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Background Worsening drug resistance in Plasmodium falciparum malaria is a major threat to health in tropical countries. We did a prospective study of malaria incidence and treatment in an area of highly multidrug-resistant P falciparum malaria. Methods We assessed incidence of P falciparum malaria and the in-vivo responses to mefloquine treatment over 13 years in two large camps for displaced Karen people on the northwest border of Thailand. During this time, the standard mefloquine dose was first increased, and then combined artesunate and mefloquine was introduced as first-line treatment for uncomplicated P falciparum malaria. Findings Early detection and treatment controlled P falciparum malaria initially while mefloquine was effective (cure rate with mefloquine [15 mg/kg] and sulphadoxine-pyrimethamine in 1985, 98% [95% CI 97–100]), but as mefloquine resistance developed, the cure rate fell (71% [67–77] in 1990). A similar pattern was seen for high-dose (25 mg/kg) mefloquine monotherapy from 1990–94. Since the general deployment of the artesunate-mefloquine combination in 1994, the cure rate increased again to almost 100% from 1998 onwards, and there has been a sustained decline in the incidence of P falciparum malaria in the study area. In-vitro susceptibility of P falciparum to mefloquine has improved significantly (p=0·003). Interpretation In this area of low malaria transmission, early diagnosis and treatment with combined artesunate and mefloquine has reduced the incidence of P falciparum malaria and halted the progression of mefloquine resistance. We recommend that antimalarial drugs should be combined with artemisinin or a derivative to protect them against resistance.

Additional file 6. All genes analysed for candidate gene approach.

Infections with tuberculosis (TB)-causing agents of the Mycobacterium tuberculosis complex threaten human, livestock and wildlife health globally due to the high capacity to cross trans-species boundaries. Tuberculosis is a cryptic disease characterized by prolonged, sometimes lifelong subclinical infections, complicating disease monitoring. Consequently, our understanding of infection risk, disease progression, and mortality across species affected by TB remains limited. The TB agent Mycobacterium suricattae was first recorded in the late 1990s in a wild population of meerkats inhabiting the Kalahari in South Africa and has since spread considerably, becoming a common cause of meerkat mortality. This offers an opportunity to document the epidemiology of naturally spreading TB in a wild population. Here, we synthesize more than 25 years' worth of TB reporting and social interaction data across 3420 individuals to track disease spread, and quantify rates of TB social exposure, progression, and mortality. We found that most meerkats had been exposed to the pathogen within eight years of first detection in the study area, with exposure reaching up to 95% of the population. Approximately one quarter of exposed individuals progressed to clinical TB stages, followed by physical deterioration and death within a few months. Since emergence, 11.6% of deaths were attributed to TB, although the true toll of TB-related mortality is likely higher. Lastly, we observed marked variation in disease progression among individuals, suggesting inter-individual differences in both TB susceptibility and resistance. Our results highlight that TB prevalence and mortality could be higher than previously reported, particularly in species or populations with complex social group dynamics. Long-term studies, such as the present one, allow us to assess temporal variation in disease prevalence and progression and quantify exposure, which is rarely measured in wildlife. Long-term studies are highly valuable tools to explore disease emergence and ecology and study host-pathogen co-evolutionary dynamics in general, and its impact on social mammals.

Economic Crisis, Civil Society, and Democratization: The Case of Zambia by Julius O. Ihonvbere (Trenton, NJ, Africa World Press, 1996, pp.335, $19.95 pb, $69.95 hb). African Conflict Resolution: The U.S. Role in Peacemaking edited by David R. Smock and Chester A. Crocker (Washington: US Institute of Peace, 1995, pp.150, $14.95 pb). Imperialism or Solidarity? International Labour and South African Trade Unions by Roger Southall (Cape Town: UCT Press, 1995, pp.398). State and Resistance in South Africa, 1939–1965 by Yvonne Muthien (Avebury: Aldershot, 1994, pp.237, £40). Kenya: Revised Edition compiled by Dalvan Coger (World Bibliographical Series, Volume 25: Oxford, Santa Barbara and Denver, Clio Press, 1996, pp.314, £50). The Egalitarian Moment: Asia and Africa, 1950–1980 by D.A. Low (Cambridge University Press, 1996, pp.xiv + 131, £10.95 pb). Multiple Identities in a Single State: Indian Federalism in Comparative Perspective edited by Balveer Arora and Douglas V. Verney (New Delhi, Konark Publishers, 1995, pp.xii + 391, US$20). Ethnicity and Citizenship: The Canadian Case edited by Jean Laponce and William Safran (London and Portland, Oregon; Frank Cass, 1996, pp.118, £25. hb, £16 pb). The Great Experiment. Labour Parties and Public Policy Transformation in Australia and New Zealand edited by Francis Castles, Rolf Gerritsen and Jack Vowles (St Leonards: Allen and Unwin, 1996, pp.x + 262, £12.99 pb). Political Legitimacy in Southeast Asia: The Quest for Moral Authority edited by Muthiah Alagappa (Stanford, Calif. Stanford University Press, 1996, pp.xiv + 446, £50 hb, £16.95 pb). Tradition versus Democracy in the South Pacific: Fiji, Tonga and Western Samoa by Stephanie Lawson (Cambridge University Press, 1996, pp.xii + 228, £35). Security, Identity and National Building by Demetrios A. Theophylactou (Aldershot: Avebury, 1995, pp.ix + 173, £30).

Rosetting, defined as the binding of two or more uninfected red blood cells (rbc) to an infected rbc, occurs when malarial parasites mature, to trophozoites and schizonts, in the second half of their asexual development. Rosetting is believed to be an important factor in the development of cerebral malaria. In a series of studies to examine the characteristics of the uninfected rbc which contribute to rosetting, the ability of rbc from healthy donors to form rosettes was found to be greater in the cells of group A and B than in those of group O (P = 0.05), and to decrease during storage under blood-bank conditions. Normal rbc exposed for a ≥30 min to quinine, artesunate or artemether (each at 0.25 µg/ml) in vitro showed significantly decreased rosetting. This effect could not be reversed by extensive washing followed by cultivation for another 24 h in drug-free medium. Mefloquine and pyrimethamine had no effect. Uninfected rbc from patients with uncomplicated or severe falciparum malaria exhibited a lower rosetting ability than rbc from healthy donors (P = 0.01). The rosetting of uninfected rbc of all blood groups from patients with uncomplicated malaria decreased significantly within 2 h of the patients starting treatment with qinghaosu derivatives (artesunate or artemether) and within 8 h of them starting quinine treatment. Similar effects were observed with uninfected rbc from patients with severe malaria after treatment with artesunate but not after quinine. The mechanisms underlying this potentially beneficial effect on rbc adherence are not known.

Highlights•Dominant meerkats live longer than those that remain subordinate•It has been suggested these lifespan differences stem from slowed aging in dominants•Rapid telomere loss suggests dominants age faster, not slower, than subordinates•Lifespan differences instead arise from subordinate dispersal, which raises mortalitySummaryIn many cooperatively breeding animal societies, breeders outlive non-breeding subordinates, despite investing heavily in reproduction [1–3]. In eusocial insects, the extended lifespans of breeders arise from specialized slowed aging profiles [1], prompting suggestions that reproduction and dominance similarly defer aging in cooperatively breeding vertebrates, too [4–6]. Although lacking the permanent castes of eusocial insects, breeders of vertebrate societies could delay aging via phenotypic plasticity (similar rank-related changes occur in growth, neuroendocrinology, and behavior [7–10]), and such plastic deferment of aging may reveal novel targets for preventing aging-related diseases [11]. Here, we investigate whether breeding dominants exhibit extended longevity and delayed age-related physiological declines in wild cooperatively breeding meerkats. We show that dominants outlive subordinates but exhibit faster telomere attrition (a marker of cellular senescence and hallmark of aging [12]) and that in dominants (but not subordinates), rapid telomere attrition is associated with mortality. Our findings further suggest that, rather than resulting from specialized aging profiles, differences in longevity between dominants and subordinates are driven by subordinate dispersal forays, which become exponentially more frequent with age and increase subordinate mortality. These results highlight the need to critically examine the causes of rank-related longevity contrasts in other cooperatively breeding vertebrates, including social mole-rats, where they are currently attributed to specialized aging profiles in dominants [4].Graphical abstract

Species may become obligate cooperative breeders when parents are unable to raise their offspring unassisted. We measured the daily energy expenditure of mothers, helpers and offspring during peak lactation in cooperatively breeding meerkats Suricata suricatta using the doubly labelled water technique. Lactating mothers expended more energy per day than allo-lactating subordinate females, non-lactating females or suckling offspring. Metabolizable energy intakes of lactating mothers were calculated from isotope-based estimates of offspring milk energy intake, and were not significantly different from the previously suggested maximal limit for mammals. Allo-lactating females were the only category of animals that lost weight during the period of study, probably because they spent more time babysitting than non-lactating females. Daily energy expenditure (DEE) of lactating mothers increased with litter size but decreased with the number of helpers. Calculations show that for every 10 helpers, even in the absence of allo-lactators, mothers are able to reduce their DEE during peak lactation by an amount equivalent to the energy cost of one pup. These results indicate that helpers have beneficial energetic consequences for lactating mothers in an obligate cooperatively breeding mammal.