Abstract

Wasting marmoset syndrome (WMS) is a major cause of morbidity and mortality in marmosets and tamarins kept in captivity. In a prior study, we demonstrated that WMS is an enteric malabsorption process with morphology similar to human celiac disease. The main objective of this research is to describe the clinical and pathologic features of marmosets on a gluten-free diet compared to animals fed a gluten diet.

The research was conducted at the Criatório Mucky de Proteção aos Pequenos Primatas, a small-primate conservationist breeding and rehabilitation center located in Jundiaí, state of São Paulo. The species included in the study were: Callithrix jacchus (common marmoset, n=14), Callithrix penicillata (ear-tufted black marmoset, n=30), Callithrix geoffroyi (Geoffroy’s marmoset, n=3) and hybrid marmosets (n=31). The animals were born at this facility or had been there for at least 6 months. Animals were kept in outdoor enclosures in pairs or in kin groups. Group 1 (three males, five females) was the control group. It consisted of animals that did not exhibit physical signs of WMS. Group 2 (18 males, 22 females) consisted of marmosets diagnosed with WMS. Groups 1 and 2 received a diet consisting of grain-based products (such as cereal and bread), fruits, cooked vegetables, cooked chicken, eggs and lactose-free milk through October of 2001. At this time, a diet change was initiated for all animals. The new diet was similar to the original diet but did not contain cereal products. As a result of the diet change, animals that were still alive and previously classified as Group 2 were classified as Group 3. The study animals underwent physical examinations, fecal observation, and periodic weight measurements.

Group 1 animals died as a result of other diseases not related to enteropathies. At necropsy, their jejunum was used for histologic examination. Group 2 animals had progressive weight loss and diarrhea, but no other identifiable diseases that would elicit these symptoms. These animals received oral vitamin and amino acid supplementation, antibiotics, antiparasitics, and subcutaneous fluid therapy. Twenty-five marmosets from this group died and were necropsied before October 2001. Group 3 animals were diagnosed with WMS and received subcutaneous vitamin and mineral treatments and oral pancreatic enzymes. Twenty-five marmosets from this group died and were necropsied before August 2003.

The main clinical changes exhibited by animals in Group 3 compared to those in Group 2 included stabilized weight loss, decreased incidences and intensities of diarrhea bouts, total or partial recovery of hindlimb paralysis, increased survival rates, and decreased incidences of abdominal distention at necropsy.

The histopathologic evaluation included villus:crypt ratio, villus height, crypt hyperplasia, the intensity of the inflammatory process, the intensity of the mononuclear infiltrate, and the density of intraepithelial lymphocytes. Group 1 animals were within standard normal ranges. Group 2 animals had severe, atrophic enteritis with partial to complete villi loss, severe crypt hyperplasia and lymphocytic-plasmocytic infiltrate in the lamina propria. Group 3 animals had chronic enteritis with mild and partial reduction of intestinal villi height, crypt hyperplasia, and lymphocytic-plasmacytic infiltrate in the lamina propria. The villus:crypt ratio, the villus height, and crypt hyperplasia were significantly different (p<0.001) among all groups. The intensity of the inflammatory process, the intensity of the mononuclear infiltrate, and the density of the intraepithelial lymphocytes were significantly different (p<0.001) between the control group (Group 1) and the WMS groups (Groups 2 and 3), but not significantly different between Groups 2 and 3. The presence of ulcerations and neutrophilic or eosinophilic infiltrate was not statistically significant for any of the groups. Intestinal parasites were not found in either group of animals diagnosed with WMS.

Removing gluten from the diet of animals with WMS resulted in symptomatic and histologic improvements. Feeding captive marmosets diets with gluten may have profound negative effects on their intestinal morphology and consequently on their health. Removing the prolamines of wheat, rye, barley, and oats from the diet of marmosets kept in captivity may help control and possibly eradicate WMS.

Acknowledgments

We would like to thank Livia Bótar and the technical staff from Criatório Mucky for facilitating and encouraging this research. This work was supported financially by FAPESP with grants 00/04412-1; this study is part of the PhD project of L.R.M. de Sá.