Joshua Levens

Mass Distribution of Azithromycin for Trachoma Control Is Associated With Increased Risk of Azithromycin-Resistant Streptococcus pneumoniae Carriage in Young Children 6 Months After Treatment

BACKGROUND Emerging evidence suggests that the mass distribution of azithromycin for trachoma control (MDA) may increase circulation of macrolide resistance in bacteria associated with severe pediatric infections in treated communities. METHODS We examined the effect of MDA on nasopharyngeal carriage of antibiotic-resistant Streptococcus pneumoniae among 1015 young children living in rural Tanzania. MDA with a single dose of oral azithromycin was provided in 4 of 8 communities where trachoma prevalence was ≥10%. Isolates were tested for susceptibility to azithromycin (AZM) and commonly used antibiotics by disk diffusion and Etest. We calculated the proportion of antibiotic-resistant S. pneumoniae carriage at baseline and again 1, 3, and 6 months after treatment, and at comparable intervals in the untreated villages. RESULTS The proportion of AZM-resistant isolates was similar between groups at baseline (MDA: 35.8% vs non-MDA: 35.4%), however, this proportion was greater in the MDA group in all subsequent surveys. At 6 months, the percentage of AZM-resistant isolates was significantly higher in the MDA group (81.9% vs 46.9%, P < .001). The odds of AZM-resistant carriage was 5-fold greater in the MDA group (odds ratio, 4.95 [95% confidence interval, 3.23-7.61]). The proportion of isolates clinically resistant to AZM (minimum inhibitory concentration ≥16 µg/mL) was also significantly greater in the MDA group at 6 months (35.3% vs 12.4%, P < .006). CONCLUSIONS Mass distribution of a single dose of oral azithromycin for trachoma was associated with increased circulation of macrolide-resistant S. pneumoniae carriage among young children in the 6 months following treatment. It is crucial that changes in antibiotic resistance patterns and their clinical significance in the treatment of severe pediatric infections be assessed in future MDA trials.

Prevalence and Density-Related Concordance of Three Diagnostic Tests for Malaria in a Region of Tanzania with Hypoendemic Malaria

ABSTRACT Accurate malaria diagnosis has dual roles in identification of symptomatic persons for effective malaria treatment and also enumeration of asymptomatic persons who contribute to the epidemiologic determinants of transmission. Three currently used diagnostic tests, microscopy, rapid diagnostic tests (RDTs), and real-time PCR, all have different sensitivities and specificities, which are parasite density dependent. Here, we compare their concordance among 451 febrile episodes in a cohort of 2,058 children and adults followed over 6 months in a region in central Tanzania with hypoendemic malaria. Microscopy, a histidine-rich protein-based RDT, and two different real-time PCR gene probes detected Plasmodium falciparum in 20, 54, 41, and 78 episodes of fever, respectively. They had complete concordance in only 9 episodes. Real-time PCR with an 18S probe was more sensitive than with a mitochondrial probe for cytochrome b despite higher copy numbers of mitochondrial DNA. Both PCR yields were increased 4-fold by glycogen/acetate precipitation with low-speed centrifugation. Duplicate PCR increases low-density malaria detection. RDT had the highest number of unique positives, presumably from persistent antigen despite the absence of parasites, although RDT did not detect 3 parasitemias with over 1,000 parasites/μl. In a latent class analysis, real-time PCR had significantly higher sensitivity than did microscopy or RDT. Agreement between real-time PCR, RDT, and microscopy was highest in March and April, when both the P. falciparum parasite rate and parasite densities are highest. Real-time PCR is more sensitive and specific than RDT and microscopy in low-prevalence, low-parasite-density settings.

Association of Mass Treatment with Azithromycin in Trachoma-Endemic Communities with Short-Term Reduced Risk of Diarrhea in Young Children

A cohort study was designed to assess the impact of mass distribution of azithromycin (MDA) for trachoma control on incidence over six months of pediatric diarrhea in eight communities in rural Tanzania. A single dose of azithromycin was offered to all residents in four communities, where trachoma prevalence was ≥ 10%. Four geographically matched communities had trachoma prevalences < 10% and did not receive MDA. All randomly selected children (n = 1036) were followed-up for six months post-MDA with bi-weekly surveillance at home. In the 0-1-month and 1-3-month periods, MDA exposure was associated with a 39% (rate ratio = 0.61, 95% confidence interval = 0.39-0.95) and 24% (rate ratio = 0.76, 95% confidence interval = 0.54-1.07) lower risk of diarrhea, respectively, compared with those unexposed, after adjustment for clustering and covariates. By the 3-6-month period, diarrhea incidence was comparable between groups. Thus, MDA was associated with a short-term reduction in diarrheal morbidity in children.

Mass distribution of azithromycin for trachoma control is associated with short-term reduction in risk of acute lower respiratory infection in young children.

Background: We evaluated the effect of a single mass distribution of azithromycin for trachoma on the risk of acute lower respiratory infection (ALRI) during a 6-month period among young children living in 8 communities in rural Tanzania. Methods: In 8 communities, a cohort of randomly selected children (n = 1036) was followed for incidence of ALRI episodes. Mass treatment for trachoma using a single dose of oral azithromycin was provided in 4 of the 8 communities where trachoma prevalence was .10%. All children were followed with biweekly surveillance at home for 6 months. Incidence of ALRI episodes was calculated for 0 to 1 month, 1 to 3 months, and 3 to 6 months posttreatment and in comparable time points in the nontreated villages. Results: In the multivariate analysis, living in a MDA village was associated with a 38% (rate ratio 5 0.62, 95% confidence interval [CI] = 0.43–0.91) decreased risk of ALRI in the 0- to 1-month follow-up period as compared with those in the untreated communities after adjusting for covariates and clustering. There were no significant differences in ALRI incidence by exposure status in the 1- to 3-month (rate ratio = 0.91, 95% CI = 0.69–1.20) and in the 3- to 6-month (rate ratio = 1.00, 95% CI = 0.76–1.30) follow-up periods. Conclusions: Mass distribution of a single dose of oral azithromycin for trachoma is associated with a significant short-term reduction in ALRI morbidity among young children.

Trends in weekly reported net use by children during and after rainy season in central Tanzania

BackgroundThe use of long-lasting insecticidal nets (LLINs) is one of the principal interventions to prevent malaria in young children, reducing episodes of malaria by 50% and child deaths by one fifth. Prioritizing young children for net use is important to achieve mortality reductions, particularly during transmission seasons.MethodsHouseholds were followed up weekly from January through June 2009 to track net use among children under seven under as well as caretakers. Net use rates for children and caretakers in net-owning households were calculated by dividing the number of person-weeks of net use by the number of person-weeks of follow-up. Use was stratified by age of the child or caretaker status. Determinants of ownership and of use were assessed using multivariate models.ResultsOverall, 60.1% of the households reported owning a bed net at least once during the study period. Among net owners, use rates remained high during and after the rainy season. Rates of use per person-week decreased as the age of the child rose from 0 to six years old; at ages 0–23 months and 24–35 months use rates per person-week were 0.93 and 0.92 respectively during the study period, while for children ages 3 and 4 use rates per person-week were 0.86 and 0.80. For children ages 5–6 person-week ratios dropped to 0.55. This represents an incidence rate ratio of 1.67 for children ages 0–23 months compared to children aged 5–6. Caretakers had use rates similar to those of children age 0–35 months. Having fewer children under age seven in the household also appeared to positively impact net use rates for individual children.ConclusionsIn this area of Tanzania, net use is very high among net-owning households, with no variability either at the beginning or end of the rainy season high transmission period. The youngest children are prioritized for sleeping under the net and caretakers also have high rates of use. Given the high use rates, increasing the number of nets available in the household is likely to boost use rates by older children.

Longitudinal Comparison of Antibiotic Resistance in Diarrheagenic and Non-pathogenic Escherichia coli from Young Tanzanian Children

Enteroaggregative, enteropathogenic, and enterotoxigenic Escherichia coli contribute significantly to the burden of diarrheal infections particularly in developing countries. Antibiotic resistance is increasingly common among bacterial pathogens including pathogenic E. coli. We assessed the relationship between pathogenic E. coli carriage and resistance to six antibiotics in E. coli isolated from young children in rural Tanzania. We surveyed temporal stability in antibiotic resistance in 2492 E. coli isolated from fecal samples obtained from young children in rural Tanzania collected over a 6 months period. Approximately half of the 377 children sampled were exposed to an azithromycin mass treatment program for trachoma control and half resided in control villages. Children were sampled at baseline, 1-, 3-, and 6 months following azithromycin treatment. We compared resistance to six antibiotics in pathogenic and non-pathogenic strains at the population level, within fecal specimens, and within individuals over time using chi-square tests, paired odds ratios, and logistic regression, respectively. Resistance to ampicillin and trimethoprim/sulfamethoxazole was highly prevalent (>65%). Resistance to 5 of 6 antibiotics tested and multi-drug resistance occurred more frequently in pathogenic isolates (p ≤ 0.001) within fecal specimens and overall. Azithromycin mass treatment exposure was significantly associated with increased odds of carriage of isolates resistant to erythromycin (OR 3.64, p < 0.001) and trimethoprim/sulfamethoxazole (OR 1.60, p < 0.05). Pathogenic isolates were approximately twice as likely to be resistant to erythromycin, ampicillin, or trimethoprim/sulfamethoxazole compared to non-pathogenic isolates from the same fecal specimen. The potential linkage between resistance and virulence in E. coli suggests hygiene and sanitation interventions aimed at reducing disease burden could play a role in controlling transmission of antibiotic resistance.

Short-term malaria reduction by single-dose azithromycin during mass drug administration for trachoma, Tanzania.

This drug might be beneficial in areas to which malaria and trachoma are endemic.