Global shifts in mammalian population trends reveal key predictors of virus spillover risk.

Emerging infectious diseases in humans are frequently caused by pathogens originating from animal hosts, and zoonotic disease outbreaks present a major challenge to global health. To investigate drivers of virus spillover, we evaluated the number of viruses mammalian species have shared with humans. We discovered that the number of zoonotic viruses detected in mammalian species scales positively with global species abundance, suggesting that virus transmission risk has been highest from animal species that have increased in abundance and even expanded their range by adapting to human-dominated landscapes. Domesticated species, primates and bats were identified as having more zoonotic viruses than other species. Among threatened wildlife species, those with population reductions owing to exploitation and loss of habitat shared more viruses with humans. Exploitation of wildlife through hunting and trade facilitates close contact between wildlife and humans, and our findings provide further evidence that exploitation, as well as anthropogenic activities that have caused losses in wildlife habitat quality, have increased opportunities for animal-human interactions and facilitated zoonotic disease transmission. Our study provides new evidence for assessing spillover risk from mammalian species and highlights convergent processes whereby the causes of wildlife population declines have facilitated the transmission of animal viruses to humans

The heterogeneous herd : drivers of close‐contact variation in African buffalo and implications for pathogen invasion

Many infectious pathogens are shared through social interactions, and examining host connectivity has offered valuable insights for understanding patterns of pathogen transmission across wildlife species. African buffalo are social ungulates and important reservoirs of directly‐transmitted pathogens that impact numerous wildlife and livestock species. Here, we analyzed African buffalo social networks to quantify variation in close contacts, examined drivers of contact heterogeneity, and investigated how the observed contact patterns affect pathogen invasion likelihoods for a wild social ungulate. We collected continuous association data using proximity collars and sampled host traits approximately every 2 months during a 15‐month study period in Kruger National Park, South Africa. Although the observed herd was well connected, with most individuals contacting each other during each bimonthly interval, our analyses revealed striking heterogeneity in close‐contact associations among herd members. Network analysis showed that individual connectivity was stable over time and that individual age, sex, reproductive status, and pairwise genetic relatedness were important predictors of buffalo connectivity. Calves were the most connected members of the herd, and adult males were the least connected. These findings highlight the role susceptible calves may play in the transmission of pathogens within the herd. We also demonstrate that, at time scales relevant to infectious pathogens found in nature, the observed level of connectivity affects pathogen invasion likelihoods for a wide range of infectious periods and transmissibilities. Ultimately, our study identifies key predictors of social connectivity in a social ungulate and illustrates how contact heterogeneity, even within a highly connected herd, can shape pathogen invasion likelihoods

Sight or Scent: Lemur Sensory Reliance in Detecting Food Quality Varies with Feeding Ecology

<div><p>Visual and olfactory cues provide important information to foragers, yet we know little about species differences in sensory reliance during food selection. In a series of experimental foraging studies, we examined the relative reliance on vision versus olfaction in three diurnal, primate species with diverse feeding ecologies, including folivorous Coquerel's sifakas (<i>Propithecus coquereli</i>), frugivorous ruffed lemurs (<i>Varecia variegata</i> spp), and generalist ring-tailed lemurs (<i>Lemur catta</i>). We used animals with known color-vision status and foods for which different maturation stages (and hence quality) produce distinct visual and olfactory cues (the latter determined chemically). We first showed that lemurs preferentially selected high-quality foods over low-quality foods when visual and olfactory cues were simultaneously available for both food types. Next, using a novel apparatus in a series of discrimination trials, we either manipulated food quality (while holding sensory cues constant) or manipulated sensory cues (while holding food quality constant). Among our study subjects that showed relatively strong preferences for high-quality foods, folivores required both sensory cues combined to reliably identify their preferred foods, whereas generalists could identify their preferred foods using either cue alone, and frugivores could identify their preferred foods using olfactory, but not visual, cues alone. Moreover, when only high-quality foods were available, folivores and generalists used visual rather than olfactory cues to select food, whereas frugivores used both cue types equally. Lastly, individuals in all three of the study species predominantly relied on sight when choosing between low-quality foods, but species differed in the strength of their sensory biases. Our results generally emphasize visual over olfactory reliance in foraging lemurs, but we suggest that the relative sensory reliance of animals may vary with their feeding ecology.</p></div

Preempting Pandemics. Rez.: The Viral Storm. The Dawn of a New Pandemic Age by Nathan Wolfe Times Books (Holt), New York, 2011

Han BA, Rushmore J, Fritzsche A, Satterfield D, Winternitz J. Preempting Pandemics. Rez.: The Viral Storm. The Dawn of a New Pandemic Age by Nathan Wolfe Times Books (Holt), New York, 2011. Science. 2012;337(6095):647-648

Diet, sample size, and predicted sensory reliance for three species of strepsirrhine primates.

<p>Diet, sample size, and predicted sensory reliance for three species of strepsirrhine primates.</p

Food-quality preferences during visual and olfactory trials.

<p>Food choices of three strepsirrhine species are depicted (for individuals that showed relatively strong food preferences during baseline trials) when (A) only visual or (B) only olfactory cues were available. Presented are the frequencies (mean ± standard error of mean) with which the animals selected red foods (i.e., young leaves or ripe fruits; shaded bars) versus green foods (i.e., mature leaves or unripe fruit; open bars) when only one sensory cue was available. Numbers at the bottom of the open bars represent the number of individuals used in the analysis (G-test: * <i>P</i><0.05, *** <i>P</i><0.001).</p

Chromatograms and principal component analysis of the chemical components in test-food items.

<p>Representative chromatograms are shown for (A) red, young leaves (<i>Photinia:</i> shaded triangle), (B) green, mature leaves (open triangle), (C) red, ripe tomatoes (<i>Solanum lycopersicum</i>: shaded circle), and (D) green, unripe tomatoes (open circle), obtained by solid phase microextraction, followed by gas chromatography and mass spectrometry. Also shown are the results from the respective principal component analyses (PCA) of the chemical components identified in both red and green (E) leaves and (F) fruit. Dashed lines represent the two main PC axes.</p

Baseline food preferences.

<p>Food choices of three strepsirrhine species are depicted for (A) all subjects tested and (B) those subjects that showed relatively strong preferences during baseline trials. Presented are the frequencies (mean ± standard error of mean) with which the animals selected red foods (i.e., young leaves or ripe fruits; shaded bars) versus green foods (i.e., mature leaves or unripe fruit; open bars) when both visual and olfactory cues were simultaneously available. Numbers at the bottom of the open bars represent the number of individuals used in the analyses (G-test: * <i>P</i><0.05, *** <i>P</i><0.001).</p

Sensory reliances during multi-sensory trials.

<p>Sensory use by three strepsirrhine species (including all subjects tested) when investigating comparable (A) red foods or (B) green foods during multi-sensory trials. Presented are the frequencies (mean ± standard error of mean) with which the animals relied on visual cues (shaded bars) versus olfactory cues (open bars) to select a given food type. Numbers at the bottom of the open bars represent the number of individuals used in the analysis (G-test: *** p<0.001).</p

The foraging tasks.

<p>A representative (A–C) sifaka and (D–F) ruffed lemur solving different foraging tasks presented to three species of strepsirrhine primates. Shown are (A–C) a baseline trial depicting visual reliance by the sifaka and (D–F) a multisensory trial depicting olfactory reliance by the ruffed lemur. In both tasks, the animal must (A, D) investigate the box contents using whatever sensory information is available or preferred, (B, E) manually open one of the two drawers, thereby making its choice, and (C, F) orally retrieve the selected food item.</p