Opportunistic infections in HIV-infected children

An Overview of Antiretroviral Agents for Treating HIV Infection in Paediatric Population

Paediatric Acquired ImmunoDeficiency Syndrome (AIDS) is a life-threatening and infectious disease in which the Human Immunodeficiency Virus (HIV) is mainly transmitted through Mother-To- Child Transmission (MTCT) during pregnancy, labour and delivery, or breastfeeding. This review provides an overview of the distinct therapeutic alternatives to abolish the systemic viral replication in paediatric HIV-1 infection. Numerous classes of antiretroviral agents have emerged as therapeutic tools for downregulation of different steps in the HIV replication process. These classes encompass Non- Nucleoside Analogue Reverse Transcriptase Inhibitors (NNRTIs), Nucleoside/Nucleotide Analogue Reverse Transcriptase Inhibitors (NRTIs/NtRTIs), INtegrase Inhibitors (INIs), Protease Inhibitors (PIs), and Entry Inhibitors (EIs). Co-administration of certain antiretroviral drugs with Pharmacokinetic Enhancers (PEs) may boost the effectiveness of the primary therapeutic agent. The combination of multiple antiretroviral drug regimens (Highly Active AntiRetroviral Therapy - HAART) is currently the standard therapeutic approach for HIV infection. So far, the use of HAART offers the best opportunity for prolonged and maximal viral suppression, and preservation of the immune system upon HIV infection. Still, the frequent administration of high doses of multiple drugs, their inefficient ability to reach the viral reservoirs in adequate doses, the development of drug resistance, and the lack of patient compliance compromise the complete HIV elimination. The development of nanotechnology-based drug delivery systems may enable targeted delivery of antiretroviral agents to inaccessible viral reservoir sites at therapeutic concentrations. In addition, the application of Computer-Aided Drug Design (CADD) approaches has provided valuable tools for the development of anti-HIV drug candidates with favourable pharmacodynamics and pharmacokinetic properties.

HIV disease and respiratory infection in children

Over one million children world-wide are living with HIV infection and respiratory disease is the commonest cause of morbidity and mortality in these children. The initial presentation of respiratory infection is usually in infancy or early childhood. There is enormous potential to prevent childhood HIV infection that is being realised in industrialised countries but not yet elsewhere. Increasingly, therefore, the burden of HIV disease is in children living in or from non-industrialised countries. This review describes and contrasts the pattern of respiratory infection from both regions. This pattern has changed with the implementation of PCP prophylaxis and the availability of potent antiretroviral therapy for children in resource-rich countries, such as the UK. More data are required from resource-poor regions such as tropical Africa, but it is clear that the major differences reflect greater background risk for respiratory infection and very limited management options rather than specific aetiology.

Clinical presentation and outcome of Pneumocystis carinii pneumonia in Malawian children

BACKGROUND

Necropsy studies from Africa have shown that Pneumocystis carinii pneumonia (PCP) is common in infants with HIV infection. We aimed to describe the rate, clinical presentation, and outcome of PCP in young Malawian children with acute severe pneumonia.

METHODS

Children aged between 2 months and 5 years who were in hospital with a diagnosis of severe pneumonia were admitted to a study ward for clinical monitoring. We carried out blood culture, immunofluorescence on nasopharyngeal aspirate samples to test for PCP, polymerase chain reaction to detect HIV, and chest radiography.

FINDINGS

16 cases of PCP were identified among 150 children with radiologically confirmed severe pneumonia. All were HIV-positive and younger than 6 months. 21 children had bacterial pneumonia (including one who was also PCP positive) and 114 were not confirmed. The most common bacterial pathogens among children without PCP were Streptococcus pneumoniae (eight) and non-typhoidal salmonellae (seven). On admission, children with confirmed PCP had a lower mean age, body temperature, and oxygen saturation than children with bacterial pneumonia and were less likely to have a focal abnormality on auscultation. Oxygen requirements were much greater in children with PCP than those with bacterial pneumonias (96 of 105 hospital days vs 15 of 94, p<0.0001). Ten of 16 children with PCP and six of 21 with bacterial pneumonia died (relative risk 2.19 [95% CI 1.0-4.7]). The overall case-fatality rate of severe pneumonia was 22%. In addition to a strong association with PCP, a fatal outcome was significantly and independently associated with HIV infection (2.98 [1.1-7.9]) and with age under 6 months (2.76 [1.0-5.2]).

INTERPRETATION

PCP is common and contributes to the high mortality from pneumonia in Malawian infants. Clinical features are helpful in diagnosis. The study highlights the impact of HIV infection and difficult issues of management in countries with few resources.

Correlation of in vitro T-cell and B-cell function with responses to childhood vaccines in children with human immunodeficiency virus infection

We analyzed T-cell responses to mitogens and antigens and B-cell differentiation in response to T-cell dependent (TCD) and independent stimuli in 22 human immunodeficiency virus (HIV)-infected children (1 to 9 years of age) according to the presence of protective humoral immunity at a mean time of 18 months after vaccination with Haemophilus influenzae type b, hepatitis B, diphtheria, and tetanus vaccines. The 17 vaccine responders had a mean of 3.2 responses. However, their antibody levels were lower compared with healthy children. The 5 nonresponders had a mean of 0.84 responses. There were no significant differences between responders and nonresponders regarding age, Centers for Disease Control and Prevention (CDC) disease class, CDC immunologic class, serum immunoglobulin (Ig) levels, or in the use of antiretroviral therapy. However, responders tended to have higher age-adjusted absolute CD4 cell counts than nonresponders (p = 0.07). Nonetheless, there was no correlation between antibody levels and age-adjusted CD4 counts for each of the 4 TCD vaccines. Responders had conserved lymphoproliferative responses to mitogens and to candida antigen; 7 (41%) had normal responses to tetanus antigen. While nonresponders had some conserved responses to mitogens, only 1 had a response to antigen. Thirteen responders (77%) and only 1 nonresponder (20%) had normal responses to at least 2 of the 3 mitogens and 1 of the 2 antigens (p = 0.04). Although defects in B-cell differentiation were detected in both groups, they were profound and generalized in the nonresponders. Fourteen responders (82%) had at least 1 normal B-cell response compared with none of the 5 nonresponders (p = 0.002). There were no correlations between normal lymphoproliferative responses and age, CD4 counts, serum immunoglobulin G (IgG) levels, or the use of antiretroviral therapy. Immunologic function is important in the evaluation of HIV-infected children.