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Use WPMLThe plasma concentration of the B cell activating factor is increased in children with acute malaria
Malaria-specific antibody responses in children often appear to be short-lived but the mechanisms underlying this phenomenon are not well understood. In this study, we investigated the relationship between the B-cell activating factor (BAFF) and its receptors expressed on B cells with antibody responses during and after acute malaria in children. Our results demonstrate that BAFF plasma levels increased during acute malarial disease and reflected disease severity. The expression profiles for BAFF receptors on B cells agreed with rapid activation and differentiation of a proportion of B cells to plasma cells. However, BAFF receptor (BAFF-R) expression was reduced on all peripheral blood B cells during acute infection, but those children with the highest level of BAFF-R expression on B cells maintained schizont-specific immunoglobin G (IgG) over a period of 4 months, indicating that dysregulation of BAFF-R expression on B cells may contribute to short-lived antibody responses to malarial antigens in children. In summary, this study suggests a potential role for BAFF during malaria disease, both as a marker for disease severity and in shaping the differentiation pattern of antigen-specific B cells.
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Validating physician-certified verbal autopsy and probabilistic modeling (InterVA) approaches to verbal autopsy interpretation using hospital causes of adult deaths
BACKGROUND: The most common method for determining cause of death is certification by physicians based either on available medical records, or where such data are not available, through verbal autopsy (VA). The physician-certification approach is costly and inconvenient; however, recent work shows the potential of a computer-based probabilistic model (InterVA) to interpret verbal autopsy data in a more convenient, consistent, and rapid way. In this study we validate separately both physician-certified verbal autopsy (PCVA) and the InterVA probabilistic model against hospital cause of death (HCOD) in adults dying in a district hospital on the coast of Kenya. METHODS: Between March 2007 and June 2010, VA interviews were conducted for 145 adult deaths that occurred at Kilifi District Hospital. The VA data were reviewed by a physician and the cause of death established. A range of indicators (including age, gender, physical signs and symptoms, pregnancy status, medical history, and the circumstances of death) from the VA forms were included in the InterVA for interpretation. Cause-specific mortality fractions (CSMF), Cohen's kappa (kappa) statistic, receiver operating characteristic (ROC) curves, sensitivity, specificity, and positive predictive values were applied to compare agreement between PCVA, InterVA, and HCOD. RESULTS: HCOD, InterVA, and PCVA yielded the same top five underlying causes of adult deaths. The InterVA overestimated tuberculosis as a cause of death compared to the HCOD. On the other hand, PCVA overestimated diabetes. Overall, CSMF for the five major cause groups by the InterVA, PCVA, and HCOD were 70%, 65%, and 60%, respectively. PCVA versus HCOD yielded a higher kappa value (kappa = 0.52, 95% confidence interval [CI]: 0.48, 0.54) than the InterVA versus HCOD which yielded a kappa (kappa) value of 0.32 (95% CI: 0.30, 0.38). Overall, (kappa) agreement across the three methods was 0.41 (95% CI: 0.37, 0.48). The areas under the ROC curves were 0.82 for InterVA and 0.88 for PCVA. The observed sensitivities and specificities across the five major causes of death varied from 43% to 100% and 87% to 99%, respectively, for the InterVA/PCVA against the HCOD. CONCLUSION: Both the InterVA and PCVA compared well with the HCOD at a population level and determined the top five underlying causes of death in the rural community of Kilifi. We hope that our study, albeit small, provides new and useful data that will stimulate further definitive work on methods of interpreting VA data.
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Congenital and neonatal malaria in a rural Kenyan district hospital: an eight-year analysis
BACKGROUND: Malaria remains a significant burden in sub-Saharan Africa. However, data on burden of congenital and neonatal malaria is scarce and contradictory, with some recent studies reporting a high burden. Using prospectively collected data on neonatal admissions to a rural district hospital in a region of stable malaria endemicity in Kenya, the prevalence of congenital and neonatal malaria was described. METHODS: From 1st January 2002 to 31st December 2009, admission and discharge information on all neonates admitted to Kilifi District Hospital was collected. At admission, blood was also drawn for routine investigations, which included a full blood count, blood culture and blood slide for malaria parasites. RESULTS: Of the 5,114 neonates admitted during the eight-year surveillance period, blood slide for malaria parasites was performed in 4,790 (93.7%). 18 (0.35%) neonates with Plasmodium falciparum malaria parasitaemia, of whom 11 were admitted within the first week of life and thus classified as congenital parasitaemia, were identified. 7/18 (39%) had fever. Parasite densities were low,
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Invasive bacterial infections in neonates and young infants born outside hospital admitted to a rural hospital in Kenya
BACKGROUND: Bacterial sepsis is thought to be a major cause of young infant deaths in low-income countries, but there are few precise estimates of its burden or causes. We studied invasive bacterial infections (IBIs) in young infants, born at home or in first-level health units ("outborn") who were admitted to a Kenyan rural district hospital during an 8-year period. METHODS: Clinical and microbiologic data, from admission blood cultures and cerebrospinal fluid cultures on all outborn infants aged less than 60 days admitted from 2001 to 2009, were examined to determine etiology of IBI and antimicrobial susceptibilities. RESULTS: Of the 4467 outborn young infants admitted, 748 (17%) died. Five hundred five (11%) had IBI (10% bacteremia and 3% bacterial meningitis), with a case fatality of 33%. The commonest organisms were Klebsiella spp., Staphylococcus aureus, Streptococcus pneumoniae, Group B Streptococcus, Acinetobacter spp., Escherichia coli, and Group A Streptococcus. Notably, some blood culture isolates were seen in outborn neonates in the first week of life but not in inborns: Salmonella, Aeromonas, and Vibrio spp. Eighty-one percent of isolates were susceptible to penicillin and/or gentamicin and 84% to ampicillin and/or gentamicin. There was a trend to increasing in vitro antimicrobial resistance to these combinations from 2008 but without a worse outcome. CONCLUSIONS: IBI is common in outborn young infants admitted to rural African hospitals with a high mortality. Presumptive antimicrobial use is justified for all young infants admitted to the hospital.
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The prognostic value of dipstick urinalysis in children admitted to hospital with severe malnutrition
BACKGROUND: Children with severe malnutrition (SAM) present to hospital with an array of complications, resulting in high mortality despite adherence to WHO guidelines. Diagnostic resources in developing countries are limited and bedside tests could help identify high-risk children. Dipstick urinalysis is a bedside screening test for urinary tract infections (UTIs). UTIs are common in SAM and can lead to secondary invasive bacterial sepsis. Very few studies have examined the usefulness of dipstick screening of urine specimens in SAM and none has explored its prognostic value. PATIENTS AND METHODS: A 2-year prospective study on children admitted in Kilifi District Hospital, Kenya, with SAM. Freshly voided, clean catch urine samples were tested using Multistix reagent test strips. Positive samples were sent for culture. RESULTS: Of the 667 children admitted, 498 children (75%) provided urine samples; of these, 119 (24%) were positive for either leucocyte esterase (LE) or nitrites. Culture-proven UTI was detected in 28 children (6% overall). All isolates were coliforms and were >50% were resistant to cotrimoxazole and gentamicin. There was no difference in severity signs between those with positive dipstick and those without. Case fatality was higher among children with a positive dipstick (29% vs 12%). Presence of a positive dipstick was a strong predictor of mortality (adjusted HR 2.5). CONCLUSIONS: A urine dipstick positive for either LE or nitrites is a useful predictor of death in children admitted with SAM. Prospective studies to determine the role of untreated UTI in these deaths are needed before any treatment recommendations can be made.
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In vitro activities of piperaquine, lumefantrine, and dihydroartemisinin in Kenyan Plasmodium falciparum isolates and polymorphisms in pfcrt and pfmdr1
We have analyzed the in vitro chemosensitivity profiles of 115 Kenyan isolates for chloroquine (CQ), piperaquine, lumefantrine (LM), and dihydroartemisinin in association with polymorphisms in pfcrt at codon 76 and pfmdr1 at codon 86, as well as with variations of the copy number of pfmdr1. The median drug concentrations that inhibit 50% of parasite growth (IC(50)s) were 41 nM (interquartile range [IQR], 18 to 73 nM), 50 nM (IQR, 29 to 96 nM), 32 nM (IQR, 17 to 46 nM), and 2 nM (IQR, 1 to 3 nM) for CQ, LM, piperaquine, and dihydroartemisinin, respectively. The activity of CQ correlated inversely with that of LM (r(2) = -0.26; P = 0.02). Interestingly, parasites for which LM IC(50)s were higher were wild type for pfcrt-76 and pfmdr1-86. All isolates had one pfmdr1 copy. Thus, the decrease in LM activity is associated with the selection of wild-type pfcrt-76 and pfmdr1-86 parasites, a feature that accounts for the inverse relationship between CQ and LM. Therefore, the use of LM-artemether is likely to lead to the selection of more CQ-susceptible parasites.
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In vitro activities of piperaquine, lumefantrine, and dihydroartemisinin in Kenyan Plasmodium falciparum isolates and polymorphisms in pfcrt and pfmdr1
We have analyzed the in vitro chemosensitivity profiles of 115 Kenyan isolates for chloroquine (CQ), piperaquine, lumefantrine (LM), and dihydroartemisinin in association with polymorphisms in pfcrt at codon 76 and pfmdr1 at codon 86, as well as with variations of the copy number of pfmdr1. The median drug concentrations that inhibit 50% of parasite growth (IC(50)s) were 41 nM (interquartile range [IQR], 18 to 73 nM), 50 nM (IQR, 29 to 96 nM), 32 nM (IQR, 17 to 46 nM), and 2 nM (IQR, 1 to 3 nM) for CQ, LM, piperaquine, and dihydroartemisinin, respectively. The activity of CQ correlated inversely with that of LM (r(2) = -0.26; P = 0.02). Interestingly, parasites for which LM IC(50)s were higher were wild type for pfcrt-76 and pfmdr1-86. All isolates had one pfmdr1 copy. Thus, the decrease in LM activity is associated with the selection of wild-type pfcrt-76 and pfmdr1-86 parasites, a feature that accounts for the inverse relationship between CQ and LM. Therefore, the use of LM-artemether is likely to lead to the selection of more CQ-susceptible parasites.
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Hypothermia in children with severe malnutrition: low prevalence on the tropical coast of Kenya
Hypothermia is stated as a common complication of severe malnutrition although there are little primary data to support this. We performed a prospective study of children with severe acute malnutrition (SAM) admitted to a district hospital in Kenya. We documented the prevalence of hypothermia and examined its association with outcome and ambient temperature. During a 2-year period 667 children were recruited. Hypothermia was recorded in only 12 out of 15 191 (0.08%) temperature observations and as a single event in 12 children (2% of cases). There was no correlation with ambient temperature. Although mortality rates were higher in children with hypothermia (4/12, 33%) than those without (121/655, 18%), the timing of hypothermia did not coincide with clinical deterioration. Hypothermia was a rare marker of severity in our setting. We recommend that other observations be highlighted to identify high risk groups and that routine temperature observations be reduced wherever staff are few.
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Chloroquine resistance before and after its withdrawal in Kenya
BACKGROUND: The spread of resistance to chloroquine (CQ) led to its withdrawal from use in most countries in sub-Saharan Africa in the 1990s. In Malawi, this withdrawal was followed by a rapid reduction in the frequency of resistance to the point where the drug is now considered to be effective once again, just nine years after its withdrawal. In this report, the polymorphisms of markers associated with CQ-resistance against Plasmodium falciparum isolates from coastal Kenya (Kilifi) were investigated, from 1993, prior to the withdrawal of CQ, to 2006, seven years after its withdrawal. Changes to those that occurred in the dihydrofolate reductase gene (dhfr) that confers resistance to the replacement drug, pyrimethamine/sulphadoxine were also compared. METHODS: Mutations associated with CQ resistance, at codons 76 of pfcrt, at 86 of pfmdr1, and at codons 51, 59 and 164 of dhfr were analysed using PCR-restriction enzyme methods. In total, 406, 240 and 323 isolates were genotyped for pfcrt-76, pfmdr1-86 and dhfr, respectively. RESULTS: From 1993 to 2006, the frequency of the pfcrt-76 mutant significantly decreased from around 95% to 60%, while the frequency of pfmdr1-86 did not decline, remaining around 75%. Though the frequency of dhfr mutants was already high (around 80%) at the start of the study, this frequency increased to above 95% during the study period. Mutation at codon 164 of dhfr was analysed in 2006 samples, and none of them had this mutation. CONCLUSION: In accord with the study in Malawi, a reduction in resistance to CQ following official withdrawal in 1999 was found, but unlike Malawi, the decline of resistance to CQ in Kilifi was much slower. It is estimated that, at current rates of decline, it will take 13 more years for the clinical efficacy of CQ to be restored in Kilifi. In addition, CQ resistance was declining before the drug's official withdrawal, suggesting that, prior to the official ban, the use of CQ had decreased, probably due to its poor clinical effectiveness.
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Chloroquine resistance before and after its withdrawal in Kenya
BACKGROUND: The spread of resistance to chloroquine (CQ) led to its withdrawal from use in most countries in sub-Saharan Africa in the 1990s. In Malawi, this withdrawal was followed by a rapid reduction in the frequency of resistance to the point where the drug is now considered to be effective once again, just nine years after its withdrawal. In this report, the polymorphisms of markers associated with CQ-resistance against Plasmodium falciparum isolates from coastal Kenya (Kilifi) were investigated, from 1993, prior to the withdrawal of CQ, to 2006, seven years after its withdrawal. Changes to those that occurred in the dihydrofolate reductase gene (dhfr) that confers resistance to the replacement drug, pyrimethamine/sulphadoxine were also compared. METHODS: Mutations associated with CQ resistance, at codons 76 of pfcrt, at 86 of pfmdr1, and at codons 51, 59 and 164 of dhfr were analysed using PCR-restriction enzyme methods. In total, 406, 240 and 323 isolates were genotyped for pfcrt-76, pfmdr1-86 and dhfr, respectively. RESULTS: From 1993 to 2006, the frequency of the pfcrt-76 mutant significantly decreased from around 95% to 60%, while the frequency of pfmdr1-86 did not decline, remaining around 75%. Though the frequency of dhfr mutants was already high (around 80%) at the start of the study, this frequency increased to above 95% during the study period. Mutation at codon 164 of dhfr was analysed in 2006 samples, and none of them had this mutation. CONCLUSION: In accord with the study in Malawi, a reduction in resistance to CQ following official withdrawal in 1999 was found, but unlike Malawi, the decline of resistance to CQ in Kilifi was much slower. It is estimated that, at current rates of decline, it will take 13 more years for the clinical efficacy of CQ to be restored in Kilifi. In addition, CQ resistance was declining before the drug's official withdrawal, suggesting that, prior to the official ban, the use of CQ had decreased, probably due to its poor clinical effectiveness.
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