Elevated plasma von Willebrand factor and propeptide levels in Malawian children with malaria

Background

In spite of the significant mortality associated with Plasmodium falciparum infection, the mechanisms underlying severe disease remain poorly understood. We have previously shown evidence of endothelial activation in Ghanaian children with malaria, indicated by elevated plasma levels of both von Willebrand factor (VWF) and its propeptide. In the current prospective study of children in Malawi with retinopathy confirmed cerebral malaria, we compared these markers with uncomplicated malaria, non malarial febrile illness and controls.

Methods and Findings

Children with cerebral malaria, mild malaria and controls without malaria were recruited into the study. All comatose patients were examined by direct and indirect ophthalmoscopy. Plasma VWF and propeptide levels were measured by ELISA. Median VWF and propeptide levels were significantly higher in patients with uncomplicated malaria than in children with non-malarial febrile illness of comparable severity, in whom levels were higher than in non-febrile controls. Median concentrations of both markers were higher in cerebral malaria than in uncomplicated malaria, and were similar in patients with and without retinopathy. Levels of both VWF and propeptide fell significantly 48 hours after commencing therapy and were normal one month later.

Conclusions

In children with malaria plasma VWF and propeptide levels are markedly elevated in both cerebral and mild paediatric malaria, with levels matching disease severity, and these normalize upon recovery. High levels of both markers also occur in retinopathy-negative ‘cerebral malaria’ cases, many of whom are thought to be suffering from diseases other than malaria, indicating that further studies of these markers will be required to determine their sensitivity and specificity.

The magnitude and kinetics of the mucosal HIV-specific CD8+ T lymphocyte response and virus RNA load in breast milk

BACKGROUND

The risk of postnatal HIV transmission is associated with the magnitude of the milk virus load. While HIV-specific cellular immune responses control systemic virus load and are detectable in milk, the contribution of these responses to the control of virus load in milk is unknown.

METHODS

We assessed the magnitude of the immunodominant GagRY11 and subdominant EnvKY9-specific CD8+ T lymphocyte response in blood and milk of 10 A*3002+, HIV-infected Malawian women throughout the period of lactation and correlated this response to milk virus RNA load and markers of breast inflammation.

RESULTS

The magnitude and kinetics of the HIV-specific CD8+ T lymphocyte responses were discordant in blood and milk of the right and left breast, indicating independent regulation of these responses in each breast. However, there was no correlation between the magnitude of the HIV-specific CD8+ T lymphocyte response and the milk virus RNA load. Further, there was no correlation between the magnitude of this response and markers of breast inflammation.

CONCLUSIONS

The magnitude of the HIV-specific CD8+ T lymphocyte response in milk does not appear to be solely determined by the milk virus RNA load and is likely only one of the factors contributing to maintenance of low virus load in milk.

Affordable pediatric CD4 counting by flow cytometry in Malawi

Background

Rapid expansion of antiretroviral therapy in Malawi has occurred in the relative absence of suitable pediatric CD4 counting facilities. We have recently validated in adults a simplified affordable flow cytometric CD4 counting method, the Blantyre count. There is a need for this technology to transfer to government laboratories run by local staff, and to be validated in children, where %CD4/lymphocyte values are required.

Methods

We assessed agreement of %CD4/lymphocyte values determined by the Blantyre count and Panleucogate methods on an EPICS XL-MCL flow cytometer on 113 venous blood samples from HIV-seropositive children in Blantyre, Malawi. All assays were performed by two Malawian laboratory technicians.

Results

Overall bias between the two methods was −0.13% (95% CI −0.37 to 0.11) and limits of agreement were −2.69 to 2.43% (95% CI −3.11 to −2.27 and 2.01 to 2.85). Limits of agreement were within −3.00 and 3.00 for each laboratory technician. Coefficient of variation for the Blantyre count assay was 2.0% and samples showed good stability over 5 days.

Conclusions

The Blantyre count method can accurately determine %CD4/lymphocyte values in blood of HIV-seropositive children on an EPIC XL-MCL flow cytometer at a reagent cost of US $0.21 per test or less. The assay can be competently carried out by local laboratory technicians.

Human Milk Vacuolating Cytotoxin A Immunoglobulin A Antibodies ModifyHelicobacter pyloriInfection in Gambian Children

We collected data, including the weights, urea breath test results, and presence of maternal milk cytotoxin-associated gene-specific and vacuolating cytotoxin A-specific immunoglobulin A monthly from 48 mothers and infants (to 44 weeks of age) in The Gambia. In all, 11 children (23%) had negative urea breath test results, and 37 (77%) had positive results. Weight loss associated with Helicobacter pylori colonization was restricted to children whose mothers did not produce anti-vacuolating cytotoxin A antibodies in their milk (P=.028, by t test).

Dietary habits of the Somali population in Liverpool, with respect to foods containing calcium and vitamin D: a cause for concern?

BACKGROUND

A large percentage of Liverpool Somalis have vitamin D deficiency and low calcium excretion. The dietary habits of Liverpool Somalis were investigated with respect to food items containing calcium and vitamin D.

METHODS

A questionnaire, administered by a Somali field worker, assessed the intake of food of 60 adult (45 females and 15 males; mean age 42 years) and 10 child (seven females and three males; mean age 10 years) Somali volunteers. Questions concerned personal details, health (bone and muscle problems) and dietary habits including the frequency of consumption of food items containing substantial amounts of calcium and vitamin D. Results Most subjects reported bone and muscle pain. Eating habits reflected traditional customs. Foods containing substantial amounts of calcium and vitamin D were consumed infrequently. Milk was only consumed in tea. Those self-reporting bone pain consumed eggs, cheese and beans rarely.

CONCLUSION

The food choices of these individuals with regard to bone health is a cause for concern and indicates a likelihood of low calcium and vitamin D intake.

Comparison of urine contamination rates using three different methods of collection: clean-catch, cotton wool pad and urine bag

Collecting uncontaminated urine specimens from infants is difficult. Commonly, an adhesive urinecollecting bag is used, which is uncomfortable. This study determined bacterial contamination rates using three methods of urine collection sequentially on the same infant (without known urinary tract infection)-clean-catch, cotton wool (sanitary) pad and urine bag. The study was undertaken in children under 3 years of age in the Institute of Maternal and Child Health of Pernambuco (IMIP), Recife, Brazil. Urine samples were analysed using phase contrast microscopy and routine culture. Culture of bacteria at any level was interpreted as a contaminated urine specimen. Cultures with > 10(5) colony-forming units/ml of one species by all three collection methods were regarded as true urinary tract infection and these children were excluded. Altogether, 534 urine samples from 191 patients were analysed. Median age was 2 months (1 day-36 months) and 124 (65%) were boys. Twelve children (6.3%) were considered to have true urinary tract infection, three were indeterminate and in 16 one or more samples were missing and all were excluded from analysis. There were more missing samples using the clean-catch method (12%) than when using the bag (4%) or pad (4%). Seventy-six of 160 (47.5%) children had evidence of bacterial contamination. Clean-catch specimens showed the least contamination (14.7%) and rates were similar between pads (29%) and bags (26.6%) (kappa = 0.40). Urine contamination rates were similar for sanitary pads and urine bags and significantly higher than for clean-catch (p<0.01). However, pads were a simple, non-invasive and comfortable alternative to bags.

Early Helicobacter pylori colonisation: the association with growth faltering in The Gambia

BACKGROUND

Helicobacter pylori is one of the commonest causes of chronic infection of mankind, yet the natural history of acute infection is poorly understood. Some studies suggest that gastric colonisation with H pylori is associated with suboptimal nutrition and growth in childhood.

AIMS

To describe the clinical features of early H pylori colonisation and assess its role in the development of infant malnutrition and growth faltering.

METHODS

Two consecutive prospective longitudinal cohort studies were conducted at the Medical Research Council Laboratories in a rural community in The Gambia, West Africa. The first birth cohort of 125 infants was followed by a second of 65 children from the same community. H pylori colonisation was detected by sequential 13C urea breath tests, and infant growth was monitored by serial measurements.

RESULTS

Children with early H pylori colonisation became significantly lighter, shorter, and thinner than their peers in late infancy. The association was found in both cohorts. No socioeconomic or demographic confounding variables were identified to explain this, and the weight deficit was no longer detectable when the children were aged 5-8 years.

CONCLUSIONS

Results suggest that H pylori colonisation in early infancy predisposes to the development of malnutrition and growth faltering, although the effect did not persist into later childhood.

Dengue infection during pregnancy and transplacental antibody transfer in Thai mothers

OBJECTIVES

The objectives of this study were to estimate dengue seroprevalence in a population of Thai pregnant women, living in a highly endemic area and placental transfer of dengue antibodies.

METHODS

A cross-sectional seroprevalence study of 245 pregnant women at delivery.

RESULTS

Dengue HAI antibodies were positive in 94.7%. Maternal age was the only risk factor associated with dengue infection as older mothers (>20 years) were significantly more likely to be seropositive than younger women (p<0.0001). Cord antibody titres varied with maternal age and antibody titre, were significantly higher in babies born to younger mothers (<20 years) (p=0.01), and were significantly correlated with maternal titre. Low birthweight babies had lower transfer ratios for DEN-2 antibody (1.06) compared to heavier babies (1.36, p=0.05). No mother or neonate had dengue IgM detected. Two women were classified as recently, but not currently infected with dengue virus and we consider it likely these were first trimester infections. As no infant became infected the fetal infection was 0%.

CONCLUSIONS

Younger mothers were more likely to have been recently infected, resulting in higher antibody titres. Maternal dengue antibody transfer was proportional to maternal antibody concentration.

Specific Immunoglobulin A Antibodies in Maternal Milk and Delayed Helicobacter pylori Colonization in Gambian Infants

BACKGROUND

Immunoglobulin A (IgA) in maternal milk may protect Gambian infants from early Helicobacter pylori colonization. This study sought evidence that this protection could be due to specific IgA antibodies.

METHODS

Sixty-five infants were screened from 12 weeks of age with [13C]-urea breath tests. Antibodies in maternal milk were measured to determine total IgA content and to detect specific IgA antibodies against crude whole-cell and recombinant H. pylori urease antigen preparations.

RESULTS

Ten children (15%) had no evidence of early H. pylori colonization, 10 (15%) had early H. pylori colonization, and 43 (66%) had mixed results. Levels of maternal circulating specific immunoglobulin G, total milk IgA, and IgA directed against crude whole-cell H. pylori antigen preparation were not significantly associated with the rate of infant H. pylori colonization. However, mothers of infants with no evidence of early colonization produced significantly higher levels of anti-recombinant urease IgA antibodies in milk than did control mothers, particularly at 8, 16, and 20 weeks postpartum (P<.01).

CONCLUSIONS

These observations support the hypothesis that antibodies in mother's milk directed against H. pylori urease can protect against colonization in human infancy.

Placental acquisition of maternal specific IgG and Helicobacter pylori colonization in infancy

BACKGROUND

Colonization with Helicobacter pylori generally occurs in infancy, and the microorganism is often acquired from close family members. Rate of infant colonization may be affected by maternal immune status.

METHODS

To investigate the potential protective effect of anti-H. pylori immunoglobulin G (IgG) acquired via the placenta, 65 mothers and their infants were studied from the infant's birth for 1 year. Circulating IgG antibodies were measured by enzyme-linked immunosorbent assay (ELISA) in cord blood and every 8 weeks. Immunoblotting was performed on sera from infants with significant increases in IgG levels. Rate of infant H. pylori colonization was measured by 13C urea breath tests every 4 weeks from the age of 12 weeks.

RESULTS

Maternal and infant cord blood specific IgG levels were correlated (R2 =.747, p <.001). Infant H. pylori specific IgG fell 5-fold compared to maternal levels over the first 6 months of life, and rose subsequently in many cases, with the development of novel immunoblot patterns. There were no significant associations between the age at first positive urea breath test and maternal or infant cord specific H. pylori IgG levels.

CONCLUSIONS

Transplacentally acquired specific IgG antibody does not protect infants from colonization by H. pylori.

The value of urine testing for verifying adherence to anti-tuberculosis chemotherapy in children and adults in Uganda

SETTING

Mulago Hospital, Kampala, Uganda.

OBJECTIVE

To evaluate the usefulness of urine dipsticks for monitoring adherence to anti-tuberculosis chemotherapy.

DESIGN

In-house urine dipsticks for detection of isoniazid (INH) metabolites were compared to commercial test strips. The value of n-butanol to detect rifampicin was compared to coloration of the urine. Non-adherence was assessed through a questionnaire and reviews of the Mulago Hospital TB register.

RESULTS

Urine was obtained from 236 patients (127 adults and 109 children) on daily chemotherapy. Using commercial test strips as standard, the sensitivity of in-house urine dipsticks was 99.5% and specificity was 96.4%. The sensitivity and the specificity of n-butanol and of coloration of urine to detect rifampicin were low (64.0% and 54.9%, and 85.5% and 64.8%, respectively). Fifty patients (21.2%) admitted non-adherence to treatment during the previous month. An additional 15 (6.8%) were detected through urine testing. Of 911 patients in the TB register of Mulago Hospital who had started treatment in the first 3 months of 2000, 39.7% did not complete their treatment. Two-thirds of these had discontinued treatment in the first 2 months.

CONCLUSION

In-house INH test strips are as effective as commercially available strips for detecting isoniazid in the urine. They are a simple tool for monitoring adherence. Adherence to anti-tuberculosis chemotherapy as determined by the use of isoniazid test strips and review of the TB register showed poor compliance. Tests for rifampicin are less sensitive and specific.

Detection of Helicobacter pylori DNA in drinking water biofilms: implications for transmission in early life

AIMS

To provide evidence of water quality as a risk factor for acquisition of Helicobacter pylori in early life, and to identify evidence for its presence within pots used to store drinking water.

METHODS AND RESULTS

A prospective cohort study of 65 infants was conducted in the rural village of Keneba, The Gambia. Age of H. pylori colonization was determined and water pot biofilms were tested for H. pylori by sequencing of amplified DNA. Use of supplemental water was a strong risk factor for H. pylori colonization in infants (OR 4.71, 95% CI 1.17-22.5). DNA with 95% homology to the 16S rRNA gene of H. pylori was isolated from biofilms of water pots.

CONCLUSIONS

Drinking water may be a reservoir for H. pylori in areas of the developing world where water quality is poor. Early introduction of water, particularly if stored in, or collected from contaminated sources, may be associated with an increased rate of H. pylori colonization.