Epidemiology of pathogenic enterobacteria in humans, livestock, and peridomestic rodents in rural Madagascar.

BACKGROUND: Among the families of enteric bacteria are globally important diarrheal agents. Despite their potential for zoonotic and environmental transmission, few studies have examined the epidemiology of these pathogens in rural systems characterized by extensive overlap among humans, domesticated and peridomestic animals. We investigated patterns of infection with Enterotoxigenic Escherichia coli, Shigella spp., Salmonella enterica, Vibrio cholerae, and Yersinia spp. (enterocolitica, and pseudotuberculosis) in Southeastern Madagascar where the potential for the aforementioned interactions is high. In this pilot project we conducted surveys to examine behaviors potentially associated with risk of infection and if infection with specific enterobacteria species was associated with diarrheal disease. METHODOLOGY/PRINCIPAL FINDINGS: PCR was conducted on DNA from human, livestock, and rodent fecal samples from three villages. Overall, human prevalence was highest (77%), followed by rodents (51%) and livestock (18%). Rodents were ∼2.8 times more likely than livestock to carry one of the bacteria. The incidence of individual species varied between villages, with the observation that, E. coli and Shigella spp. were consistently associated with co-infections. As an aggregate, there was a significant risk of infection linked to a water source in one village. Individually, different pathogens were associated with certain behaviors, including: those who had used medication, experienced diarrhea in the past four weeks, or do not use toilets. CONCLUSIONS/SIGNIFICANCE: Different bacteria were associated with an elevated risk of infection for various human activities or characteristics. Certain bacteria may also predispose people to co-infections. These data suggest that a high potential for transmission among these groups, either directly or via contaminated water sources. As these bacteria were most prevalent in humans, it is possible that they are maintained in humans and that transmission to other species is infrequent. Further studies are needed to understand bacterial persistence, transmission dynamics, and associated consequences in this and similar systems

Morphometric signals of population decline in diademed sifakas occupying degraded rainforest habitat in Madagascar.

Anthropogenic habitat change can have varied impacts on primates, including both negative and positive outcomes. Even when behavioural shifts are seen, they may reflect decreased health, or simply behavioural flexibility; understanding this distinction is important for conservation efforts. This study examines habitat-related variation in adult and immature morphometrics among diademed sifakas (Propithecus diadema). We collected morphometric data from sifakas at Tsinjoarivo, Madagascar (19 years, 188 captures, 113 individuals). Captures spanned 12 groups, five within continuous forest ("CONT"), and seven in degraded fragments ("FRAG") where sifakas have lower nutritional intakes. Few consistent differences were found between CONT and FRAG groups. However, using home range quality as a covariate rather than a CONT/FRAG dichotomy revealed a threshold: the two FRAG groups in the lowest-quality habitat showed low adult mass and condition (wasting), and low immature mass and length (stunting). Though less-disturbed fragments apparently provide viable habitat, we suggest the sifakas in the most challenging habitats cannot evolve fast enough to keep up with such rapid habitat change. We suggest other long-lived organisms will show similar morphometric "warning signs" (wasting in adults, stunting in immatures); selected morphometric variables can thus be useful at gauging vulnerability of populations in the face of anthropogenic change

Summary of significant findings for infection with Enterobacteriaceae in human, livestock, and rodent populations.

<p>Summary of significant findings for infection with Enterobacteriaceae in human, livestock, and rodent populations.</p

Prevalence of Enterobacteriaceae infection by subject and location.

<p>Prevalence of Enterobacteriaceae infection by subject and location.</p

Incidence of each Enterobacteriaceae species in humans, livestock, and rodents by village.

<p>*Cattle and pigs.</p

Risk factors for infection with Enterobacteriaceae in people living in villages in Southeast Madagascar.

<p>*Total n varies due to incomplete notation on some surveys or respondents do not participate in the given activity (e.g. tend livestock).</p><p><b>Bold</b>  =  statistically significant associations.</p

Risk factors for infection with individual Enterobacteriaceae species in people living in villages in Southeast Madagascar.

<p>*Total n varies due to incomplete notation on some surveys or respondents do not participate in the given activity.</p

Bacterial strains (positive controls), target genes, and primers^* used in this study.

<p>*All primer sequences and sensitivities obtained from Wang et al. (1997) except <i>Yersinia</i> obtained from Thoerner et al. (2003).</p>a<p>Product size with <i>Y. enterocolitica</i> serogroup 03 or 09 strains.</p>b<p>Product size with <i>Y. enterocolitica</i> serogroup 08 strains.</p

Variation in SARS-CoV-2 outbreaks across sub-Saharan Africa

A surprising feature of the SARS-CoV-2 pandemic to date is the low burdens reported in sub-Saharan Africa (SSA) countries relative to other global regions. Potential explanations (for example, warmer environments 1, younger populations 2–4) have yet to be framed within a comprehensive analysis. We synthesized factors hypothesized to drive the pace and burden of this pandemic in SSA during the period from 25 February to 20 December 2020, encompassing demographic, comorbidity, climatic, healthcare capacity, intervention efforts and human mobility dimensions. Large diversity in the probable drivers indicates a need for caution in interpreting analyses that aggregate data across low- and middle-income settings. Our simulation shows that climatic variation between SSA population centers has little effect on early outbreak trajectories; however, heterogeneity in connectivity, although rarely considered, is likely an important contributor to variance in the pace of viral spread across SSA. Our synthesis points to the potential benefits of context-specific adaptation of surveillance systems during the ongoing pandemic. In particular, characterizing patterns of severity over age will be a priority in settings with high comorbidity burdens and poor access to care. Understanding the spatial extent of outbreaks warrants emphasis in settings where low connectivity could drive prolonged, asynchronous outbreaks resulting in extended stress to health systems. </p