Partha Sarathi Banerjee graduated with a BVSc and AH degree from Bidhan Chandra Krishi Viswavidyalaya, West Bengal, in 1985 and subsequently completed a master’s degree (Vet., Parasitology) from JNKVV, Jabalpur, in 1988. After serving as a veterinary surgeon for 3 years in West Bengal, he joined as an Assistant Professor in the Department of Veterinary Parasitology, GB Pant University of Agriculture and Technology, Pantnagar, in 1991 and was selected as an Associate Professor in 1998. In the meantime, he completed PhD from GBPUA and T, Pantnagar. He was selected as a Sr. Scientist in the Division of Parasitology, ICAR-IVRI, Izatnagar, in 2005. Dr. Banerjee was selected as the head of the Parasitology Division in 2011. He has 32 years of experience in teaching, research, and extension. His research interest includes molecular epidemiology and diagnosis of important parasitic diseases of domestic and wild animals. During his time at IVRI, he carried out research contributing to molecular epidemiology and diagnosis of Cryptosporidium parvum, Ehrlichia canis, Babesia gibsoni, poultry Coccidia, and Trichinella spp. He was also actively involved in several disease investigations in wild animals and human trypanosomosis. He has guided 10 MVSc and four PhD students and published more than 155 research articles in national and international journals, apart from contributing to seven books/chapters, five laboratory manuals, one mobile application (both in English and Hindi), and one Colour Atlas on Parasites of Veterinary Importance. In recognition of his teaching excellence, he was awarded the “Best Teacher Award” at GBPUA and T, Pantnagar, in 2001–2002 and the same at IVRI Deemed University in 2014–2015. He has handled several research projects, including one international project funded by BBSRC, UK. He served as the Editor-in-Chief of the Journal of Veterinary Parasitology, the official journal published by the Indian Association for the Advancement of Veterinary Parasitology, during 2011–2015. At present, he is serving as the Station in-charge of the Eastern Regional Station, ICAR-IVRI, Kolkata
1. Tropical Parasitology (TP): As an eminent member of various prestigious organizations, please share your views and experiences in parasitology.
Dr. P. S. Banerjee(PSB): I feel proud to be associated with two prestigious organizations of the country – G. B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, the first agricultural university in India, and the Indian Veterinary Research Institute (ICAR-IVRI), which is considered one of the premiere research institutes in veterinary science in Asia. While working as a parasitology teacher in the first institute, I learned most of the techniques from my seniors and got the opportunity to work independently. My simple target was to see the parasites, which I studied during graduation, and this paid dividends. The collection of different parasites from slaughterhouses and demonstrating the specimens to the graduating students gave me confidence. At IVRI, I got the opportunity to interact with a galaxy of learned colleagues and brilliant students, who were instrumental in igniting my interest in the application of molecular biology techniques in parasitology.
2. TP: As an expert in veterinary parasitology, please shed some light on its current trends and significance on human health.
PSB: Veterinary parasitology plays a crucial role not only in animal health but also in public health. Being a multidisciplinary subject, parasitology today is not restricted to conventional morphology and the lifecycle of parasites. It includes the application of bioinformatics, molecular biology, genomics and proteomics, artificial intelligence, satellite imagery, mathematical modeling, and enabling researchers to develop accurate diagnostics, vaccines, and disease forecasting systems. All this advanced knowledge will ultimately help in developing strategies to combat parasitic diseases. The effect of climate change on the epidemiology of animal diseases is another important area of research, the data of which may be extrapolated for human diseases too. Veterinary parasitologists play a role in monitoring and understanding emerging parasitic diseases that could potentially impact both animal and human populations. The recent concept of the One Health approach signifies concerted efforts of veterinary, public health, and environment specialists to keep diseases at bay. Another important issue is the scarcity of new antiparasitic drugs available for treatment. Anthelmintic resistance is widespread among helminth parasites of domestic animals. Similarly, some of the protozoan parasites of animals are also reported to be resistant to most of the available drugs currently in use. Although no such problem has so far been reported in human parasites, still it may emerge at any time because just like antimicrobials, anthelmintics of the same classes are used in both veterinary and human medicine.
3. TP: What are your favorite areas of research interest in parasitology?
PSB: Throughout my career in parasitology research, I worked on epidemiology and diagnosis of parasitic diseases inflicting economic losses to farmers. I was also involved in the diagnosis of parasitic diseases in wild animals and a few human cases. Many of these parasitic diseases are of zoonotic importance. Genetic characterization and molecular epidemiology of Cryptosporidium parvum, Babesia spp. infecting domestic animals, human trypanosomiasis, Trichinella spp., and poultry Coccidia kept me busy during my research career.
4. TP: Please share your work experience, especially related to challenging zoonotic infections diagnosed in humans.
PSB: Timely and accurate diagnosis is crucial for initiating appropriate treatment and mitigating the potential long-term health consequences associated with zoonotic parasites. Many of the parasitic zoonoses are difficult to diagnose due to the fact that no stage of the parasite comes out of the host in any excretion or secretion. In such a situation, immunodiagnosis or other diagnostic techniques (computed tomography/magnetic resonance imaging) may be useful. Immunodiagnosis has its own limitations, as the simple presence of antibodies cannot rule out past infection. Demonstration of circulating antigen, rather than antibody, will be more valuable. The paucity of highly sensitive and specific serodiagnostic tests for parasitic infections is the major bottleneck in this direction. There is an urgent need to develop pen-side tests for accurate diagnosis. Lack of funding for research on parasitic diseases is the main huddle, which should be brought to the notice of the policymakers.
5. TP: What is the main role of animal reservoirs and transmission patterns of animal parasites to humans in the world?
PSB: Animals play a pivotal role in the transmission and maintenance of zoonotic parasites. Parasitic diseases of animals are mostly chronic in nature, and once infected, the animals carry residual infection and act as reservoirs for humans. The contamination of the soil and water with the parasitic stages, excreted by the animals, is resistant to harsh environmental conditions and remains viable for a prolonged time. Humans often come in contact with these infective stages either through contaminated food and water or through green vegetables grown in contaminated soil. Humans also become infected by eating the meat of infected animals (Taenia solium, Taenia saginata, Paragonimus, Trichinella, and Toxoplasma). Game animals like wild boars are good sources of taeniasis, trichinellosis, and toxoplasmosis. Massive deforestation has resulted in the migration of monkeys into the cities, where they contaminate the overhead water tanks by defecating, thus transmitting giardiasis, cryptosporidiosis, and amebiasis. The close interaction between animals and humans, through agricultural practices, companion animals, or wildlife, creates opportunities for the spillover of parasitic infections. In addition, vectors such as ticks and mosquitoes can move between animals and humans, serving as efficient carriers of zoonotic parasites.
6. TP: What is your take on the characteristics of trypanosomes in animals compared with those recovered from humans?
PSB: Domestic animals in India are susceptible to only two trypanosomes – Trypanosoma evansi (pathogenic) and Trypanosoma theileri (nonpathogenic). Apart from these, rats harbor Trypanosoma lewisi (nonpathogenic). Of these three, the first one is a salivarian trypanosome (transmitted through the bite of the vector) and the remaining two are stercorarian trypanosomes (transmitted through contamination of wounds with the excreta of the vectors). These two types of trypanosomes can be distinguished easily by studying morphology under a compound microscope. The shape, size, and position of the nucleus and kinetoplast are distinctive in these two groups. In addition, live T. lewisi in freshly collected blood has a typical movement when viewed under a microscope (very fast progressive movement) and this helps in identification. African trypanosomes, grouped under the salivarian type, look alike and cannot be differentiated from each other. Hitherto, three species of trypanosomes have been recorded from human cases in India – T. evansi, T. lewisi, and Trypanosoma brucei rhodesiense (recorded thrice in human patients returning from Africa). For distinguishing the species, molecular techniques like polymerase chain reaction and sequencing are confirmative.
7. TP: You have worked with several parasites that cause infections in animals. In your opinion, do any of these pathogens have the potential to become a serious human hazard?
PSB: Of course, almost all of them have got the potential to infect humans. This is more true when we consider the humans who are immunocompromised due to one or the other reason. Humans are known to harbor around 300 species of helminths and more than 70 species of protozoa, out of which around 90 are quite common. They have acquired these parasites either from their ancestors (heirloom parasites) or from their animal counterparts (souvenir parasites) during evolution (Cox, 2002). There is ample evidence, that animal parasites, which are considered host-specific, jumped the species barrier and reached humans. The recent report of human neural larva migrans in an Australian woman, caused by Ophidascaris robertsi, the ascarid worm of Australian carpet pythons, is an eye-opener (Hossain et al., 2023). From India, few cases of human trypanosomiasis have been reported in the recent past and all of these were caused by animal trypanosomes, either T. evansi (Joshi et al. 2005) or T. lewisi (Verma et al. 2011, Bharodiya et al. 2018). The zoonotic potential of Toxoplasma, Cryptosporidium, Echinococcus/hydatid, Taenia/neurocysticercosis, and Paragonimus is well established.
8. TP: In your opinion, what newer perspectives can be addressed in national programs for eliminating parasites with multiple hosts?
PSB: To be honest, it is next to impossible to eliminate parasites from a vast country like India having varied geoclimatic zones with a population of nearly 1.5 billion humans and more than a billion of livestock, pets, synanthropic, and wild animals, which are a potent source of infections. However, advanced technologies and innovative research methodologies can significantly contribute toward minimizing the impact of parasitic diseases on animal as well as human health. Artificial intelligence, genomics, bioinformatics, and molecular biology marked a watershed, which can provide deeper insights into the epidemiology and genetic diversity of parasites, thereby helping in targeted interventions. The One Health concept, encompassing human, animal, and environmental health, is crucial for a comprehensive understanding of parasitic diseases and transmission dynamics. Strengthening collaboration between public health agencies, veterinary services, and environmentalists can lead to more effective surveillance and control measures. Keeping pace with global developments is a prerequisite to achieve the goal at the national level.
9. TP: Please share a few words of advice for budding scientists in the field of parasitology.
PSB: Being served in three different roles as a veterinary parasitology, namely, as a field veterinarian in a remote village and treating animals for various diseases, second, as a teacher of veterinary parasitology at the first agricultural university in the country, and finally, as a scientist engaged in parasitology research and disease investigation at a premiere veterinary research institute, my ultimate realization and honest suggestion to budding scientists are to take up research on parasitic diseases, which is usually neglected. Humans often pick up parasitic infections from the environment through water, soil, and a variety of foods (both animal origin and vegetables). The inquisitive minds of the budding scientists are the key component for their success. Perseverance is another very important factor to get the results of the hard work. Microscopy is still considered the “gold standard” to diagnose parasitic infections as it is considered to be cent percent specific. All budding scientists, who want to take up the challenge, must spend some time with microscopy on a regular basis. Pen-side diagnostics and molecular techniques can supplement microscopic diagnosis, but cannot replace it.
