Ecology Determines Rabies Infection in Bats

A new approach to rabies virus epidemiology in bats shows that the risk of infection is higher in large and multispecies colonies. The research, published on the journal PLOS ONE, was led by Jordi Serra-Cobo, professor from the Department of Animal Biology at the UB and the Biodiversity Research Institute (IRBio).

Bats are a large group of mammals that appeared in our planet around 65 million years ago (Figure 1). They have colonized many natural habitats —except the poles—, and act as primary predators of vast numbers of insects in ecosystems. They are also the mammals which present the widest variety of virus infection (rabies, SARS, Ebola, etc.). Moreover, they are able to neutralize virus and survive infections. “Chiropters, a quite ancient animal group, are major reservoirs for diverse infectious viral diseases”, highlights Serra-Cobo. They have co-lived with virus for a long time and their immunological responses are more effective. According to Serra-Cobo, “this fact opens new research lines on the organisms’ immunological response and strategies to fight against infectious diseases”.

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Figure 1. A vespertilionid bat from Spain, one of the more than 1,150 bat species.

It is the first time that a research analyses ecological factors that might affect the infection dynamics of the rabies virus in bat colonies. Between 2001 and 2011, 2,393 blood samples were collected from 20 bats species and 25 localities in Catalonia, Aragon and Balearic Islands. The research is centered on the detection of
European bat Lyssavirus 1 (EBL1), one of the twelve different groups of the genus Lyssavirus related to rabies, an emergent zoonosis that affects mammals all over the world.

Jordi Serra-Cobo explains that “EBLV-1 seroprevalence is strongly affected by colony size and species richness. Previous studies have analyzed other aspects such as the seasonal variability. Ecological factors play a relevant role in seroprevalence variability, but they were to date unknown” (Figure 2).

journal.pone.0064467.g002
Figure 2. Variation in the percentages of seropositive bats as a function of species richness and colony size. (from Serra-Cobo et al. 2013)


All bat species do not response in the same way to viral infections. This research proves that immunological response to rabies virus varies among species. “Order Chiroptera has been widely diversified along its evolutionary history —affirms Serra Cobo— and their responses to ultrasound orientation mechanisms, immunological defense, etc. vary with different lineages”.

There are more than 1,150 bat species all over the world and new specimens are described every year. However, the loss of natural habitats due to human activity and climate change poses a major threat to bats. “It is a process of environmental degradation which favors the formation of larger bat colonies, which have a higher probability of EBLV-1 infection”, remarks Serra Cobo.
 
Spain has been free of rabies in terrestrial mammals since 1977. Nevertheless, in some countries it continues to be a problem of public Health. To know risk factors involved in viral disease transmission is essential to improve preventive policies. The new article published on
PLOS ONE will provide new tools to know more about viral infections epidemiology and natural resources management.

Source: Modified from materials provide by The Universitat de Barcelona.


Reference

Jordi Serra-Cobo,, Marc López-Roig,, Magdalena Seguí,, Luisa Pilar Sánchez,, Jacint Nadal,, Miquel Borrás,, Rachel Lavenir,, & Hervé Bourhy (2013). Ecological Factors Associated with European Bat Lyssavirus Seroprevalence in Spanish Bats PLOS ONE DOI: 10.1371/journal.pone.0064467.t003


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