Dynamics of an Infectious Keratoconjunctivitis Outbreak by Mycoplasma conjunctivae on Pyrenean Chamois Rupicapra p. pyrenaica

Between 2006 and 2008, an outbreak of Infectious Keratoconjunctivitis (IKC) affected Pyrenean chamois Rupicapra p. pyrenaica, an endemic subspecies of mountain ungulate that lives in the Pyrenees. The study focused on 14 mountain massifs (180,000 ha) where the species’ population is stable. Cases of IKC were detected in ten of the massifs and, in five of them, mortality was substantial. The outbreak spread quickly from the first location detected, with two peaks in mortality that affected one (2007) and three (2008) massifs. In the latter, the peak was seasonal (spring to autumn) and, in the former, the outbreak persisted through winter. To identify the outbreak’s aetiology, we examined 105 Pyrenean chamois clinically affected with IKC. TaqMan rt-PCR identified Mycoplasma conjunctivae in 93 (88.5%) of the chamois. Another rt-PCR detected Chlamydophila spp. in 14 of chamois, and 12 of those had mixed infections with mycoplasmas. In the period 2000–2007, the chamois population increased slightly (λ 1.026) but decreased significantly during the IKC outbreak (λ 0.8, 2007–2008; λ 0.85, 2008–2009) before increasing significantly after the outbreak (λ 1.1, 2009–2010). Sex-biased mortality shifted the adult sex ratio toward males (from 0.6 to 0.7 males per female) and reduced productivity slightly. Hunting was practically banned in the massifs where chamois experienced significant mortality and allowed again after the outbreak ended. Long-term monitoring of wild populations provides a basis for understanding the impacts of disease outbreaks and improves management decisions, particularly when species are subject to extractive exploitation.     

Age,growth and hatch dates of ingressing larvae and surviving juveniles of Atlantic menhaden Brevoortia tyrannus

Ages, growth and hatch dates of ingressing Brevoortia tyrannus larvae were determined in a 3 year sampling survey at the mouth of the Chesapeake Bay, U.S.A. To determine if otolith‐aged cohorts had variable relative survival, hatch dates of summer‐caught young‐of‐the‐year (YOY) juveniles collected throughout the Chesapeake Bay were compared with hatch dates of ingressing larvae. Modal total length of ingressing larvae was similar among years: 28 mm in 2005–2006 and 2007–2008, and 30 mm in 2006–2007. Ages of ingressing larvae ranged from 9 to 96 days post hatch (dph); mean ages were similar among years, but significantly older in 2006–2007 (50 dph) than in 2005–2006 (44 dph) and 2007–2008 (46 dph). Larval growth rates differed among years. Earliest growth, when larvae were offshore (0–20 dph), was faster in 2006–2007 (0·62 mm day^?1), than in 2005–2006 and 2007–2008 (0·55 mm day^?1 in these years). Subsequently, from 30 to 80 dph, growth was slowest in 2006–2007. Hatch dates of ingressing larvae occurred from September to March and 90% (2007–2008) to 98% (2006–2007) had hatched prior to 31 December. In contrast, most surviving YOY juvenile B. tyrannus had hatched in January to February, suggesting selective mortality of early‐hatched individuals, apparently during the overwinter, larval to juvenile transition period.     

南京市高温热浪特征及其对人体健康的影响

利用1951 -2009年(6—9月)气象资料、2005-2008年(6-9月)南京市逐日死亡人数、2005 -2007年(6-9月)中暑相关的逐时急诊人数,采用描述性研究、回归分析等流行病学统计方法,研究南京市高温热浪特征及其对人体健康的影响.结果表明:南京是各种级别高温和热浪频发的城市,近60年来,南京市每年平均高温日数14.5 d,危害高温日数1.1d,高温热浪1.9次,强高温热浪0.8次;高温热浪过程造成的人群超额死亡率在20％以上,其中女性超额死亡率稍大于男性,对冠心病和脑血管病患者的伤害较大,而且不存在滞后性;由于人体的适应性,发生在夏季早期的高温热浪比发生在季节中、末阶段的高温热浪危害大,但热浪持续的时间对超额死亡率的影响较小;另外,由于城市居民工作需要和出行时间的选择,导致夏季逐时高温对人体危害呈双峰型分布,2个峰值分别出现在9:00-11:00和19:00-21:00;高温热浪对人体的危害与年龄约呈三次函数关系,对0～5岁的婴幼儿和60～80岁的高龄人群危害较大.这些结果可为人体健康风险管理提供参考.     

Evidence that Life History Characteristics of Wild Birds Influence Infection and Exposure to Influenza A Viruses

We report on life history characteristics, temporal, and age-related effects influencing the frequency of occurrence of avian influenza (AI) viruses in four species of migratory geese breeding on the Yukon-Kuskokwim Delta, Alaska. Emperor geese (Chen canagica), cackling geese (Branta hutchinsii), greater white-fronted geese (Anser albifrons), and black brant (Branta bernicla), were all tested for active infection of AI viruses upon arrival in early May, during nesting in June, and while molting in July and August, 2006–2010 (n = 14,323). Additionally, prior exposure to AI viruses was assessed via prevalence of antibodies from sera samples collected during late summer in 2009 and 2010. Results suggest that geese are uncommonly infected by low pathogenic AI viruses while in Alaska. The percent of birds actively shedding AI viruses varied annually, and was highest in 2006 and 2010 (1–3%) and lowest in 2007, 2008, and 2009 (<0.70%). Contrary to findings in ducks, the highest incidence of infected birds was in late spring when birds first arrived from staging and wintering areas. Despite low prevalence, most geese were previously exposed to AI viruses, as indicated by high levels of seroprevalence during late summer (47%–96% across species; n = 541). Seroprevalence was >95% for emperor geese, a species that spends part of its life cycle in Asia and is endemic to Alaska and the Bering Sea region, compared to 40–60% for the other three species, whose entire life cycles are within the western hemisphere. Birds <45 days of age showed little past exposure to AI viruses, although antibodies were detected in samples from 5-week old birds in 2009. Seroprevalence of known age black brant revealed that no birds <4 years old had seroconverted, compared to 49% of birds ≥4 years of age.     

The influence of planting date,transgenic Bt maize and hybrid relative maturity on European corn borer Ostrinia nubilalis (Lepidoptera: Crambidae) ovipositional patterns

A three year study was carried out at Hoytville and at Wooster, Ohio, USA from 2006 to 2008 to investigate the influence of planting date, transgenic maize and hybrid maturity on Ostrinia nubilalis (Hubner) population dynamics and oviposition patterns. Maize plants were planted in late April or early May, mid‐May and early June during each year. The moth flight pattern showed bivoltine generations during the three years. The first moth flight peaked in June, with the populations declining during July. The second moth flight peaked in August and declined towards the end of September or early October. Egg mass density did not differ significantly between transgenic and non‐transgenic maize of different maturities. Significant differences were observed, however, among planting dates, sampling dates, and sampling date × planting date interactions. Generally higher numbers of egg masses from second generation moths were deposited on late planted maize than middle and early plantings.     

Interruption of Infection Transmission in the Onchocerciasis Focus of Ecuador Leading to the Cessation of Ivermectin Distribution

Introduction: A clinically significant endemic focus of onchocerciasis existing in Esmeraldas Province, coastal Ecuador has been under an ivermectin mass drug administration program since 1991. The main transmitting vector in this area is the voracious blackfly, Simulium exiguum. This paper describes the assessments made that support the decision to cease mass treatment. Methodology and Principle Findings: Thirty-five rounds of ivermectin treatment occurred between 1991–2009 with 29 of these carrying >85% coverage. Following the guidelines set by WHO for ceasing ivermectin distribution the impact on parasite transmission was measured in the two vector species by an O-150 PCR technique standard for assessing for the presence of Onchocerca volvulus. Up to seven collection sites in three major river systems were tested on four occasions between 1995 and 2008. The infectivity rates of 65.0 (CI 39–101) and 72.7 (CI 42–116) in 1995 dropped to zero at all seven collection sites by 2008. Assessment for the presence of antibodies against O. volvulus was made in 2001, 2006, 2007 and 2008 using standard ELISA assays for detecting anti-Ov16 antibodies. None of total of 1810 children aged 1–15 years (between 82 and 98% of children present in the surveyed villages) tested in the above years were found to be carrying antibodies to this antigen. These findings were the basis for the cessation of mass drug treatment with ivermectin in 2009. Significance: This fulfillment of the criteria for cessation of mass distribution of ivermectin in the only known endemic zone of onchocerciasis in Ecuador moves the country into the surveillance phase of official verification for national elimination of transmission of infection. These findings indicate that ivermectin given twice a year with greater than 85% of the community can move a program to the final stages of verification of transmission interruption.     

Genetic structure of human A/H1N1 and A/H3N2 influenza virus on Corsica Island: phylogenetic analysis and vaccine strain match, 2006-2010

Background

The aim of this study was to analyse the genetic patterns of Hemagglutinin (HA) genes of influenza A strains circulating on Corsica Island during the 2006–2009 epidemic seasons and the 2009–2010 pandemic season.

Methods

Nasopharyngeal samples from 371 patients with influenza-like illness (ILI) were collected by General Practitioners (GPs) of the Sentinelles Network through a randomised selection routine.

Results

Phylogenetic analysis of HA revealed that A/H3N2 strains circulating on Corsica were closely related to the WHO recommended vaccine strains in each analyzed season (2006–2007 to 2008–2009). Seasonal Corsican influenza A/H1N1 isolated during the 2007–2008 season had drifted towards the A/Brisbane/59/2007 lineage, the A/H1N1 vaccine strain for the 2008–2009 season. The A/H1N1 2009 (A/H1N1pdm) strains isolated on Corsica Island were characterized by the S220T mutation specific to clade 7 isolates. It should be noted that Corsican isolates formed a separate sub-clade of clade 7 as a consequence of the presence of the fixed substitution D222E.The percentages of the perfect match vaccine efficacy, estimated by using the p _epitope model, against influenza viruses circulating on Corsica Island varied substantially across the four seasons analyzed, and tend to be highest for A/H1N1 compared with A/H3N2 vaccines, suggesting that cross-immunity seems to be stronger for the H1 HA gene.

Conclusion

The molecular analysis of the HA gene of influenza viruses that circulated on Corsica Island between 2006–2010 showed for each season the presence of a dominant lineage characterized by at least one fixed mutation. The A/H3N2 and A/H1N1pdm isolates were characterized by multiples fixation at antigenic sites. The fixation of specific mutations at each outbreak could be explained by the combination of a neutral phenomenon and a founder effect, favoring the presence of a dominant lineage in a closed environment such as Corsica Island.     

中国叶蜂属两新种(膜翅目,叶蜂科)

记述中国叶蜂科Tenthredinidae叶蜂属Tenthredo2新种,三斑槌腹叶蜂Tenthredo trixanthomacula Wei et Yan,sp.nov.和褐跗短角叶蜂Tenthredo rubitarsalitia W ei et Xu,sp.nov.。前者隶属于槌腹种团T.formosana group,后者隶属于短角种团T.potanini group。新种模式标本保存于中南林业科技大学昆虫系统与进化生物学实验室昆虫模式标本室(CSCS)。     

Grazing and Metabolism of Euphausia pacifica in the Yellow Sea

Grazing and metabolism of Euphausia pacifica in the Yellow Sea were studied from September 2006 to August 2007. Euphausia pacifica is a selective-feeding omnivore and grazing rates among different months were monitored using a Coulter Counter and batch culture feeding experiments. Euphausia pacifica mainly grazed microzooplankton in August and September, which resulted in an increase in chlorophyll a concentration. Oxygen consumption rate of E. pacifica was 38.7–42.5 μmol O₂ g^-1 DW h^-1 in March, which was four times higher than the oxygen consumption rates in September and December. The vigorous metabolism of E. pacifica in March consumed 3.1% of body carbon daily, which is likely related to its high reproduction and grazing rate. Respiration and metabolism of E. pacifica in September and December were similar and were lower. O:N ratio of E. pacifica was the highest (17.3–23.8) in March when spawning activity occurred and when food was abundant. The energetic source of E. pacifica during September and December was mostly protein from eating a carnivorous diet, including such items as microzooplankton. Euphausia pacifica was found in cold water at the bottom of the Yellow Sea in summer and autumn and maintained a low consumption status. O:N ratios of E. pacifica in March, September, and December were negatively correlated with SSTs and no significant correlation was found between O:N ratios and chlorophyll a concentration. Seawater temperature is clearly the most important parameter influencing the metabolism of E. pacifica.     

Household rat infestation in urban slum populations: Development and validation of a predictive score for leptospirosis

Domestic rats are the principal reservoir for urban leptospirosis. However, few studies have identified infestation markers in slums and evaluated their predictivity for leptospirosis risk. We compared households with leptospirosis cases in Salvador, Brazil between 2007 and 2009 and their neighbors using a case control design, surveying for rodent infestation signs and environmental characteristics. With the 2007–2008 data, a conditional logistic regression modeling identified the peridomiciliar presence of rodent burrows (OR, 3.30; 95% CI, 1.50–7.26), rat feces (2.86; 1.24–6.59), runs (2.57; 1.06–6.22), households bordering abandoned houses (2.48; 1.04–6.02), and unplastered walls (2.22; 1.02–6.02) as risk factors and developed a predictive score for leptospirosis. With an independent data set from 2009, a receiver operating characteristic (ROC) curve analysis evaluated the prediction score performance, with the area under the curve being 0.70 (95% CI, 0.64–0.76) for score development and 0.71 (0.65–0.79) for validation. Results indicate that high proportions of urban slum households are infested with R. norvegicus. The score performed well when identifying high-risk households within slums. These findings need confirmation in other urban centers, but suggest that community-based screening for rodent infestation can allow to target rodent and environmental control measures in populations at highest risk for leptospirosis.     

Movement Patterns and Residency of the Critically Endangered Horseshoe Crab Tachypleus tridentatus in a Semi-Enclosed Bay Determined Using Acoustic Telemetry

The horseshoe crab Tachypleus tridentatus is critically endangered in Japan due to rapidly decreasing numbers resulting from the loss of tidal flats and sandy beaches, and the deterioration of coastal environments. We monitored the year-round migratory patterns and residency of this species in a coastal embayment at Tsuyazaki, Japan, using acoustic telemetry. Total 20 adult crabs (15 males and 5 females) were tagged with ultrasonic transmitters and tracked during two periods (2006–2008; n = 10 and 2007–2009; n = 10). Adult crabs were more active during periods of higher water temperatures and their activity peaked in July, during the spawning period. Water temperature appeared to be one of the key factors influencing the movement patterns for the species. Moreover, the crabs tended to be more active at night than in the day. The nocturnal activity pattern was clearly evident before and during the reproductive period (May–August). Tracking data also showed that one pair-bond was maintained for a maximum of 17 days after the pair-bonded female had spawned. Overall, 11 males (73% of 15 individuals) remained in the bay area over winter, whereas three females (60% of 5 individuals) overwintered outside of the bay. Telemetry data showed that over 60% (13 of 20) of tagged crabs overwintered within the bay where there are sandy beaches, mudflats, and scattered seagrass beds. This year-round residence by adult T. tridentatus in the bay area identifies it as a critical habitat for the management of this species, regardless of life-stage. Not only is it a comprehensive management strategy that effectively reflects this species’ habitat use patterns but also its implementation, such as the establishment of a protected area, would contribute to its conservation.     

Population-level reduction in adult mortality after extension of free anti-retroviral therapy provision into rural areas in northern Malawi

Background

Four studies from sub-Saharan Africa have found a substantial population-level effect of ART provision on adult mortality. It is important to see if the impact changes with time since the start of treatment scale-up, and as treatment moves to smaller clinics.

Methods and Findings

During 2002-4 a demographic surveillance site (DSS) was established in Karonga district, northern Malawi. Information on births and deaths is collected monthly, with verbal autopsies conducted for all deaths; migrations are updated annually. We analysed mortality trends by comparing three time periods: pre-ART roll-out in the district (August 2002–June 2005), ART period 1 (July 2005–September 2006) when ART was available only in a town 70 km away, and ART period 2 (October 2006–September 2008), when ART was available at a clinic within the DSS area. HIV prevalence and ART uptake were estimated from a sero-survey conducted in 2007/2008. The all-cause mortality rate among 15–59 year olds was 10.2 per 1000 person-years in the pre-ART period (288 deaths/28285 person-years). It fell by 16% in ART period 1 and by 32% in ART period 2 (95% CI 18%–43%), compared with the pre-ART period. The AIDS mortality rate fell from 6.4 to 4.6 to 2.7 per 1000 person-years in the pre-ART period, period 1 and period 2 respectively (rate ratio for period 2 = 0.43, 95% CI 0.33–0.56). There was little change in non-AIDS mortality. Treatment coverage among individuals eligible to start ART was around 70% in 2008.

Conclusions

ART can have a dramatic effect on mortality in a resource-constrained setting in Africa, at least in the early years of treatment provision. Our findings support the decentralised delivery of ART from peripheral health centres with unsophisticated facilities. Continued funding to maintain and further scale-up treatment provision will bring large benefits in terms of saving lives.     

Effectiveness of SIMBLIGHT1 and SIMPHYT1 models for predicting Phytophthora infestans in north-eastern United States

Accurate prediction of Phytophthora infestans outbreak in a cropping season is crucial for the effective management of late blight on potato. The SIMBLIGHT1, SIMPHYT1 and modified SIMPHYT1 models were assessed for predicting late blight outbreaks relative to NOBLIGHT model by using climatic and crop data from field experiments at Presque Isle, ME, from 2004 to 2009. The dynamics of late blight infection pressures were computed by SIMPHYT3 model to assess the conduciveness of environmental conditions for late blight infection and potential for disease development. Infection pressure indicated conditions were moderately conducive for late blight development but varied across years. The SIMPHYT1 model recommended fungicide applications to commence on 11 July, 21 July, 8 July, 10 July, 7 July and 7 July for 2004, 2005, 2006, 2007, 2008 and 2009, respectively. The modified SIMPHYT1 model (US-version) recommended similar fungicide application dates for the same years with the exception of 2007. Model simulations of disease outbreak differed from actual recorded observations in untreated plots by 24–65 days. Simulation of SIMBLIGHT1 based on high and low soil moisture conditions in the field resulted in vast differences in dates of first fungicide application. Validation of the models (differences in the number of days between recommendation of fungicide treatment and late blight outbreak) indicated a better goodness of fit for the models (intervals of 6–20 days from the start of fungicide application to first disease outbreak). The NOBLIGHT model was accurate in forecasting the timing of first fungicide applications for late blight control. Significant improvements in late blight predictions could result if these models were modified to account for external sources of inoculum, by combining weather-based forecasts with spore traps, disease detection methods or complimentary systems.     

Seasonal Variation in Biting Rates of Simulium damnosum sensu lato,Vector of Onchocerca volvulus,in Two Sudanese Foci

Background

The abundance of onchocerciasis vectors affects the epidemiology of disease in Sudan, therefore, studies of vector dynamics are crucial for onchocerciasis control/elimination programs. This study aims to compare the relative abundance, monthly biting-rates (MBR) and hourly-based distribution of onchocerciasis vectors in Abu-Hamed and Galabat foci. These seasonally-based factors can be used to structure vector control efforts to reduce fly-biting rates as a component of onchocerciasis elimination programs.

Methods

A cross-sectional study was conducted in four endemic villages in Abu-Hamed and Galabat foci during two non-consecutive years (2007–2008 and 2009–2010). Both adults and aquatic stages of the potential onchocerciasis vector Simulium damnosum sensu lato were collected following standard procedures during wet and dry seasons. Adult flies were collected using human landing capture for 5 days/month. The data was recorded on handheld data collection sheets to calculate the relative abundance, MBR, and hourly-based distribution associated with climatic factors. The data analysis was carried out using ANOVA and Spearman rank correlation tests.

Results

Data on vector surveillance revealed higher relative abundance of S. damnosum s.l. in Abu- Hamed (39,934 flies) than Galabat (8,202 flies). In Abu-Hamed, vector populations increased in January-April then declined in June-July until they disappeared in August-October. Highest black fly density and MBR were found in March 2007 (N = 9,444, MBR = 58,552.8 bites/person/month), and March 2010 (N = 2,603, MBR = 16,138.6 bites/person/month) while none of flies were collected in August-October (MBR = 0 bites/person/month). In Galabat, vectors increased in September-December, then decreased in February-June. The highest vector density and MBR were recorded in September 2007 (N = 1,138, MBR = 6,828 bites/person/month) and September 2010 (N = 1,163, MBR = 6,978 bites/person/month), whereas, none appeared in collection from April to June. There was a significant difference in mean monthly density of S. damnosum s.l. across the two foci in 2007–2008 (df = 3, F = 3.91, P = 0.011). Minimum temperature showed significant correlation with adult flies counts in four areas sampled; the adult counts were increased in Nady village (r_s = 0.799) and were decreased in Kalasecal (r_s = - 0.676), Gumaiza (r_s = - 0.585), and Hilat Khateir (r_s = - 0.496). Maximum temperature showed positive correlation with black fly counts only in Galabat focus. Precipitation was significantly correlated with adult flies counts in Nady village, Abu-Hamed, but no significance was found in the rest of the sampled villages in both foci. Hourly-based distribution of black flies showed a unimodal pattern in Abu-Hamed with one peak (10:00–18:00), while a bimodal pattern with two peaks (07:00–10:00) and (14:00–18:00) was exhibited in Galabat.

Conclusion

Transmission of onchocerciasis in both foci showed marked differences in seasonality, which may be attributed to ecology, microclimate and proximity of breeding sites to collection sites. The seasonal shifts between the two foci might be related to variations in climate zones. This information on black fly vector seasonality, ecology, distribution and biting activity has obvious implications in monitoring transmission levels to guide the national and regional onchocerciasis elimination programs in Sudan.     

Rift Valley Fever Risk Map Model and Seroprevalence in Selected Wild Ungulates and Camels from Kenya

Since the first isolation of Rift Valley fever virus (RVFV) in the 1930s, there have been multiple epizootics and epidemics in animals and humans in sub-Saharan Africa. Prospective climate-based models have recently been developed that flag areas at risk of RVFV transmission in endemic regions based on key environmental indicators that precede Rift Valley fever (RVF) epizootics and epidemics. Although the timing and locations of human case data from the 2006–2007 RVF outbreak in Kenya have been compared to risk zones flagged by the model, seroprevalence of RVF antibodies in wildlife has not yet been analyzed in light of temporal and spatial predictions of RVF activity. Primarily wild ungulate serum samples from periods before, during, and after the 2006–2007 RVF epizootic were analyzed for the presence of RVFV IgM and/or IgG antibody. Results show an increase in RVF seropositivity from samples collected in 2007 (31.8%), compared to antibody prevalence observed from 2000–2006 (3.3%). After the epizootic, average RVF seropositivity diminished to 5% in samples collected from 2008–2009. Overlaying maps of modeled RVF risk assessments with sampling locations indicated positive RVF serology in several species of wild ungulate in or near areas flagged as being at risk for RVF. Our results establish the need to continue and expand sero-surveillance of wildlife species Kenya and elsewhere in the Horn of Africa to further calibrate and improve the RVF risk model, and better understand the dynamics of RVFV transmission.     

Spatial and temporal patterns of intraspecific morphological variation in Dactylogyrus simplexus from fathead minnows in Nebraska

Dactylogyrus simplexus Monaco and Mizelle, 1955, occurs on the gills of fathead minnows (Pimephales promelas). Previous research on parasites of fathead minnows from 3 converging Nebraska streams, Elk Creek, Oak Creek, and West Oak Creek, shows that fish in each stream constitute distinct populations. To determine whether their parasites had diverged structurally in response to such isolation, or in response to seasonal change, we searched for patterns of intraspecific morphometric variation among D. simplexus. Over 3 collection dates in fall 2007, spring 2008, and fall 2009, 203 D. simplexus were collected from Elk and West Oak Creeks. We ran 1-way ANOVA to compare differences in 15 distinct point-to-point measurements of sclerotized parts across sites and collection dates. Significant differences were found in some D. simplexus measurements between Elk and West Oak Creeks for all 3 collection dates, but the characteristics that differed and the trend of variation between the creeks were not consistent over time. Dactylogyrus simplexus from both Elk and West Oak Creeks showed consistent patterns of variation over time for 5 measurements, including hamulus gap width, bar length, marginal hook length, sickle length, and sickle width. In conclusion, D. simplexus demonstrate consistent patterns of seasonal variation, but not spatial.     

Carbon Cycling of Lake Kivu (East Africa): Net Autotrophy in the Epilimnion and Emission of CO2 to the Atmosphere Sustained by Geogenic Inputs

We report organic and inorganic carbon distributions and fluxes in a large (>2000 km²) oligotrophic, tropical lake (Lake Kivu, East Africa), acquired during four field surveys, that captured the seasonal variations (March 2007–mid rainy season, September 2007–late dry season, June 2008–early dry season, and April 2009–late rainy season). The partial pressure of CO₂ (pCO₂) in surface waters of the main basin of Lake Kivu showed modest spatial (coefficient of variation between 3% and 6%), and seasonal variations with an amplitude of 163 ppm (between 579±23 ppm on average in March 2007 and 742±28 ppm on average in September 2007). The most prominent spatial feature of the pCO₂ distribution was the very high pCO₂ values in Kabuno Bay (a small sub-basin with little connection to the main lake) ranging between 11213 ppm and 14213 ppm (between 18 and 26 times higher than in the main basin). Surface waters of the main basin of Lake Kivu were a net source of CO₂ to the atmosphere at an average rate of 10.8 mmol m⁻² d⁻¹, which is lower than the global average reported for freshwater, saline, and volcanic lakes. In Kabuno Bay, the CO₂ emission to the atmosphere was on average 500.7 mmol m⁻² d⁻¹ (∼46 times higher than in the main basin). Based on whole-lake mass balance of dissolved inorganic carbon (DIC) bulk concentrations and of its stable carbon isotope composition, we show that the epilimnion of Lake Kivu was net autotrophic. This is due to the modest river inputs of organic carbon owing to the small ratio of catchment area to lake surface area (2.15). The carbon budget implies that the CO₂ emission to the atmosphere must be sustained by DIC inputs of geogenic origin from deep geothermal springs.     

Prevalence of Anti-Tuberculosis Drug Resistance in Foreign-Born Tuberculosis Cases in the U.S. and in Their Countries of Origin

Background

Foreign-born individuals comprise >50% of tuberculosis (TB) cases in the U.S. Since anti-TB drug resistance is more common in most other countries, when evaluating a foreign-born individual for TB, one must consider the risk of drug resistance. Naturally, clinicians query The Global Project on Anti-tuberculosis Drug Resistance Surveillance (Global DRS) which provides population-based data on the prevalence of anti-TB drug resistance in 127 countries starting in 1994. However, foreign-born persons in the U.S. are a biased sample of the population of their countries of origin, and Global DRS data may not accurately predict their risk of drug resistance. Since implementing drug resistance surveillance in 1993, the U.S. National TB Surveillance System (NTSS) has accumulated systematic data on over 130,000 foreign-born TB cases from more than 200 countries and territories. Our objective was to determine whether the prevalence of drug resistance among foreign-born TB cases correlates better with data from the Global DRS or with data on foreign-born TB cases in the NTSS.

Methods and Findings

We compared the prevalence of resistance to isoniazid and rifampin among foreign-born TB cases in the U.S., 2007–2009, with US NTSS data from 1993 to 2006 and with Global DRS data from 1994–2007 visually with scatterplots and statistically with correlation and linear regression analyses. Among foreign-born TB cases in the U.S., 2007–2009, the prevalence of isoniazid resistance and multidrug resistance (MDR, i.e. resistance to isoniazid and rifampin), correlated much better with 1993–2006 US surveillance data (isoniazid: r = 0.95, P<.001, MDR: r = 0.75, P<.001) than with Global DRS data, 1994–2007 (isoniazid: r = 0.55, P = .001; MDR: r = 0.50, P<.001).

Conclusion

Since 1993, the US NTSS has accumulated sufficient data on foreign-born TB cases to estimate the risk of drug resistance among such individuals better than data from the Global DRS.