year intervals between survey waves for most groups in order to provide yearly updates on behavioral trends for programmatic adjustments; (v) use internationally standardized indicators and question wording; (vi) maintain strict quality control standards to enhance data validity and reliability; and (vii) develop a clear dissemination strategy during BSS design to increase the likelihood of utilization of BSS results.

CONCLUSION

BSS represents a cost-effective way to determine whether programmatic behavioral targets and goals are being met, to identify persisting risk behaviors over time, and to indicate whether new intervention approaches are necessary.

Maternal behavioural risk factors for severe childhood diarrhoeal disease in Kinshasa, Zaire

This study examines the relationship between severe diarrhoeal disease and maternal knowledge and behaviours related to hygiene and sanitation. Some 107 paediatric cases admitted to two hospitals in Kinshasa, Zaire in 1988 were matched on age and nearest-neighbour status to 107 controls. Personal interviews and observational methods were used to assess knowledge and behaviours related to hygiene and sanitation. Cases and controls had equivalent socioeconomic status, demographic profiles and access to water and sanitation facilities. However, cases generally exhibited lower levels of knowledge and less sanguine sanitary practices than did controls. Of particular interest was the finding that very specific behavioural items distinguished cases from controls. The disposal of the child faeces and household garbage and mother's knowledge that poor caretaker cleanliness was a cause of diarrhoea in children showed the strongest associations with risk of diarrhoea. There was an exponential relationship between the number of these items a mother answered incorrectly and the odds of diarrhoeal disease. The risk attributable to these three variables was as high as 70%. These findings provide further support for the view that focused educational interventions may have a substantial impact on the occurrence of severe diarrhoeal disease in low-income countries.