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ABSTRACT Hantaviruses are globally distributed zoonotic pathogens capable of causing fatal disease in humans. Addressing the risk of hantavirus spillover from animal reservoirs to humans requires identifying the local reservoirs (usually rodents and other small mammals) and the predictors of infection, such as habitat characteristics and human exposure. We screened a collection of 1663 terrestrial small mammals and 227 bats for hantavirus RNA, comprised of native and non‐native species from northeastern Madagascar, trapped over 5 successive years. We specifically investigated the influence of diverse habitat types: villages, agricultural fields, regrowth areas, secondary and semi‐intact forests on infection with hantaviruses. We detected Hantavirus RNA closely related to the previously described Anjozorobe virus in 9.5% ofRattus rattussampled, with an absence of detection in other species. Land‐use had a complex impact on hantavirus infections: intensive land‐use positively correlated with the abundance ofR. rattusand the averageR. rattusbody size varied between habitats. Larger individuals had a higher probability of infection, regardless of sex. Thus, villages and pristine forests which host the smallest, and hence, least infected rats, represent the lowest risk for hantavirus exposure to people while flooded rice fields which were home to the largest rats, and subsequently most infected rats, represent the greatest exposure risk. These findings provide new insights into the relationship between rat ecology and the gradients of hantavirus exposure risk for farmers in northeastern Madagascar as they work in different land‐use types.
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Urban rat exposure to anticoagulant rodenticides and zoonotic infection risk
Anticoagulant rodenticides (ARs) deployed to control rodent pest populations can increase the risk of pathogen infection for some wildlife. However, it is unknown whether ARs also increase infection risk for target rodents, which are common hosts for zoonotic (animal-to-human transmitted) pathogens. In this study, we tested whether rats exposed to ARs were more likely to be infected with zoonotic pathogens, specifically Leptospira spp. or Escherichia coli , after controlling for known predictors of infection (i.e. sex, age, body condition). We collected biological samples from 99 rats trapped in Chicago alleys and tested these for Leptospira infection, E. coli shedding and AR exposure. We found that rats that had been exposed to ARs and survived until the time of trapping, as well as older rats, were significantly more likely to be infected with Leptospira spp. than other rats. We found no significant association between E. coli shedding and any predictors. Our results show that human actions to manage rats can affect rat disease ecology and public health risks in unintended ways, and more broadly, contribute to a growing awareness of bidirectional relationships between humans and natural systems in cities.
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- Award ID(s):
- 1923882
- PAR ID:
- 10302043
- Date Published:
- Journal Name:
- Biology Letters
- Volume:
- 17
- Issue:
- 8
- ISSN:
- 1744-957X
- Page Range / eLocation ID:
- 20210311
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract ObjectivesUnderstanding disease transmission is a fundamental challenge in ecology. We used transmission potential networks to investigate whether a gastrointestinal protozoan (Blastocystisspp.) is spread through social, environmental, and/or zoonotic pathways in rural northeast Madagascar. Materials and MethodsWe obtained survey data, household GPS coordinates, and fecal samples from 804 participants. Surveys inquired about social contacts, agricultural activity, and sociodemographic characteristics. Fecal samples were screened forBlastocystisusing DNA metabarcoding. We also tested 133 domesticated animals forBlastocystis. We used network autocorrelation models and permutation tests (networkk‐test) to determine whether networks reflecting different transmission pathways predicted infection. ResultsWe identified six distinctBlastocystissubtypes among study participants and their domesticated animals. Among the 804 human participants, 74% (n = 598) were positive for at least oneBlastocystissubtype. Close proximity to infected households was the most informative predictor of infection with any subtype (model averaged OR [95% CI]: 1.56 [1.33–1.82]), and spending free time with infected participants was not an informative predictor of infection (model averaged OR [95% CI]: 0.95 [0.82–1.10]). No human participant was infected with the same subtype as the domesticated animals they owned. DiscussionOur findings suggest thatBlastocystisis most likely spread through environmental pathways within villages, rather than through social or animal contact. The most likely mechanisms involve fecal contamination of the environment by infected individuals or shared food and water sources. These findings shed new light on human‐pathogen ecology and mechanisms for reducing disease transmission in rural, low‐income settings.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1098/rsbl.2021.0311
