A boxplot showing the terrain ruggedness index values within 100 m, 250 m and 500 m of wild dog dens (“den”) and random contrast locations (“random”) within each of the four study populations.

<p>Median values are indicated in the boxes while the error bars indicate the 10^th and 90^th percentiles. Outliers not shown due to scaling of the graphs.</p

Unrooted neighbour-joining dendrogram of ITS1, 5.8S and ITS2 sequences for <i>Trypanosoma vivax</i>.

<p>Bootstrap values are shown at nodes with >70% support. Sequences generated in this study shown in black; other sequences retrieved from Genbank and listed in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0001828#pntd-0001828-t003" target="_blank">Table 3</a>. Sequence locations are shown by colour: Tanzania (this study, black); Kenya (blue); Mozambique (green); Nigeria (purple); South America (red). Host species from which sequence was amplified are indicated. Accession numbers for reference sequences are: IL3905 cl8, Genbank ID:DQ316040; IL3905 cl4Ro, DQ316043; IL3905 cl4, DQ316039; IL3905 cl3Ro, DQ316042; IL3905 cl2Ro, DQ316041; IL3905 cl5Ro, DQ316044; IL3905 cl2 DQ316037; IL3905 cl3, DQ316038; TviBrMi cl4, DQ316048; TviBrPo cl13, DQ316049; TviBrCa cl2, DQ316045; Y485, U22316; TviBrMi cl2, DQ316047; TviVeMe cl1, DQ316051; TviVeMe cl12, DQ316052; TviBrCa cl13, DQ316046; TviBrPo cl6, DQ316050; TviMzNy cl5, EU482080; TviMzNy cl2, EU482079; TviMzNy cl8, EU482082; TviMzNy cl1, EU482078; TviMzNy cl6, EU482081.</p

PCR primers and cycling conditions.

<p>PCR primers and cycling conditions.</p

Neighbour-joining tree based on partial 18S, 5.8S and partial 28S trypanosomatid sequences.

<p><i>Bodo caudatus</i> was included as an outgroup. Bootstrap values are shown where support is >70%. Sequences generated in this study are shown in blue (identified sequences in dark blue, unidentified sequences in light blue), and labelled with sample identity; pathogen species (UnK if unknown); host species; Genbank ID. Other sequences were retrieved from Genbank and are shown in black, and are labelled with pathogen species and Genbank ID. <i>T. brucei</i> clade indicated in grey box.</p

Summary of the host range and pathogenicity of the Salivarian trypanosomes.

<p>Summary of the host range and pathogenicity of the Salivarian trypanosomes.</p

Geographic location of African sites where baboons have tested seropositive for <i>T. pallidum</i> antibodies.

<p>This map is based on the results presented in this paper (East African sites) as well as the results in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050882#pone.0050882-FribourgBlanc1" target="_blank">[1]</a>,<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050882#pone.0050882-Baylet1" target="_blank">[2]</a> (West African sites). Inset: East African sites examined in this paper, with circles proportional to the number of animals tested serologically at each site. Years of serum collection ranged from 1977–2006, as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050882#pone-0050882-t001" target="_blank">Table 1</a>.</p

Primers used in this study.

a<p>primers found in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050882#pone.0050882-Harper1" target="_blank">[8]</a>.</p>b<p>primers found in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050882#pone.0050882-Gray1" target="_blank">[7]</a>.</p

A phylogeny demonstrates that <i>T. pallidum</i> strains infecting baboons in Serengeti National Park and Lake Manyara National Park are genetically distinct from one another.

<p>Phylogenies were constructed using both Maximum Parsimony and Maximum Likelihood methods to analyze 25 polymorphisms in six concatenated regions of the <i>Treponema</i> genome. The phylogenies were congruent and a Maximum Parsimony tree was chosen for display, with bootstrap support displayed at all nodes that received greater than 50% using both methods.</p

<em>Treponema pallidum</em> Infection in the Wild Baboons of East Africa: Distribution and Genetic Characterization of the Strains Responsible

<div><p>It has been known for decades that wild baboons are naturally infected with <em>Treponema pallidum</em>, the bacterium that causes the diseases syphilis (subsp. <em>pallidum</em>), yaws (subsp. <em>pertenue</em>), and bejel (subsp. <em>endemicum</em>) in humans. Recently, a form of <em>T. pallidum</em> infection associated with severe genital lesions has been described in wild baboons at Lake Manyara National Park in Tanzania. In this study, we investigated ten additional sites in Tanzania and Kenya using a combination of macroscopic observation and serology, in order to determine whether the infection was present in each area. In addition, we obtained genetic sequence data from six polymorphic regions using <em>T. pallidum</em> strains collected from baboons at two different Tanzanian sites. We report that lesions consistent with <em>T. pallidum</em> infection were present at four of the five Tanzanian sites examined, and serology was used to confirm treponemal infection at three of these. By contrast, no signs of treponemal infection were observed at the six Kenyan sites, and serology indicated <em>T. pallidum</em> was present at only one of them. A survey of sexually mature baboons at Lake Manyara National Park in 2006 carried out as part of this study indicated that roughly ten percent displayed <em>T. pallidum</em>-associated lesions severe enough to cause major structural damage to the genitalia. Finally, we found that <em>T. pallidum</em> strains from Lake Manyara National Park and Serengeti National Park were genetically distinct, and a phylogeny suggested that baboon strains may have diverged prior to the clade containing human strains. We conclude that <em>T. pallidum</em> infection associated with genital lesions appears to be common in the wild baboons of the regions studied in Tanzania. Further study is needed to elucidate the infection's transmission mode, its associated morbidity and mortality, and the relationship between baboon and human strains.</p> </div

Sampling and site characteristics of baboon troops in which animals were tested for <i>T. pallidum</i>, including seroprevalence and the prevalence of outward signs of infection with <i>T. pallidum</i>.

a<p>Sample seroprevalence may be inflated at GSNP, LMNP, and SNP, as some baboons were purposively sampled in the serological survey. Three of eight animals in GSNP, seven of nineteen at LMNP, and five of twenty-five at SNP were included because they displayed anogenital lesions.</p>b<p>GSNP has a history of antibiotic treatment of affected individuals <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050882#pone.0050882-Wallis1" target="_blank">[11]</a>, which may affect prevalence of infection there.</p>c<p>The collection of biological samples was not permitted at this site.</p