No abstract is provided for this article.
During a prospective evaluation of malaria prophylaxis in pregnancy in a refugee population on the north-western border of Thailand from 1987 to 1990, an extremely high infant mortality rate (18%) was documented despite good access to health care. Infantile beri-beri was recognized as the main cause of death accounting for 40% of all infant mortality. Thereafter, severe vitamin B1 deficiency in infants was diagnosed and treated promptly. The impact of this was assessed prospectively from 1993 to 1996 in a second cohort study. The case fatality of infantile beri-beri fell from almost 100% to 7%. The overall infant mortality rates declined from 183 to 78 per 1000 live births. Post-neonatal deaths fell by 79% (95% CI 65-87%) while neonatal mortality remained unchanged. Mortality resulting from acute respiratory infections did not change (15 and 11 per 1000, respectively), whereas mortality attributable to beri-beri decreased from 73 to 5 per 1000 (P < 0.0001). Before its recognition approximately 7% of all infants in this population died from infantile beri-beri. This lethal but preventable syndrome may be more common than hitherto recognized, particularly in refugee populations, in this populous region.
Recent comparative studies show that cooperative breeding is positively correlated with harsh and unpredictable environments and it is suggested that this association occurs because helpers buffer the negative effects of adverse ecological conditions on fitness. In the Kalahari, rainfall varies widely between- and within years, affecting primary production and the availability of the principal prey of cooperatively breeding Kalahari meerkats, Suricata suricatta. Our study aimed to establish whether the presence and number of helpers buffer the negative effects of variation in rainfall on the fecundity and body mass of breeding females, and the survival and growth of pups. We investigate the relationship between group size and variation in rainfall on dominant female fecundity, body mass, and offspring survival and growth using an additive modelling approach on 21 years of individual-based records of the life histories of individual meerkats. We show that breeding female fecundity is reduced during periods of low rainfall but that the effects of low rainfall are mitigated by increases in group size and body mass because heavier females and those in larger groups have increased fecundity and reduced interbirth intervals. Pup growth and survival are also reduced during periods of low rainfall, but only in smaller groups. Our results support the suggestion that cooperative breeding mitigates the detrimental effects of adverse environmental conditions and may enhance the capacity of species to occupy environments where food availability is low and unpredictable.
No abstract is provided for this article.
Malaria still kills some 0.5–2.5 million people per year in the tropics. Resistance to the cheap, most commonly used antimalarials continues to spread alarmingly and could outpace drug development. The artemisinin derivatives have had an important clinical impact both on the treatment of resistant falciparum malaria and on the incidence of disease in low-transmission areas. A few promising new antimalarials are being tested clinically but there is an imperative need for cheap, well-tolerated drugs that can be used in short courses, and for strategies to delay the onset of drug resistance. Bed nets have been shown to reduce the incidence of severe malaria in many areas but an effective vaccine is urgently needed.
Malaysia’s Second Emergency is a little known phenomenon even in Malaysia itself where, as the author points out, the nation-building project combined with archival lacunae has induced historical a...
No abstract is provided for this article.
Changing environmental conditions cause changes in the distributions of phenotypic traits in natural populations. However, determining the mechanisms responsible for these changes and, in particular, the relative contributions of phenotypic plasticity vs evolutionary responses, is difficult. To date, to our knowledge no study has reported evidence that evolutionary change underlies the most widely-reported phenotypic response to climate change: the advancement of breeding times. In a wild population of red deer, average parturition date has advanced by nearly two weeks in four decades. Here we quantify the contribution of plastic, demographic and genetic components to this change. In particular, we quantify the role of direct phenoytpic plasticity in response to increasing temperatures and the role of changes in the population age and stage structure. Importantly, we show that adaptive evolution likely played a role in the shift towards earlier parturition dates. The observed rate of evolution was consistent with a response to selection, and was less likely to be due to genetic drift. Our study provides a rare example of observed rates of genetic change being consistent with theoretical predictions, although the consistency would not have been detected with a solely phenotypic analysis. It also provides, to our knowledge, the first evidence of both evolution and phenotypic plasticity contributing to advances in phenology in a changing climate.
