Necropsies disclose a low helminth parasite diversity in periurban howler monkeys.

Primate-parasite interactions are often investigated via coprological studies given ethical and conservation restrictions of collecting primate hosts. Yet, these studies are inadequate to recover adult helminths for taxonomic identification and to accurately assess their prevalence, intensity, abundance, and site of infection. Fresh carcasses found in anthropogenic landscapes come as informative and reliable alternatives. In this study, we identified the helminths of brown howler monkeys (Alouatta guariba clamitans) and their sites of infection, and measured their prevalence, intensity, and abundance of infection. We necropsied 18 adult males, 11 adult females, and 7 juvenile males that died in conflicts with the anthropogenic environment (domestic dog attacks, n = 11; electrocutions and road-kills, n = 10 each; unknown, n = 5) in periurban landscapes of southern Brazil between 2013 and 2019. We found three nematodes (Trypanoxyuris minutus, Dipetalonema gracile, and Parabronema bonnei) and one cestode (Bertiella cf. studeri), a diversity estimated to account for a sampling completeness of 99%. Prevalence ranged from 3% for P. bonnei to 100% for T. minutus. Mean abundance ranged from 2 (D. gracile and B. cf. studeri) to 55,116 (T. minutus) and mean intensity of infection ranged from 4 (B. cf. studeri) to 55,116 (T. minutus). Trypanoxyuris minutus sex ratio was strongly male-biased. The intensity of infection with T. minutus was higher in juvenile males and adult females than in adult males. The low parasite diversity and the helminths' mode of transmission are compatible with howlers' arboreality and folivorous-frugivorous diet. The howlers were not infected with soil-transmitted helminth parasites of humans and domestic animals on the ground and probably did not eat invertebrates to complement the diet. Given the lack of evidence of howler health problems, we suggest that the causes of death of the necropsied howlers are the major threats to the long-term conservation of the species at the study periurban landscapes.

The mitochondrial genome of Dipetalonema gracile from a squirrel monkey in China.

Dipetalonema gracile is a common parasite in squirrel monkeys (Saimiri sciureus), which can cause malnutrition and progressive wasting of the host, and lead to death in the case of massive infection. This study aimed to identify a suspected D. gracile worm from a dead squirrel monkey by means of molecular biology, and to amplify its complete mitochondrial genome by polymerase chain reaction (PCR) and sequence analysis. The results identified the worm as D. gracile, and the full length of its complete mitochondrial genome was 13,584 bp, which contained 22 tRNA genes, 12 protein-coding genes, two rRNA genes, one AT-rich region and one small non-coding region. The nucleotide composition included A (16.89%), G (20.19%), T (56.22%) and C (6.70%), among which A + T = 73.11%. The 12 protein-coding genes used TTG and ATT as start codons, and TAG and TAA as stop codons. Among the 22 tRNA genes, only trnS1AGN and trnS2UCN exhibited the TΨC-loop structure, while the other 20 tRNAs showed the TV-loop structure. The rrnL (986 bp) and rrnS (685 bp) genes were single-stranded and conserved in secondary structure. This study has enriched the mitochondrial gene database of Dipetalonema and laid a scientific basis for further study on classification, and genetic and evolutionary relationships of Dipetalonema nematodes.

Occurrence of Dipetalonema gracile in a wild population of woolly monkey Lagothrix poeppiigii in the northeastern Peruvian Amazon / Ocorrência de Dipetalonema gracile em uma população selvagem de macaco barrigudo Lagothrix poeppigii no nordeste da Amazônia peruana

Abstract Dipetalonema gracile (Rudolphi, 1809) (Filarioidea: Onchocercidae) is one of six species of cavities filarial parasites of Neotropical non-human primates. The present study recorded the occurrence of D. gracile, provides morphological and morphometric data and extends the geographical distribution. Adult filariae were obtained from the thoracic and abdominal cavities of 38 specimens of woolly monkey, which were used for local human consumption, in the northeastern Peruvian Amazon. Male and female filarids were processed and analysed using light and scanning electron microscopy. Details of the cephalic papillae, post-cloacal bands and papillae, vulva, phasmid position and lateral appendages are showed by scanning electron microscopy and is recorded the occurrencce of Lagothrix poeppigii monkey as a new host of this filaria in the Yavari-Mirin river basin, Peruvian Amazon.

Resumo Dipetalonema gracile (Rudolphi, 1809) (Filarioidea: Onchocercidae), é uma das seis espécies de filarias parasitas de primatas não humanos neotropicais. O presente trabalho registra a ocorrência de D. gracile , proporciona dados morfológicos e morfométricos e amplia sua distribuição geográfica. Filárias adultas foram obtidas da cavidade torácica e abdominal de 38 espécimes de macaco barrigudo, que foram utilizados para consumo humano local. Essa espécie de primatas não humanos neotropicais tem distribuição ao nordeste da Amazônia peruana. Filarídeos machos e fêmeas foram processados e analisados pela microscopia de luz e microscopia eletrônica de varredura. Detalhes das papilas cefálicas, bandas e papilas pós-cloacais, vulva, posição dos fasmídeos e apêndices laterais são mostradas pela microscopia eletrônica de varredura e registra-se a ocorrência do macaco Lagothrix poeppigii como novo hospedeiro desta filaria na bacia do rio Yavari-Mirin na Amazônia peruana.