A novel multi-scale immuno-epidemiological model of visceral leishmaniasis in dogs

Leishmaniasis is a neglected and emerging disease prevalent in Mediterranean and tropical climates. As such, the study and development of new models are of increasing importance. We introduce a new immuno-epidemiological model of visceral leishmaniasis in dogs. The within-host system is based on previously  collected  and published data, showing the movement and proliferation of the parasite in the skin and the bone-marrow, as well as the IgG response. The between-host system structures the infected individuals in  time-since-infection and is of vector-host type. The within-host system has a parasite-free equilibrium and at least one endemic equilibrium, consistent with the fact that infected dogs do not recover without treatment. We compute the basic reproduction number R0 of the immuno-epidemiological model  and provide the existence and stability results of the population-level  disease-free equilibrium. Additionally, we prove existence of an unique  endemic equilibrium when R0 > 1, and evidence of backward bifurcation and existence of multiple endemic equilibria when R0 < 1

Analysis and simulations with a multi-scale model of canine visceral leishmaniasis

Visceral leishmaniasis in dogs is believed to have an impact on the prevalence of the disease in human populations. Here, we continue the analysis of the nested immuno-epidemiological model of visceral leishmaniasis in dogs, including a proof of well-posedness using functional analytical methods. Once well-posedness is established, we continue stability analysis of the endemic equilibria and provide necessary and sufficient conditions for the presence of backward bifurcation, and prove the instability of the lower endemic equilibrium in the presence of backward bifurcation. Lastly, we provide a number of simulations of the model using a number of control strategies. Control measures currently in use attempt to reduce the parasite load in the host, reduce the vector population, reduce the vector biting rate, and remove infected hosts. We examine various combinations of these strategies and conclude that a strategy combining culling infected dogs and removing vectors from the population by means such as insecticide will be the most effective

Roads and Military Provisioning During the French and Indian War (1754–1763): The Faunal Remains of Fort Shirley, PA in Context

Early British generals faced serious challenges in delivering and storing sufficient provisions for 18th British soldiers and colonial militia. This analysis investigates the influence of developed road systems that facilitated delivery of provisions and resulted in distinctive dietary patterning. The comparison of faunal data from forts located on major road systems with frontier garrisons and associated Native American villages like Fort Shirley and Aughwick Old Town, a short-lived (1754–1756) French and Indian War frontier fortification in central Pennsylvania, indicates a significantly reduced reliance on domestic livestock at these more inaccessible locations. These results suggest that road infrastructure heavily influenced military provisioning, encouraged adaptation to frontier living through reliance on wild game, and resulted in varied dietary practices at military installations in eastern North America

\u3ci\u3eDrosophila\u3c/i\u3e Muller F Elements Maintain a Distinct Set of Genomic Properties Over 40 Million Years of Evolution

The Muller F element (4.2 Mb, ~80 protein-coding genes) is an unusual autosome of Drosophila melanogaster; it is mostly heterochromatic with a low recombination rate. To investigate how these properties impact the evolution of repeats and genes, we manually improved the sequence and annotated the genes on the D. erecta, D. mojavensis, and D. grimshawi F elements and euchromatic domains from the Muller D element. We find that F elements have greater transposon density (25–50%) than euchromatic reference regions (3–11%). Among the F elements, D. grimshawi has the lowest transposon density (particularly DINE-1: 2% vs. 11–27%). F element genes have larger coding spans, more coding exons, larger introns, and lower codon bias. Comparison of the Effective Number of Codons with the Codon Adaptation Index shows that, in contrast to the other species, codon bias in D. grimshawi F element genes can be attributed primarily to selection instead of mutational biases, suggesting that density and types of transposons affect the degree of local heterochromatin formation. F element genes have lower estimated DNA melting temperatures than D element genes, potentially facilitating transcription through heterochromatin. Most F element genes (~90%) have remained on that element, but the F element has smaller syntenic blocks than genome averages (3.4–3.6 vs. 8.4–8.8 genes per block), indicating greater rates of inversion despite lower rates of recombination. Overall, the F element has maintained characteristics that are distinct from other autosomes in the Drosophila lineage, illuminating the constraints imposed by a heterochromatic milieu