Imelda Bates

Severe Anemia in Malawian Children

BACKGROUND Severe anemia is a major cause of sickness and death in African children, yet the causes of anemia in this population have been inadequately studied. METHODS We conducted a case-control study of 381 preschool children with severe anemia (hemoglobin concentration, <5.0 g per deciliter) and 757 preschool children without severe anemia in urban and rural settings in Malawi. Causal factors previously associated with severe anemia were studied. The data were examined by multivariate analysis and structural equation modeling. RESULTS Bacteremia (adjusted odds ratio, 5.3; 95% confidence interval [CI], 2.6 to 10.9), malaria (adjusted odds ratio, 2.3; 95% CI, 1.6 to 3.3), hookworm (adjusted odds ratio, 4.8; 95% CI, 2.0 to 11.8), human immunodeficiency virus infection (adjusted odds ratio, 2.0; 95% CI, 1.0 to 3.8), the G6PD(-202/-376) genetic disorder (adjusted odds ratio, 2.4; 95% CI, 1.3 to 4.4), vitamin A deficiency (adjusted odds ratio, 2.8; 95% CI, 1.3 to 5.8), and vitamin B12 deficiency (adjusted odds ratio, 2.2; 95% CI, 1.4 to 3.6) were associated with severe anemia. Folate deficiency, sickle cell disease, and laboratory signs of an abnormal inflammatory response were uncommon. Iron deficiency was not prevalent in case patients (adjusted odds ratio, 0.37; 95% CI, 0.22 to 0.60) and was negatively associated with bacteremia. Malaria was associated with severe anemia in the urban site (with seasonal transmission) but not in the rural site (where malaria was holoendemic). Seventy-six percent of hookworm infections were found in children under 2 years of age. CONCLUSIONS There are multiple causes of severe anemia in Malawian preschool children, but folate and iron deficiencies are not prominent among them. Even in the presence of malaria parasites, additional or alternative causes of severe anemia should be considered.

Vulnerability to malaria, tuberculosis, and HIV/AIDS infection and disease. Part 1: determinants operating at individual and household level

A high burden of malaria, tuberculosis, and HIV infection contributes to national and individual poverty. We have reviewed a broad range of evidence detailing factors at individual, household, and community levels that influence vulnerability to malaria, tuberculosis, and HIV infection and used this evidence to identify strategies that could improve resilience to these diseases. This first part of the review explores the concept of vulnerability to infectious diseases and examines how age, sex, and genetics can influence the biological response to malaria, tuberculosis, and HIV infection. We highlight factors that influence processes such as poverty, livelihoods, gender discrepancies, and knowledge acquisition and provide examples of how approaches to altering these processes may have a simultaneous effect on all three diseases.

Malaria and urbanization in sub-Saharan Africa

There are already 40 cities in Africa with over 1 million inhabitants and the United Nations Environmental Programme estimates that by 2025 over 800 million people will live in urban areas. Recognizing that malaria control can improve the health of the vulnerable and remove a major obstacle to their economic development, the Malaria Knowledge Programme of the Liverpool School of Tropical Medicine and the Systemwide Initiative on Malaria and Agriculture convened a multi-sectoral technical consultation on urban malaria in Pretoria, South Africa from 2nd to 4th December, 2004. The aim of the meeting was to identify strategies for the assessment and control of urban malaria. This commentary reflects the discussions held during the meeting and aims to inform researchers and policy makers of the potential for containing and reversing the emerging problem of urban malaria.

Vulnerability to malaria, tuberculosis, and HIV/AIDS infection and disease. Part II: determinants operating at environmental and institutional level

This review summarises a wide range of evidence about environmental and institutional factors that influence vulnerability to malaria, tuberculosis, and HIV infection. By combining this information with that obtained on factors operating at individual, household, and community level, we have identified potential common strategies for improving resilience to all three diseases simultaneously. These strategies depend on collaborations with non-health sectors and include progress in rapid access to funds, provision of education about disease transmission and management, reduction of the burden on carers (predominantly women), and improvement in the quality of health services.

Improving the accuracy of malaria-related laboratory tests in Ghana

BackgroundInaccurate malaria results can lead to patient mismanagement, misperceptions about malaria resistance patterns and public health misinformation. All laboratories need to be able to demonstrate that their results are accurate. Establishing and maintaining a system for monitoring test accuracy is a complex, expensive and technically demanding process, which very few poor countries have been able to implement. This study described the process and assessed the feasibility of establishing a nation-wide system for improving the accuracy of malaria-related tests in peripheral laboratories in Ghana.Programme implementationA baseline survey of all 693 laboratory staff in 205 sub-regional government and mission health laboratories in Ghana was conducted by a national network of laboratory supervisors. Survey results guided a training programme to improve test accuracy. Outcomes included changes in the quality of laboratory tests and the system was considered to be feasible if >50% of laboratory staff in each region received training and if test accuracy could be documented.Programme indicators74% (mean) of the 693 laboratory staff were assistants with no professional qualifications. There were marked differences between regions in the availability of essential resources for malaria diagnosis (e.g. microscopes). 93% of laboratory staff received training; in six months there were increases of 11% and 7% respectively in the number of laboratories producing haemoglobin and malaria microscopy results of acceptable quality.ConclusionsIt is possible to establish a system for improving and monitoring test accuracy in peripheral laboratories on a country-wide basis in a developing country using a model that could be adapted for use in other countries and for other components of health care provision.

Eosinophilia in returning travellers and migrants from the tropics: UK recommendations for investigation and initial management.

Eosinophilia is a common finding in returning travellers and migrants, and in this group it often indicates an underlying helminth infection. Infections are frequently either asymptomatic or associated with non-specific symptoms, but some can cause severe disease. Here the British Infection Society guidelines group reviews common and serious infectious causes of eosinophilia, and outlines a scheme for investigating returning travellers and migrants. All returning travellers and migrants with eosinophilia should be investigated with concentrated stool microscopy and strongyloides serology, in addition to tests specific to the region they have visited. Terminal urine microscopy and serology for schistosomiasis should also be performed in those returning from Africa. Eosinophilia is also a feature of significant non-infective conditions, which should be considered.

Transfusion-Transmitted Malaria in Countries Where Malaria Is Endemic: A Review of the Literature from Sub-Saharan Africa

Although international policies recommend that blood for transfusion should be screened for transfusion-transmitted infections, malaria screening is not performed in most malaria-endemic countries in sub-Saharan Africa. Our literature review identified 17 relevant studies from the period 1980-2009 and indicated that the median prevalence of malaria among 33,029 blood donors was 10.2% (range, 0.7% in Kenya to 55.0% in Nigeria). Malaria screening methods, including microscopy (used in 16 of 17 studies), are either insensitive or impractical for donor screening in resource-poor countries. Even if a suitable screening method were available, rejection of malaria-positive donors would jeopardize the blood supply. Only 1 study established the prevalence of parasitemia among transfusion recipients. This review highlights the need for more evidence about the clinical impact of transfusion-transmitted malaria to justify the policy of screening for blood for malaria in areas of endemicity and for a critical analysis of the feasibility of implementing such a policy and its effect on blood supply.

HIV-associated anemia in children: a systematic review from a global perspective

Objectives:To assess the importance of anemia in HIV-infected children in western and tropical settings. Design:A systematic review with a descriptive component. Methods:Four databases were searched and reference lists of pertinent articles were checked. Studies that reported data on anemia or hemoglobin levels in HIV-infected children were selected and grouped according to the location and the definition of anemia. Results:Thirty-six studies met the inclusion criteria. Mild (hemoglobin <11 g/dl) and moderate (hemoglobin <9 g/dl) anemia were more prevalent with HIV infection (odds ratio 4.5; 95% confidence interval 2.5–8.3 and odds ratio 4.5; 95% confidence interval 2.0–10.3, respectively). Mean hemoglobin levels were lower (standardized mean difference; 0.79; 95% confidence interval 0.47–1.10). These differences were observed in both western and tropical settings. Anemia incidence ranged from 0.41 to 0.44 per person-year. There was limited data on more severe anemia (hemoglobin <7 or <5 g/dl). As anemia was frequently identified as an independent risk factor for disease progression and death, we next reviewed the limited data to formulate better strategies. Failure of erythropoiesis was the most important mechanism for anemia in HIV-infected children. Therapeutic options include highly active antiretroviral therapy and prevention or treatment of secondary infections. Erythropoietin can improve anemia in children, but it has not been evaluated in developing countries. Micronutrient supplementation may be helpful in individual children. The potential benefits or risks of iron supplementation in HIV-infected children require evaluation. Conclusion:Anemia is a very common complication of pediatric HIV infection, associated with a poor prognosis. With the increasing global availability of highly active antiretroviral therapy, more data on the safety and efficacy of possible interventions in children are urgently needed.

New cut-off values for ferritin and soluble transferrin receptor for the assessment of iron deficiency in children in a high infection pressure area

Background: Due to the potential risk of iron supplementation in iron replete children, it is important to properly identify children who may require iron supplementation. However, assessment of the iron status has proven to be difficult, especially in children living in areas with high infection pressure (including malaria). Aims and Methods: Biochemical iron markers were compared to bone marrow iron findings in 381 Malawian children with severe anaemia. Results: Soluble transferrin receptor/log ferritin (TfR-F index), using a cut-off of 5.6, best predicted bone marrow iron stores deficiency (sensitivity 74%, specificity 73%, accuracy 73%). In order to improve the diagnostic accuracy of ferritin or sTfR as a stand-alone marker, the normal cut-off value needed to be increased by 810% and 83% respectively. Mean cell haemoglobin concentration (MCHC), using a cut-off of 32.1 g/dl, had a sensitivity of 67% and specificity of 64% for detecting iron stores deficiency. Conclusion: TfR-F index incorporated the high sensitivity of sTfR, a proxy for cellular iron need, and the high specificity of ferritin, a proxy for iron stores. In areas with a high infection pressure, the TfR-F index best predicted iron deficiency. However, in settings where diagnostic tests are limited, MCHC may be an acceptable alternative screening test.

Urban malaria and anaemia in children: a cross-sectional survey in two cities of Ghana.

Objective  To describe the epidemiology of urban malaria, an emerging problem in sub‐Saharan Africa.