Differential response of seven duiker species to human activities in Taï National Park,Côte d'Ivoire

African rainforest is severely impacted by human activities, ranging from resource collection, selective logging to fragmentation and scale deforestation. Consequently, large mammal communities occurring therein are strongly modified. Here, we present a study conducted in Taï National Park (TNP), which characterises the spatial distribution and differential response of seven duiker species to human activities. Based on extensive survey data recorded between 2005 and 2015, we used a maximum entropy modelling approach for predicting duiker species distribution and a hierarchical clustering approach to identify potential subgroups in the duiker community. The seven duiker species clearly differed in their spatial distribution, with Cephalophus dorsalis and Philantomba maxwellii being the most common and widely distributed with no clear response towards gradients of impact from human activities. In contrast, Cephalophus ogilbyi, Cephalophus jentinki, Cephalophus sylvicultor and Cephalophus zebra showed increasing responses towards anthropogenic impact gradients, with the latter two being particularly sensitive. These duikers are not found in areas of illegal human activities. The restricted distribution of Cephalophus niger seems artificial and may indicate species misidentification. The strong spatial signature of human activities in the duiker community of TNP is of concern. Effective park management, including extensive ranger patrols, is vital for ensuring the persistence of this unique duiker community in West Africa.     

High variety of different simian T-cell leukemia virus type 1 strains in chimpanzees (Pan troglodytes verus) of the Taï National Park, Côte d'Ivoire

We found human T-cell leukemia virus type 1- and simian T-cell leukemia virus type 1 (STLV-1)-related infections in 5 of 10 chimpanzees originating from three groups of wild chimpanzees. The new virus isolates showed a surprising heterogeneity not only in comparison to STLV-1 described previously in other primate species but also between the different chimpanzee groups, within a group, or even between strains isolated from an individual animal. The interdisciplinary combination of virology, molecular epidemiology, and long-term behavioral studies suggests that the primary route of infection might be interspecies transmission from other primates, such as red colobus monkeys, that are hunted and consumed by chimpanzees.     

Territory Characteristics among Three Neighboring Chimpanzee Communities in the Taï National Park,Côte d'Ivoire

We studied territory characteristics among three neighboring chimpanzee communities in the Taï National Park, Côte d'Ivoire, and compared them with other chimpanzee populations. We characterized territories and ranging patterns by analyzing six variables:, (1) territory size, (2) overlap zone, (3) territory utilization, (4) core area, (5) territory shift, and (6) travel distance. Data collection covered a period of 10 mo, during which we simultaneously sampled the local positions of mostly large parties, including males in each community, in 30-min intervals. In Taï, chimpanzees used territories in a clumped way, with small central core areas being used preferentially over large peripheral areas. Although overlap zones between study communities mainly represented infrequently visited peripheral areas, overlap zones with all neighboring communities also included intensively used central areas. Territory utilization was not strongly seasonal, with no major shift of activity center or shift of areas used over consecutive months. However, we observed shorter daily travel distances in times of low food availability. Territory sizes of Taï chimpanzees tended to be larger than territories in other chimpanzee communities, presumably because high food availability allows for economical defense of territorial borders and time investment in territorial activities. Therefore we suggest, that use of territory in Taï chimpanzees is strongly influenced by intercommunity relations. To understand differences in territory characteristics between various populations, it is of major importance to consider not only the intracommunity but also the intercommunity context.     

Morphological variation in adult chimpanzees (Pan troglodytes verus) of the Taï National Park, Côte d'Ivoire

Twenty five adult chimpanzee skeletons (Pan troglodytes verus) of known age and sex (15 females, 10 males) from a long‐term study site in Taï National Park, Cote d'Ivoire present new data on variation. These skeletons provide a rare opportunity to measure the cranium and postcranium from the same individuals. We compare measurements and indices of the Taï sample with those of relatively complete Pan troglodytes schweinfurthii skeletons from Gombe National Park, Tanzania. Measurements of Pan paniscus are included as an outside comparison. The Taï and Gombe samples are analyzed by sex; combined sex samples are compared between the two groups, and the two sexes to each other. Taï females and males do not differ in most long bone lengths or in pelvic dimensions, but do differ significantly in cranial capacity, facial measurements, clavicle length, scapular breadth, and femur length. Gombe females and males differ significantly in some facial measurements and in scapular breadth. In combined sex samples, Taï individuals have lower cranial capacity, longer palate and mandible, and greater dimensions in the trunk and limb lengths. Taï females account for most of the variation; males differ from each other only in greater length of humerus and femur. The Taï skeletons provide new data for assessing individual variation and sexual dimorphism within and between populations and species. The combination of cranial and postcranial data provides a clearer picture of chimpanzee intraspecific and interspecific variation than can be gained from either data set alone. Am J Phys Anthropol, 2008. © 2007 Wiley‐Liss, Inc.     

How feeding competition determines female chimpanzee gregariousness and ranging in the Taï National Park, Côte d'Ivoire

Socioecological theory suggests that feeding competition shapes female social relationships. Chimpanzees (Pan troglodytes) live in fission–fusion societies that allow them to react flexibly to increased feeding competition by forming smaller foraging parties when food is scarce. In chimpanzees at Gombe and Kibale, female dominance rank can crucially influence feeding competition and reproductive success as high‐ranking females monopolize core areas of relatively high quality, are more gregarious, and have higher body mass and reproductive success than low‐ranking females. Chimpanzee females in Taï National Park do not monopolize core areas; they use the entire territory as do the males of their community and are highly gregarious. Although female chimpanzees in Taï generally exhibit a linear dominance hierarchy benefits of high rank are currently not well understood. We used a multivariate analysis of long‐term data from two Taï chimpanzee communities to test whether high‐ranking females (1) increase gregariousness and (2) minimize their travel costs. We found that high‐ranking females were more gregarious than low‐rankers only when food was scarce. During periods of food scarcity, high rank allowed females to enjoy benefits of gregariousness, while low‐ranking females strongly decreased their gregariousness. High‐ranking females traveled more than low‐ranking females, suggesting that low‐rankers might follow a strategy to minimize energy expenditure. Our results suggest that, in contrast to other chimpanzee populations and depending on the prevailing ecological conditions, female chimpanzees at Taï respond differently to varying levels of feeding competition. Care needs to be taken before generalizing results found in any one chimpanzee population to the species level. Am. J. Primatol. 73:305–313, 2011. © 2010 Wiley‐Liss, Inc.     

Effects of Forest Management on Diversity and Abundance of Fruit-feeding Nymphalid Butterflies in South-eastern Côte d'Ivoire

The effects of forest management on vegetation structure and capture frequencies of nymphalid butterflies were studied in a logged rain forest in south-east Côte d'Ivoire. An experimental compartment, where liberation thinning was carried out 3 years before, and a 5-year-old mono-dominant tree plantation were compared to a regenerating control compartment; 3642 specimens of 97 species were trapped. Accumulated species richness and diversity indices were lower in the control compared to the liberation thinning compartment, but lowest in the plantation. However, the habitat preference for traps situated in the control compartment was negatively correlated with the size of the species geographical range. Four out of five species with a lower capture frequency in the liberation thinning compartment showed preferences for mature succession stages and were either Upper Guinean endemics or Guinea–Congolian–restricted species. The seven species with higher capture frequencies in the liberation thinning compartment were all geographically widespread. Five of them showed higher frequencies in younger succession stages. Eight species, three canopy specialists and two Guinea savannah species, significantly preferred the plantation, while 17 species avoided this management type. Liberation thinning seems to affect the more specialised species with smaller geographic ranges, thus risking loss of regional diversity.     

Market Hunting in the Taï Region,Côte d’Ivoire and Implications for Monkey Populations

We studied the effect of market hunting on primate species in the Taï National Park and adjacent forests in Côte d’Ivoire. We assessed the impact of hunting by comparing the calculated maximal reproduction rate with the current off-take rate. We assessed the average bushmeat consumption per capita/per year from weekly investigations on bushmeat available in 88 bushmeat restaurants and markets over a 12-mo period in 1999. We derived data on preferences for particular game species from interviews of 162 bushmeat consumers, 25 subsistence hunters and 3 groups of professional hunters. Hunting pressure was highest on the larger primate species such red colobus (Procolobus badius), black- and- white colobus (Colobus polykomos) and sooty mangabeys (Cercocebus atys). The amount of primate bushmeat extracted from the Taï National Park and surrounding forests was 249,229 kg in 1999. We estimated population densities using line transect surveys. By referring to current population densities we calculated the maximum production of each species using the Robinson Redford model (2001) and assuming unhunted conditions. A comparison of current harvest levels with maximum production suggests that harvest of Procolobus badius is sustainable, whereas current off-take of Colobus polykomos, Cercocebus atys, Cercopithecus diana (diana monkey) and C. campbelli (Campbell’s monkeys) exceeds sustainability by ≤3 times. We recommend that wildlife managers promote programs that encourage the production of domestic animals as a substitute for wild meat.     

Habituation of wild chimpanzees (Pan troglodytes) of the South Group at Taï Forest, Côte d'Ivoire: empirical measure of progress

The last part of the chimpanzee (Pan troglodytes) habituation process of the Ta? South Group was monitored over 2 years (1994-1996), during which all males and most of the females became habituated to observation by humans. The time needed (5-7 years) to habituate the community was similar to that recorded for the Ta? North Group and is comparable to other populations studied in Africa. Variation emerged in habituation rate: males were habituated earlier than females, and among females, sexually cycling individuals were habituated faster than non-cycling females. Such differences may be a function of both the methods used to find the chimpanzees and the sex of the individual. Reproductive status and individuality may also have influenced habituation rates by affecting the number of contacts required to habituate a chimpanzee to neutral humans.     

Plant Species Diversity in the Southern Part of the Taï National Park (Côte d’Ivoire)

Plant species diversity is surveyed in the southern part of the Taï National Park (TNP), Côte d’Ivoire. This park is the largest remaining tract of pristine forest in the West African rainforest biodiversity hotspot. Plant assemblages and environment factors were surveyed in 39 temporary 625-m² plots within three areas. The species list was completed thanks to itinerant prospections. TWINSPAN classification and detrended correspondence analysis were applied to the 39 relevés. We recorded a total of 916 plant species, including 169 West African endemics, that rises the floristic richness of TNP in 1233 species. Most plant species recorded were Guineo-Congolian species (90.9%) among which 8% were ‘Sassandrian species’, i.e. endemics of the extreme southwest Côte d’Ivoire. Eight of these endemics were exclusive of the southern part of TNP. The forest is very species-rich, particularly in Rubiaceae, Leguminosae and Euphorbiaceae. Most of the sampled species (59.5%) were erect phanerophytes with a dbh≤10 cm. We distinguished 7 plant community types, mainly determined by geomorphology and disturbance history. Lowland forests were typical dense evergreen forests with different degrees of maturity related to historical human impact. Inselbergs and swampy depressions provide an original azonal vegetation. We conclude that the southern part of TNP contributes significantly to the regional biodiversity hotspot since it includes the last remnants of primary evergreen rainforest and contains species assemblages from both higher rainfall biomes on moist soils derived from schist parent material and lower rainfall biomes on inselberg slopes and top. As anthropogenic disturbance clearly reduces biodiversity, these last remnants should be integrally protected.     

A contribution to the study of the avifauna of the Bossematie Forest (Abengorou/Côte d'Ivoire). The future of Bossematie Forest: current status

Yaokokore Beibro, K.H. & Ellenberg, H. 2000. A contribution to the study of the avifauna of the Bossematie Forest (Abengorou/Côte D'Ivoire). The future of Bossematie Forest: current status. Ostrich 71 (1 & 2): 292–294.

The Bossematie forest, eastern Cdte d'Ivoire (3°35'-3°20' longitude west and 6°35'6°20' latitude north), has been heavily exploited in the past and is now being rehabilitated by the SODEFOR (Societe de Developpement des Forêts) and the GTZ (German Technical Co-operation). To estimate the potential for the rehabilitation, the bird fauna was studied during a four year period including the field work of three observers of about 24 person-months. Until now we recorded in the forest and the surroundings 337 species belonging to 203 genera and 58 families. 251 species were present within the forest borders with 133 only observed there and not outside. Five species are considered as near-threatened and four species as vulnerable. To study the ecology of forest species in more detail, an intensive analysis of the communities of different forest stages and treatments was carried out by the first author.     

Naïve and memory cell turnover as drivers of CCR5-to-CXCR4 tropism switch in human immunodeficiency virus type 1: implications for therapy

Early human immunodeficiency virus infection is characterized by the predominance of CCR5-tropic (R5) virus. However, in many individuals CXCR4-tropic (X4) virus appears in late infection. The reasons for this phenotypic switch are unclear. The patterns of chemokine receptor expression suggest that X4 and R5 viruses have a preferential tropism for na?ve and memory T cells, respectively. Since memory cells divide approximately 10 times as often as na?ve cells in uninfected individuals, a tropism for memory cells in early infection may provide an advantage. However, with disease progression both na?ve and memory cell division frequencies increase, and at low CD4 counts, the na?ve cell division frequency approaches that of memory cells. This may provide a basis for the phenotypic switch from R5 to X4 virus observed in late infection. We show that a model of infection using observed values for cell turnover supports this mechanism. The phenotypic switch from R5 to X4 virus occurs at low CD4 counts and is accompanied by a rapid rise in viral load and drop in CD4 count. Thus, low CD4 counts are both a cause and an effect of X4 virus dominance. We also investigate the effects of different antiviral strategies. Surprisingly, these results suggest that both conventional antiretroviral regimens and CCR5 receptor-blocking drugs will promote R5 virus over X4 virus.     

Risk factors and spatial patterns of hookworm infection among schoolchildren in a rural area of western Côte d'Ivoire

This study is aimed at investigating the risk factors for hookworm infection among schoolchildren in a rural area of western C?te d'Ivoire and predicting and mapping the spatial distribution of infection. We used demographic and socio-economic data from a cross-sectional survey of 6-16-year-old schoolchildren from 56 schools. Infection with hookworm was determined by microscopic examination of stool samples employing the Kato-Katz technique and an ether-concentration method. Environmental data were derived from satellite images and digitised maps. Bayesian variogram models were applied to investigate the variation of hookworm infection in relation to demographic, socio-economic and environmental factors. The overall hookworm infection prevalence, based on the pooled microscopic diagnoses, was 43.3% and ranged from 5.4 to 79.1% in the schools surveyed. Bivariate analyses showed that sex, age, socio-economic status, elevation, rainfall and land cover were significantly associated with the spatial distribution of hookworm infection. The final multivariate spatial model consisted of the covariates age, sex, socio-economic status, elevation and land cover. When assuming non-stationary underlying spatial dependency, the results of the model suggested that spatial correlation depended on the location only marginally. We conclude that, at the current resolution, it seems more reasonable to target interventions based on well-established epidemiologic risk factors, rather than on spatial factors.     

Naïve T-cell dynamics in human immunodeficiency virus type 1 infection: effects of highly active antiretroviral therapy provide insights into the mechanisms of naive T-cell depletion

Both na?ve CD4+ and na?ve CD8+ T cells are depleted in individuals with human immunodeficiency virus type 1 (HIV-1) infection by unknown mechanisms. Analysis of their dynamics prior to and after highly active antiretroviral therapy (HAART) could reveal possible mechanisms of depletion. Twenty patients were evaluated with immunophenotyping, intracellular Ki67 staining, T-cell receptor excision circle (TREC) quantitation in sorted CD4 and CD8 cells, and thymic computed tomography scans prior to and approximately 6 and approximately 18 months after initiation of HAART. Na?ve T-cell proliferation decreased significantly during the first 6 months of therapy (P < 0.01) followed by a slower decline. Thymic indices did not change significantly over time. At baseline, na?ve CD4+ T-cell numbers were lower than naive CD8+ T-cell numbers; after HAART, a greater increase in na?ve CD4+ T cells than na?ve CD8+ T cells was observed. A greater relative change (n-fold) in the number of TREC+ T cells/mul than in na?ve T-cell counts was observed at 6 months for both CD4+ (median relative change [n-fold] of 2.2 and 1.7, respectively; P < 0.01) and CD8+ T cell pools (1.4 and 1.2; P < 0.01). A more pronounced decrease in the proliferation than the disappearance rate of na?ve T cells after HAART was observed in a second group of six HIV-1-infected patients studied by in vivo pulse labeling with bromodeoxyuridine. These observations are consistent with a mathematical model where the HIV-1-induced increase in proliferation of na?ve T cells is mostly explained by a faster recruitment into memory cells.     

Parasitic worms: knowledge, attitudes, and practices in Western Côte d'Ivoire with implications for integrated control

Background

In the developing world where parasitic worm infections are pervasive, preventive chemotherapy is the key strategy for morbidity control. However, local knowledge, attitudes, and practices (KAP) of parasitic worms are poorly understood, although such information is required for prevention and sustainable control.

Methods

We carried out KAP surveys in two rural communities of Côte d''Ivoire that were subjected to school-based and community-based research and control activities. We used qualitative and quantitative methods. The former included observations, in-depth interviews with key informants, and focus group discussions with school children and adults. Quantitative methods consisted of a structured questionnaire administered to household heads.

Principal Findings

Access to clean water was lacking in both communities and only a quarter of the households had functioning latrines. There was a better understanding of soil-transmitted helminthiasis than intestinal schistosomiasis, but community-based rather than school-based interventions appeared to improve knowledge of schistosomiasis. In the villages with community-based interventions, three-quarters of household interviewees knew about intestinal schistosomiasis compared to 14% in the village where school-based interventions were implemented (P<0.001). Whereas two-thirds of respondents from the community-based intervention village indicated that the research and control project was the main source of information, only a quarter of the respondents cited the project as the main source.

Conclusions/Significance

Preventive chemotherapy targeting school-aged children has limitations, as older population segments are neglected, and hence lack knowledge about how to prevent and control parasitic worm infections. Improved access to clean water and sanitation is necessary, along with health education to make a durable impact against helminth infections.     

Novel arenavirus sequences in Hylomyscus sp. and Mus (Nannomys) setulosus from Côte d'Ivoire: implications for evolution of arenaviruses in Africa

This study aimed to identify new arenaviruses and gather insights in the evolution of arenaviruses in Africa. During 2003 through 2005, 1,228 small mammals representing 14 different genera were trapped in 9 villages in south, east, and middle west of C?te d'Ivoire. Specimens were screened by pan-Old World arenavirus RT-PCRs targeting S and L RNA segments as well as immunofluorescence assay. Sequences of two novel tentative species of the family Arenaviridae, Menekre and Gbagroube virus, were detected in Hylomyscus sp. and Mus (Nannomys) setulosus, respectively. Arenavirus infection of Mus (Nannomys) setulosus was also demonstrated by serological testing. Lassa virus was not found, although 60% of the captured animals were Mastomys natalensis. Complete S RNA and partial L RNA sequences of the novel viruses were recovered from the rodent specimens and subjected to phylogenetic analysis. Gbagroube virus is a closely related sister taxon of Lassa virus, while Menekre virus clusters with the Ippy/Mobala/Mopeia virus complex. Reconstruction of possible virus-host co-phylogeny scenarios suggests that, within the African continent, signatures of co-evolution might have been obliterated by multiple host-switching events.     

Malaria transmission dynamics in central Côte d'Ivoire: the influence of changing patterns of irrigated rice agriculture

The dynamics of malaria transmission was studied comparatively in the villages of Zatta and Tiemelekro, central Cote d'Ivoire, from February 2002 to August 2003. Prominent agroecosystems in these villages are irrigated rice growing and vegetable farming, respectively. Mosquitoes (Diptera: Culicidae) were collected on human bait at night and by pyrethrum knock-down spray sheet collections at four randomly selected sentinel sites in each village. In 2002, for a total of 96 man-nights per village, 7716 mosquitoes were collected in Zatta and 3308 in Tiemelekro. In 2003, with half the sampling effort, 859 and 2056 mosquitoes were collected in Zatta and Tiemelekro, respectively. Anopheles gambiae Giles s.l. was the predominant mosquito and the key malaria vector throughout, followed by An. funestus Giles. Anthropophily among adult female Anopheles exceeded 95% in both villages. Comparison between years revealed that the biting rate of An. gambiae s.l. in Zatta decreased several-fold from 49.3 bites per person per night (b/p/n) in 2002 to 7.9 b/p/n in 2003 (likelihood ratio test (LRT) = 1072.66; P < 0.001). Although the biting rate remained fairly constant in Tiemelekro, the difference between years was significant (16.1 vs. 18.2 b/p/n; LRT = 148.06; P < 0.001). These observations were paralleled by a marked decrease in the infective rate of An. gambiae s.l. in Zatta (4.6-1.2%), and an increase in Tiemelekro (3.1-7.6%). Meanwhile, the entomological inoculation rate of An. gambiae s.l. decreased 21-fold in Zatta, from 789 to 38 infective bites per person per year (ib/p/y), whereas it remained high in Tiemelekro (233 vs. 342 ib/p/y). The interruption of irrigated rice growing in Zatta in 2003, consequential to a farmers' conflict over land, might be the underlying cause for the significant reduction in malaria transmission, whereas more stable conditions occurred in Tiemelekro.