Clonal Waves of Neisseria Colonisation and Disease in the African Meningitis Belt: Eight- Year Longitudinal Study in Northern Ghana

BACKGROUND: The Kassena-Nankana District of northern Ghana lies in the African “meningitis belt” where epidemics of meningococcal meningitis have been reoccurring every eight to 12 years for the last 100 years. The dynamics of meningococcal colonisation and disease are incompletely understood, and hence we embarked on a long-term study to determine how levels of colonisation with different bacterial serogroups change over time, and how the patterns of disease relate to such changes. METHODS AND FINDINGS: Between February 1998 and November 2005, pharyngeal carriage of Neisseria meningitidis in the Kassena-Nankana District was studied by twice-yearly colonisation surveys. Meningococcal disease was monitored throughout the eight-year study period, and patient isolates were compared to the colonisation isolates. The overall meningococcal colonisation rate of the study population was 6.0%. All culture-confirmed patient isolates and the majority of carriage isolates were associated with three sequential waves of colonisation with encapsulated (A ST5, X ST751, and A ST7) meningococci. Compared to industrialised countries, the colonising meningococcal population was less constant in genotype composition over time and was genetically less diverse during the peaks of the colonisation waves, and a smaller proportion of the isolates was nonserogroupable. We observed a broad age range in the healthy carriers, resembling that of meningitis patients during large disease epidemics. CONCLUSIONS: The observed lack of a temporally stable and genetically diverse resident pharyngeal flora of meningococci might contribute to the susceptibility to meningococcal disease epidemics of residents in the African meningitis belt. Because capsular conjugate vaccines are known to impact meningococcal carriage, effects on herd immunity and potential serogroup replacement should be monitored following the introduction of such vaccines

Winning Fights Induces Hyperaggression via the Action of the Biogenic Amine Octopamine in Crickets

Winning an agonistic interaction against a conspecific is known to heighten aggressiveness, but the underlying events and mechanism are poorly understood. We quantified the effect of experiencing successive wins on aggression in adult male crickets (Gryllus bimaculatus) by staging knockout tournaments and investigated its dependence on biogenic amines by treatment with amine receptor antagonists. For an inter-fight interval of 5 min, fights between winners escalated to higher levels of aggression and lasted significantly longer than the preceding round. This winner effect is transient, and no longer evident for an inter-fight interval of 20 min, indicating that it does not result from selecting individuals that were hyper-aggressive from the outset. A winner effect was also evident in crickets that experienced wins without physical exertion, or that engaged in fights that were interrupted before a win was experienced. Finally, the winner effect was abolished by prior treatment with epinastine, a highly selective octopamine receptor blocker, but not by propranolol, a ß-adrenergic receptor antagonist, nor by yohimbine, an insect tyramine receptor blocker nor by fluphenazine an insect dopamine-receptor blocker. Taken together our study in the cricket indicates that the physical exertion of fighting, together with some rewarding aspect of the actual winning experience, leads to a transient increase in aggressive motivation via activation of the octopaminergic system, the invertebrate equivalent to the adrenergic system of vertebrates

Compiler Supported Interval Optimisation for Communication Induced Checkpointing

There exist mainly three different approaches of checkpoint-based recovery mechanisms for distributed systems: coordinated checkpointing, uncoordinated checkpointing and communication induced checkpointing. It can be shown that communication induced checkpointing theoretically has the least minimum overhead, but also that the effective overhead depends on the communication behaviour and the resulting forced checkpoints. If the placement of checkpoints and the communication pattern is disadvantageous, the overhead can get arbitrary large due to a high number of forced checkpoints. We introduce a compiler supported approach to avoid unfavourable combinations of communication behaviour and local checkpoint placement. We analyse the application statically and prepare the placement of voluntary checkpoints. These placement decisions are reviewed during runtime. With this approach we optimise the effective checkpoint-intevals of voluntary and forced checkpoints and thus reduce the overhead of communication induced checkpointing

Age and Sex Patterns of Colonisation and Disease

<div><p>(A) Carriage of meningococci (all serogroups and NG; cumulation of all surveys) in the different age groups of the male (light grey bars) and female (dark grey bars) population are shown. 95% CIs are indicated. These CIs do not allow for repeated sampling.</p> <p>(B) Carriage of N. lactamica in the different age groups (mean over all surveys) of the male (light grey bars) and the female population (dark grey bars) are shown. 95% CIs are indicated. These CIs do not allow for repeated sampling.</p> <p>(C) Age spectrum of IR of meningococcal meningitis in the male (circles) and female (triangles) population of the KND in the epidemic of 1996–1997 (dark grey) versus the interepidemic period 2001–2005 (light grey). Denominator is the district population 1995–1999. On the primary y-axis the epidemic IRs and on the secondary y-axis the interepidemic IRs are indicated.</p></div

Waves of Colonisation and Disease in the KND from April 1998 until November 2005

<div><p>Carriage rates recorded during 16 colonisation surveys (April and November each year) and monthly numbers of confirmed meningitis cases of <i>N. meningitidis.</i></p> <p>(A) Genoclouds of serogroup A ST5 and ST7 meningococci are shown.</p> <p>(B) Genoclouds of serogoup X ST851 and NG ST192 meningococci are shown.</p> <p>(C) Carriage rates of other serogroups and meningococci unrelated to the A, X, or NG ST192 genoclouds are shown.</p> <p>(D) Carriage rates of N. lactamica are shown.</p></div

Acidithiobacillus ferrivorans SS3 presents little RNA transcript response related to cold stress during growth at 8 A degrees C suggesting it is a eurypsychrophile

Acidithiobacillus ferrivorans is an acidophilic bacterium that represents a substantial proportion of the microbial community in a low temperature mining waste stream. Due to its ability to grow at temperatures below 15 °C, it has previously been classified as ‘psychrotolerant’. Low temperature-adapted microorganisms have strategies to grow at cold temperatures such as the production of cold acclimation proteins, DEAD/DEAH box helicases, and compatible solutes plus increasing their cellular membrane fluidity. However, little is known about At. ferrivorans adaptation strategies employed during culture at its temperature extremes. In this study, we report the transcriptomic response of At. ferrivorans SS3 to culture at 8 °C compared to 20 °C. Analysis revealed 373 differentially expressed genes of which, the majority were of unknown function. Only few changes in transcript counts of genes previously described to be cold adaptation genes were detected. Instead, cells cultured at cold (8 °C) altered the expression of a wide range of genes ascribed to functions in transcription, translation, and energy production. It is, therefore, suggested that a temperature of 8 °C imposed little cold stress on At. ferrivorans, underlining its adaptation to growth in the cold as well as suggesting it should be classified as a ‘eurypsychrophile’