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Background Despite the advancement in our understanding of cholera and its etiological agent, Vibrio cholerae, the prevention and treatment of the disease are often hindered due to rapid changes in drug response pattern, serotype, and the major genomic islands namely, the CTX-prophage, and related genetic characteristics. In the present study, V. cholerae (n = 172) associated with endemic cholera in Dhaka during the years 2015–2021 were analyzed for major phenotypic and genetic characteristics, including drug resistance patterns. Results Results revealed that the V. cholerae strains belonged to serogroup O1 biotype El Tor carrying El Tor -specific genes rtxC, tcpA El Tor, and hlyA El Tor, but possessed classical-biotype cholera toxin. Serotypes of V. cholerae strains differed temporally in predominance with Inaba during 2015–2017, and again in 2020–2021, while Ogawa was the predominant serotype in 2018–2019. Also, ctxB1 was predominant in V. cholerae associated with cholera during 2015–2017, while ctxB7 was predominant in 2018, and in the subsequent years, as observed until 2021. V. cholerae strains differed in their antibiotic resistance pattern with a majority (97%) being multi-drug resistant (MDR) and belonging to six sub-groups. Notably, one of these MDR strains was resistant to eleven of the eighteen antibiotics tested, with resistance to fourth-generation cephalosporin (cefepime), and aztreonam. This extreme drug resistant (XDR) strain carried resistance-related genes namely, extended-spectrum β-lactamases (ESBL), blaOXA-1 and blaPER-3. Conclusion The observed temporal switching of serotypes, as well as the ctxB genotype, and the emergence of MDR/XDR V. cholerae and their association with endemic cholera in Dhaka underscore the need for routine monitoring of the pathogen for proper patient management.

After the recent announcement of COVID-19 vaccine efficacy in clinical trials by several manufacturers for protection against severe disease, a comprehensive post-efficacy strategy for the next steps to ensure vaccination of the global population is now required. These considerations should include how to manufacture billions of doses of high-quality vaccines, support for vaccine purchase, coordination of supply, the equitable distribution of vaccines and the logistics of global vaccine delivery, all of which are a prelude to a massive vaccination campaign targeting people of all ages. Furthermore, additional scientific questions about the vaccines remain that should be answered to improve vaccine efficacy, including questions regarding the optimization of vaccination regimens, booster doses, the correlates of protection, vaccine effectiveness, safety and enhanced surveillance. The timely and coordinated execution of these post-efficacy tasks will bring the pandemic to an effective, and efficient, close.

Under the right circumstances, fluid-fluxed crustal melting occurs, as demonstrated by some amphibolite-facies migmatites, but the relatively low temperatures involved make this mode of formation an unsatisfactory model for most silicic magma genesis in arcs. The concept of silicic arc magma formation through either partial melting of metabasalts or fractionation of hydrous basaltic parent magmas should also be treated with scepticism, as both these processes produce sodic and moderately to strongly peraluminous liquids that are chemically unlike most arc silicic rocks and glasses. Furthermore, if the silicic magmas are formed in the deep crust, the fractionation model predicts evolved liquids with extreme H2O contents. Thus, the answer to the question posed in the title is that neither of these two models, in isolation, seems likely for the formation of the majority of the more silicic magmas in arc environments. Given the totality of the evidence, we favour models in which high-T processes dominate. These could include fluid-absent partial melting of older non-basaltic arc crust, entrainment of source-derived crystal cargos, hybridisation with mantle-derived magmas and, in some cases, crystal fractionation of andesitic magmas at shallow crustal levels.

Background In Kenya, typhoid fever and invasive non-typhoidal salmonellosis present a huge burden of disease, especially in poor-resource settings where clean water supply and sanitation conditions are inadequate. The epidemiology of both diseases is poorly understood in terms of severity and risk factors. The aim of the study was to determine the disease burden and spatial distribution of salmonellosis, as well as socioeconomic and environmental risk factors for these infections, in a large informal settlement near the city of Nairobi, from 2013 to 2017. Methods Initially, a house-to-house baseline census of 150,000 population in Mukuru informal settlement was carried out and relevant socioeconomic, demographic, and healthcare utilization information was collected using structured questionnaires. Salmonella bacteria were cultured from the blood and faeces of children Salmonella serotypes and risk factors were conducted using Pearson Chi-Square (χ2) test. Results A total of 16,236 children were recruited into the study. The prevalence of bloodstream infections by Non-Typhoidal Salmonella (NTS), consisting of Salmonella Typhimurium/ Enteriditis, was 1.3%; Salmonella Typhi was 1.4%, and this was highest among children Salmonella Typhimurium/ Enteriditis was not significantly associated with rearing any domestic animals. Rearing chicken was significantly associated with high prevalence of S. Typhi (2.1%; p = 0.011). The proportion of children infected with Salmonella Typhimurium/ Enteriditis was significantly higher in households that used water pots as water storage containers compared to using water directly from the tap (0.6%). Use of pit latrines and open defecation were significant risk factors for S. Typhi infection (1.6%; p = 0.048). The proportion of Salmonella Typhimurium/ Enteriditis among children eating street food 4 or more times per week was higher compared to 1 to 2 times/week on average (1.1%; p = 0.032). Conclusion Typhoidal and NTS are important causes of illness in children in Mukuru informal settlement, especially among children less than 16 years of age. Improving Water, Sanitation and Hygiene (WASH) including boiling water, breastfeeding, hand washing practices, and avoiding animal contact in domestic settings could contribute to reducing the risk of transmission of Salmonella disease from contaminated environments.

Observations in the S-type granites (s.l.) of the Wilson’s Promontory batholith demonstrate that one type of schlieren in granitic rocks represent accumulations of mainly mafic magmatic minerals, with internal layering formed through pulsed magma flow. Loss of interstitial magmatic liquid played, at most, a minor role in shaping the preserved compositions of the schlieren; filter pressing was not involved, and simple gravity settling of crystals was also insignificant. Through dissolution-reprecipitation and reactions with residual magmatic liquids in the Wilsons Promontory schlieren, the original accumulated crystals of mafic minerals were largely supplanted by later generations or completely new phases. In the present case, the original accumulating minerals were garnet and orthopyroxene, with minor biotite and accessory minerals. The schlieren retain some of the early, euhedral, compositionally distinct, accumulated biotite, but most biotite formed through reaction of accumulated orthopyroxene and garnet with residual liquid. Some early, accumulated garnet remains, but this is not the peritectic garnet that was originally entrained into the magmas, at source depths. Rather, these are magmatic crystals formed, at mid-crustal depths, through dissolution–reprecipitation of the original peritectic garnet. At emplacement level, another episode of garnet dissolution–reprecipitation occurred, close to the solidus, extensively reorganising the grain-scale igneous textures. Although schlieren preserve structural, chemical and some textural features that can be used to infer their origins, their present microtextures do not fully reflect their initial formation mechanisms. Also, the physical mechanisms of schlieren formation most commonly have little similarity with the processes that were responsible for the main chemical variations in the batholith. Nevertheless, the presence of schlieren indicates that the granitic magmas were flowing in sheet-like laminae, and they provide information on the high-temperature igneous minerals that were suspended in their parent magmas, prior to emplacement.

The high-K, calcalkaline granitic rocks of the 370 Ma, post-orogenic Harcourt batholith in southeastern Australia have I-type affinities but are mildly peraluminous and have remarkably radiogenic isotope characteristics, with 87Sr/86Srt in the range 0.70807 to 0.714121 and eNdt in the range − 5.6 to − 4.3. This batholith appears to be a good example of magmas that were derived through partial melting of distinctly heterogeneous source rocks that vary from intermediate meta-igneous to mildly aluminous metasedimentary rocks, with the balance between the two rock types on the metasedimentary side. Such transitional S-I-type magmas, formed from mainly metasedimentary source rocks, may be more common than is generally realised. The Harcourt batholith also contains mainly granodioritic igneous microgranular enclaves (IMEs). Like their host rocks, the IMEs are peraluminous and have rather radiogenic isotope signatures (87Sr/86Srt of 0.71257–0.71435 and eNdt of − 7.3 to − 4.3), though some are hornblende-bearing. Origins of these IMEs by mixing a putative mantle end member with the host granitic magma can be excluded because of the variability in whole-rock isotope ratios and, for the same reason, the IME magmas cannot represent quench cumulates (autoliths) from the host magmas. Less abundant monzonitic to monzosyenitic IMEs cannot represent accumulations of magmatic biotite and/or alkali feldspar because K-feldspar is absent, and there is no co-enrichment of K2O and FeO + MgO, nor can they be mixtures of anything plausible with the host-rock magma. The granodioritic IMEs probably originated through high degrees of assimilation of a range of crustal materials (partial melts?) by basaltic magmas in the deep crust, and the monzonitic IMEs as melts of enriched subcontinental mantle. Such enclave suites provide little or no information on the chemical evolution of their host granitic rocks.

The Saldanha eruption centre, on the West Coast of South Africa, consists of 542 Ma, intracaldera, S-type, rhyolite ignimbrites divided into the basal Saldanha Ignimbrite and the partly overlying Jacob’s Bay Ignimbrite. Depleted-mantle Nd model ages suggest magma sources younger than the Early Mesoproterozoic, and located within the Neoproterozoic Malmesbury Group and Swartland complex metasedimentary and metavolcanic rocks that form the regional basement. The Sr isotope systematics suggest that the dominant source rocks were metavolcaniclastic rocks and metagreywackes, and that the magmas formed from separate batches extracted from the same heterogeneous source. No apparent magma mixing trends relate the Saldanha to the Jacob’s Bay Ignimbrites, or either of these to the magmas that formed the Plankiesbaai or Tsaarsbank Ignimbrites in the neighbouring Postberg eruption centre. The magmas were extracted from their source rocks carrying small but significant proportions of peritectic and restitic accessory minerals. Variations in the content of this entrained crystal cargo were responsible for most of the chemical variations in the magmas. Although we cannot construct a cogent crystal fractionation model to relate these groups of magmas, at least some crystal fractionation occurred, as an overlay on the primary signal due to peritectic assemblage entrainment (PAE). Thus, the causes of the cryptic chemical variation among the ignimbrite magmas of the Saldanha centre are variable, but dominated by the compositions of the parent melts and PAE. The preservation of clear, source-inherited chemical signatures, in individual samples, calls into question the common interpretation of silicic calderas as having been formed in large magma reservoirs, with magma compositions shaped by magma mingling, mixing, and fractional crystallization. The Saldanha rocks suggest a more intimate connection between source and erupted magma, and perhaps indicate that silicic magmas are too viscous to be significantly modified by magma-chamber processes.

To investigate their genesis and relations with their host rocks, we study igneous microgranular enclaves (IMEs) in the c. 370 Ma, post-orogenic, high-level, felsic plutons and volcanic rocks of Central Victoria, Australia. The IMEs are thermally quenched magma globules but are not autoliths, and they do not form mixing series with their host magmas. These IMEs generally represent hybrids between mantle-derived magmas and very high-T crust-derived melts, modified by fractionation, ingestion of host-derived crystals and, to a lesser extent, by chemical interactions with their hosts. Isotopic and elemental evidence suggests that their likely mafic progenitors formed by partial melting of subcontinental mantle, but that the IME suites from different felsic host bodies did not share a common initial composition. We infer that melts of heterogeneous mantle underwent high-T hybridisation with melts from a variety of crustal rocks, which led to a high degree of primary variability in the IME magmas. Our model for the formation of the Central Victorian IMEs is likely to be applicable to other occurrences, especially in suites of postorogenic granitic magmas emplaced in the shallow crust. However, there are many different origins for the mingled magma globules that we call IMEs, and different phenomena seem to occur in differing tectonic settings. The complexity of IME formation means that it is difficult to unravel the petrogenesis of these products of chaotic magma processes. Nevertheless, the survival of fine-grained, non-equilibrium mineralogy and texture in the IMEs suggests that their tenure in the host magmas must have been geologically brief.

The areally extensive (>5000 km2), syn-tectonic, ca. 520 Ma, mainly S-type Donkerhuk batholith was constructed through injection of thousands of mainly sheet-like magma pulses over 20–25 Myr. It intruded schists of the Southern Zone accretionary prism in the Damara Belt of Namibia. Each magma pulse had at least partly crystallised prior to the arrival of the following batch. However, much of the batholith may have remained partially molten for long periods, close to the H2O-saturated granite solidus. The batholith shows extreme variation in chemistry, while having limited mineralogical variation, and seems to be the world’s most heterogeneous granitic mass. The Nd model ages of ~2 Ga suggest that Eburnean rocks of the former magmatic arc, structurally overlain by the accretionary wedge, are the most probable magma sources. Crustal melting was initiated by mantle heat flux, probably introduced by thermal diffusion rather than magma advection. The granitic magmas were transferred from source to sink, with minimal intermediate storage; the whole process having occurred in the middle crust, resulting in feeble crustal differentiation despite the huge volume of silicic magma generated. Source heterogeneity controlled variation in the magmas and neither mixing nor fractionation was prominent. However, due to the transpressional emplacement regime, local filter pressing formed highly silicic liquids, as well as felsic cumulate rocks. The case of the Donkerhuk batholith demonstrates that emplacement-level tectonics can significantly influence compositional evolution of very large syn-tectonic magma bodies.

In the Lachlan Orogen of south-eastern Australia, the high-level, postorogenic, 368-Ma, I-type Tynong pluton contains granitic to granodioritic rocks that crystallised from a variety of mainly crustally derived magmas emplaced in the shallow crust, in an extensional regime. The isotopic characteristics of the main plutonic rocks are relatively unevolved (87Sr/86Sr t ~ 0.705–0.706 and eNd t ~ −0.4 to 0.6), suggesting source rocks not long separated from the mantle. We infer that arc mafic to intermediate rocks and associated immature greywackes formed the main crustal source rocks and that these are located in the largely unexposed Neoproterozoic–Cambrian Selwyn Block that forms the basement. As exposed near its southern margin, the pluton also contains minor, pillowed sheet-like intrusions of quartz dioritic rock that show mainly mingling structures with the enclosing granodiorites, as well as some hybrid pods and fairly abundant igneous microgranular enclaves that we infer to have been derived from the quartz dioritic sheets. Despite this evidence of direct mantle input into the Tynong magma system, the main granodioritic series do not appear to have been formed by magma mixing processes. Of any I-type granite in the region, the Tynong pluton has perhaps the most direct connection with mantle magmas. Nevertheless, the main mantle connection here is probably in the mantle-derived protolith for these crustal magmas and in the mantle thermal event that gave rise to melting of the deep crust in the Selwyn Block. This degree of mantle connectedness seems typical for I-type granitic rocks worldwide.

Cholera occurs in sporadic cases and outbreaks in Nepal each year. Vibrio cholerae O1 (n = 522) isolated during 2007-2010 from diarrheal patients at 10 different hospital laboratories in Nepal were characterized. Biochemical and serologic identifications showed that all the isolates belonged to serogroup O1, El Tor biotype. Except 72 isolates of Inaba serotype isolated in the year 2007, all the remaining isolates were of Ogawa serotype. All isolates were resistant to nalidixic acid and furazolidone. Resistance to tetracycline, ciprofloxacin, erythromycin and co-trimoxazole were 21, 4, 16 and 90 % respectively. Seventy-seven of these isolates were selected for further characterization for ctxB gene and MLVA typing. Two different variants of classical type cholera toxin were observed. Ogawa strains from 2007 and 2010-Western Nepal outbreak harbored CTX-3 type cholera toxin, whereas Inaba serotypes in 2007 and the remaining Ogawa serotypes in 2008-2010 harbored CTX 3b-type toxin. MLVA analysis showed circulation of four different groups of altered V. cholerae O1 El Tor strains. Two different profiles were seen among 2007 Inaba (9, 3, 6, x, x) and Ogawa (10, 7, 6, x, x) isolates. The MLVA profile of 2008 and 2009 Ogawa isolates were similar to those of Inaba strains of 2007. Isolates from 2010 also showed three different MLVA profiles; profile 9, 3, 6, x, x in 3 isolates, 11, 7, 6, x, x among 2010 Western Nepal outbreak strains and profile 8, 3, 6, x, x among isolates from Butwal and Kathmandu.

Cholera is a major global health problem, causing approximately 100,000 deaths annually, about half of which occur in sub-Saharan Africa. Although early-generation parenteral cholera vaccines were abandoned as public health tools owing to their limited efficacy, newer-generation oral cholera vaccines have attractive safety and protection profiles. Both killed and live oral vaccines have been licensed, although only killed oral vaccines are currently manufactured and available. These killed oral vaccines not only provide direct protection to vaccinated individuals, but also confer herd immunity. The combination of direct vaccine protection and vaccine herd immunity effects makes these vaccines highly cost-effective and, therefore, attractive for use in developing countries. Administration of these oral vaccines does not require qualified medical personnel, which makes their use practical--even in developing countries. Although new-generation oral cholera vaccines should not be considered in isolation from other preventive approaches, especially improved water quality and sanitation, they represent important tools in the public health armamentarium to control both endemic and epidemic cholera.

We use the theory of Borel equivalence relations to analyze the equivalence relation of isomorphism among one-dimensional subshifts. We show that this equivalence relation is a universal countable Borel equivalence relation, so that it admits no definable complete invariants fundamentally simpler than the equivalence classes. We also see that the classification of higher dimensional subshifts up to isomorphism has the same complexity as for the one-dimensional case.

Two natural, low K2O/Na2O, TTG tonalitic gneisses (one hornblende-bearing and the other biotite-bearing) were partially melted at 0.8–1.2 GPa (fluid-absent). The chief melting reactions involve the breakdown of the biotite and hornblende. The hornblende tonalite is slightly less fertile than the biotite tonalite, but melt volumes reach around 30% at 1,000°C. This contrasts with results of most previous work on more potassic TTGs, which generally showed much lower fertility, though commonly producing more potassic melts. Garnet is formed in biotite-bearing tonalitic protoliths at P > 0.8 GPa and at > 1.0 GPa in hornblende-bearing tonalitic protoliths. All fluid-absent experiments produced peraluminous granitic to granodioritic melts, typically with SiO2 > 70 wt.%. For the biotite tonalite, increasing T formed progressively more melt with progressively lower K2O/Na2O. However, the compositions of melts from the hornblende tonalite do not vary significantly with T. With increasing P, melts from the biotite tonalite become less potassic, due to the increasing thermal stability of biotite. For the hornblende tonalite, again there is no consistent trend. Fluid-absent melting of sodic TTGs produces melts with insufficient K2O to model the magmas that formed the voluminous, late, potassic granites that are common in Archaean terranes. Reconnaissance fluid-present experiments at 0.6 GPa imply that H2O-saturated partial melting of TTGs is also not a viable process for producing magmas that formed these granites. The protoliths for these must have been more potassic and less silicic. Nevertheless, at granulite-facies conditions, sodic TTGs will produce significant quantities of broadly leucogranodioritic melt that will be more potassic than the protoliths. Upward abstraction of this melt would result in some LILE depletion of the terrane. Younger K-rich magmatism is unlikely to represent recycling of TTG crust on its own, and it seems most likely that evolved crustal rocks and/or highly enriched mantle must be involved.

There is a growing need for vaccine trials in developing countries. This need arises from the fact that some vaccines do not perform as well in developing as in industrialized country populations and because some newly developed candidates target diseases found only in less-developed countries. Here we discuss several key issues in the design and implementation of vaccine trials in less-developed countries. These include the phasing of vaccine trials on safety, immunogenicity and efficacy to achieve licensure; the recent use of trials to obtain other information crucial to the ultimate deployment of vaccines (such as immunological correlates of protection, indirect vaccine effects, and practical information on the feasibility, costs and acceptability of vaccine introduction); and several ethical issues that have arisen in connection with trials done in developing countries.

The Strathbogie Igneous Complex is comprised of the ignimbritic rocks of the Violet Town Volcanics and the granitic rocks of the Strathbogie batholith. It is Late Devonian in age and postorogenic-extensional in tectonic setting. The batholith was constructed from peraluminous, metasediment-derived magmas emplaced as several internally heterogeneous plutons. Chemical variation in the magmas was largely inherited from the protolith rather than having been produced by differentiation (crystal–liquid separation) or magma mixing. The Strathbogie magmas formed during a granulite-facies metamorphic event that caused partial melting of the rocks of the Proterozoic Selwyn Block, which forms the basement in this region. The chemistry of the Strathbogie batholith, the Violet Town Volcanics and various other felsic complexes of similar age, implies that the Selwyn Block here originally consisted of andesite, dacite, greywacke and pelite, probably deposited in a back-arc extensional setting. The sedimentary components of this protolith may have been deposited in a basin that was extending and deepening with time, so that the sediments contained progressively higher ratios of clay to volcanic materials. Much later, in the Late Devonian, extensional tectonics allowed the emplacement of mantle magmas into the deep and middle crust, causing the low-pressure granulite-facies metamorphic event that was responsible for the production of the crustal components in the granitic magmas of Central Victoria.

Numerous batches of initially heterogeneous magma aggregated to form the I-type Lysterfield Granodiorite, with four geochemically distinct series of granodioritic rocks, emplaced in the shallow crust. The compositional heterogeneities originated through variations in the stoichiometries of melting reactions in the protolith terrane and variable degrees of peritectic assemblage entrainment. The high-K series contains igneous, microgranular enclaves that most probably formed through deep-level hybridisation of enriched mantle magmas with crustal melts. In the model presented here, this heterogeneous collection of magmas ascended to form a thin, sheet-like intrusion, quenched against cold wall rocks. Later, laccolithic inflation, through ingress of voluminous more felsic magmas, arched the pluton roof and fragmented the initial sheet, pieces of which fell back into the Granodiorite to become enclaves, some of which were further hybridised by plastic deformation and mechanical incorporation of host-derived crystals. This may be a common mechanism for the formation of such enclave suites.

The strong negative correlation between the temperatures and melt H2O contents of granitoid magmas implies that the crustal melting reactions that produced the magmas were strongly buffered, with T and aH2O co-varying within a narrow band. This observation can only be explained if the partial melting reactions that created the magmas were either fluid-absent from the outset or evolved toward this condition as melting progressed. Since these melting reactions occur during upper amphibolite- to granulite-facies metamorphism, it is reasonable to conclude that metamorphic events responsible for the generation of granitoid magmas generally occur in the absence of excess pervasive fluid.

Recognition of partial melting in metamorphic rocks is a difficult task, as leucosomes can have a variety of origins. By comparing the observed values of the solid-solid dihedral angles with the known equilibrium values, and close examination of the shapes and compositions of feldspar grains, it is possible to unequivocally identify melt textures. Textural relations in a series of meta-arkose samples from the contact aureole of the Ballachulish Igneous Complex in the Scottish Highlands demonstrate that, when former melt pockets are not highly deformed, their presence can be recognized petrographically, by detailed examination of textures on the grain scale. Identification of melt textures and their distribution in the Ballachulish aureole has led to appreciation of the fundamental role of magmatically derived H2O in producing the partial melting. It has also allowed calculation of the H2O flux involved, and recognition that fractures were the major fluid pathways during metamorphism.

The Ballachulish Igneous Complex consists of an outer quartz diorite and an inner granite, emplaced at about 300 MPa, initially at 1000 to 1050 °C. The contact aureole (0.5–2 km wide) occurs in metapelites and metapsammites plus minor graphitic slates, carbonate rocks and metaquartzites. A textural examination of the arkosic Appin Quartzite, which was previously believed to have melted only within a few metres of the intrusion, demonstrates that partial melting occurred up to 500 m away from the vertical eastern contact. Coupling petrographic observations with Qtz-Ab-Or-H2O phase relations, we determined both the amounts of actual melt and the maximum possible amounts of melt in the samples. Melting efficiency was everywhere less than 100% and decreased with distance from the intrusion. Though perhaps not the only possible source of fluid throughout the aureole, simple models demonstrate that H2O evolution from the pluton would have been volumetrically sufficient and persisted long enough to account for the observed partial melting. A time-integrated fluid flux of 7000 kg/m2 from the pluton is necessary to account for the observed amounts of partial melt in the Appin Quartzite. From its inefficiency, we infer that infiltration of the Appin Quartzite cannot have occurred along interconnected grain-edge channels. Rather, it was controlled by hydraulic fracturing, with fracture density determining melting efficiency. Bulk-rock permeability is calculated to be 10−20 m2, an order of magnitude lower than that necessary to permit pervasive flow of all the fluid exsolving from the pluton. There is little difference between the calculated time-integrated fluid flux through the Appin Quartzite on the eastern flank and an estimate of the infiltrating flux through the pelitic Leven Schist on the western flank in the time interval during which both rock types were above their solidus temperature, despite differences in their equilibrium quartz-H2O dihedral angles at temperatures immediately below the solidus, and differences in the attitude of the contact. The rates of H2O expulsion from the cooling pluton are consistent with highly efficient fracture-dominated flow, allowing insufficient time for textural equilibration.

We report the first detection of P[14], G8 rotaviruses isolated in Egypt from the stool of children participating in a 3 year study of rotavirus epidemiology. Two strains, EGY1850 and EGY2295, were characterized by a serotyping enzyme immunoassay (EIA), virus neutralization, and sequence analysis of the genes encoding VP7 and the VP8* portion of the VP4 gene. These two strains shared a high level of homology of their VP7s (87.8% nucleotide [nt], 97.2% amino acid [aa]) and VP4s (89.6% nt, 97.1% aa) and had the highest VP7 identity to serotype G8 (> 82% nt, > 92% aa) and VP4 identity to genotype P[14] (> or = 81% nt, > 91% aa) strains. Serological results with a VP7 G8-specific and VP4 P[14]-specific neutralizing monoclonal antibodies supported the genetic classification of EGY1850 and EGY2295 as P[14], G8. Genogroup analysis supports earlier findings that human G8 rotaviruses may be genetically related to bovine rotaviruses. These findings demonstrate that our understanding of the geographic distribution of rotavirus strains is incomplete, emphasize the need to monitor rotavirus serotypes, and extend the known distribution of serotype G8 and genotype P[14] strains in Africa.

The system KAlO2–MgO–SiO2–H2O–CO2 has long been used as a model for the processes of granulite-facies metamorphism and the development of orthopyroxene-bearing mineral assemblages through the breakdown of biotite-bearing assemblages. There has been considerable controversy regarding the role of carbon dioxide in metamorphism and partial melting. We performed new experiments in this system (at pressures of 342 to 1500 MPa with T between 710 and 1045 °C and XFlH2O between 0.05 and 1.00), accurately locating most of the dehydration and melting equilibria in P-T-XFlH2O space. The most important primary result is that the univariant reaction Phl + Qtz + Fl = En + Sa + melt must be almost coincident with the fluid-absent reaction (Phl + Qtz = En + Sa + melt) in the CO2-free subsystem. In conjunction with the results of previous measurements of CO2 solubility in silicate melts and phase equilibrium experiments, our theoretical analysis and experiments suggest that CO2 cannot act as a flux for partial melting. Crustal melting in the presence of H2O–CO2 mixed fluids will always occur at temperatures higher than with pure H2O fluid present. Magmas produced by such melting will be granitic (s.l.) in composition, with relatively high SiO2 and low MgO contents, irrespective of the H2O–CO2 ratio in any coexisting fluid phase. We find no evidence that lamprophyric magmas could be generated by partial fusion of quartz-saturated crustal rocks. The granitic melts formed will not contain appreciable dissolved CO2. The channelled passage of hot CO2-rich fluids can cause local dehydration of the rocks through which they pass. In rock-dominated (as opposed to fluid-dominated) systems, minor partial melting can also occur in veins initially filled with CO2-rich fluid, as dehydration and local disequilibrium drive the fluid towards H2O-rich compositions. However, CO2 is unlikely to be a significant agent in promoting regional granulite-grade metamorphism, melting, magma generation, metasomatism or long-range silicate mass transfer in Earth's crust. The most viable model for the development of granulite-facies rocks involves the processes of fluid-absent partial melting and withdrawal of the melt phase to higher crustal levels.

We conducted fluid-absent partial melting experiments, at 0.5 and 1.0 GPa in the temperature range 750 to 1000 °C, to investigate the influence of bulk rock Mg ? [100Mg/(Mg+Fe)] and the effects of additional TiO2 on the granulite-grade anatectic evolution of relatively magnesian metapelites and metagreywackes. In these experiments, melting began between 780 and 830 °C by the incongruent breakdown of biotite to produce quartz-saturated, granulite-facies residual mineral assemblages in equilibrium with H2O-undersaturated granitic melt. The glass (quenched melt) compositions produced in this study vary little. Generally, the glasses have compositions similar to those of many natural strongly peraluminous leucogranites. The solidus temperatures in both rock types increase with increasing Mg ?, but are unaffected by the presence or absence of a TiO2 component. At 0.5 GPa the metapelites melted at temperatures up to 50 °C lower than the equivalent metagreywackes, but at 1 GPa there was no discernible difference. This study suggests that the fluid-absent solidus has a steep positive dP/dT slope in metapelites and steep negative dP/dT slope in metagreywackes. The pattern of melt production with increasing temperature is strongly controlled by the upper limit of biotite stability. In TiO2-free compositions this was found to increase by 15 to 20 °C in the metapelites and by 30 to 40 °C in the metagreywackes, as a function of increasing Mg ? from 49 to 81. The presence of a TiO2 component increases the upper limit of biotite stability by ∼50 °C in the metapelites and by ∼80 °C in the metagreywackes, over that observed in the equivalent TiO2-free compositions. In consequence, in the TiO2-free samples large pulses of melt (up to 35 wt%) are produced over narrow temperature ranges (as little as 15 °C in these experiments) between 830 and 875 °C. In the TiO2-bearing samples the major pulse of melt production occurs more gradually between 830 and >900 °C.

One of the most popular petrogenetic concepts is that of simultaneous assimilation and fractional crystallisation (AFC). The equations governing these processes are well known and widely applied. The power and attraction of the model are that, with the minimum of constraints, petrogenetic schemes can be erected for essentially any group of rocks. These models are usually based on the observed variations in a small number of trace elements and/or isotopic systems. In this paper we have generated well-constrained AFC models for the Variscan, calc-alkaline Querigut complex in the French Pyrenees. Our models are based on geological constraints on the identities of the parent magma and candidate assimilants, and the Sm-Nd and Rb-Sr isotope systematics of the rocks. The modelling is successful in mimicking the isotope array for the actual rocks. However, the results are massively inconsistent with those produced using the major- and trace-element concentrations. Our major conclusion is that AFC modelling should be undertaken only with robust initial constraints on the compositions of the parent magma and the proposed assimilant, with due respect for crystal-liquid partition coefficients, in so far as they are known. The results should then be accepted only if the isotope-based model parameters are consistent with those derived from major- and trace-element variations.

In a population-based case-control study of 642 childhood cancer cases and the same number of matched controls in Shanghai, China, we evaluated the relationship between diagnostic X-ray (preconception, pre- and post-natal) and antenatal ultrasound exposure and the subsequent risk of developing three major types of childhood cancer (acute leukaemia, lymphoma and brain tumours) and all childhood neoplasms combined. Consistent with previous studies, prenatal X-ray exposure was found to be associated with an 80% increased risk of childhood cancers, although the estimation was based on 4% and 2% exposed cases and controls and was only marginally statistically significant (P = 0.08). Post-natal X-ray exposure was also linked with a small elevation in the risk of all cancers and the major categories of malignancies in children. Little evidence, however, was found to relate parental preconception X-ray exposure with the subsequent cancer risk in offspring, regardless of the exposure window and the anatomical site of X-ray exposures. This study adds further to the growing literature indicating that antenatal ultrasound exposure is probably not associated with an increased risk of childhood cancer.

This study aims at understanding the individual and community-level characteristics that influenced participation in two consecutive vaccine trials (typhoid and cholera) in urban slums of Kolkata, India. The study area was divided into 80 geographic clusters (communities), with 59,533 subjects agedor = 2 years for analysis. A multi-level model was employed in which the individuals were seen nested within the cluster. Rates of participation in both the trials were nearly the same; those who participated in the initial trial were likely to participate in the subsequent cholera vaccine trial. Communities with predominantly Hindu population, lower percentage of households with an educated household head, or lower percentage of households owning a motorbike had higher participation than their counterparts. At individual scale, higher participation was observed among younger subjects, females, and individuals from households with a household head who had no or minimal education. Geographic patterns were also observed in participation in the trials. The results illustrated that participation in the trial was mostly influenced by various individual and community-level factors, which need to be addressed for a successful vaccination campaign.

Background The diagnosis of typhoid fever is confirmed by culture of Salmonella enterica serotype Typhi (S. typhi). However, a more rapid, simpler, and cheaper diagnostic method would be very useful especially in developing countries. The Widal test is widely used in Africa but little information exists about its reliability. Methods We assessed the performance of the Widal tube agglutination test among febrile hospitalized Tanzanian children. We calculated the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of various anti-TH and -TO titers using culture-confirmed typhoid fever cases as the "true positives" and all other febrile children with blood culture negative for S. typhi as the "true negatives." Results We found that 16 (1%) of 1,680 children had culture-proven typhoid fever. A single anti-TH titer of 1:80 and higher was the optimal indicator of typhoid fever. This had a sensitivity of 75%, specificity of 98%, NPV of 100%, but PPV was only 26%. We compared our main findings with those from previous studies. Conclusion Among febrile hospitalized Tanzanian children with a low prevalence of typhoid fever, a Widal titer of ≥ 1:80 performed well in terms of sensitivity, specificity, and NPV. However a test with improved PPV that is similarly easy to apply and cost-efficient is desirable.

The Mineralogical Society's Millennium Winter Conference was held at the University of Reading on Monday 13 to Wednesday 15 December 1999. The idea behind the conference was to bring together workers from as wide a cross-section of the mineralogical sciences as possible. The conference theme was clays, how they are created from volcanic materials, their environmental roles, and how they become components of supracrustal rocks, are metamorphosed and ultimately recycled back to magma during crustal anatexis.

Background Hepatitis C virus (HCV) infection and schistosomiasis are major public health problems in the Nile Delta of Egypt. To control schistosomiasis, mass treatment campaigns using tartar emetic injections were conducted in the 1960s through 1980s. Evidence suggests that inadequately sterilized needles used in these campaigns contributed to the transmission of HCV in the region. To corroborate this evidence, this study evaluates whether HCV infections clustered within houses in which household members had received parenteral treatment for schistosomiasis. Methods A serosurvey was conducted in a village in the Nile Delta and residents were questioned about prior treatment for schistosomiasis. Sera were evaluated for the presence of antibodies to HCV. The GEE2 approach was used to test for clustering of HCV infections, where correlation of HCV infections within household members who had been treated for schistosomiasis was the parameter of interest. Results A history of parenteral treatment for schistosomiasis was observed to cluster within households, OR for clustering: 2.44 (95% CI: 1.47–4.06). Overall, HCV seropositivity was 40% (321/796) and was observed to cluster within households that had members who had received parenteral treatment for schistosomiasis, OR for clustering: 1.76 (95% CI: 1.05–2.95). No such evidence for clustering was found in the remaining households. Conclusion Clustering of HCV infections and receipt of parenteral treatment for schistosomiasis within the same households provides further evidence of an association between the schistosomiasis treatment campaigns and the high HCV seroprevalence rates currently observed in the Nile delta of Egypt.

THERE has been considerable controversy regarding the role of carbon dioxide in the metamorphism and melting of the Earth's crust, fuelled principally by reports of experimental evidence for CO2-enhanced partial melting of the assemblage phlogopite mica + quartz in the model system KAlO2–MgO–SiO2H2O–CO21,2. The analogous process in the crust would lead to the formation of granulite–facies rocks at temperatures characteristic of amphibolite-facies metamorphism; the granulite fades3–5 would thus be indicative not of unusually high temperatures, but of the influx of carbonic fluids4–6. Moreover, the similarity of their low-temperature melts to the compositions of some calc-alkaline lamprophyres led Peterson and Newton2 to suggest that such magmas might be generated by the introduction of CO2-rich fluids, providing a means of large-scale mass transfer in the deep crust. These ideas have been highly influential6, but there are aspects of Peterson and Newton's results that are hard to reconcile with other available data. I have accordingly tried to replicate the results of refs 1 and 2 but, as I report here, have been unable to do so. The present results thus cast doubt on the general idea of melt fluxing by CO2, and the formation of magnesium-and CO2-rich magmas at crustal pressures.

The Late Devonian Tolmie Igneous Complex (in north-eastern Victoria, Australia) contains S-type, intracaldera, rhyolitic ignimbrites with multiple generations of phenocrysts of biotite, garnet, cordierite and orthopyroxene; one unit also contains fayalitic olivine. Geothermometry and calculated phase relations indicate high-T deep- to mid-crustal origins for the magmas, with crystallisation at several levels. At least four separate magma groups make up the complex. Compositional variations within and between ignimbrites are adequately modelled by selective entrainment of peritectic garnet, ilmenite, orthopyroxene and plagioclase into the magmas. Neither crystal fractionation nor mafic-felsic magma mixing played a role. Chemical and isotope data suggest that the magma sources were once variably Ba-enriched arc greywackes with different proportions of clay. The deep origin of some of the Tolmie Complex magmas means that supracrustal rocks underlie parts of north-eastern Victoria at depths of around 35 km. This has important implications for understanding the region’s tectonic development.

Human Milk Antibody Titers to Enterotoxigenic Escherichia coli (ETEC) Antigens Among 118 Lactating Egyptian Women

The Epidemiology of Infant Colonization and Early-Onset Group B Streptococcal(GBS) Disease in the U.S., a Multi-Center Study from 1995-97

Although immunocompromise due to HIV-1 (HIV) infection increases the importance of receipt of routine childhood vaccines, such vaccines appear to have decreased immunogenicity in these children. The study's objectives were to evaluate the immunogenicity of Haemophilus influenzae type B(Hib) conjugate vaccines among HIV-infected children according to clinical and immunologic disease progression as well as viral load. The concentration of antibody to polyribosylribitolphosphate (PRP) was measured at approximately nine and 24 months of age in plasma specimens from children of HIV-infected women enrolled in the Women and Infants Transmission Study. Of 227 children at the 9-month visit known to have received age-appropriate immunization with a Hib conjugate vaccine, the geometric mean antibody concentration (GMAC) was lower among 35 HIV-infected children (1.64 μg/ml) as compared to uninfected children (2.70 μg/ml), although the difference was not statistically significant. The proportion of children with antibody concentrations ≥ 1.0μg/ml did not differ significantly according to HIV infection status (73% uninfected, 74% infected). Neither the GMAC nor the proportion of children with antibody concentrations ≥ 1.0 μg/ml varied significantly among these HIV-infected children with predominantly mild-moderate disease progression according to clinical category, immunologic stage, or viral load(p ≥ 0.37). Similar results were obtained among 127 children (17 HIV-infected) eligible for analysis at the 24-month study visit. Changes in antibody concentrations over time did not differ significantly among HIV-infected as compared to uninfected children (p = 0.87). These results suggest that HIV-infected children with mild-moderate disease progression may have an adequate quantitative antibody response to Hib conjugate vaccines during the first two years of life. Additional investigations of the immune response to Hib conjugate vaccines, including the qualitative antibody response to immunization, should be pursued.

The association between maternal smoking during pregnancy and childhood cancer was investigated using prospectively-collected data from a cohort of 44,621 pregnant women who gave birth to 54,795 live born children. The children were followed a median of 88 months. Cases of cancer had a histologic diagnosis and/or a compatible clinical course. There were 51 children with cancer (17 leukemia, 8 CNS tumors, 7 Wilms tumor, 6 neuroblastoma, 5 lymphoma, 3 retinoblastoma, 2 rhabdomyosarcoma, 2 hepatoblastoma, 1 fibrosarcoma); 83% of still-borns were autopsied and none had cancer. The cumulative incidence of cancer to age 7½ years was 1.1/1000. Maternal smoking was determined at each prenatal visit; 52% of mothers reported smoking at one or more visits. By age 7½, cancer occurred in 1.4/1000 children whose mothers did not smoke during pregnancy, compared to 0.9/1000 children whose mothers smoked(p=0.15 by logrank test); the hazard ratio was 0.67 (95% CI 0.38-1.17). There was no dose-response effect of smoking compared to non-smokers (hazard ratio for ½ pack/day or less=0.45, over ½ pack/day=0.83, p for trend=0.39). The hazard ratio for leukemia among children whose mothers smoked was 0.82 (0.31-2.11); the hazard ratio for cancers other than leukemia was 0.60 (0.30-1.20). Adjustment for race, date of birth, parity, maternal education and x-ray exposure did not materially change the odds ratios. Although the relatively small number of cases precluded extensive study of individual types of cancer, we conclude that maternal smoking in pregnancy is not associated with an increased risk of childhood cancer in this cohort.

The Violet Town Volcanics are a 373 Ma old, comagmatic, S-type volcanic sequence mainly comprising crystal-rich intracaldera ignimbrites. Rock types vary from rhyolites to rhyodacites, all containing magmatic cordierite and garnet phenocrysts. Variation in the suite is primarily due to fractionation of early-crystallized quartz, plagioclase and biotite (plus minor accessory phases) in a high-level magma chamber prior to eruption. Early magmatic crystallization occurred at around 4 kb and 850° C with melt water contents between 2.8 and 4 wt.%. This high-temperature, markedly water-undersaturated, restite-poor, granitic magma was generated by partial melting reactions involving biotite breakdown in a dominantly quartzofeldspathic source terrain, leaving a granulite facies residue.

The melting of phlogopite-quartz and sanidine-quartz under vapor-absent conditions and in the presence of H2O-CO2 vapor have been determined from 5–20 kbar. In the lower crust (P=6–10 kbar), phlogopite + quartz melts incongruently to enstatite + liquid at temperatures as low as 710° C in the presence of H2O. When the activity of water is sufficiently reduced by addition of CO2, phlogopite + quartz undergoes a dehydration reaction to enstatite + sanidine + vapor, for example at 790±10° C, 5 kbar, with \(X_{H_2 O}^V\)=0.35. In the absence of vapor, phlogopite + quartz is stable up to a maximum temperature of 900° C in the crust; at higher temperatures this assemblage melts incongruently to enstatite + sanidine + liquid. The melting of sanidine-quartz in the presence of H2O-CO2 vapor shows marked topological differences from melting in the system albite-H2O-CO2, and as a result, apparent activity coefficients for water calculated from sanidine-quartz H2O-CO2 are less than those calculated from albite-H2O-CO2 by up to a factor of five.

N6d61ec and Paquet (N. and P.) (1981) examined high-grade pelitic gneisses from the Precambrian and Hercynian HautAllier Massif in France. They noted the presence, in their samples, of an "amorphous" phase which they interpret as glass representing quenched melt formed by partial melting of biotite. N. and P. have made a creditable attempt to integrate TEM and Raman spectroscopic studies with classical petrological techniques. However, after examination of the mineralogical, textural, chemical and spectroscopic evidence presented in their paper, we disagree with the conclusions drawn by N. and P. regarding biotite "melting". Figure 5a of N. and P. shows an electron diffraction pattern of diffuse rings taken by them to indicate an amorphous phase in their original sample. Without further supporting evidence this is not necessarily correct. It is wellknown that samples in electron beam experiments may easily become amorphous due to beam damage. This is especially true of samples that are poorly-crystallized and hydrous and when high accelarating voltages are used. It is of interest that randomly-oriented crystallites of kaolinite were found in some regions of the "glass" (Fig. 5b; N. and P.). Those "crystallites" could correspond to bettercrystallized areas or areas with less beam damage. Here we discuss the textural, mineralogical and spectroscopic observations of N. and P. and show that their "amorphous" material is consistent with altered cordierite rather than glass derived from partial melting. Biotite in the rocks is commonly corroded and sur

202 THE CHANGING SPECTRUM OF PEDIATRIC INFECTIVE ENDOCARDITIS (IE): AN ANALYSIS OF 26 CASES AT YALE-NEW HAVEN HOSPITAL, 1970–1979