Rosario Panadero: «60% of pathogens that cause human diseases originate in domestic or wild animals»

Elements as significant for the progress and development of our society as animal health, human health, and safe, healthy, and accessible food coexist under the same umbrella: the concept of One Health.

The key to this term lies in close scientific collaboration of a multidisciplinary and cross-cutting nature, in which disciplines such as Veterinary Parasitology play a critical role. This is a fascinating field of research, and Rosario Panadero Fontán is one of its greatest advocates.

Professor of Animal Health, researcher and lecturer at the Faculty of Veterinary Science at Campus Terra, coordinator of the competitive reference group INVESAGA, secretary of the Department of Animal Pathology, a de facto member of the European Veterinary Parasitology College for more than two decades...

The milestones of her well-established scientific career speak for themselves. And they will always be linked to concepts such as effort, curiosity, excellence and, above all, passion.

Today, we talk to Rosario Panadero about the challenges facing humanity in relation to animal health, the impact that myiasis can have on our environment, and the challenges and lessons that have shaped her prolific career as a researcher.

-As coordinator of the INVESAGA group, what are the main lines of research in animal health that you are currently addressing?

-INVESAGA is a research group that works in the field of epidemiology, diagnosis, prevention, and control of infectious and parasitic diseases that affect domestic and wild animals.

We currently have several lines of research, including:

• Environmental detection of pathogens and their applications in animal health.
• Epidemiological aspects of tick-borne pathogens and their impact on animal and public Health.
• Evaluation of the efficacy of drugs against pathogens and determination of antibiotic resistance, as well as field studies for the application of new products or strategies for the prevention and control of pathogens in domestic and wild animals.

-In recent years, animal health has become increasingly linked to the concept of 'One Health'. To what extent does work such as yours contribute to this global vision?

-The 'One Health' concept argues that human health depends on the good health of animals and ecosystems, as they are all deeply interlinked. For this reason, interdisciplinary collaboration between different professionals, doctors, veterinarians, biologists, engineers, etc., is necessary to protect the global health of the planet.

The work we are doing contributes to this global vision by preventing zoonoses (diseases that can be transmitted between animals and humans), promoting the health of wild species such as roe deer that help maintain the balance of ecosystems, and encouraging the responsible use of antimicrobials and antiparasitics in animals, reducing problems of resistance and the release of residues into the environment.

Furthermore, climate change and the movement of humans and animals are altering the abundance and temporal and spatial distribution of certain arthropods, such as ticks, causing the emergence or re-emergence of new infections for humans and animals worldwide. Therefore, any action aimed at controlling these vectors and the diseases they transmit must be carried out through coordinated plans that integrate the vectors (ticks), hosts (animals and humans), and the environmental conditions that determine their distribution and abundance.

-What sparked your interest in animal health and, in particular, veterinary parasitology?

I grew up in a rural environment, and from a very young age, I showed a great interest and curiosity in “bugs,” both large and small. I was just as fascinated by a cow as by a snail or a bee.

Studying veterinary medicine allowed me to get even closer to animals and learn more about their care. But it was in my fourth year of university, when I took Parasitology and Parasitic Diseases, that a fascinating new world opened up to me, where these two universes—that of large animals and that of small animals—converged.

I was amazed to discover these often invisible but almost omnipresent creatures that threaten the health of animals and people and have life cycles that are as complex as they are surprising. From then on, I knew I wanted to devote myself to veterinary parasitology. I began my bachelor's thesis on parasitic diseases in bees and later my doctoral dissertation on bovine hypodermosis, a disease caused by fly larvae.

-For those unfamiliar with your field of expertise, what impact does veterinary parasitology have on people's daily lives and food safety?

-According to the World Organization for Animal Health (OIE), 60% of pathogens that cause human diseases originate in domestic or wild animals.

These pathogens include well-known and important parasites such as Trichinella, Toxoplasma, and Anisakis, which are transmitted to humans through food (meat, vegetables, fish), and others such as Cryptosporidium, Giardia, and Amoeba through water.

In recent years, diseases transmitted by arthropod bites, such as ticks and mosquitoes, have become increasingly important. These include diseases of great relevance, such as Lyme disease, Crimean-Congo haemorrhagic fever, West Nile virus, etc.

In short, veterinary parasitology not only improves animal health but also contributes to human health and ensures safe, healthy, and accessible food for society.

-Myiasis in ruminants is an animal health problem that is little known outside the veterinary field. Could you explain what it is and why it is relevant?

-Myiasis is a disease caused by fly larvae that feed on animal tissue, causing significant economic losses and a major impact on animal health and welfare, which, in severe cases, can lead to death. Myiasis also predisposes animals to other diseases and, in some cases, can affect people who work in direct contact with animals.

Many types of myiasis are cutaneous, in which flies lay their eggs on the skin of animals, often attracted by the presence of wounds. However, in the case of the strides of ruminants that we study, the larvae are located in internal organs such as the oesophagus, nasal cavity, pharynx, stomach, etc., causing very significant alterations.

Currently, thanks to control programs based on the use of antiparasitics, myiasis such as hypodermosis and oestrosis are fairly well controlled in domestic ruminant herds. However, in wild ruminants, given the impossibility of implementing control measures, their incidence is increasing at an alarming rate.

-In your research, you developed advanced early diagnosis techniques. How did these tools improve the detection and treatment of myiasis?

-In the case of internal myiasis, the larvae can only be observed after the animal's death through a necropsy, which is very laborious. However, thanks to the development of immunological techniques capable of detecting the presence of specific antibodies, we can tell if an animal has been in contact with the parasite by simply analysing a blood sample. This allows for early diagnosis and enables the treatment of positive individuals before the larvae cause serious damage.

The main advantage of the technique we use is that it is multi-species, so with the same protocol, we can detect the presence of antibodies in any animal species that may be affected by these parasites. We have even used it successfully to confirm several cases of myiasis in humans.

In addition, in the case of nasal myiasis (Cephenemyia and Oestrus), we are working on a PCR test using nasal swabs, which will be a very promising non-invasive diagnostic alternative.

-The study of myiasis in roe deer and other wild ruminants in the Iberian Peninsula is another of your lines of research. What impact do these infections have on wildlife and ecosystems?

-Given the difficulty of implementing effective control measures in wildlife, the incidence of certain types of myiasis, such as cephenemyiosis, is increasing at an alarming rate. The larval development of C. stimulator takes place in the nasal and pharyngeal cavities of roe deer, where the larvae prevent the passage of air and make it difficult to swallow food. The presence of between 30 and 80 mature larvae can be enough to cause the death of the animal.

Currently, in the province of Lugo, virtually all adult roe deer are parasitized, which makes it necessary to seek alternative control measures to the use of drugs to prevent a decline in the populations of this ungulate. This would have a major negative impact on ecosystems, as roe deer are a source of food for other species, such as wolves.

-You have worked and continue to work with researchers from different countries. What are the main challenges and lessons learned from these international collaborations?

-I was fortunate to be able to train in France and Canada with the best international experts in estuarine myiasis, and in some cases, we collaborated for almost 30 years. I learned a lot from these collaborations, but I also realized that our level of research was on par with that carried out in those more pioneering laboratories.

Thanks to the experience I have gained, I can now contribute to the training of other researchers. These collaborations are always enriching, not only from a scientific point of view but also on a personal level, because, in most cases, bonds are formed that last forever.

Today, international collaboration is much easier than it was several decades ago because, thanks to technological advances, there are no longer language barriers or barriers to the exchange of information, and it is easier to organize a telematic meeting than a face-to-face meeting.

The main challenge I have faced is bureaucratic barriers when obtaining visas or organizing the transport of samples, especially with certain third countries.

-In addition to your research work, you have trained numerous students and supervised doctoral theses. What advice would you give to someone who wants to pursue a career in animal health research today?

-Climate change and globalization are leading to the emergence of new and re-emerging diseases, creating major challenges and opportunities for research in the field of animal health.

The first thing I would recommend to someone who wants to pursue a career in research is to be very patient because this is a long-distance race, and there are often a lot of obstacles. In the best-case scenario, you get a grant or a research contract to get started; the results of experiments don't always come out right the first time or even the second time...

Perseverance and a continuous learning attitude are essential. There will always be new challenges and questions to solve.