The study targeted the Getúlio Vargas Zoobotanical Park, a 25-hectare green space in the heart of Salvador that preserves remnants of secondary Atlantic Forest under a tropical, hot and humid climate, with roughly 1,800 millimeters of annual rainfall and mean temperatures around 25 degrees Celsius. That setting matters: Brazil harbors approximately 20 percent of the world’s biodiversity across its six major biomes, and zoos like this one hold a substantial share of threatened species in their collections. In total, the survey covered 75 species and 409 individual animals, including 40 mammal species with 229 individuals, 27 bird species with 153 individuals, and seven reptile species with 27 individuals, ranging from jaguars and maned wolves to harpy eagles, scarlet ibises, and Burmese pythons.

Because sampling relied on fecal material rather than invasive procedures, the team collected pooled samples directly from enclosure floors during routine cleaning periods in December 2021, taking care to gather only the inner portions of each fecal mass to avoid contact with soil and reduce the risk of environmental contamination. Samples were preserved in 5 percent formalin and shipped to the Animal Parasitology Laboratory at the Federal Rural University of the Semi-Arid Region for analysis. Not every animal could be sampled; some reptiles, particularly those that defecate infrequently or spend extended periods in water, such as freshwater turtles and caimans, did not produce usable material during the collection window. The researchers therefore treated the enclosure, not the individual animal, as their sampling unit, a conservative choice that shapes how the results should be read.

The methodological heart of the study lies in its decision to run four complementary coproparasitological techniques in parallel on every sample: the direct method, spontaneous sedimentation, Willis flotation in hypersaturated sodium chloride, and the Mini-FLOTAC system, a modern flotation device that also allows quantification of eggs, oocysts, and larvae per gram of feces. The choice was deliberate, because each technique excels at recovering different parasitic structures. Flotation methods preferentially float light eggs and oocysts in dense solutions, sedimentation is better suited to heavier eggs such as those of trematodes that resist flotation, and the direct method, though less sensitive in low-intensity infections, provides rapid detection of larvae, protozoan stages, and eggs in fresh material. Each slide for the first three techniques was read independently by two evaluators to increase reliability.

The headline number is stark: 52.8 percent of the 144 samples analyzed were positive for endoparasites. Among the positive samples, nematodes dominated at 80.3 percent, followed by protozoa at 23.7 percent, cestodes at 13.2 percent, and trematodes at 10.5 percent, and just over a quarter of positive samples, 26.3 percent, harbored mixed infections involving two or more parasite groups. Descriptively, the direct method detected parasite structures in 38.2 percent of all samples, spontaneous sedimentation in 36.1 percent, Willis flotation in 32.6 percent, and Mini-FLOTAC in 26.4 percent, a spread that vividly illustrates why no single diagnostic test tells the whole story. The researchers cautioned that they used the techniques as complementary tools rather than competing benchmarks, and did not formally compare their diagnostic performance.

Broken down by host group, the results overturned a familiar pattern. Zoological surveys typically report higher parasite frequencies in birds and mammals than in reptiles, but here reptiles led with 66.7 percent positivity, followed by birds at 60.0 percent and mammals at 47.8 percent. The authors suggest this inversion may reflect the specific species sampled and the nature of parasitism in reptiles, which is often asymptomatic or oligosymptomatic and therefore easy to miss clinically. Within mammals, the parasite inventory was rich and taxonomy-specific: primates carried coccidia, Strongyloides roundworms, the tapeworm genus Bertiella, and the fluke Platynosomum; carnivores harbored Strongyloides and pinworms of the family Oxyuridae; even-toed ungulates such as deer and peccaries carried the ciliate Balantioides alongside whipworms and Strongyloides; odd-toed ungulates, including the South American tapir and plains zebra, showed strongyles and Balantioides; and opossums proved to be a hotspot, hosting Eimeria, Cruzia, Aspidodera, and an assortment of other nematodes at strikingly high egg counts.

Birds and reptiles added their own distinctive entries. Psittacines, from macaws to parakeets, tested positive for Capillaria hairworms, ascarid roundworms, and strongyles, with red-browed amazons showing ascarid loads of up to 3,700 eggs per gram. Passerines, including rufous-bellied thrushes and sayaca tanagers, carried Isospora and unsporulated coccidia, with one tanager sample reaching a remarkable 80,304 oocysts per gram. Among reptiles, snakes shed coccidia and rhabditiform larvae, the green iguana carried pinworm eggs, and the red-footed tortoise proved especially diverse, yielding Nyctotherus and Balantioides protozoa, strongyle eggs, coccidia, and larvae of the family Atractidae. Notably, several of the identified parasites, including Balantioides, Strongyloides, Trichuris, and Platynosomum, have known or suspected zoonotic potential, meaning they can pose a genuine occupational risk to keepers, veterinarians, and anyone in close contact with the animals or their enclosures.

The most consequential findings are the first-ever parasite records for specific host species. The team reports, for the first time, the occurrence of Strongyloides roundworms in the white-cheeked spider monkey and the golden-headed lion tamarin, Bertiella tapeworms in the blond titi monkey and the common squirrel monkey, and Capillaria hairworms in the red-browed amazon, the peach-fronted parakeet, and the red-shouldered macaw. Several of these hosts are themselves conservation priorities, and the blond titi monkey in particular is a critically endangered species endemic to the Caatinga. Documenting these associations expands the known host ranges of common parasite genera and gives veterinarians managing captive populations a better map of what to screen for, when to treat, and how to design quarantine and deworming protocols that protect both collection animals and staff.

Why does parasitism run so high in captivity in the first place? The authors point to a convergence of factors: limited space, elevated host density, close proximity between species, and chronic stress that can suppress immune responses, all of which favor transmission. Many of the dominant parasites, including most nematodes and protozoa, have direct life cycles requiring no intermediate host, so infective stages accumulate quickly in shared enclosures. Contact with synanthropic wildlife, free-roaming animals that thrive around human settlements, adds another transmission route that is notoriously difficult to control. Left unchecked, these infections can progress from silent subclinical states to anorexia, weight loss, gastrointestinal disease, anemia, and reduced survival and reproductive success, outcomes that directly undercut the conservation mission zoos exist to serve.

The study is candid about its limits. Feces were collected as pooled samples from enclosure floors, so results describe positivity at the enclosure or sample level rather than true individual prevalence, and the single December 2021 sampling campaign captures only a moment in time, leaving seasonal fluctuations unexplored. Formalin preservation and the absence of molecular confirmation restricted some identifications to morphological categories, and the Mini-FLOTAC dilution followed the manufacturer’s recommendation for dogs and cats, which may not be optimized for every host group examined. Even so, the authors argue that the takeaway is clear and urgent: systematic parasitological monitoring is not an optional extra for zoological institutions but a cornerstone of animal health management, and longitudinal studies with repeated seasonal sampling are the logical next step. For a park sheltering jaguars, lion tamarins, and harpy eagles in the remnants of the Atlantic Forest, knowing which parasites share the enclosures is the first line of defense for the animals, the people who care for them, and the species they may one day help return to the wild.

Subject of Research: Endoparasitic fauna in captive mammals, birds, and reptiles at a Brazilian zoobotanical park, detected through complementary coproparasitological methods

Article Title: Parasitological study of animals maintained under human care at a Zoobotanical Park in Bahia, Northeastern Brazil

Article References: Batista, A. I. V., Gurgel, J. V. D. O., Pereira, L. M. F., Ferreira, P. R. B., Gomes, M. C., Brasil, A. W. D. L., Lima, V. F. S., Coelho, W. A. C., Carvalho, L. R. R. A., & Pereira, J. S. (2026). Parasitological study of animals maintained under human care at a Zoobotanical Park in Bahia, Northeastern Brazil. Frontiers in Parasitology, 5, Article 1929185. https://doi.org/10.3389/fpara.2026.1929185

Image Credits: AI Generated

DOI: 10.3389/fpara.2026.1929185

Keywords: coproparasitology, zoo animals, endoparasites, nematodes, zoonoses, Strongyloides, Bertiella, Capillaria, conservation, Brazil, Mini-FLOTAC, captive wildlife

The core idea is deceptively simple. Animal State (AS) covers what is directly expressed by the animal: body condition, visible clinical signs, feeding behaviour, behavioural diversity, abnormal repetitive behaviour, social interactions, responsiveness and reactions to humans. Husbandry Context (HC), by contrast, covers what is currently observable about the environment: enclosure space, thermal conditions, hygiene, lighting, shelter, substrate, retreat opportunities, nutrition, choice and control, group composition, structural complexity, enrichment, safety and visitor exposure. The two are related, the authors stress, but they are not equivalent, and the links between them are not established for every indicator.

Under limited-access conditions, the distinction matters even more. When assessors cannot enter off-exhibit areas, interview keepers or consult veterinary records, an observed problem cannot safely be attributed to current husbandry. A stereotypy seen today may reflect past housing, learning history or individual factors, and some behaviours persist after conditions improve. The reverse inference is equally risky: the absence of visible distress does not prove that the current environment is free of concern. Keeping the two domains separate at the observation stage, the researchers argue, prevents premature causal storytelling while still capturing where concern is located.

To test the framework, eleven assessors worked in three-person teams, each assigned to particular species, from African crested porcupines and Asian elephants to chimpanzees, fennec foxes, meerkats, siamangs and western lowland gorillas. All evidence came from public viewing areas during regular opening hours between April and June 2026. Assessors took behavioural videos of at least three minutes each, photographed appearance and enclosure features, and used laser distance meters, lux meters, sound level meters and thermo-hygrometers to record environmental conditions. Every scored item was rated on a six-level anchored scale from 1 to 10, with higher numbers indicating greater concern.

The scoring procedure was deliberately structured to avoid groupthink. Each assessor first scored independently, then the team held a structured evidence-review discussion lasting roughly 80 to 120 minutes, comparing photographs, videos, measurements and species-specific reference material. Crucially, no consensus score was produced: each assessor revised their own scores individually afterwards, and the three revised sets were retained separately. Agreement was then measured with Krippendorff’s alpha, and the results were impressive at the overall level: 0.961 for Animal State, 0.932 for Husbandry Context and 0.939 for the combined ASHC score.

Agreement was weaker for some specific items, however. Nutritional provision reached only 0.657, enrichment 0.721 and choice and control 0.766, all falling into the tentative range. The authors note that these indicators may be genuinely harder to judge from public viewing areas, because provision can change over time and animals’ functional use of resources is not always visible. They suggest that clearer scoring guidance and evidence requirements may be needed for such items. The team also cautions that the high overall agreement reflects scores revised after shared review, not fully independent reproducibility, and that consistency is not the same as validity.

The headline finding is about what summary scores conceal. Across the 20 species, mean Husbandry Context was 4.24 and mean Animal State was 2.78, with HC exceeding AS in 18 of 20 species. Yet the paired profiles told far richer stories. The siamang and the western lowland gorilla had almost identical overall ASHC values of 4.36 and 4.31, but their compositions were radically different. The siamang showed strong husbandry concern (HC 6.61) against a low animal-state score of 2.10, with animals observed brachiating, playing, grooming and vocalising. The gorilla, an older female, showed regurgitation and re-ingestion, self-clasping and low responsiveness, producing a higher AS of 4.08 and a nearly balanced profile.

Only two species, the jaguar and the sun bear, showed the opposite pattern, with animal-state concern exceeding husbandry concern. The jaguar displayed repetitive behaviour and repeated fur licking, while the sun bears showed repeated aggression, wounds and marked panting in warm conditions. The researchers are careful to stress that these negative gaps do not demonstrate that current husbandry caused the observed states; unobservable management or health history could be responsible, and follow-up information would be needed before any causal claim. Indicator-level contrasts reinforced the point: the fennec fox and South American coati shared an identical husbandry summary of 3.86, but the fox’s concerns centred on thermal environment, noise, enrichment and choice, while the coati’s centred on substrate, shelter, retreat and drainage.

Even behavioural summaries hid divergent realities. The African crested porcupine and the meerkat both scored 3.11 on behavioural AS, but for different reasons. The porcupines repeatedly huddled in one area with little postural variation, minimal enrichment use and repeated social avoidance across more than ten observation periods, while the meerkats’ vigilance, a normal part of their sentinel behaviour, was repeatedly tied to visitors approaching or tapping on glass. The Asian elephant, meanwhile, had a low overall score yet retained a focal concern for retreat and concealment. In each case, the detailed profile narrows the questions that follow-up assessment should ask, rather than delivering a diagnosis.

The authors position ASHC not as a replacement for comprehensive internal welfare assessment, nor as a validated composite welfare index, but as a complementary framework for organising observable evidence and directing further investigation. Species were purposively selected, individual numbers ranged from one to nine per species, and a sensitivity analysis confirmed the main pattern under an alternative weighting scheme. The practical message for zoos, welfare scientists and even concerned visitors is that a single number can flatten a complex story. Separating what the animal shows from what the environment offers preserves the location and composition of welfare concern, and points precisely to where keeper records, veterinary history and longitudinal data should be examined next.

Subject of Research: Zoo animal welfare assessment using the Animal State–Husbandry Context Grid across 20 mammalian species

Article Title: Animal state and husbandry context profiles in limited-access zoo welfare assessment: evidence from 20 mammalian species

Article References: Kim, J.-Y., Lee, W., Jeong, D.-W., & Kim, M.-G. (2026). Animal state and husbandry context profiles in limited-access zoo welfare assessment: evidence from 20 mammalian species. Frontiers in Ethology, 5, Article 1919787. https://doi.org/10.3389/fetho.2026.1919787

Image Credits: AI Generated

DOI: 10.3389/fetho.2026.1919787

Keywords: animal welfare, zoo animals, welfare assessment, animal behaviour, husbandry, mammals, Krippendorff's alpha, stereotypic behaviour, enclosure design, enrichment, limited-access observation, Frontiers in Ethology