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Zoonotic diseases and the value of natural history

By Teresa Kearney

Knowledge around zoonotic disease research is perhaps more vital than ever considering the ongoing Covid-19 pandemic. In this article, Curator of Small Mammals at DITSONG: National Museum of Natural History (DNMNH) Teresa Kearney talks us through the importance of such research.

Teresa Kearney Covid-19 bats
Dr Kearney using a caliper to measure the forearm of a live bat

During this Covid-19 pandemic, which is having considerable global impact, it seems relevant to focus people’s attention on zoonotic disease research that is being undertaken in southern Africa, and in particular, South Africa. You may have heard, or read, that the likely host for the virus, SARS-CoV-2, which causes the disease Covid-19, is considered to have originated in bats before spilling over and reaching the human population. Prior to this pandemic, bats in different parts of the world were already known to be the host for a variety of different viruses (e.g. SARS-related, Marburg, Hendra, Nipah, Rabies, and rabies related lyssavirus).
     However, bear in mind that bats are not the only hosts to viruses. Other hosts include a variety of living organisms such as bacteria, plants, and other animals. As people are populating more and more areas of the world, humans are living in closer contact with species that we previously did not have much contact with. This can provide opportunities for viruses that have resided in wild animals for many millions of years to spill over into other species.
     See the articles ‘Nipah: The Very Model of a Pandemic’ and ‘Six-Year Study Indicates Nipah Virus More Widespread than Previously Thought’ for work that has been done to understand how Nipah virus spilled over from bats, sometimes through intermediary hosts, i.e. pigs, into humans in south-east Asia.
     Since 2007, I have undertaken collaborative research with a virologist Prof. Wanda Markotter (Centre for Viral Zoonoses (CVZ), University of Pretoria). Prof. Markotter, together with a large group of post-graduate students and colleagues from the National Institute of Communicable Diseases, has been trying to identify which viruses are in which species of small mammals, primarily bats, occurring in southern and South Africa. The objective is not only to identify, but also try and understand the ecology of the hosts, alongside where and when the viruses appear. This information is necessary to limit spill over events, without causing unnecessary harm to the hosts, particularly bats. Bats provide a valuable service to the ecosystem; eating insects (including crop pests), pollinating plants, and dispersing seeds.

Teresa Kearney Covid-19 bats
CVZ virology post-graduate students at work in the field

Bats account for a quarter of all mammal species, with more than 1200 species globally, and more than 100 species in the southern African region. In recent years, DNA sequence information has also indicated additional, previously unrecognised species. Collection of a limited number of bat voucher specimens provides a link between DNA sequence of the bat host and viruses, as well as between DNA and morphological characters retained by the voucher specimen. Over time, with changes in bat taxonomy, voucher specimens can be revisited, enabling host species information to be re-evaluated and updated, while keeping links to any viral results. Besides assistance in the field, capturing, measuring, weighing, and sexing small mammals, my role has been to incorporate voucher specimens into the small mammal collection of DNMNH, and provide morphological identifications.

Teresa Kearney Covid-19 bats
Dr Teresa Kearney helping CVZ postgraduate students to identify the gender of bats caught exiting a cave (the bat trap is behind them)

This close attention to the host of the virus is relatively new in zoonotic work in South Africa. Publications on Bartonella, Coronaviruses, Paramyxoviruses, lyssaviruses and Rickettsia, have included links to vouchers in DNMNH (See articles here, here, here, and here).
     Having recently been awarded a large grant from the Defence Threat Reduction Agency (DTRA) Prof Markotter and her co-principal investigator, Prof Jonathan Epstein (EcoHealth Alliance), who led the work indicated above on Nipah virus, will be intensifying the work on zoonotic disease in southern Africa with a large transdisciplinary team. DNMNH is included as the repository of any voucher specimens, in order to provide the important link to the host species.

Find out more about Dr Teresa Kearney here, and learn all about the work being done at DITSONG: National Museum of Natural History here.

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