“Biomarkers in a One Health perspective: current knowledge of their ability to merge human and animal health

Biomarkers are nowadays essential tools to be one step ahead for fighting disease, enabling an enhanced focus on disease prevention and on the probability of its occurrence. Research in a multidisciplinary approach has been an important step towards the repeated discovery of new biomarkers. Biomarkers are defined as biochemical measurable indicators of the presence of disease or as indicators for monitoring disease progression. Currently, biomarkers have been used in several domains such as oncology, neurology, cardiovascular, inflammatory and respiratory disease, and several endocrinopathies. Bridging biomarkers in a One Health perspective has been proven useful in almost all of these domains. In oncology, humans and animals are found to be subject to the same environmental and genetic predisposing factors: examples include the existence of mutations in BR-CA1 gene predisposing to breast cancer, both in human and dogs, with increased prevalence in certain dog breeds and human ethnic groups. Also, breast feeding frequency and duration has been related to a decreased risk of breast cancer in women and bitches. When it comes to infectious diseases, this parallelism is prone to be even more important, for as much as 75% of all emerging diseases are believed to be zoonotic. Examples of successful use of biomarkers have been found in several zoonotic diseases such as Ebola, dengue, leptospirosis or West Nile virus infections. Acute Phase Proteins (APPs) have been used for quite some time as biomarkers of inflammatory conditions. These have been used in human health but also in the veterinary field such as in mastitis evaluation and PRRS (porcine respiratory and reproductive syndrome) diagnosis. Advantages rely on the fact that these biomarkers can be much easier to assess than other conventional disease diagnostic approaches (example: measured in easy to collect saliva samples). Another domain in which biomarkers have been essential is food safety: the possibility to measure exposure to chemical contaminants or other biohazards present in the food chain, which are sometimes analytical challenges due to their low bioavailability in body fluids, is nowadays a major breakthrough. Finally, biomarkers are considered the key to provide more personalized therapies, with more efficient outcomes and fewer side effects. This approach is expected to be the correct path to follow also in veterinary medicine, in the near future.

"Portuguese Observatory of Taeniasis and Cysticercosis": A "One Health" example for epidemiological surveillance of one neglected disease in a European country

Cysticercosis results from the ingestion Taenia solium eggs directly by faecal-oral route or contaminated food or water. Human tapeworm carriers who have become infected after ingesting pork meat contaminated with cysticerci release these eggs. Cysticercosis occurs after tapeworm eggs are ingested by an intermediate host (pig or human) and then hatch, migrate, and lodge in the host's tissues, where they develop onto larval cysticerci. When they lodged in the central nervous system of humans, results in the disease condition called Neurocysticercosis (NCC), with a heterogeneous manifestations depending of the locations of cysts, number, size and their stage of evolution (1). Consequently the prognostic ranges from asymptomatic to situations leading to death in 2% to 9.8%. of cases (7) In swine’s there are few studies, but recent works have proved that animals, for the same reasons, also have neurological abnormalities, expressed by seizures, stereotypic walk in circles, chewing motions with foamy salivation included tonic muscle contractions followed by a sudden diminution in all muscle tone leading to collapse (2). Conventional domestic wastewater treatment processes may not be totally effective in inactivating parasites eggs from Taenia solium, allowing some contamination of soils and agricultural products (11). In Portugal there are some evidence of aggregation of human cysticercosis cases in specific regions, bases in ecological design studies (6). There are few information about human tapeworm carriers and social and economic factors associated with them. Success in knowledge and consequently in lowering transmission is limited by the complex network of biological and social factors that maintain the spread. Effective control of mostly zoonosis require One Health approach, after a real knowledge and transparency in the information provided by the institutions responsible for both animal and human health, allowing sustained interventions targeted at the transmission cycle's crucial nodes. In general, the model used to control, reflects a rural reality, where pigs are raised freely, poor sanitation conditions and incipient sanitary inspection. In cysticercosis, pigs are obligate intermediate hosts and so considered as first targets for control and used as sentinels to monitor environmental T. solium contamination (3). Usually environmental contamination with Taenia spp. eggs is a key issue in most of studies with landscape factors influencing presence of Taenia spp. antigens in both pigs and humans (5). Soil-related factors as well as socio-economic and behavioural factors are associated with the emergence of significant clustering human cysticercosis (4,5). However scarce studies has been produced in urban environmental and in developed countries with the finality to characterize the spatial pattern. There are still few data available regarding its prevalence and spatial distribution; Transmission patterns are likely to exhibit correlations as housing conditions, water supply, basic sanitation, schooling and birthplace of the individual or relatives, more than pigs rearing free, soil conditions (9). As a matter of fact, tapeworm carriers from endemic zones can auto-infect or transmit infection to other people or arrive already suffering NCC (as a result of travelling to or being a citizen from an endemic cysticercosis country) to a free cysticercosis country. Transmission is fecal-oral; this includes transmission through person-to-person contact, through autoinfection, or through contaminated food This has been happening in different continents as North America (5.4–18% been autochthonous), Europe and Australia (7). Recently, case reports of NCC have also emerged from Muslim countries. (10). Actually, different papers relate an epidemic situation in Spain and Portugal (7, 8). However the kind of study done does not authorize such conclusion. There are no evidence that infections were acquired in Portugal and there are not characterized the mode of transmission. Papers with these kind of information will be allow to have economic consequences resulted from artificial trade barriers with serious consequences for pig producers and pig meat trade. We need transparency in information’s that allow provide the basis to support the development and targeting of future effective control programmes (and prove we need that). So, to have a real picture of the disease, it is necessary integrate data from human, animal and environmental factors surrounding human and pig cases to characterize the pattern of the transmission. The design needs to be able to capture unexpected, and not common outcomes (routine data). We need to think “One Health” to get a genuine image of the situation.