Gastrointestinal Parasites in Captive Animals at the Rio de Janeiro Zoo

Gastrointestinal parasites may determine diarrhea, dysentery or even death in captive mammals. These animals tend to be more susceptible to parasitic infections due to confinement and stress. Purpose To increase the information about these etiological agents in captive animals in Brazil, the gastrointestinal parasites of the captive mammals of the Rio de Janeiro Zoo were investigated.

From 2016 to 2018, 180 fecal samples were collected from animals housed in the Rio de Janeiro Zoo: 63 from animals of the order Primates, 26 of Carnivora, 78 of Artiodactyla, 9 of Perissodactyla and 4 of the order Rheiformes. The feces were processed by direct examination and by the techniques of Faust et al., Sheather, Ritchie, Lutz, and smears were stained with safranin. Immunoenzymatic assays were also performed to investigate antigens of Giardia duodenalis, Cryptosporidium spp., Entamoeba histolytica/Entamoeba dispar.

Parasite positivity was identified in 68.3% of the fecal samples, with a parasite positivity rate of 68.2% among primates, 65.3% among carnivores, 69.2% among artiodactyls, 33.3% among perissodactyls, and 100% among rheiformes. The most frequently detected parasite was Entamoeba histolytica/E. dispar antigens, which showed a statistically significant positivity rate (33.3%; p = 0.000), particularly in the feces of carnivores (30.7%) and artiodactyls (53.8%). A statistically significant positivity rate of Balantioides coli (11.1%; p = 0.001) was also detected in feces from nonhuman primates, tapirs, collared peccaries and rheas. The positivity of Cryptosporidium sp. antigens in feces of the orders Carnivora, Artiodactyla and Primates was also statistically significant (7.2%, p = 0.010). Oocysts compatible with Cryptosporidium spp. were detected in 6.3% from primates. The helminths most frequently detected were thin-shelled eggs of nematodes (17.7%, p = 0.000), nematode larvae (15.5%, p = 0.000) and Trichuris trichiura eggs (6.1%, p = 0.018).

The positivity rate for gastrointestinal parasites demonstrates the need for a sanitation management program to be implemented in the zoo, including routine diagnostic parasitology tests followed by specific treatment for each parasitosis.