Pneumocystis carinii pneumonia in Malawian children

Pneumocystis jirovecii pneumonia in tropical and low and middle income countries: a systematic review and meta-regression

Objective

Pneumocystis jirovecii pneumonia (PCP), the commonest opportunistic infection in HIV-infected patients in the developed world, is less commonly described in tropical and low and middle income countries (LMIC). We sought to investigate predictors of PCP in these settings.

Design

Systematic review and meta-regression.

Methods

Meta-regression of predictors of PCP diagnosis (33 studies). Qualitative and quantitative assessment of recorded CD4 counts, receipt of prophylaxis and antiretrovirals, sensitivity and specificity of clinical signs and symptoms for PCP, co-infection with other pathogens, and case fatality (117 studies).

Results

The most significant predictor of PCP was per capita Gross Domestic Product, which showed strong linear association with odds of PCP diagnosis (p<0.0001). This was not explained by study design or diagnostic quality. Geographical area, population age, study setting and year of study also contributed to risk of PCP. Co-infection was common (444 episodes/1425 PCP cases), frequently with virulent organisms. The predictive value of symptoms, signs or simple tests in LMIC settings for diagnosis of PCP was poor. Case fatality was >30%; treatment was largely appropriate. Prophylaxis appeared to reduce the risk for development of PCP, however 24% of children with PCP were receiving prophylaxis. CD4 counts at presentation with PCP were usually <200×10^3/ml.

Conclusions

There is a positive relationship between GDP and risk of PCP diagnosis. Although failure to diagnose infection in poorer countries may contribute to this, we also hypothesise that poverty exposes at-risk patients to a wide range of infections and that the relatively non-pathogenic P. jirovecii is therefore under-represented. As LMIC develop economically they eliminate the conditions underlying transmission of virulent infection: P. jirovecii, ubiquitous in all settings, then becomes a greater relative threat.

An evaluation of the emerging vaccines and immunotherapy against staphylococcal pneumonia in children

Background

Staphylococcus aureus is a commensal of human skin and nares. It is also one of the leading nosocomial pathogens in both developed and developing countries and is responsible for a wide range of life threatening infections, especially in patients who are immunocompromised, post-surgery, undergoing haemodialysis and those who are treated with catheters and ventilators. Over the past two decades, the incidence of nosocomial staphylococcal infections has increased dramatically. Currently there are at least seven vaccine and immunotherapy candidates against S. aureus in the developmental phase targeting both active and passive immunization.

Methods

We used a modified CHNRI methodology for setting priorities in health research investments. This was done in two stages. In Stage I, we systematically reviewed the literature related to emerging vaccines against Staphylococcus aureus relevant to several criteria of interest: answerability; cost of development, production and implementation; efficacy and effectiveness; deliverability, affordability and sustainability; maximum potential impact on disease burden reduction; acceptability to the end users and health workers; and effect on equity. In Stage II, we conducted an expert opinion exercise by inviting 20 experts (leading basic scientists, international public health researchers, international policy makers and representatives of pharmaceutical companies) to participate. The policy makers and industry representatives accepted our invitation on the condition of anonymity, due to sensitive nature of their involvement in such exercises. They answered questions from CHNRI framework and their “collective optimism” towards each criterion was documented on a scale from 0 to 100%.

Results

The panel of experts expressed low levels of optimism (score around or below 50%) on the criteria of answerability, efficacy, maximum disease burden reduction potential, low cost of production, low cost of implementation and affordability; moderate levels of optimism (scores around 60 to 80%) that these vaccines could be developed at a low cost, and thus on the deliverability, sustainability and impact on equity; and high levels of optimism (scores above 80%) regarding acceptable of such a product to both the end-users and health workers. While assessing the candidates for passive immunization against S.aureus, the experts were poorly optimistic regarding low production cost, low implementation cost, efficacy, deliverability, sustainability, affordability and equity; moderately optimistic regarding answerability and acceptability to health workers and end-users. They were of the opinion that these interventions would have only a modest impact (3 to 5%) on the burden of childhood pneumonia. .

Conclusion

In order to provide an effective vaccine against S. aureus, a number of unresolved issues in vaccine development relating to optimal antigenic target identification, criteria for acceptable efficacy, identification of target population, commercial development limitations, optimal timing of immunization strategy, storage, cold chain requirements and cost need to be addressed properly. There is still a great deal unknown about the complex interaction between S. aureus and the human host. However, given the nature of S. aureus and the lessons learned from the recent failure of two emerging vaccines, it is clear that a multi-component vaccine is essential. Combating only one virulence factor is not sufficient in the human host but finding the right combination of factors will be very challenging.

The prevalence of hypoxaemia among ill children in developing countries: a systematic review

Hypoxaemia is a common complication of childhood infections, particularly acute lower respiratory tract infections. In pneumonia-a disease that disproportionately impacts developing countries, and accounts for more than two million deaths of children worldwide-hypoxaemia is a recognised risk factor for death, and correlates with disease severity. Hypoxaemia also occurs in severe sepsis, meningitis, common neonatal problems, and other conditions that impair ventilation and gas exchange or increase oxygen demands. Despite this, hypoxaemia has been overlooked in worldwide strategies for pneumonia control and reducing child mortality. Hypoxaemia is also often overlooked in developing countries, mainly due to the low accuracy of clinical predictors and the limited availability of pulse oximetry for more accurate detection and oxygen for treatment. In this Review of published and unpublished studies of acute lower respiratory tract infection, the median prevalence of hypoxaemia in WHO-defined pneumonia requiring hospitalisation (severe and very severe classifications) was 13%, but prevalence varied widely. This corresponds to at least 1.5 to 2.7 million annual cases of hypoxaemic pneumonia presenting to health-care facilities. Many more people do not access health care. With mounting evidence of the impact that improved oxygen systems have on mortality due to acute respiratory infection in limited-resource health-care facilities, there is a need for increased awareness of the burden of hypoxaemia in childhood illness.

Epidemiology and etiology of childhood pneumonia

Childhood pneumonia is the leading single cause of mortality in children aged less than 5 years. The incidence in this age group is estimated to be 0.29 episodes per child-year in developing and 0.05 episodes per child-year in developed countries. This translates into about 156 million new episodes each year worldwide, of which 151 million episodes are in the developing world. Most cases occur in India (43 million), China (21 million) and Pakistan (10 million), with additional high numbers in Bangladesh, Indonesia and Nigeria (6 million each). Of all community cases, 7-13% are severe enough to be life-threatening and require hospitalization. Substantial evidence revealed that the leading risk factors contributing to pneumonia incidence are lack of exclusive breastfeeding, undernutrition, indoor air pollution, low birth weight, crowding and lack of measles immunization. Pneumonia is responsible for about 19% of all deaths in children aged less than 5 years, of which more than 70% take place in sub-Saharan Africa and south-east Asia. Although based on limited available evidence, recent studies have identified Streptococcus pneumoniae, Haemophilus influenzae and respiratory syncytial virus as the main pathogens associated with childhood pneumonia.

Radiographic features of paediatric pneumocystis pneumonia -- a historical perspective

AIM

To determine differences between the plain radiographic features of paediatric pneumocystis pneumonia (PCP) recorded before the emergence of human immunodeficiency virus (HIV) in 1982 and those documented in the HIV era. To establish differences in the radiographic features of PCP documented in HIV-infected children in developed and developing countries.

METHOD

A Medline search of articles was conducted from 1950 to 2006, using the terms "pneumocystis pneumonia in children" and "chest radiographic features" or "bilateral opacification" or "lobar consolidation" or "asymmetrical opacification" or "pneumatocoeles" or "cavities" or "pneumothorax" or "pneumomediastinum" or "pleural effusion" or "mediastinal adenopathy" or "nodules" or "normal chest radiography". Appropriate articles were retrieved, radiological data extracted, reference lists examined and hand searches of referenced articles conducted.

RESULTS

Diffuse bilateral "ground-glass" or alveolar pulmonary opacification, which may show some asymmetry, has been consistently documented as the commonest radiographic finding in childhood PCP throughout the period under review. The less common radiological features of PCP in children are similar to those in adults. In developed countries, PCP-related pulmonary air cysts have been reported at an earlier age in HIV-infected children, compared with uninfected children. PCP-related air cysts, pneumothorax, and pneumomediastinum have been reported in children in developed but not in developing countries.

CONCLUSION

The radiological features of paediatric PCP documented before the HIV epidemic are similar to those recorded in the HIV era. Further study of the determinants of the uncommon radiographic features in children is warranted.

Pneumocystis carinii pneumonia in patients in the developing world who have acquired immunodeficiency syndrome

We review Pneumocystis carinii pneumonia (PCP) in patients in the developing world (i.e., Africa, Asia, the Philippines, and Central and South America) who have acquired immunodeficiency disease (AIDS). During the first decade of the AIDS pandemic, PCP rarely occurred in African adults. More recent reports have noted that PCP comprises a significantly greater percentage of cases of pneumonia than it did in the past. This trend dramatically contrasts with that observed in industrialized nations, where a reduction in the number of cases of PCP has occurred as a result of the widespread use of primary P. carinii prophylaxis and highly active antiretroviral therapy. Throughout the developing world, the rate of coinfection with Mycobacterium tuberculosis and PCP is high, ranging from 25% to 80%. Initiation of treatment when PCP is in an advanced stage may account for the high mortality rates (20%-80%) associated with pediatric PCP in the developing world.

Lung diseases at necropsy in African children dying from respiratory illnesses: a descriptive necropsy study

BACKGROUND

Accurate information about specific causes of death in African children dying of respiratory illnesses is scarce, and can only be obtained by autopsy. We undertook a study of children who died from respiratory diseases at University Teaching Hospital, Lusaka, Zambia.

METHODS

137 boys (93 HIV-1-positive, 44 HIV-1-negative], and 127 girls (87 HIV-1-positive, 40 HIV-1-negative) aged between 1 month and younger than 16 years underwent autopsy restricted to the chest cavity. Outcome measures were specific lung diseases, stratified by age and HIV-1 status.

FINDINGS

The presence of multiple diseases was common. Acute pyogenic pneumonia (population-adjusted prevalence 39.1%, 116/264), Pneumocystis carinii pneumonia (27.5%, 58/264), tuberculosis (18.8%, 54/264), and cytomegalovirus infection (CMV, 20.2%, 43/264) were the four most common findings overall. The three most frequent findings in the HIV-1-negative group were acute pyogenic pneumonia (50%), tuberculosis (26%), and interstitial pneumonitis (18%); and in the HIV-1-positive group were acute pyogenic pneumonia (41%), P carinii pneumonia (29%), and CMV (22%). HIV-1-positive children more frequently had P carinii pneumonia (odds ratio 5.28, 95% CI 2.12-15.68, p=0.0001), CMV (7.71, 2.33-40.0, p=0.0002), and shock lung (4.15, 1.20-22.10, p=0.03) than did HIV-1-negative children. 51/58 (88%) cases of P carinii pneumonia were in children younger than 12 months, and five in children aged over 24 months. Tuberculosis was common in all age groups, irrespective of HIV-1 status.

INTERPRETATION

Most children dying from respiratory diseases have preventable or treatable infectious illnesses. The presence of multiple diseases might make diagnosis difficult. WHO recommendations should therefore be updated with mention of HIV-1-positive children. Improved diagnostic tests for bacterial pathogens, tuberculosis, and P carinii pneumonia are urgently needed.

Immunologic aspects of tropical lung disease

Respiratory tract infections are a major cause of morbidity and mortality in adults and children worldwide. Because of its anatomical features, which allow gaseous exchange, the respiratory tract is constantly exposed to the outer environment and to the systemic and pulmonary circulation, which may allow infectious microbes, toxins, allergens, dust, and other antigens to enter the lung. The human host is a perpetual battleground between the body's immune system and invading antigens, whether they are microorganisms, chemicals, or cancer cells. Although a vast amount of literature is accumulating on the subject of immune responses to pathogens, the mechanisms underlying specific immunity to many organisms remain unknown. Paradoxically, while the immune response has evolved to confer protection against invading antigens, much human pathology arises when the immune responses are evoked.

Epidemiologic and clinical features of HIV-infected and HIV-uninfected Ugandan children younger than 18 months

METHODS

Groups of HIV-infected and HIV-uninfected infants younger than 18 months (mainly younger than 6 months) were compared to identify clinical features that could differentiate the two groups. The HIV-infected group also was compared with HIV-infected children older than 18 months. Recruitment was as follows for the group younger than 18 months: 708 children admitted with sepsis and clinical features suggestive of HIV infection were screened for HIV1 and HIV2 by HIV enzyme-linked immunosorbent assay (ELISA), and polymerase chain reaction (PCR) was undertaken on all ELISA-seropositive blood samples (270). HIV infection was confirmed in 136 (19.2%), 438 (61.9%) were HIV-seronegative, 27 (3.8%) were HIV seroreverters, 36 (5.1%) were HIV-seropositive but PCR negative (uninfected), and 71 (10.0%) were indeterminate. One hundred thirty-six HIV-infected children were compared with 501 uninfected children. Confirmed HIV-infected children older than 18 months attending the pediatric HIV clinic were compared with the 136 HIV-infected children younger than 18 months.

RESULTS

Under 18 months, the median age of HIV-infected children (n = 136) was 4.0 months (range, 3 d -18 mo ) and the median age of the uninfected children (n = 501) was 1.0 month (range, 3 d -18 mo ). HIV-infected children were more likely to have had injections, chloroquine, and nystatin, and to have attended a health center or hospital (p <.001). In the HIV-infected group, the Z score for weight-for-age was -1.75, length-for-age -0.78, and weight-for-length 1.86, significantly lower scores than those of the uninfected group, which were -0.60, -0.23, and 3.05, respectively (p <.05). The mean head circumference was below the third percentile in 40% of HIV-infected compared with 22% of uninfected children (p <.001). Overall, 56 (8%) children had marasmus, 6 (0.8%) kwashiorkor, and 3 (0.4%) marasmic kwashiorkor. Sixteen percent of the HIV-infected and 7% of uninfected children had marasmus (p <.05). The 1989 revised World Health Organization clinical criteria for diagnosis of AIDS had sensitivity, specificity, and positive predictive values of 28%, 98%, and 93%, respectively. Older than 18 months (n = 109), the median age was 24 months (range, 18-60 mo ). The following were significantly more common in HIV-infected children older than 18 months than in those younger than 18 months: bacille Calmette-Guérin vaccination scar, parotid enlargement, nonspecific generalized dermatitis, and chronic diarrhea ( p <.001). Oral candidiasis was more common in the group younger than 18 months (p <.001). In infants examined in the hospital for infective conditions, oropharyngeal candidiasis, ear discharge, dermatologic disorders, generalized lymphadenopathy, lobar consolidation, hepatosplenomegaly, and failure to thrive, especially marasmus, were important indicators of HIV infection.

Pneumocystis carinii pneumonia in patients being registered for smear-negative pulmonary tuberculosis in Malawi

The National TB Control Programme of Malawi registers and treats large numbers of patients with chronic cough for smear-negative pulmonary tuberculosis (PTB). Smear-negative PTB is diagnosed according to clinical and radiographic criteria, as mycobacterial cultures are not routinely available. In an area of high HIV seroprevalence there is a concern that other opportunistic infections apart from TB, such as Pneumocystis carinii, may be missed owing to lack of diagnostic facilities. The aims of this study were to investigate (i) the extent of P. carinii pneumonia (PCP) in patients about to be registered for smear-negative PTB; (ii) whether there were any clinical or radiological features that could help identify PCP in the absence of more detailed investigations; and (iii) the treatment outcome of PCP patients. A cohort of 352 patients who were about to be started on treatment for smear-negative PTB were investigated further in 1997-99 by clinical assessment, HIV testing and bronchoscopy. HIV sero-prevalence was 89% (278/313). A total of 186 patients underwent bronchoscopy and bronchoalveolar lavage, and PCP was diagnosed by indirect immunofluorescence or polymerase chain reaction in 17 (9%) of this subgroup. Dyspnoea was significantly more common in PCP cases compared to non-PCP cases (RR 1.35; 95% CI 1.24-1.48; P = 0.008), but discrimination between the groups was difficult using clinical criteria alone. The outcome of PCP cases was poor despite management with high-dose co-trimoxazole and secondary co-trimoxazole prophylaxis, with a median survival of 4 months (25-75% range: 2-12 months).

Fatal Pneumocystis carinii pneumonia in HIV-seropositive infants in Harare, Zimbabwe

Lung biopsies taken post mortem from 24 HIV-seropositive children who died of pneumonia in Harare Hospital (Zimbabwe) during 1995 were examined for pathogens using histology, culture, microscopy and polymerase chain reaction (PCR). Pneumocystis carinii was detected in 16 (67%) children, in 5 of whom bacterial pathogens were also detected. There were 2 cases of cytomegalovirus infection. On the basis of histology and PCR, none of the children had tuberculosis. These data add to the evidence that P. carinii pneumonia may be a significant cause of death in HIV-infected children in southern Africa. Policies on treatment for severe pneumonia, and on prophylaxis for children born to HIV-seropositive mothers need to be re-examined.

Pneumocystis carinii pneumonia in South African children infected with human immunodeficiency virus

BACKGROUND

Pneumocystis carinii pneumonia (PCP) has been regarded as uncommon in HIV-infected patients in Africa, but diagnostic difficulties and geographic variability may partly account for this. There is little information on the incidence of PCP in HIV-infected children in Africa.

AIM

To investigate (1) the incidence and associated features of PCP in African HIV-infected children and (2) the usefulness of sputum induction and nasopharyngeal aspirates (NPAs) for diagnosis of PCP.

METHODS

HIV-infected children hospitalized with pneumonia were prospectively enrolled in a 1-year study in South Africa. History, examination, chest radiology and blood tests (including HIV testing) were performed. Sputum induction (5% NaCl nebulization) or nondirected bronchoalveolar lavage in intubated patients was performed for P. carinii identification using immunofluorescence and silver stain; immunofluorescence was also done on nasopharyngeal aspirates (NPAs).

RESULTS

Of 151 HIV-infected children [47% female; median age, 9 (range, 3 to 23) months], 87 had been previously diagnosed with HIV whereas 64 (42.4%) were found to be HIV-positive at the time of admission. PCP occurred in 15 children (9.9%; 95% confidence interval, 5.9 to 15.5) and was the AIDS-defining infection in 13 of 64 (20.3%; 95% confidence interval, 11.8 to 31.5). Only 1 of 59 children receiving prophylaxis (1.7%) developed PCP compared with 14 of 92 (15.2%) not taking prophylaxis [relative risk, 0.11 (0.02 to 0.82), P = 0.007]. PCP-infected children were younger [3 (range, 3 to 4) vs. 10 (range, 4 to 24) months, P < 0.001] and presented with more severe pulmonary disease as indicated by a higher respiratory rate [63 (range, 60 to 73) vs. 50, (range, 40 to 60) P < 0.001], heart rate [160 (range, 136-180) vs. 140 (range, 120-152) P = 0.025] and a greater incidence of cyanosis (53% vs. 26%, P = 0.025). Clinical signs of HIV infection, occurring in 96% of children, were equally prevalent in both groups. High serum lactate dehydrogenase was the only laboratory investigation that distinguished PCP-infected from uninfected children [626 (range, 450 to 1098) vs. 307 (range, 243 to 465) units/l], P < 0.001. No radiologic features were found to be diagnostic of PCP. P. carinii was identified in 9 sputa and 6 bronchoalveolar lavage specimens, but all corresponding NPAs were negative. Seven of 15 (47%) children with PCP died while hospitalized compared with 24 of 136 (18%) without PCP [relative risk, 1.21 (range, 0.99 to 1.47), P = 0.008].

CONCLUSION

PCP is an important pathogen in HIV-infected infants in South Africa and is associated with a high mortality. Induced sputum is effective for obtaining lower respiratory tract secretions for diagnosis of PCP but an NPA is not useful.

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.

Persistent and chronic lung disease in HIV-1 infected and uninfected African children

OBJECTIVE

The causes of persistent lung disease (PLD) and chronic lung disease (CLD) are unknown in HIV-infected children in developing countries. We describe the causes and course of PLD and CLD in HIV-infected and uninfected children.

METHOD

Of 194 children with lung disease persisting for at least 1 month who were seen at the paediatric respiratory clinic over a 2-year period, 42 underwent invasive investigations after failed initial management over 3 months. PLD was defined as the presence of clinical and radiological features of lung disease for more than 1 month, and CLD as these features for more than 3 months.

RESULTS

One hundred and thirty-eight (71%) of the 194 children with PLD were HIV-infected, 52 (27%) were not infected and four (2%) were of undetermined HIV status. Forty-eight per cent of the HIV-infected children and 52% of the HIV-uninfected children responded to initial treatment over 3 months; the presumptive diagnoses in these were tuberculosis, interstitial pneumonitis, bronchiectasis and post-ventilation lung syndrome. Of the 28 HIV-infected children with CLD who underwent invasive investigations 16 (57%) had lymphoid interstitial pneumonitis, eight (29%) had tuberculosis and four (14%) had non-specific interstitial pneumonitis. Of the 14 HIV-uninfected children with CLD who had invasive testing there were four cases (29%) each of tuberculosis and interstitial pneumonitis, three (22%) cases of bronchiectasis and one case of each of extrinsic allergic alveolitis, crytogenic fibrosing alveolitis and non-Hodgkin's lymphoma.

CONCLUSION

This is the first set of data on the causes of CLD in HIV-infected children in a developing country. Every effort should be made to identify the infectious agent, whether M. tuberculosis or a secondary bacterial infection in LIP, in order to treat most appropriately these children with lung disease.