The AIDS epidemic in Lyon: patient characteristics and defining illnesses between 1985 and 2000

Pneumocystis jirovecii colonisation in HIV-positive and HIV-negative subjects in Cameroon

OBJECTIVE

To determine the prevalence of Pneumocystis pneumonia (PCP), a major opportunistic infection in AIDS patients in Europe and the USA, in Cameroon.

MATERIALS AND METHODS

Induced sputum samples from 237 patients without pulmonary symptoms (126 HIV-positive and 111 HIV-negative outpatients) treated at a regional hospital in Cameroon were examined for the prevalence of Pneumocystis jirovecii by specific nested polymerase chain reaction (nPCR) and staining methods. CD₄ counts and the history of antiretroviral therapy of the subjects were obtained through the ESOPE database system.

RESULTS AND CONCLUSION

Seventy-five of 237 study participants (31.6%) were colonised with Pneumocystis, but none showed active PCP. The Pneumocystis colonisation rate in HIV-positive subjects was more than double that of HIV-negative subjects (42.9% vs. 18.9%, P < 0.001). In the HIV-positive group, the colonisation rate corresponds to the reduction in the CD₄ lymphocyte counts. Subjects with CD₄ counts >500 cells/μl were colonised at a rate of 20.0%, subjects with CD₄ counts between 200 and 500 cells/μl of 42.5%, and subjects with CD₄ counts <200 cells/μl of 57.1%. Colonisation with Pneumocystis in Cameroon seems to be comparable to rates found in Western Europe. Prophylactic and therapeutic measures against Pneumocystis should be taken into account in HIV care in western Africa.

Immune impairment thresholds in HIV infection

Longitudinal studies of patients infected with HIV-1 reveal a long and variable length of asymptomatic phase between infection and development of AIDS. Some HIV infected patients are still asymptomatic after 15 or more years of infection but some patients develop AIDS within 2 years. The mechanistic basis of the disease progression has remained obscure but many researchers have been trying to explain it. For example, the possible importance of viral diversity for the disease progression and the development of AIDS has been very well worked out in the early-1990s, especially by some important works of Martin A. Nowak. These studies can give an elegant explanation for a variability of asymptomatic phase. Here, a simple mathematical model was used to propose a new explanation for a variable length of asymptomatic phase. The main idea is that the immune impairment rate increases over the HIV infection. Our model suggested the existence of so-called "Risky threshold" and "Immunodeficiency threshold" on the impairment rate. The former implies that immune system may collapse when the impairment rate of HIV exceeds the threshold value. The latter implies that immune system always collapses when the impairment rate exceeds the value. We found that the length of asymptomatic phase is determined stochastically between these threshold values depending on the virological and immunological states. Furthermore, we investigated a distribution of the length of asymptomatic phase and a survival rate of the immune responses in one HIV patient.

Pneumococcal pneumonia in HIV-infected patients by antiretroviral therapy periods

OBJECTIVE

To ascertain the relationship between periods of various antiretroviral therapies and the incidence of first community-acquired pneumococcal pneumonia (CAPP) among HIV-1 infected patients.

METHODS

We analysed 4075 patients enrolled prospectively in the Lyon section of the French Hospital Database on HIV between 1993 and 2004, stratified into three groups. The first group (G1) included patients for whom enrolment and last follow-up were before the highly active antiretroviral therapy (HAART) period (beginning 1 July 1996); the second group (G2) comprised patients who were enrolled before HAART but had last follow-up in the HAART period; the third group (G3) included patients for whom both enrolment and last follow-up took place in the HAART period.

RESULTS

Fifty-five CAPP episodes were identified. The incidence of CAPP per 1000 patient-years declined over time, from 10.6 to 1.5 and 2.5 in calendar periods G1, G2 and G3, respectively (P=0.004 for linear trend). Factors associated with a decreased risk of CAPP were lower age, baseline CD4 count >or=200 cells/microL and more recent years of enrolment, when HAART use became extensive (P<0.001). The use of intravenous drugs increased the risk of CAPP (P<0.001).

CONCLUSIONS

There has been a significant reduction in the incidence of CAPP in HIV-1 infected patients since the advent of HAART.

Discrimination against HIV-infected people and the spread of HIV: some evidence from France

BACKGROUND

Many people living with HIV/AIDS (PLWHA) suffer from stigma and discrimination. There is an ongoing debate, however, about whether stigma, fear and discrimination actually fuel the persisting spread of HIV, or slow it down by reducing contacts between the whole population and high-risk minorities. To contribute to this debate, we analysed the relationship between perceived discrimination and unsafe sex in a large sample of French PLWHAs.

METHODOLOGY/PRINCIPAL FINDINGS

In 2003, we conducted a national cross-sectional survey among a random sample of HIV-infected patients. The analysis was restricted to sexually active respondents (N = 2,136). Unsafe sex was defined as sexual intercourse without a condom with a seronegative/unknown serostatus partner during the prior 12 months. Separate analyses were performed for each transmission group (injecting drug use (IDU), homosexual contact, heterosexual contact). Overall, 24% of respondents reported experiences of discrimination in their close social environment (relatives, friends and colleagues) and 18% reported unsafe sex during the previous 12 months. Both prevalences were higher in the IDU group (32% for perceived discrimination, 23% for unsafe sex). In multivariate analyses, experience of discrimination in the close social environment was associated with an increase in unsafe sex for both PLWHAs infected through IDU and heterosexual contact (OR = 1.65 and 1.80 respectively).

CONCLUSIONS

Our study clearly confirms a relationship between discrimination and unsafe sex among PLWHAs infected through either IDU or heterosexual contact. This relationship was especially strong in the heterosexual group that has become the main vector of HIV transmission in France, and who is the more likely of sexual mixing with the general population. These results seriously question the hypothesis that HIV-stigma has no effect or could even reduce the infection spread of HIV.

Pneumonia associated with HIV infection

PURPOSE OF REVIEW

Pneumonia occurs commonly in HIV-infected patients and this review highlights some of the recent findings in the epidemiology, pathogenesis, clinical features, treatment and prevention of this condition.

RECENT FINDINGS

Pneumonia remains an important cause of morbidity and mortality in HIV-infected patients. A number of factors have been identified that increase the risk of pneumonia. Cigarette smoking increases the risk of lung colonization, as well acute pneumonia due to Pneumocystis jiroveci, and has been documented to produce significant depression of the phagocytic function of alveolar macrophages in HIV-infected patients, which may underlie this risk. Legionella pneumophila infections appear to be uncommon in HIV-infected patients, while pneumonia with Streptococcus pneumoniae continues to occur with regularity, including infections with antibiotic-resistant isolates. Pneumocystis pneumonia occurs with a low incidence in patients receiving HAART, once the CD4 count increases to over 200 microl. Studies of invasive pneumococcal infections (predominantly pneumonia) indicate that in critically ill cases, including HIV-seropositive patients, combination antibiotic therapy is associated with a lower mortality than monotherapy. The 23-polyvalent pneumococcal vaccine has been shown to reduce the risk of pneumococcal infection in HIV-infected adults receiving HAART, and a 9-valent conjugate pneumococcal vaccine has been shown to reduce the incidence of radiologically confirmed pneumonia in HIV-seropositive and HIV-seronegative children.

SUMMARY

Pneumonia remains an important condition in HIV-infected patients, but recent studies demonstrate that antibiotic prophylaxis, the introduction of HAART, recognition of specific risk factors, new antibiotic treatment strategies and effective vaccines should serve to decrease its impact.