2,455 publications from this institution
Malaria is the most important parasitic disease of man. It infects approximately 5% of the world’s population and kills somewhere between one and two million people each year. Of the four species of malaria parasites that infect humans, only <i>Plasmodium falciparum</i> is lethal. Cerebral involvement causing coma in severe falciparum malaria is a characteristic but ominous development carrying a 15–20% treated case fatality. Untreated it is considered uniformly fatal. Cerebral malaria is widely quoted as being the most common cause of coma in tropical areas of the world. <b>WHO GETS CEREBRAL MALARIA?</b> In some parts of the tropics malaria is acquired as many as two or three times every day and thus everyone in the community has malaria all the time. At the other end of the spectrum, there are many areas where the chances of acquiring malaria are relatively low. For example, along the western border of Thailand,
Evolutionary explanations of cooperative breeding based on kin selection have predicted that the individual contributions made by different helpers to rearing young should be correlated with their degree of kinship to the litter or brood they are raising. In the cooperative mongoose or meerkat, Suricata suricatta, helpers babysit pups at the natal burrow for the first month of pup life and frequent babysitters suffer substantial weight losses over the period of babysitting. Large differences in contributions exist between helpers, which are correlated with their age, sex and weight but not with their kinship to the young they are raising. Provision of food to some group members raises the contributions of individuals to babysitting. We discuss the implications of these results for evolutionary explanations of cooperative behaviour.
In polygynous, sexually dimorphic species, sexual selection should be stronger in males than in females. Although this prediction extends to the effects of early development on fitness, few studies have documented early determinants of lifetime reproductive success in a natural mammal population. In this paper, we describe factors affecting the reproductive success of male and female red deer (Cervus elaphus) on the island of Rum, Scotland. Birthweight was a significant determinant of total lifetime reproductive success in males, with heavier–born males being more successful than lighter ones. In contrast, birthweight did not affect female reproductive success. High population density and cold spring temperatures in the year of birth decreased several components of fitness in females, but did not affect the breeding success of males. The results confirm the prediction that selection on a sexually dimorphic trait should be greater in males than in females, and explain the differential maternal expenditure between sons and daughters observed in red deer. Differences between the sexes in the effects of environmental and phenotypic variation on fitness may generate differences in the amount of heritable genetic variation underlying traits such as birthweight.
1. Land & People 2. The Prehistory of South-East Asia 3. South-East Asia's Middle Ages' c. 400-c. 1500 4. South-East Asia in the 'Age of Commerce' 5. European Imperialism c. 1800-1941 6. World War, Nationalism & Decolonisation 1941-65 7. Problems of Independence 8. The Future Includes historical gazetter, lists of rulers, chronology of major events.
No abstract is provided for this article.
Introduction: Relapses are important contributors to illness and morbidity in Plasmodium vivax and P. ovale infections. Relapse prevention (radical cure) with primaquine is required for optimal management, control and ultimately elimination of Plasmodium vivax malaria. A review was conducted with publications in English, French, Portuguese and Spanish using the search terms 'P. vivax' and 'relapse'.Areas covered: Hypnozoites causing relapses may be activated weeks or months after initial infection. Incidence and temporal patterns of relapse varies geographically. Relapses derive from parasites either genetically similar or different from the primary infection indicating that some derive from previous infections. Malaria illness itself may activate relapse. Primaquine is the only widely available treatment for radical cure. However, it is often not given because of uncertainty over the risks of primaquine induced haemolysis when G6PD deficiency testing is unavailable. Recommended dosing of primaquine for radical cure in East Asia and Oceania is 0.5 mg base/kg/day and elsewhere is 0.25 mg base/kg/day. Alternative treatments are under investigation.Expert commentary: Geographic heterogeneity in relapse patterns and chloroquine susceptibility of P. vivax, and G6PD deficiency epidemiology mean that radical treatment should be given much more than it is today. G6PD testing should be made widely available so primaquine can be given more safely.
Among the several ‘tropical’ diseases that affect humans, malarin poses special control problems due to the increasing population at risk from the disease, the difficulties in eradicating the mosquito vector in the tropics and the emergence and spread of parasite resistance to commonly used antimalarial drugs. There is both clinical experience and experimental evidence that, however effective when first introduced, the lifespan of drugs is inevitably curtailed by the emergence of resistant parasites. Resistance is the most important factor in determining the useful lifespan of antimalarial drugs. In this review, Nick White and Piero Olliaro discuss the rationale for combination chemotherapy.
Social animal groups often make consensus decisions about when to return to a sleeping site after a day of foraging. These decisions can depend on extrinsic as well as intrinsic factors, and can range from unshared to shared. Here we investigated how decisions of meerkats, Suricata suricatta, to return to their burrows are coordinated, whether they are shared or monopolized by dominant individuals, and what factors influence the timing and speed of return. Individual meerkats can initiate group movements using ‘lead’ calls, and groups can change foraging patches using ‘move’ calls in a quorum response. We found that both call types could be produced during the return to the burrow, with the probability of move calls increasing as sunset approached, and the probability of lead calls increasing with greater distance to the burrow when sunset was imminent. Dominant and subordinate individuals did not differ significantly in move and lead call rate. Further, the time of return was better predicted by the foraging success of all subordinates in the group (with the group returning later when success was low) than by the foraging success of the dominant individuals. This suggests that decisions to return are shared rather than controlled by dominants. The speed of return depended both on extrinsic factors, such as the presence of pups, the time until sunset and the distance to the burrow, and on intrinsic factors such as satiation. Our results indicate that both the speed and timing of the return depend on urgency, and the higher incidence of lead calls when groups are far away from the burrow near dark suggests a possible change in the decision process from shared to unshared as urgency increases. Our study highlights the impact of time constraints during decision-making processes and in particular on the level of decision sharing.
The interaction between philopatry and nonrandom mating has important consequences for the genetic structure of populations, influencing co‐ancestry within social groups but also inbreeding. Here, using genetic paternity data, we describe mating patterns in a wild population of red deer ( C ervus elaphus ) which are associated with marked consequences for co‐ancestry and inbreeding in the population. Around a fifth of females mate with a male with whom they have mated previously, and further, females frequently mate with a male with whom a female relative has also mated (intralineage polygyny). Both of these phenomena occur more than expected under random mating. Using simulations, we demonstrate that temporal and spatial factors, as well as skew in male breeding success, are important in promoting both re‐mating behaviours and intralineage polygyny. However, the information modelled was not sufficient to explain the extent to which these behaviours occurred. We show that re‐mating and intralineage polygyny are associated with increased pairwise relatedness in the population and a rise in average inbreeding coefficients. In particular, the latter resulted from a correlation between male relatedness and rutting location, with related males being more likely to rut in proximity to one another. These patterns, alongside their consequences for the genetic structure of the population, have rarely been documented in wild polygynous mammals, yet they have important implications for our understanding of genetic structure, inbreeding avoidance and dispersal in such systems.
No abstract is provided for this article.
