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BACKGROUND: There are few epidemiologic data on invasive bacterial infections among children in sub-Saharan Africa. We studied every acute pediatric admission to a rural district hospital in Kenya to examine the prevalence, incidence, types, and outcome of community-acquired bacteremia. METHODS: Between August 1998 and July 2002, we cultured blood on admission from 19,339 inpatients and calculated the incidence of bacteremia on the basis of the population served by the hospital. RESULTS: Of a total of 1783 infants who were under 60 days old, 228 had bacteremia (12.8 percent), as did 866 of 14,787 children who were 60 or more days of age (5.9 percent). Among infants who were under 60 days old, Escherichia coli and group B streptococci predominated among a broad range of isolates (14 percent and 11 percent, respectively). Among infants who were 60 or more days of age, Streptococcus pneumoniae, nontyphoidal salmonella species, Haemophilus influenzae, and E. coli accounted for more than 70 percent of isolates. The minimal annual incidence of community-acquired bacteremia was estimated at 1457 cases per 100,000 children among infants under a year old, 1080 among children under 2 years, and 505 among children under 5 years. Of all in-hospital deaths, 26 percent were in children with community-acquired bacteremia. Of 308 deaths in children with bacteremia, 103 (33.4 percent) occurred on the day of admission and 217 (70.5 percent) within two days. CONCLUSIONS: Community-acquired bacteremia is a major cause of death among children at a rural sub-Saharan district hospital, a finding that highlights the need for prevention and for overcoming the political and financial barriers to widespread use of existing vaccines for bacterial diseases.

BACKGROUND: Acute bacterial meningitis (ABM) is an important cause of mortality in Africa, but most studies are based in urban referral hospitals. Poor laboratory facilities make diagnosis difficult, and treatment is limited to inexpensive antibiotics. METHODS: We retrospectively reviewed data from children admitted with ABM to a Kenyan district hospital from 1994 through 2000. We calculated the minimum incidence in children admitted from a defined area. We also examined the antibiotic susceptibility patterns. RESULTS: We identified 390 cases (1.3% of all admissions) of whom 88% were

Despite the frequent association of respiratory symptoms and signs with malarial morbidity and mortality in sub-Saharan Africa, the value of individual symptoms and signs has rarely been assessed. We have prospectively examined the association of individual clinical findings with the summary diagnosis of respiratory distress, outcome, and the presence of metabolic acidosis in children admitted with severe malaria to a Kenyan district hospital. Respiratory distress was present in 119 of the 350 children included in the study and in 23 of the 30 deaths (relative risk = 6.5, 95% confidence interval = 2.8-14.4). The features of a history of dyspnea, nasal flaring, and indrawing or deep breathing (Kussmaul's respiration) were individually most closely associated with the summary diagnosis of respiratory distress. Of these, deep breathing, which was sensitive (91%) and specific (83%) for the presence of severe metabolic acidosis (base excess < or = -12), is the best candidate sign to represent the prognostically important syndrome of malarial respiratory distress. Therefore, it warrants further prospective evaluation in different clinical settings and areas of different malaria endemicity.

Summary Background Many investigators have suggested that malaria infection predisposes individuals to bacteraemia. We tested this hypothesis with mendelian randomisation studies of children with the malaria-protective phenotype of sickle-cell trait (HbAS). Methods This study was done in a defined area around Kilifi District Hospital, Kilifi, Kenya. We did a matched case-control study to identify risk factors for invasive bacterial disease, in which cases were children aged 3 months to 13 years who were admitted to hospital with bacteraemia between Sept 16, 1999, and July 31, 2002. We aimed to match two controls, by age, sex, location, and time of recruitment, for every case. We then did a longitudinal case-control study to assess the relation between HbAS and invasive bacterial disease as malaria incidence decreased. Cases were children aged 0–13 years who were admitted to hospital with bacteraemia between Jan 1, 1999, and Dec 31, 2007. Controls were born in the study area between Jan 1, 2006, and June 23, 2009. Finally, we modelled the annual incidence of bacteraemia against the community prevalence of malaria during 9 years with Poisson regression. Results In the matched case-control study, we recruited 292 cases—we recruited two controls for 236, and one for the remaining 56. Sickle-cell disease, HIV, leucocyte haemozoin pigment, and undernutrition were positively associated with bacteraemia and HbAS was strongly negatively associated with bacteraemia (odds ratio 0·36; 95% CI 0·20–0·65). In the longitudinal case-control study, we assessed data from 1454 cases and 10 749 controls. During the study period, the incidence of admission to hospital with malaria per 1000 child-years decreased from 28·5 to 3·45, with a reduction in protection afforded by HbAS against bacteraemia occurring in parallel (p=0·0008). The incidence of hospital admissions for bacteraemia per 1000 child-years also decreased from 2·59 to 1·45. The bacteraemia incidence rate ratio associated with malaria parasitaemia was 6·69 (95% CI 1·31–34·3) and, at a community parasite prevalence of 29% in 1999, 62% (8·2–91) of bacteraemia cases were attributable to malaria. Interpretation Malaria infection strongly predisposes individuals to bacteraemia and can account for more than half of all cases of bacteraemia in malaria-endemic areas. Interventions to control malaria will have a major additional benefit by reducing the burden of invasive bacterial disease. Funding Wellcome Trust.

Background: Malnutrition is common in the developing world and associated with disease and mortality. Because malnutrition frequently occurs among children in the community as well as those with acute illness, and because anthropometric indicators of nutritional status are continuous variables that preclude a single definition of malnutrition, malnutrition-attributable fractions of admissions and deaths cannot be calculated by simply enumerating individual children. Objective: We determined the malnutrition-attributable fractions among children admitted to a rural district hospital in Kenya, among inpatient deaths and among children with the major causes of severe disease. Design: We analyzed data from children between 6 and 60 mo of age, comprising 13 307 admissions, 674 deaths, 3068 admissions with severe disease, and 562 community controls by logistic regression, using anthropometric z scores as the independent variable and admission or death as the outcome, to calculate the probability of admission as a result of “true malnutrition” for individual cases. Probabilities were averaged to calculate attributable fractions. Results: Z scores < −3 were insensitive for malnutrition-attributable deaths and admissions, and no single threshold was both specific and sensitive. The overall malnutrition-attributable fraction for in-hospital deaths was 51% (95% CI: 42%, 61%) with midupper arm circumference. Similar malnutrition-attributable fractions were seen for the major causes of severe disease (severe malaria, gastroenteritis, lower respiratory tract infection, HIV, and invasive bacterial disease). Conclusions: Despite global improvements, malnutrition still underlies half of the inpatient morbidity and mortality rates among children in rural Kenya. This contribution is underestimated by using conventional clinical definitions of severe malnutrition.

Background Clinical trials of interventions designed to prevent severe falciparum malaria in children require a clear endpoint. The internationally accepted definition of severe malaria is sensitive, and appropriate for clinical purposes. However, this definition includes individuals with severe nonmalarial disease and coincident parasitaemia, so may lack specificity in vaccine trials. Although there is no “gold standard” individual test for severe malaria, malaria-attributable fractions (MAFs) can be estimated among groups of children using a logistic model, which we use to test the suitability of various case definitions as trial endpoints. Methods and Findings A total of 4,583 blood samples were taken from well children in cross-sectional surveys and from 1,361 children admitted to a Kenyan District hospital with severe disease. Among children under 2 y old with severe disease and over 2,500 parasites per microliter of blood, the MAFs were above 85% in moderate- and low-transmission areas, but only 61% in a high-transmission area. HIV and malnutrition were not associated with reduced MAFs, but gastroenteritis with severe dehydration (defined by reduced skin turgor), lower respiratory tract infection (clinician's final diagnosis), meningitis (on cerebrospinal fluid [CSF] examination), and bacteraemia were associated with reduced MAFs. The overall MAF was 85% (95% confidence interval [CI] 83.8%–86.1%) without excluding these conditions, 89% (95% CI 88.4%–90.2%) after exclusions, and 95% (95% CI 94.0%–95.5%) when a threshold of 2,500 parasites/μl was also applied. Applying a threshold and exclusion criteria reduced sensitivity to 80% (95% CI 77%–83%). Conclusions The specificity of a case definition for severe malaria is improved by applying a parasite density threshold and by excluding children with meningitis, lower respiratory tract infection (clinician's diagnosis), bacteraemia, and gastroenteritis with severe dehydration, but not by excluding children with HIV or malnutrition., The accepted definition of severe malaria is appropriate for clinical purposes, but Philip Bejon and colleagues show its specificity in clinical trials may be improved by a parasite density threshold and by excluding children with certain conditions., Editors' Summary Background. Malaria is responsible for over a million deaths every year, and most of those who die are children in Africa. Until a few years ago, not enough research was being done on malaria, but now many researchers are active in this field. Doctors describe some cases of malaria as being “severe.” Severe malaria in children is very hard to diagnose precisely. Current protocols for diagnosing severe malaria are very sensitive: that is, virtually all children who do have severe malaria will be correctly diagnosed as such. However, the protocols are not very specific: many children who do not have severe malaria, but whose symptoms are instead caused by other diseases, will be defined as suffering from severe malaria. This definition is acceptable for the clinical care of sick children, because it ensures that antimalarial drugs are given to all who might benefit from them, plus some additional children for whom those drugs are not required. However, this definition is not particularly useful for research purposes. When conducting a clinical trial aimed at preventing cases of malaria, it is important to evaluate whether the intervention being tested actually works. Therefore, a more specific method of calculating the number of malaria cases within a population is needed for this type of research. Why Was This Study Done? The current definition for diagnosing severe malaria includes a set of signs and symptoms that may be observed at the bedside or as a result of laboratory investigation, along with the detection of malaria parasites in the patient's blood. However, in many malarious areas, a large proportion of the population carries malaria parasites without signs of disease; at the same time, the signs and symptoms of malaria are shared with other diseases. The investigators here wanted to find out whether they could develop an accurate “case definition” of severe malaria that can be used in research. What Did the Researchers Do and Find? In this study, two groups of children were studied: first, 1,422 children admitted to the children's wards of the Kilifi District Hospital in Kenya, and second, 4,583 children from the surrounding community. Blood samples were taken in order to find out how common malaria parasites were in the children's blood, and standard clinical and laboratory data were also collected from the children admitted to the hospital. The researchers then compared these data using a computer and tried to find out whether, by excluding certain children who had particular signs, symptoms, or observations, from the diagnosis of severe malaria, they were able to improve the accuracy of their definition. Essentially, for each patient group, the authors calculated “malaria-attributable fractions,” i.e., the proportion of individuals studied whose disease was likely caused by malaria. The researchers found that in areas with low and moderate transmission of malaria, the proportion of individuals whose disease could be attributed to malaria was high—nearly 85%. In areas with a high transmission rate of malaria, this fraction was much lower, but could be improved by including only children with a high proportion of parasites in their blood. Importantly, the researchers were also able to increase the recognition of children with disease likely caused by malaria by excluding individuals who had also been diagnosed with gastroenteritis, lower respiratory tract infections, meningitis, and bacterial infection in the blood. If all of these individuals were excluded—so only individuals with more than 2,500 parasites per microliter in their blood were regarded as having severe malaria—the “malaria-attributable fraction” rose to 95%. What Do These Findings Mean? These findings should not be directly used to change the clinical care of children with the signs and symptoms of severe malaria, but rather can be used within a clinical trial to create a “case definition” of malaria particular to that trial. This ability will help researchers more accurately find out whether the intervention being tested in their trial really does help to prevent cases of malaria or not. Additional Information. Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0040251. The World Health Organization Global Malaria Programme details the organization's activities in fighting malaria, and provides a number of helpful resources; a factsheet on children and malaria is also available The US Centers for Disease Control and Prevention provides many malaria resources General information about malaria, including illustrations, is available from the“Medline Plus” encyclopedia

BACKGROUND: Nontyphoidal Salmonella spp. are among the leading causes of childhood bacteremia in sub-Saharan Africa, yet there are few published clinical series, and the risk factors for acquiring infection are not fully understood. METHODS: We examined data from 166 cases of nontyphoidal Salmonella bacteremia identified during a large prospective study of bacteremia among all children admitted to a district hospital in Kenya. We also investigated the importance of comorbidities, including current malaria parasitemia, recent malaria (detectable Plasmodium falciparum histidine rich protein 2 in the absence of parasitemia), sickle cell disease, malnutrition and human immunodeficiency virus (HIV) infection. RESULTS: Nontyphoidal Salmonella bacteremia was associated with severe malnutrition (33% cases), HIV infection (18% cases), a history of illness >7 days, recent hospital admission, splenomegaly, anemia and recent (but not current) malaria but was not associated with diarrhea. Seventy-seven (46%) children with nontyphoidal Salmonella bacteremia fulfilled World Health Organization clinical criteria for a diagnosis of pneumonia. Independent risk factors for death were diarrhea, tachypnea, HIV infection, severe malnutrition, meningitis and young age. CONCLUSIONS: Clinical diagnosis of invasive nontyphoidal Salmonella infection in African children is difficult without microbiology facilities because clinical features overlap with other conditions. The common risk factors for nontyphoidal Salmonella infection differ from developed countries, with high a prevalence of malnutrition, HIV, malaria and anemia. Children with nontyphoidal Salmonella infection who fulfill World Health Organization clinical criteria for severe pneumonia may receive ineffective therapy in the form of penicillin.

CONTEXT: Severe malnutrition has a high mortality rate among hospitalized children in sub-Saharan Africa. However, reports suggest that malnutrition is often poorly assessed. The World Health Organization recommends using weight for height, but this method is problematic and often not undertaken in practice. Mid upper arm circumference (MUAC) and the clinical sign "visible severe wasting" are simple and inexpensive methods but have not been evaluated in this setting. OBJECTIVES: To evaluate MUAC and visible severe wasting as predictors of inpatient mortality at a district hospital in sub-Saharan Africa and to compare these with weight-for-height z score (WHZ). DESIGN, SETTING, AND PARTICIPANTS: Cohort study with data collected at admission and at discharge or death. Predictive values for inpatient death were determined using the area under receiver operating characteristic curves. Participants were children aged 12 to 59 months admitted to a district hospital in rural Kenya between April 1, 1999, and July 31, 2002. MAIN OUTCOME MEASURE: MUAC, WHZ, and visible severe wasting as predictors of inpatient death. RESULTS: Overall, 4.4% (359) of children included in the study died while in the hospital. Sixteen percent (1282/8190) of admitted children had severe wasting (WHZ < or =-3) (n = 756), kwashiorkor (n = 778), or both. The areas under the receiver operating characteristic curves for predicting inpatient death did not significantly differ (MUAC: 0.75 [95% confidence interval, 0.72-0.78]; WHZ: 0.74 [95% confidence interval, 0.71-0.77]) (P = .39). Although sensitivity and specificity for subsequent inpatient death were 46% and 91%, respectively, for MUAC less than or equal to 11.5 cm, 42% and 92% for WHZ less than or equal to -3, and 47% and 93% for visible severe wasting, the 3 indices identified different sets of children and were independently associated with mortality. Clinical features of malnutrition were significantly more common among children with MUAC less than or equal to 11.5 cm than among those with WHZ less than or equal to -3. CONCLUSIONS: MUAC is a practical screening tool that performs at least as well as WHZ in predicting subsequent inpatient mortality among severely malnourished children hospitalized in rural Kenya. Visible severe wasting is also a potentially useful sign at this level, providing appropriate training has been given.

OBJECTIVES: To determine the pattern of resistance among Gram-negative bacilli causing invasive bacterial disease for the antibiotics that are already in common use in Kilifi, Kenya and for two potential alternatives, ciprofloxacin and cefotaxime. Also, to determine whether prevalence and severity of resistance was increasing over time, to identify patients who are particularly at risk of resistant infections, and to explore which factors are associated with the development of resistance in our setting. METHODS: We used Etest to study antibiotic susceptibility patterns of 90 Gram-negative bacilli cultured in blood or CSF from paediatric inpatients over 8 years. RESULTS: Susceptibility to amoxicillin 28%, cefotaxime 95% and ciprofloxacin 99% did not vary significantly with age. Susceptibilities for isolates from children aged less than 14 days were: chloramphenicol, 81%; trimethoprim/sulfamethoxazole, 71%; and gentamicin, 91%. From older children, susceptibilities were: chloramphenicol, 62%; trimethoprim/sulfamethoxazole, 39%; and gentamicin, 73%. Chloramphenicol susceptibility was significantly more common among non-typhi salmonellae than other species (79% versus 53%, P < 0.0005). The combination of gentamicin and chloramphenicol covered 91% of all isolates. The prevalence of resistance did not increase over time and was not more common in patients with HIV or malnutrition. Age was the only clinical feature that predicted resistance. CONCLUSIONS: Gentamicin or chloramphenicol alone was suboptimal therapy for Gram-negative sepsis, although in this retrospective study, there was no association between resistance and mortality.

Etest susceptibilities to amoxicillin, chloramphenicol, and trimethoprim-sulfamethoxazole of 240 invasive isolates of Haemophilus influenzae cultured from children in rural Kenya were 66%, 66%, and 38%, respectively. Resistance increased markedly over 9 years and was concentrated among serotype b isolates. In Africa, the increasing cost of treating resistant infections supports economic arguments for prevention through conjugate H. influenzae type b immunization.

Objective. Acute bacterial meningitis remains an important cause of death and neurologic sequelae in African children. The clinical features of meningitis are often nonspecific and in this setting may overlap with those of malaria. Early diagnosis and appropriate antibiotic treatment are perhaps the most important steps in management, but published data suggest that fewer than half of the cases of childhood meningitis are identified at first assessment in hospitals in this region. The objective of this study was to identify clinical indicators of acute bacterial meningitis by examining components of the World Health Organization Integrated Management of Childhood Illness (IMCI) referral criteria for meningitis (lethargy, unconsciousness, inability to feed, stiff neck, or seizures) and other symptoms and signs. Methods. Kilifi District Hospital, serving ∼200 000 people in a rural, malaria-endemic area of the Kenyan coast, was studied. A Kenya Medical Research Institute research center is located at the hospital. All pediatric admissions aged ≥60 days between June 2001 and July 2002 were eligible. Results. A total of 91 (2.0%) of 4582 admissions had meningitis, including 77 (4.0%) of 1929 of those who met the IMCI referral criteria for meningitis at admission (sensitivity: 85%; specificity: 59%). Independent indicators of the presence of meningitis were a bulging fontanel, neck stiffness, cyanosis, impaired consciousness, partial seizures, and seizures outside the febrile convulsions age range. One or more of these indicators was present in 895 (19%) of admissions, 72 (8.0%) of whom had meningitis (sensitivity: 79%; specificity: 80%). Independent indicators of the absence of meningitis were the absence of a history of fever, a history of diarrhea, and a positive malaria slide. The area under the receiver operating characteristic curve for a set of simple screening rules based on the positive indicators identified was 0.88 (95% confidence interval: 0.85–0.92). Conclusions. The presence of ≥1 of a bulging fontanel, neck stiffness, cyanosis, impaired consciousness, partial seizures, and seizures outside the febrile convulsions age range is a clear indication for lumbar puncture and/or presumptive treatment. However, careful observation and reassessment may be the only practical way to identify one fifth of meningitis cases in this setting.

Data collected from 200 children admitted to a hospital on the Kenyan coast who met a broad definition of severe acute respiratory infection (ARI) indicated that simple clinical signs alone are unable absolutely to distinguish severe ARI and severe malaria. However, laboratory data showed that marked differences exist in the pathophysiology of unequivocal malaria and unequivocal ARI. Children in the former group had a higher mean oxygen saturation (97 vs. 94, P < 0.001), mean blood urea level (5.3 vs. 1.9 mmol/L, P < 0.001) and geometric mean lactate level (4.5 vs. 2.1 mmol/L, P < 0.001), and lower mean haemoglobin level (5.3 vs. 9.0 g/dL, P < 0.001) and base excess (-9.4 vs. -2.6, P < 0.001) than those in the latter group. Using these discriminatory variables it was estimated that up to 45% of children admitted with respiratory signs indicative of severe ARI probably had malaria as the primary diagnosis. Radiological examination supported this conclusion, indicating that pneumonia characterized by consolidation was uncommon in children with respiratory signs and a high malarial parasitaemia (> or = 10,000/microliters). There is no specific radiological sign of severe malaria. In practice, all children with respiratory signs warranting hospital admission in a malaria endemic area should be treated for both malaria and ARI unless blood film examination excludes malaria. In those with malaria and clinical evidence of acidosis, but no crackles, antibodies may be withheld while appropriate treatment for dehydration and anaemia is given. However, if clinical improvement is not rapid, antibiotics should be started.

To the Editor .— Arias et al1 and Bell and Redelmeier2 recently identified associations between timing of admission and mortality rates in North America. Such studies highlight potential areas for improvement in health care delivery. Hospitals in less-developed countries are typically under-resourced and understaffed all of the time.3 However, similar to North America, there may be differences in health care delivery outside of office hours. We previously conducted a prospective study of 12 893 consecutive admissions of children ≥90 days old to our own district hospital in Kenya and developed prognostic scores for inpatient deaths occurring

CONTEXT: Haemophilus influenzae type b (Hib) conjugate vaccine is not perceived as a public health priority in Africa because data on Hib disease burden and vaccine effectiveness are scarce. Hib immunization was introduced in Kenyan infants in 2001. OBJECTIVE: To define invasive Hib disease incidence and Hib vaccine program effectiveness in Kenya. DESIGN, SETTING, AND PATIENTS: Culture-based surveillance for invasive Hib disease at Kilifi District Hospital from 2000 through 2005 was linked to demographic surveillance of 38,000 children younger than 5 years in Kilifi District, Kenya. Human immunodeficiency virus (HIV) infection and Hib vaccination status were determined for children with Hib disease admitted 2002-2005. INTERVENTIONS: Introduction of conjugate Hib vaccine within the routine childhood immunization program at ages 6, 10, and 14 weeks beginning November 2001. MAIN OUTCOME MEASURES: Incidence of culture-proven Hib invasive disease before and after vaccine introduction and vaccine program effectiveness. RESULTS: Prior to vaccine introduction, the median age of children with Hib was 8 months; case fatality was 23%. Among children younger than 5 years, the annual incidence of invasive Hib disease 1 year before and 1 and 3 years after vaccine introduction was 66, 47, and 7.6 per 100,000, respectively. For children younger than 2 years, incidence was 119, 82, and 16 per 100,000, respectively. In 2004-2005, vaccine effectiveness was 88% (95% confidence interval, 73%-96%) among children younger than 5 years and 87% (95% confidence interval, 66%-96%) among children younger than 2 years. Of 53 children with Hib admitted during 2002-2005, 29 (55%) were age-ineligible to have received vaccine, 12 (23%) had not been vaccinated despite being eligible, and 12 (23%) had received 2 or more doses of vaccine (2 were HIV positive). CONCLUSIONS: In Kenya, introduction of Hib vaccine into the routine childhood immunization program reduced Hib disease incidence among children younger than 5 years to 12% of its baseline level. This impact was not observed until the third year after vaccine introduction.

Summary Background In sub-Saharan Africa, community-acquired bacteraemia is an important cause of illness and death in children. Our aim was to establish the magnitude and causes of hospital-acquired (nosocomial) bacteraemia in African children. Methods We reviewed prospectively collected surveillance data of 33 188 admissions to Kilifi District Hospital, Kenya, between April 16, 2002, and Sept 30, 2009. We defined bacteraemia as nosocomial if it occurred 48 h or more after admission. We estimated the per-admission risk, daily rate, effect on mortality, and microbial cause of nosocomial bacteraemia and analysed risk factors by multivariable Cox regression. The effect on morbidity was measured as the increase in hospital stay by comparison with time-matched patients without bacteraemia. Findings The overall risk of nosocomial bacteraemia during this period was 5·9/1000 admissions (95% CI 5·2–6·9) but we recorded an underlying rise in risk of 27% per year. The incidence was 1·0/1000 days in hospital (0·87–1·14), which is about 40 times higher than that of community-acquired bacteraemia in the same region. Mortality in patients with nosocomial bacteraemia was 53%, compared with 24% in community-acquired bacteraemia and 6% in patients without bacteraemia. In survivors, nosocomial bacteraemia lengthened hospital stay by 10·1 days (3·0–17·2). Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus, Acinetobacter spp, group D streptococci, and Pseudomonas aeruginosa accounted for three-quarters of nosocomial infections. Nosocomial bacteraemia was significantly associated with severe malnutrition (hazard ratio 2·52, 95% CI 1·79–3·57) and blood transfusion in children without severe anaemia (4·99; 3·39–7·37). Interpretation Our findings show that although nosocomial bacteraemia is rare, it has serious effects on morbidity and mortality, and the microbiological causes are distinct from those of community-acquired bacteraemia. Nosocomial infections are largely unrecognised or undocumented as a health risk in low-income countries, but they are likely to become public health priorities as awareness of their occurrence increases and as other prominent childhood diseases are progressively controlled. Funding Wellcome Trust.