Background. Hyperlactatemia is a strong predictor of mortality in severe falciparum malaria. Sequestered parasitized erythrocytes and reduced uninfected red blood cell deformability (RCD) compromise microcirculatory flow, leading to anaerobic glycolysis. Methods. In a cohort of patients with falciparum malaria hospitalized in Chittagong, Bangladesh, bulk RCD was measured using a laser diffraction technique, and parasite biomass was estimated from plasma concentrations of Plasmodium falciparum histidine-rich protein 2 (PfHRP2). A multiple linear regression model was constructed to examine their associations with plasma lactate concentrations. Results. A total of 286 patients with falciparum malaria were studied, of whom 224 had severe malaria, and 70 died. Hyperlactatemia (lactate level, ≥4 mmol/L) was present in 111 cases. RCD at shear stresses of 1.7 Pa and 30 Pa was reduced significantly in patients who died, compared with survivors, individuals with uncomplicated malaria, or healthy individuals (P < .05, for all comparisons). Multiple linear regression analysis showed that the plasma PfHRP2 level, parasitemia level, total bilirubin level, and RCD at a shear stress of 1.7 Pa were each independently correlated with plasma lactate concentrations (n = 278; R2 = 0.35). Conclusions. Sequestration of parasitized red blood cells and reduced RCD both contribute to decreased microcirculatory flow in severe disease.
The battle between man and malaria has continued for thousands of years. Antimalarial drugs are essential weapons to fight the disease, but their efficacy is threatened by drug resistance which continues to emerge creating a major obstacle to malaria control and jeopardizing renewed hopes for elimination. As 2016 is the first year under WHO Global Technical Strategy for Malaria 2016–2030, it is a good time to ponder the progress of both sides and plan for the future.
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Cooperative breeders are animals where parents are assisted in protecting and provisioning their young by helpers that seldom or never breed themselves. Systems of this kind occur in birds, mammals and some fish, and have usually evolved from ancestors with monogamous breeding systems. Helpers are often previous offspring of breeders and are usually closely related to the young they help to raise though, in some systems, they can also be unrelated immigrants. Their contributions commonly enhance the growth and survival of juveniles and reduce the workload of their parents, increasing their fecundity. Cooperative breeding systems appear to have evolved where the costs of dispersal are high, helping provides substantial fitness benefits to related recipients or to helpers themselves and the fitness costs of helping are low.
Although malaria has been largely eradicated from temperate countries, it is on the increase in the tropics. Infection with Plasmodium falciparum affects a vast number of people and kills over a million annually. Severe malaria is a multisystem disease affecting particularly the central nervous system (causing coma and convulsions), the kidneys (resulting in acute tubular necrosis), and the liver (contributing to lactic acidosis and hypoglycaemia). Acute pulmonary oedema (acute respiratory distress syndrome) may occur in adults particularly in association with renal impairment. In children these symptoms are rare, whereas hypoglycaemia, lactic acidosis and severe anaemia are more common. Malaria should be suspected in any febrile patient living in or returning from the tropics, and a blood smear examined. Chloroquine has been the mainstay of antimalarial treatment for the past 40 years, but resistance in P. falciparum is now widespread throughout the tropics and has recently been recognised in P. vivax from Oceania. Sulfadoxine-pyrimethamine resistance is also common. Fortunately, quinine, and the newly introduced compounds, halofantrine and mefloquine, can be relied upon nearly everywhere. The most rapidly acting and effective of all antimalarial drugs, artemisinin and its derivatives, have come from China. They offer a genuine prospect of reducing mortality from malaria in the tropics.
In many mammals, the energetic costs of lactation double a female's daily energy requirements on her activity budgets, food choice and ranging behaviour–but the effects of lactation have rarely been documented. In this paper, the ecological consequences of lactation in free‐ranging Red deer ( Cervus elaphus ) hinds on the lsle of Rhum is examined by comparing the feeding behaviour, habitat use and ranging behaviour of hinds that were supporting calves (milk hinds) with hinds that did not have calves (yeld hinds). In summer, milk hinds graze for approximately two hours longer per day then yeld hinds. This difference has disappeared by the latter half of the winter, when the grazing budgets of milk and yeld hinds are similar. Both in summer and winter milk hinds spend more time grazing on the most strongly selected plant communities (short, herb‐rich greens) where standing crops are low but food quality is comparatively high. Inter‐year variation in habitat use by milk hinds is also closely related to variation in rainfall—while this is not the case among yeld hinds. Both in summer and winter, yeld hinds range more widely than milk hinds.
