Brazza's Monkey Research Articles

Human-De Brazza’s monkey conflict in Kafa Biosphere Reserve, Kafa Zone South West, Ethiopia

BackgroundHuman-wildlife conflict (HWC) is any interaction between humans and wildlife that arises when wildlife necessities encroach on those of the human population. It affects all areas where animal and peoples cohabit regardless of geography or climatic circumstances; but the burden is great in developing nations. De Brazza’s monkey (DM) (Cercopithecus neglectus) is one of the most unusual species in the group of Old-World monkeys commonly known as guenons. The De Brazza’s monkey is distributed in different parts of African forests from Guinea to Ethiopia. This study was conducted in Kafa Biosphere Reserve, Kafa Zone, South West Ethiopia, to assess the causes of human wildlife conflict in the area. The methods used were, household questionnaire, focus group discussion and direct field observation from June 2022 to May 2023.ResultsThe study revealed that the major causes of human De Brazza’s monkey conflicts were; habitat destruction 52.9%, (n = 72), human proximity to natural forest, 25.7%, (n = 35) and increasing of its population size 8.1 %, (n = 11). These monkeys’ raids crop usually early in the morning 42.6%, (n = 58), and late evening 29.4%, (n = 40). Maize was the most damaged crop by De Brazza’s monkey followed by coffee. The study also confirmed that guarding was the most common method used to protect crops from crop raiding wildlife in the area. Majority 66.2%, (n= 90) of the informants had negative attitude but 22.1%, (n = 30) had positive attitude towards De Brazza’s monkey conservation.ConclusionThe study discovered that, in contrast to olive baboons and grivet monkeys in the area, De Brazza's monkeys were not previously identified as crop raiders; however, they are currently causing damage to crops, especially maize and coffee crops. This could be due to habitat destruction and human proximity to the forest boundary. Thus, the conflict between humans and De Brazza's monkeys is escalating. As such, we recommended more research on the population status of the monkeys and strategies for coexist in the area.

Differentiation of Trichuris species eggs from non-human primates by geometric morphometric analysis.

Human trichuriasis is a neglected tropical disease which affects millions of people worldwide, mostly living in low socio-economic conditions. Numerous studies have been conducted over the past 10 years to compare the different techniques for T. trichiura eggs detection. Our study provides the first geometric morphometric analysis for the specific detection of eggs of Trichuris sp. isolated from stools of macaque (M. sylvanus), colobus (C. g. kikuyensis), grivets (C. aethiops) and the Brazza's monkey (C. neglectus) from zoos in Spain. Principal Component Analysis (PCA) arises as an efficient method to determine Trichuris spp. eggs. The selected measurements to be included in the PCA were proposed for the first time in the present work, as far as we know, as we could not find previous studies reporting standardized parameters.

Sniffing Behaviours in Guenons

In Old World monkeys (OWM), the olfactory sense is thought to be less important than in other primate taxa. However, during the last decade experimental studies have shown that OWM possess much better olfactory capabilities than suspected. Here, we investigate for the very first time sniffing behaviours in three guenon species (Diana, de Brazza's and owl-faced monkeys) held in the Leipzig Zoo, Germany. We recorded frequencies and contexts of sniffing. The sniff index was used to allow comparisons across species. It was found that individuals sniffed 6.12 ± 7.69 times per hour. Most sniffing occurred in food-related contexts. Furthermore, Diana monkeys sniffed less often than de Brazza's and owl-faced monkeys. Thus, natural selection may drive the differences in using the olfactory sense in closely related primate species.

Dilated cardiomyopathy in a De Brazza's monkey (Cercopithecus neglectus)

Cardiomyopathies have been reported in many primates. They may result from an inflammatory response to an infectious agent, nutritional deficiency, familial-genetic inheritance or toxic agents, but in many cases they are idiopathic. A De Brazza's monkey (Cercopithecus neglectus) presented with weight loss and inappetence. Physical examination, blood collection and diagnostic imaging and an electrocardiogram were performed. Radiographs and echocardiogram revealed pleural effusion with partially collapsed lungs, cardiomegaly, and reduced myocardial contractility from myocardial failure. Necropsy revealed pulmonary infarction, subsequent to heart failure from dilated cardiomyopathy.

Voice discrimination in four primates

One accepted function of vocalisations is to convey information about the signaller, such as its age–sex class, motivation, or relationship with the recipient. Yet, in natural habitats individuals not only interact with conspecifics but also with members of other species. This is well documented for African forest monkeys, which form semi-permanent mixed-species groups that can persist for decades. Although members of such groups interact with each other on a daily basis, both physically and vocally, it is currently unknown whether they can discriminate familiar and unfamiliar voices of heterospecific group members. We addressed this question with playbacks on monkey species known to form polyspecific associations in the wild: red-capped mangabeys, Campbell's monkeys and Guereza colobus monkeys. We tested subjects’ discrimination abilities of contact calls of familiar and unfamiliar female De Brazza monkeys. When pooling all species, subjects looked more often towards the speaker when hearing contact calls of unfamiliar than familiar callers. When testing De Brazza monkeys with their own calls, we found the same effect with the longest gaze durations after hearing unfamiliar voices. This suggests that primates can discriminate, not only between familiar and unfamiliar voices of conspecifics, but also between familiar and unfamiliar voices of heterospecifics living within a close proximity.

Manual laterality and strategy use for a coordinated bimanual task requiring precise and power grip in guenons and mangabeys

Bimanual tasks have been repeatedly shown to elicit manual asymmetries supposed to reflect hemispheric specialization. And yet, a coordinated bimanual task, the BOX task, appears to be inefficient in detecting biases of hand preferences. The BOX task involves two sequential actions requiring a precise grip, lift the lid of a box and grasp a small item inside the box (while holding the lid). In the present study, we compared manual laterality exhibited for the classic bimanual BOX task and for a unimanual BOX task in 11 De Brazza's monkeys (Cercopithecus neglectus) and 19 red-capped mangabeys (Cercocebus torquatus). In addition, we assessed strategy use for solving the bimanual BOX task. We found that left-hand use for grasping the item was higher in the BOX-bimanual task than in the BOX-unimanual task. We propose that this increase in left-hand use for grasping the item results from both a hemispheric specialization for lifting the lid and an advantage in using a skillful strategy. Indeed, we revealed (1) group-level right biases for lifting the lid and (2) a complete differentiation between the roles of the two hands in subjects showing a left-hand preference for grasping the item. Finally, the bimanual BOX task showed age differences in the two species, either in manual laterality for grasping the item or in strategy use. This study provides additional evidence that manual laterality might be sensitive to maturational factors and characteristics of the bimanual tasks such as the order and the features of sequential actions.

Which are the features of the TUBE task that make it so efficient in detecting manual asymmetries? An investigation in two Cercopithecine species (Cercopithecus neglectus and Cercocebus torquatus).

In the last decade, the TUBE task has been repeatedly shown to be highly efficient in detecting manual asymmetries that are strong hand preferences reflecting hemispheric specialization, in non human primates. The TUBE task was thus classified as a high-level task, presumably because it involves bimanual coordination. However, this task also requires a precise action made by digit(s), which may also be a crucial feature in eliciting manual asymmetries. In the present study, we compared hand preferences for a new TUBE-unimanual task and the classic TUBE-bimanual task, both performed mostly by using the forefinger, in 12 guenons (De Brazza's monkey: Cercopithecus neglectus) and 18 mangabeys (red-capped mangabey: Cercocebus torquatus). We found a relationship between hand preferences exhibited for the two tasks, suggesting that precise use of the forefinger may induce the activation of a specialized hemisphere in both the TUBE-unimanual and the TUBE-bimanual task. However, we showed that the strength of manual laterality was higher in the TUBE-bimanual task than in the TUBE-unimanual task, indicating that bimanual coordination may enhance the expression of hand preferences. We propose that the TUBE-bimanual task is highly efficient in detecting hemispheric specialization because bimanual role differentiation would make precise digit use highly skillful. Finally, we revealed species differences in hand use, especially in females: the most arboreal species, De Brazza's monkeys, increased left-hand use from the TUBE-unimanual to the TUBE-bimanual task whereas the most terrestrial species, red-capped mangabeys, increased right-hand use.

Social complexity parallels vocal complexity: a comparison of three non-human primate species.

Social factors play a key role in the structuring of vocal repertoires at the individual level, notably in non-human primates. Some authors suggested that, at the species level too, social life may have driven the evolution of communicative complexity, but this has rarely been empirically tested. Here, we use a comparative approach to address this issue. We investigated vocal variability, at both the call type and the repertoire levels, in three forest-dwelling species of Cercopithecinae presenting striking differences in their social systems, in terms of social organization as well as social structure. We collected female call recordings from twelve De Brazza's monkeys (Cercopithecus neglectus), six Campbell's monkeys (Cercopithecus campbelli) and seven red-capped mangabeys (Cercocebus torquatus) housed in similar conditions. First, we noted that the level of acoustic variability and individual distinctiveness found in several call types was related to their importance in social functioning. Contact calls, essential to intra-group cohesion, were the most individually distinctive regardless of the species, while threat calls were more structurally variable in mangabeys, the most “despotic” of our three species. Second, we found a parallel between the degree of complexity of the species' social structure and the size, diversity, and usage of its vocal repertoire. Mangabeys (most complex social structure) called twice as often as guenons and displayed the largest and most complex repertoire. De Brazza's monkeys (simplest social structure) displayed the smallest and simplest repertoire. Campbell's monkeys displayed an intermediate pattern. Providing evidence of higher levels of vocal variability in species presenting a more complex social system, our results are in line with the theory of a social-vocal coevolution of communicative abilities, opening new perspectives for comparative research on the evolution of communication systems in different animal taxa.

Cross-Taxa Similarities in Affect-Induced Changes of Vocal Behavior and Voice in Arboreal Monkeys

Measuring the affective state of an individual across species with comparable non-invasive methods is a current challenge in animal communication research. This study aims to explore to which extent affect intensity is conveyed in the vocal behaviours of three nonhuman primate species (Campbell's monkeys, De Brazza's monkeys, red-capped mangabeys), which vary in body size, ecological niche and social system. Similarly in the three species, we experimentally induced a change in captive social groups' affect by locking all group members together in their outside enclosure. The two experimental conditions which varied in affect intensity consisted in imposing a pre-reunion 90 mn-separation by splitting up the respective group into two subgroups (High affect condition) or not (Low affect condition). We measured call rates as well as voice features at the time of reunion in both conditions. The three studied species reacted in a very similar way. Across species, call rates changed significantly between the behaviourally defined states. Furthermore, contact call duration and, to some extent, voice pitch increased. Our results suggest, for the first time in arboreal Old World monkeys, that affect intensity is conveyed reliably in vocal behaviour and specific acoustic characteristics of voice, irrespective of body size and ecological niche differences between species. Cross-taxa similarities in acoustic cues of affect intensity point to phylogenetic constraints and inheritance from a common ancestor, whereas variations in vocal behaviour and affect intensity-related acoustic cues between species may be an adaptation to specific social requirements and depend on social systems. Our findings as well as a comparison with published works on acoustic communication in other vertebrate groups support the hypothesis that affect intensity in human voice originates from precursors already found deep inside the vertebrate phylogeny.

Long-Term Persistence of de Brazza's Monkey (Cercopithecus neglectus) in a Kenyan Forest Fragment

Tropical forests are at the forefront of species-extinction crises as a consequence of widespread habitat loss and alteration. Knowledge of how populations respond to a particular milieu of habitat loss and disturbance effects requires long-standing monitoring programs. Unfortunately, such programs are rare. Here we report on population trends of de Brazza's monkey (Cercopithecus neglectus) over 20 years in Kenya’s Kisere Forest, a biologically-rich moist forest remnant under intense anthropogenic pressure. We found that although abundance of this shy primate did not change across four censuses, group composition differed, with groups containing fewer juveniles after the first census. This result, in concert with a suite of recent empirical and predictive studies showing ongoing forest disturbance, suggests that we may see this population decline as it ages.

Age‐ and sex‐specific patterns of vocal behavior in De Brazza's monkeys (Cercopithecus neglectus)

Although vocal production is strongly genetically determined in nonhuman primates, vocal usage is more likely to be influenced by experience. Nonetheless, sex differences in both production and usage can be found in the vocal repertoire of adults, but little attention has been paid to their ontogeny. Here, we provide the first comprehensive analysis of the vocal repertoire of De Brazza's monkeys (Cercopithecus neglectus), with particular attention to age- and sex-specific patterns. This species has special interest because it is the only monogamous species of guenons, but it nevertheless shares the strong sexual morphological and behavioral dimorphism seen in other guenons. A structurally based classification of calls recorded in 23 captive individuals has been cross-validated by an analysis of the associated contexts of emission. We identified sound units that could be uttered alone or concatenated to form 10 call types, including only three types shared by all age-sex-classes. Both age- and sex-discrepancy in terms of phonation could be explained by maturational changes and morphological dimorphism. In general, call production and usage parallel those seen in other guenons, suggesting that phylogeny and sexual dimorphism play important roles in vocal communication in this species. However, the boundary between adult male and female vocal repertoires appeared to be less strict than previously reported, suggesting that both sexes have the capacity to produce calls of the other sex but that social roles may constrain this expression. Similarly, age-specific vocal patterns would reflect respective social roles, and experience to some extent. Finally, calling rates would reflect age-/sex-specific degree of involvement in intragroup social networks. These findings highlight the relative importance of phylogeny, morphology, and social system on the shaping of individual repertoires in nonhuman primates.

Le Singe de Brazza: Une stratégic originale

The main ecological, social and behavioural features of the De Brazza's monkey are described. Radio-tracking techniques have been used. The species lives in small family groups including the adult ♂, the adult ♀ and their offspring. Home ranges vary from 4 to 10 ha, always located near the riversides, and day ranges from 250 m to 1010 m. Variations in range utilization may be related to the fructification of some tree species. Behavioral mechanisms of group cohesion and defence, together with protective types of locomotion, seem to be adapted to avoid attracting the attention of predators rather than distracting them. They combine to distinguish the De Brazza's monkey from sympatric Cercopithecus species.

Detectability and Conservation of De Brazza's Monkey (Cercopithecus neglectus) in the Lesio-Louna and South-West Lefini Reserves, Bateke Plateau, Republic of Congo

The Lesio-Louna and south-west Lefini Reserves in the Bateke Plateau region of the Republic of Congo are not generally included as part of the geographic range of de Brazza's monkey (Cercopithecus neglectus). I present here observations made between 2002 and 2007 showing the species to be widely distributed within the gallery forests of the two reserves. Most sight records were of one or two individuals, although groups of up to six were also observed. De Brazza's monkeys could be heard calling on approximately 50% of days at project camps, and it was the most frequently detected large mammal during MacKinnon List surveys. Detectability was significantly lower during surveys that began after 07:00, a finding that may explain why the species has been largely overlooked during structured wildlife surveys. A review of grey literature suggests that the reserve management activities linked to a gorilla reintroduction program have led to recovery of the species following years of heavy hunting. However, the connectivity of the gallery forests of the Lefini watershed to the major forest areas to the east is threatened by human activity. The maintenance of forest corridors to avoid isolation of the gallery forests may be an important consideration for the long-term sustainable management of the region.Les Réserves de Lesio-Louna et sud-ouest Lefini, situées dans la région du Plateau Bateke de la République du Congo, ne sont généralement pas inclues au sein de l'aire de répartition géographique du cercopithèque de Brazza Cercopithecus neglectus. Je présente ici des observations faites entre 2002 et 2007, montrant que l'espèce est largement distribuée dans les forêts-galeries des deux réserves. La plupart des observations concernaient un ou deux individus, bien que des groupes contenant jusqu' à six animaux aient également été observés. Des cercopithèques de Brazza pouvaient être entendus depuis les camps du projet environ 50% des jours, et il était le grand mammifère le plus fréquemment détecté au cours des études effectuées pour les Listes MacKinnon. La détectabilité était sensiblement plus basse lors des études commencées après 07:00, ce qui pourrait expliquer pourquoi l'espèce a été largement négligée au cours d'études structurées de la faune. Une révision de la littérature grise suggère que les activités de gestion de la réserve liées à un programme de réintroduction de gorilles ont conduit au rétablissement de l'espèce après des années de pression de chasse énorme. Néanmoins, la connectivité entre les forêts-galeries du bassin de la Lefini et les principales zones forestières situées à l'est est menacée par l'activité humaine. Le maintien de corridors forestiers pour éviter l'isolement des galeries forestières peut être un facteur important à prendre en considération pour la gestion durable de la région à long terme.

A New Population of De Brazza's Monkey in Kenya

Until recently, de Brazza's monkey (Cercopithecus neglectus) was not known to occur east of the Great Rift Valley in Kenya. However, after eight months of intensive surveys in the remote and isolated Mathews Range Forest Reserve of Samburu, we were able to count a total of 162 de Brazza's monkeys in 24 groups; including 139 adults and sub-adults and 23 infants. They were found in ten separate laggas distributed throughout the mountain range, with the highest concentration in the central part of the reserve. By extrapolating information gathered on this study—from interviews and field observations—the population of the entire Mathews Range Forest Reserve was estimated at 200–300. Although the threats arising from the human activities in the forest ecosystem are generally minimal, they were considerable on the lower elevations, affecting especially this species. The most affected habitats are those near human settlements on the lower altitudes (where 75% of the total population of de Brazza's monkeys occurs) since they are easily accessible. During the onset of the dry season and periods of drought, communities invade these areas with large herds of livestock, where they feed them on leaves of evergreen tree species such as Faidherbia albida, Ficus sp., and Olea sp. The people cut the branches almost denuding the tree. These species are important in the diet of de Brazza's monkey. The study resulted in the first record of de Brazza's monkeys occurring above 2,100 m above sea level. They were seen in Olkaela in the Mathews range at an elevation of 2,203 m.

New Northwestern and Southwestern Range Limits of De Brazza's Monkey, Mbam et Djerem National Park, Cameroon, and Bateke Plateau, Gabon and Congo

Recent surveys carried out in Cameroon in the Mbam Djerem National Park, in Gabon in the Bateke Plateau National Park, and the adjoining Bateke Plateau area in Congo, have recorded the presence of de Brazza's monkey (Cercopithecus neglectus) on both sides of the Djerem River in Cameroon, along the Mpassa and its tributaries in Gabon, along the Nambouli River in the Lefini Reserve in Congo, and up to the right bank of the Ogooué River on the Congo side of the border. These areas lie at the northern and southern edges of the Central African forest block, where rivers have relatively wide bands of riparian forest. As for the range extension of the talapoin (this volume), the species may simply have been overlooked by previous rapid wildlife surveys. It has an antipredator behavior that renders it relatively inconspicuous, tends to live in small family groups in the region, and lives in habitats that are difficult to survey on foot. However, unlike talapoin, it calls every morning along major watercourses, and can be heard for some distance. It is possible that the southern limit of this species in Gabon may be the Ogooué River. Future survey teams are encouraged to familiarize themselves with the long call of this species and to be aware that it can occur in gallery forests throughout the savannas of the Bateke Plateau and also in the area between the Mbam, the Djerem, and the Lom in Cameroon.

Widely varying SIV prevalence rates in naturally infected primate species from Cameroon

Although it is now well established that a substantial proportion of wild-living primates in sub-Saharan Africa harbor SIV, no study to date has examined to what extent the various species are naturally infected. In this study, we first describe the development and validation of sensitive and specific SIV antibody detection assays representing all major known primate lentiviral lineages on a panel of 207 sera from 11 different primate species with known infection status. The newly developed assays were then used to determine SIV prevalence rates in nine primate species native to Cameroon. Analysis of 722 sera revealed widely varying prevalence rates, ranging from an apparent absence of SIV infection in crested mona (0/70), grey cheeked (0/36) and agile mangabeys (0/92), to prevalence rates of 3%, 4%, 11%, 27%, 39% and 52% for mustached (6/203), greater spot-nosed (8/193), northern talapoin (3/26), mantled guereza (14/52), De Brazza's (9/23) and mandrill (14/27) monkeys, respectively. The epidemiology of naturally occurring SIV infections is thus more complex than previously appreciated and the various non-human primate hosts seem to differ in their susceptibility to SIV infection. The newly developed assays should now permit to define with greater accuracy existing SIV reservoirs and associated human zoonotic risk.

Characterization of a novel vpu-harboring simian immunodeficiency virus from a Dent's Mona monkey (Cercopithecus mona denti).

We report the identification of a new simian immunodeficiency virus (SIV), designated SIVden, in a naturally infected Dent's Mona monkey (Cercopithecus mona denti), which was kept as pet in Kinshasa, capital of the Democratic Republic of Congo. SIVden is genetically distinct from the previously characterized primate lentiviruses. Analysis of the full-length genomic sequence revealed the presence of a vpu open reading frame. This gene is also found in the virus lineage of human immunodeficiency virus type 1 (HIV-1) and chimpanzee immunodeficiency virus (SIVcpz) and was recently described in viruses isolated from Cercopithecus nictitans, Cercopithecus mona, and Cercopithecus cephus. The SIVden vpu coding region is shorter than the HIV-1/SIVcpz and the SIVgsn, SIVmon, and SIVmus counterparts. Unlike Pan troglodytes schweinfurthii viruses (SIVcpzPts) and Cercopithecus monkey viruses (SIVgsn, SIVmon, and SIVmus), the SIVden Vpu contains the characteristic DSGXES motif which was shown to be involved in Vpu-mediated CD4 and IkappaBalpha proteolysis in HIV-1 infected cells. Although it harbors a vpu gene, SIVden is phylogenetically closer to SIVdeb isolated from De Brazza's monkeys (Cercopithecus neglectus), which lacks a vpu gene, than to Cercopithecus monkey viruses, which harbor a vpu sequence.

Manual laterality and task complexity in De Brazza's monkey (Cercopithecus neglectus)

We investigated manual specialisation of six Brazza monkeys, both under structured experimental conditions and while they engaged in unconstrained natural behaviour. Five tasks that varied in complexity, degree of visual guidance, and bimanual coordination were used in the experimental condition. Individual preferences were revealed for each task, and in the case of simple tasks the position of a monkey relative to the task device was shown to impact on manual preference. Strength of laterality and performance were not found to be related. Task complexity influenced strength, but not direction, of manual preference. The small number of animals precluded generalisation to population preferences but the large number of observations and choice of tasks can serve as model for the study of manual preferences in primates.

New simian immunodeficiency virus infecting De Brazza's monkeys (Cercopithecus neglectus): evidence for a cercopithecus monkey virus clade.

Nearly complete sequences of simian immunodeficiency viruses (SIVs) infecting 18 different nonhuman primate species in sub-Saharan Africa have now been reported; yet, our understanding of the origins, evolutionary history, and geographic distribution of these viruses still remains fragmentary. Here, we report the molecular characterization of a lentivirus (SIVdeb) naturally infecting De Brazza's monkeys (Cercopithecus neglectus). Complete SIVdeb genomes (9,158 and 9227 bp in length) were amplified from uncultured blood mononuclear cell DNA of two wild-caught De Brazza's monkeys from Cameroon. In addition, partial pol sequences (650 bp) were amplified from four offspring of De Brazza's monkeys originally caught in the wild in Uganda. Full-length (9068 bp) and partial pol (650 bp) SIVsyk sequences were also amplified from Sykes's monkeys (Cercopithecus albogularis) from Kenya. Analysis of these sequences identified a new SIV clade (SIVdeb), which differed from previously characterized SIVs at 40 to 50% of sites in Pol protein sequences. The viruses most closely related to SIVdeb were SIVsyk and members of the SIVgsn/SIVmus/SIVmon group of viruses infecting greater spot-nosed monkeys (Cercopithecus nictitans), mustached monkeys (Cercopithecus cephus), and mona monkeys (Cercopithecus mona), respectively. In phylogenetic trees of concatenated protein sequences, SIVdeb, SIVsyk, and SIVgsn/SIVmus/SIVmon clustered together, and this relationship was highly significant in all major coding regions. Members of this virus group also shared the same number of cysteine residues in their extracellular envelope glycoprotein and a high-affinity AIP1 binding site (YPD/SL) in their p6 Gag protein, as well as a unique transactivation response element in their viral long terminal repeat; however, SIVdeb and SIVsyk, unlike SIVgsn, SIVmon, and SIVmus, did not encode a vpu gene. These data indicate that De Brazza's monkeys are naturally infected with SIVdeb, that this infection is prevalent in different areas of the species' habitat, and that geographically diverse SIVdeb strains cluster in a single virus group. The consistent clustering of SIVdeb with SIVsyk and the SIVmon/SIVmus/SIVgsn group also suggests that these viruses have evolved from a common ancestor that likely infected a Cercopithecus host in the distant past. The vpu gene appears to have been acquired by a subset of these Cercopithecus viruses after the divergence of SIVdeb and SIVsyk.

Some gastro-intestinal tract parasites in wild De Brazza's monkeys (Cercopithecus neglectus) in Kenya.

Fresh faecal droppings of wild group of De Brazza's monkeys (Cercopithecus neglectus), earmarked for translocation, were collected between January and July 1998. The samples were analysed using direct smears, ether-sedimentation and the Harada-Mori culture techniques for gastro-intestinal tract parasites (GIT). Two species of helminths and three of protozoa were detected. Entamoeba coli was found in all 40 samples screened from 11 monkeys. Entamoeba histolytica was detected in 71.8% of the total samples screened, Streptopharagus spp. in 12.8% and Strongyloides spp. and Balantidium coli each in 7.7% of the samples. E. histolytica and Streptopharagus spp. were most prevalent in faecal samples of juveniles while Strongyloides spp. and B. coli were mostly found in adult females. This, to our knowledge, is the first report of GIT parasites in a wild population of De Brazza's monkeys and our results are baseline.