Breast Milk and Gut Microbiota in African Mothers and Infants from an Area of High HIV Prevalence

Background

Human milk and infant gut microbiota are essential for the immune system maturation and protection against infections. There is scarce information on the microbiological composition of breast milk in general, and none from developing countries. The objective of the study was to characterize the breast milk and gut microbiota from mothers and infants from southern Mozambique, where infections and breastfeeding are prevalent.

Methods

A community-based study was undertaken among 121 pairs of women and infants. Breast milk and infant''s faeces were analyzed by bacterial culture and molecular methods. Breast milk samples were screened for HIV RNA by RT-PCR.

Results

The most frequent bacterial groups isolated by culture media in breast milk were Staphylococci (96.4%), Streptococci (92.7%) and Lactobacilli (56.4%). HIV RNA was detected in 24% of the samples. Staphylococcus hominis, S. aureus, and S.parasanguis were more frequently isolated in infants ≤14 days of life. Women on exclusive breastfeeding presented higher proportion of S. parasanguis in breast milk than those on mixed infant feeding (36.4% versus 11.1%, p = 0.035). Bacterial diversity (mean number of bacterial species isolated by sample: 10.4 versus 8.5; p = 0.004) and the frequency of Lactobacillus spp (75.9% versus 36%, p = 0.003) were higher in the specimens with HIV RNA than in those without it. The main bacterial groups found in infant''s faeces were Bifidobacterium, Streptococci and Enterococci.

Conclusions

Women with HIV RNA in breast milk had a different pattern of microbiological composition, suggesting specific immunopathological phenomena in HIV-infected women. Both breast milk and faecal microbiota composition varied with lactation period, which might be related to changes in the type of feeding over time and/or in the milk''s biochemical characteristics. These findings provide insights into interactions between commensal bacteria and HIV infection in human milk and the role of these bacteria in mucosal protection against infections in breastfed infants.     

Diarrheal Disease in Rural Mozambique: Burden,Risk Factors and Etiology of Diarrheal Disease among Children Aged 0–59 Months Seeking Care at Health Facilities

BackgroundDiarrheal disease remains a leading cause of illness and death, particularly in low-income countries. Its burden, microbiological causes and risk factors were examined in children aged 0–59 months living in Manhiça, rural southern Mozambique.MethodsTrends of diarrhea-related burden of disease were estimated during the period 2001–2012. A prospective, age-stratified and matched (by age, gender and geographical origin), case-control study was conducted during 2007–2011. Clinical, epidemiology, anthropometric measurement and fecal samples obtained from recruited children were used to estimate moderate-to-severe diarrhea (MSD) weighted attributable fractions.ResultsOver the last decade the incidence of acute diarrhea has dropped by about 80%. Incidence of MSD per 100 child years at risk for the period 2007–2011 was 9.85, 7.73 and 2.10 for children aged 0–11, 12–23 and 24–59 months respectively. By adjusted population attributable fractions, most cases of MSD were due to rotavirus, Cryptosporidium, ETEC ST (ST only or ST/LT), Shigella and Adenovirus 40/41. Washing hands and having facilities to dispose child’s stools were associated with a reduced risk of MSD, while giving stored water to the child was associated with an increased risk of MSD.ConclusionsDespite the predominantly decreasing trends observed throughout the last decade, diarrheal diseases remain today a major cause of morbidity among children aged 0–59 months living in this rural Mozambican area. Rotavirus, cryptosporidium, Shigella, ETEC ST and Adenovirus 40/41 were the most important aetiologies of MSD. Thus, well-known preventive strategies such as washing hands, improving the treatment of stored water, having facilities to dispose children stools, and accelerating the introduction of the rotavirus vaccine should be promoted on a wider scale to reduce the current burden of diarrheal diseases.     

Evaluation of antibody serology to determine current helminth and Plasmodium falciparum infections in a co-endemic area in Southern Mozambique

BackgroundSoil-transmitted helminths (STH), Schistosoma spp. and Plasmodium falciparum are parasites of major public health importance and co-endemic in many sub-Saharan African countries. Management of these infections requires detection and treatment of infected people and evaluation of large-scale measures implemented. Diagnostic tools are available but their low sensitivity, especially for low intensity helminth infections, leaves room for improvement. Antibody serology could be a useful approach thanks to its potential to detect both current infection and past exposure.MethodologyWe evaluated total IgE responses and specific-IgG levels to 9 antigens from STH, 2 from Schistosoma spp., and 16 from P. falciparum, as potential markers of current infection in a population of children and adults from Southern Mozambique (N = 715). Antibody responses were measured by quantitative suspension array Luminex technology and their performance was evaluated by ROC curve analysis using microscopic and molecular detection of infections as reference.Principal findingsIgG against the combination of EXP1, AMA1 and MSP2 (P. falciparum) in children and NIE (Strongyloides stercoralis) in adults and children had the highest accuracies (AUC = 0.942 and AUC = 0.872, respectively) as markers of current infection. IgG against the combination of MEA and Sm25 (Schistosoma spp.) were also reliable markers of current infection (AUC = 0.779). In addition, IgG seropositivity against 20 out of the 27 antigens in the panel differentiated the seropositive endemic population from the non-endemic population, suggesting a possible role as markers of exposure although sensitivity could not be assessed.ConclusionsWe provided evidence for the utility of antibody serology to detect current infection with parasites causing tropical diseases in endemic populations. In addition, most of the markers have potential good specificity as markers of exposure. We also showed the feasibility of measuring antibody serology with a platform that allows the integration of control and elimination programs for different pathogens.