High prevalence and two dominant host-specific genotypes of Coxiella burnetii in U.S. milk

BackgroundCoxiella burnetii causes Q fever in humans and Coxiellosis in animals; symptoms range from general malaise to fever, pneumonia, endocarditis and death. Livestock are a significant source of human infection as they shed C. burnetii cells in birth tissues, milk, urine and feces. Although prevalence of C. burnetii is high, few Q fever cases are reported in the U.S. and we have a limited understanding of their connectedness due to difficulties in genotyping. Here, we develop canonical SNP genotyping assays to evaluate spatial and temporal relationships among C. burnetii environmental samples and compare them across studies. Given the genotypic diversity of historical collections, we hypothesized that the current enzootic of Coxiellosis is caused by multiple circulating genotypes. We collected A) 23 milk samples from a single bovine herd, B) 134 commercial bovine and caprine milk samples from across the U.S., and C) 400 bovine and caprine samples from six milk processing plants over three years.ResultsWe detected C. burnetii DNA in 96% of samples with no variance over time. We genotyped 88.5% of positive samples; bovine milk contained only a single genotype (ST20) and caprine milk was dominated by a second type (mostly ST8).ConclusionsThe high prevalence and lack of genotypic diversity is consistent with a model of rapid spread and persistence. The segregation of genotypes between host species is indicative of species-specific adaptations or dissemination barriers and may offer insights into the relative lack of human cases and characterizing genotypes

High <i>Leptospira</i> Diversity in Animals and Humans Complicates the Search for Common Reservoirs of Human Disease in Rural Ecuador

<div><p>Background</p><p>Leptospirosis is a zoonotic disease responsible for high morbidity around the world, especially in tropical and low income countries. Rats are thought to be the main vector of human leptospirosis in urban settings. However, differences between urban and low-income rural communities provide additional insights into the epidemiology of the disease.</p><p>Methodology/Principal findings</p><p>Our study was conducted in two low-income rural communities near the coast of Ecuador. We detected and characterized infectious leptospira DNA in a wide variety of samples using new real time quantitative PCR assays and amplicon sequencing. We detected infectious leptospira in a high percentage of febrile patients (14.7%). In contrast to previous studies on leptospirosis risk factors, higher positivity was not found in rats (3.0%) but rather in cows (35.8%) and pigs (21.1%). Six leptospira species were identified (<i>L</i>. <i>borgpetersenii</i>, <i>L kirschnerii</i>, <i>L santarosai</i>, <i>L</i>. <i>interrogans</i>, <i>L noguchii</i>, and an intermediate species within the <i>L</i>. <i>licerasiae</i> and <i>L</i>. <i>wolffii</i> clade) and no significant differences in the species of leptospira present in each animal species was detected (χ² = 9.89, adj.p-value = 0.27).</p><p>Conclusions/Significance</p><p>A large portion of the world’s human population lives in low-income, rural communities, however, there is limited information about leptospirosis transmission dynamics in these settings. In these areas, exposure to peridomestic livestock is particularly common and high prevalence of infectious leptospira in cows and pigs suggest that they may be the most important reservoir for human transmission. Genotyping clinical samples show that multiple species of leptospira are involved in human disease. As these genotypes were also detected in samples from a variety of animals, genotype data must be used in conjunction with epidemiological data to provide evidence of transmission and the importance of different potential leptospirosis reservoirs.</p></div

Details of assays for detecting pathogenic and intermediate leptospira species.

<p>These two assays amplify the same region but the probes anneal to different targets within the amplified region. See also <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0004990#pntd.0004990.s004" target="_blank">S3 Fig</a>.</p

<i>Leptospira</i> DNA positivity in samples collected in 2014 and the first 6 months of 2015 from two rural communities in Manabi-Ecuador.

<p><i>Leptospira</i> DNA positivity in samples collected in 2014 and the first 6 months of 2015 from two rural communities in Manabi-Ecuador.</p

Leptospira genotyping results in febrile patients, cattle, pigs and rats sampled at our study sites.

<p>Concentric circles represent the sample size in Site 1 (colored with light gray) and Site 2 (dark gray). The order of these concentric circles is dependent on the sample size at each site. The proportion of each <i>Leptospira</i> genotype is marked with a different color, however white portions represent the percentage of samples for which genotyping was unsuccessful. Sample sizes for each group is detailed in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0004990#pntd.0004990.t002" target="_blank">Table 2</a> and <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0004990#pntd.0004990.s010" target="_blank">S6 Table</a>.</p