Quails could be the unknown reservoir of Tuscany and Sicilian viruses

Quails could be the unknown reservoir of the Toscana virus (TOSV) and the Sandfly Fever Sicilian virus (SFSV), mosquito-borne pathogens that can infect domestic animals and also cause disease in humans. This conclusion is drawn from a study published in the journal Frontiers in Microbiology, and led by Jordi Serra-Cobo, professor at the Faculty of Biology and the Biodiversity Research Institute (IRBio) of the University of Barcelona, and Remi Charrel, from the Aix-Marseille University (France).

This is the first time that researchers find neutralizing antibodies to TOSV and SFSV in wild birds. "To date, the reservoir for these two viruses was unknown, although they have been sought for years. Dogs and bats had been proposed as reservoirs, but the results showed that neither of them were," says Jordi Serra-Cobo, an expert in epidemiological studies with bats as natural reservoirs of infectious agents such as coronaviruses.

The study, whose first author is Nazli Ayhan, from Aix-Marseille University, includes the participation of José Domingo Rodríguez Teijeiro, Marc López-Roig, Dolors Vinyoles and Abir Monastiri (UB Faculty of Biology and IRBio) and Josep Anton Ferreres (UB Faculty of Biology).

Emerging viruses in the Mediterranean basin

TOSV and SFSV belong to the Phlebovirus genus and are considered emerging pathogens. They are spherical, single-stranded RNA viruses with a high mutation rate and are transmitted by mosquito bites (Phlebotomus genus), insects found mainly in the warmer, drier areas of the Iberian Peninsula. These viruses are distributed in most Mediterranean countries in Western Europe, as well as Cyprus and Turkey. With no actual vaccine against infection, epidemiological surveillance, control, and prevention measures to avoid phlebotomine sandfly bites are crucial to avoid viral infections.

"Both TOSV and SFSV have been detected in a variety of domestic animals (dogs, cats, goats, horses, pigs, cows), but they can also infect humans and cause diseases," says the researcher, a member of the UB Department of Evolutionary Biology, Ecology and Environmental Sciences.

In humans, feblovirus infections are usually symptomless and often result in a three-day fever—pappatasis feve—which is very similar to influenza. "SFSV can cause a period of short-length high fever, accompanied by headache, rash, photophobia, eye pain, myalgia and general weakness. TOSV can cause the same manifestations as SFSV, but it can also be responsible for various central or peripheral neurological signs, such as meningitis and encephalitis. In fact, part of the encephalitis that occurs in summer is caused by TOSV," Serra-Cobo notes.

Viruses in migratory birds

The results of the new study suggest that birds could be the reservoir or amplifying agents of these viruses. From infected birds, mosquitoes can become infected and then bite animals or humans. In particular, the study highlights the important role of quails (Coturnix coturnix) in the infection dynamics of phleboviruses.

"Migratory birds play an important role in disease transmission due to their high mobility from one area to another, which makes them potential vectors of diseases that can affect domestic animals and human health," Serra-Cobo stresses.

"The quail is a migratory and also a hunter species, which enhances the potential transmission of diseases by direct contact through the food chain. In this context, regular pathogen detection is of great importance to predict future disease risks for both wildlife and humans," concludes the researcher.