Gilbert Isabirye-Basuta

Gastrointestinal bacterial transmission among humans, mountain gorillas, and livestock in Bwindi Impenetrable National Park, Uganda.

Habitat overlap can increase the risks of anthroponotic and zoonotic pathogen transmission between humans, livestock, and wild apes. We collected Escherichia coli bacteria from humans, livestock, and mountain gorillas (Gorilla gorilla beringei) in Bwindi Impenetrable National Park, Uganda, from May to August 2005 to examine whether habitat overlap influences rates and patterns of pathogen transmission between humans and apes and whether livestock might facilitate transmission. We genotyped 496 E. coli isolates with repetitive extragenic palindromic polymerase chain reaction fingerprinting and measured susceptibility to 11 antibiotics with the disc-diffusion method. We conducted population genetic analyses to examine genetic differences among populations of bacteria from different hosts and locations. Gorilla populations that overlapped in their use of habitat at high rates with people and livestock harbored E. coli that were genetically similar to E. coli from those people and livestock, whereas E. coli from gorillas that did not overlap in their use of habitats with people and livestock were more distantly related to human or livestock bacteria. Thirty-five percent of isolates from humans, 27% of isolates from livestock, and 17% of isolates from gorillas were clinically resistant to at least one antibiotic used by local people, and the proportion of individual gorillas harboring resistant isolates declined across populations in proportion to decreasing degrees of habitat overlap with humans. These patterns of genetic similarity and antibiotic resistance among E. coli from populations of apes, humans, and livestock indicate that habitat overlap between species affects the dynamics of gastrointestinal bacterial transmission, perhaps through domestic animal intermediates and the physical environment. Limiting such transmission would benefit human and domestic animal health and ape conservation.

Food Competition Among Individuals in a Free-Ranging Chimpanzee Community in Kibale Forest, Uganda

Competition for fruit within chimpanzee foraging parties was investigated by testing the hypotheses that food patch size was a limiting factor to foraging party size and to foraging efficiency while chimpanzees were foraging in Pseudospondias microcarpa trees for fruit. Large food patches (as measured by phenological score or the product of diameter at breast height and phenological score) supported significantly larger parties than did smaller food patches. In addition, foraging efficiency was apparently higher for small parties than for large ones, although the difference was marginally statistically significant. Per-capita feeding time for individuals in small parties was significantly higher than for those in large parties when chimpanzees had access to both Pseudospondias and Uvariopsis congensis fruit trees. Per-capita feeding time was not significantly correlated with food patch size. When Uvariopsis fruit trees became exhausted in mid-August, some chimpanzees apparently avoided severe competition for fruit by leaving the C.C. area, where they had been feeding on both Uvariopsis and Pseudospondias fruit. Social factors did not significantly affect foraging party size nor per-capita feeding time.

High Rates of Escherichia coli Transmission between Livestock and Humans in Rural Uganda

ABSTRACT Escherichia coli is a zoonotic bacterium that is important to both public health and livestock economics. To date, most studies of zoonotic E. coli transmission have been conducted in developed nations with industrialized agricultural economies. In this study, E. coli bacteria were collected from people and livestock in two communities in rural western Uganda in order to investigate patterns of interspecific bacterial transmission in a developing rural economy characterized by very close human-livestock associations. Six hundred seventy-two E. coli isolates were genotyped using repetitive element-PCR (Rep-PCR) fingerprinting, and genetic distances between populations of bacteria from different hosts and locations were calculated. Genetic distances between human and livestock bacteria were generally very low, indicating high rates of bacterial gene flow among host species. Bacteria from humans and livestock in the same communities were virtually indistinguishable genetically. Data from surveys administered at the time of sample collection showed that people who did not regularly wash their hands before eating harbored bacteria approximately twice as similar genetically to bacteria of their livestock as did people who regularly washed their hands before eating. These results suggest that both rates of human-livestock interactions and patterns of human hygiene affect human-livestock bacterial transmission in this setting. This conclusion has implications not only for human and livestock health in subsistence-based agricultural economies but also for the emergence of zoonotic diseases out of such areas as a result of increasing globalization.

Primate Populations and Their Interactions with Changing Habitats

Given that 90% of nonhuman primates depend on tropical forests, the most effective way to conserve them must emphasize the conservation of tropical forest habitats. To achieve this effectively, we need to address root causes of forest disturbance in developing nations: poverty, high population growth rates, crippling foreign debts, and the overdependence on tree and land resources. Moreover, it is now generally accepted that most primate populations will in future live in modified forest habitats. Studies of how primate populations respond to forest habitat modifications are therefore critical to future primate conservation. Currently most studies of primate responses to forest habitat alterations are difficult to interpret owing to differences in research methods and lack of information on the past histories of the modified forests. We review potential factors that may have to be considered while evaluating primate responses to forest habitat changes such as degradation and fragmentation.

How do human activities influence the status and distribution of terrestrial mammals in forest reserves

Tropical forests support a rich biodiversity of terrestrial mammals, yet our knowledge of the conservation of forest reserves is lacking. We investigate the relationship between human activities and the abundance of medium-sized terrestrial mammals within 4 forest reserves in Uganda. These reserves allow firewood collection, timber cutting, gardening, and pole cutting. Illegal hunting also takes place. We found a general decline in terrestrial mammal signs in the reserves compared to the better protected adjacent Kibale National Park. Signs of aardvarks, bushbucks, bush pigs, duikers (blue and red), giant pangolin, giant forest hogs, porcupines, and jackals are still present in some of our reserves.

Beehive and Honey Losses Caused by Bush burning in Adjumani District, Uganda

This paper seeks to quantify numbers of beehives and honey losses together with economic losses accruing annually to beekeepers from the rampant bush burning. The hope is that government agencies can counter any breakdown in livelihood strategies and improve the quality of life of the beekeepers. Environmental degradation caused by burning and roaming of livestock in search for pasture is clearly evident. If these things can be controlled, there is great potential for increased honey production, household incomes and increased local revenue.

Amount of Plant Foods Eaten and Sexual Differences in Feeding among Wild Chimpanzees (Pan troglodytes) of Kanyawara Community

The amount of plant foods eaten and sexual differences in food intake among chimpanzees in Kibale Forest was investigated between July 2007 and January 2008. Continuous focal animal sampling was used to collect data on the diet, number, and duration of feeding bouts of 18 individuals of the Kanyawara chimpanzee community. Chimpanzees utilized 42 plant species for fruits, leaves, and piths. Among plant parts eaten, fruits contributed the greatest percentage of fresh weight (18) in the diets compared to leaves (5.1) and piths (3.6). The duration of feeding bouts varied, ranging from 1.5 to 45.8 minutes. When Mimusops bagshawei fruits were eaten, the numbers of feeding bouts per chimpanzee per day were high compared to when they were not. While our study agrees with previous studies that females spend more time feeding per day, it shows that the long feeding time among females does not translate to increased food weight. We suggest that the social role of females in taking care of the young and their attention being taken up by this role while feeding and fears associated with male presence is the reason for long feeding time among females.