Inside the outbreak of the 2009 influenza A (H1N1)v virus in Mexico

Background

Influenza viruses pose a threat to human health because of their potential to cause global disease. Between mid March and mid April a pandemic influenza A virus emerged in Mexico. This report details 202 cases of infection of humans with the 2009 influenza A virus (H1N1)v which occurred in Mexico City as well as the spread of the virus throughout the entire country.

Methodology and Findings

From May 1st to May 5th nasopharyngeal swabs, derived from 751 patients, were collected at 220 outpatient clinics and 28 hospitals distributed throughout Mexico City. Analysis of samples using real time RT-PCR revealed that 202 patients out of the 751 subjects (26.9%) were confirmed to be infected with the new virus. All confirmed cases of human infection with the strain influenza (H1N1)v suffered respiratory symptoms. The greatest number of confirmed cases during the outbreak of the 2009 influenza A (H1N1)v were seen in neighbourhoods on the northeast side of Mexico City including Iztapalapa, Gustavo A. Madero, Iztacalco, and Tlahuac which are the most populated areas in Mexico City. Using these data, together with data reported by the Mexican Secretariat of Health (MSH) to date, we plot the course of influenza (H1N1)v activity throughout Mexico.

Conclusions

Our data, which is backed up by MSH data, show that the greatest numbers of the 2009 influenza A (H1N1) cases were seen in the most populated areas. We speculate on conditions in Mexico which may have sparked this flu pandemic, the first in 41 years. We accept the hypothesis that high population density and a mass gathering which took in Iztapalapa contributed to the rapid spread of the disease which developed in three peaks of activity throughout the Country.     

Geographic patterns of (genetic, morphologic, linguistic) variation: how barriers can be detected by using Monmonier's algorithm

When sampling locations are known, the association between genetic and geographic distances can be tested by spatial autocorrelation or regression methods. These tests give some clues to the possible shape of the genetic landscape. Nevertheless, correlation analyses fail when attempting to identify where genetic barriers exist, namely, the areas where a given variable shows an abrupt rate of change. To this end, a computational geometry approach is more suitable because it provides the locations and the directions of barriers and because it can show where geographic patterns of two or more variables are similar. In this frame we have implemented Monmonier's (1973) maximum difference algorithm in a new software package to identify genetic barriers. To provide a more realistic representation of the barriers in a genetic landscape, we implemented in the software a significance test by means of bootstrap matrices analysis. As a result, the noise associated with genetic markers can be visualized on a geographic map and the areas where genetic barriers are more robust can be identified. Moreover, this multiple matrices approach can visualize the patterns of variation associated with different markers in the same overall picture. This improved Monmonier's method is highly reliable and can be applied to nongenetic data whenever sampling locations and a distance matrix between corresponding data are available.     

Multiparasitism by the pupal parasitoids, Xanthopimpla stemmator (Hymenoptera: Ichneumonidae) and Pediobius furvus (Hymenoptera: Eulophidae) on two African cereal stemborers, Chilo partellus (Lepidoptera: Crambidae) and Busseola fusca (Lepidoptera: Noctuidae)

The outcome of multiparasitism by two pupal parasitoids, the exotic solitary ichneumonid Xanthopimpla stemmator and the indigenous gregarious eulophid Pediobius furvus, was studied using the invasive crambid stem borer Chilo partellus and the indigenous noctuid Busseola fusca as hosts. Two parasitism sequences were observed, where X. stemmator oviposited before P. furvus, and vice versa. In addition, the effect of time between first and second parasitism on parasitoid emergence, development, sex ratio, and number of offspring was assessed. For most treatments, time interval between parasitism had no significant effect on the percentage if pupae producing either P. furvus or X. stemmator. In general, X. stemmator outcompeted P. furvus irrespective of the order of oviposition, time interval between ovipositions and host species. Further studies, especially on host finding capacity of the two parasitoid species are required to determine the competitiveness of the two species under field conditions.     

Urogenital syndrome (us): a developmental mutation on Chromosome 2 of the mouse

Urogenital syndrome (us) is a recessive mutation in mice characterized primarily by abnormalities of the axial skeleton and urogenital organs. We established linkage of us with the centromeric end of Chromosome (Chr) 2, using the Robertsonian Chr Rb(2.8)2Lub. Analysis of progeny from crosses using the Chr 2 markers Danforth's short tail (Sd) and ulnaless (Ul) positioned us near two loci that have recently been mapped by RFLPs, nonerythroid -spectrin (Spna-2) and the paired-box-containing-gene-8 (Pax-8). The position of us relative to these loci was established by analysis of progeny from interspecific backcrosses between the us strains and Mus spretus. The estimated map distances and most likely gene order are centromere-Pax-8-2.1±1.2-us-0.7±0.7-Spna-2; however, the reverse order cannot be ruled out. Our data make it unlikely that us is a mutation in either Spna-2 or Pax-8. Spna-2 is close enough to us, however, to be a useful marker for positional cloning of the us gene. The human mutation Nail-patella-syndrome (NPS1) maps to the region of human Chr 9 (9q34) that is homologous to the us region of mouse Chr 2. Phenotypic similarities between the two syndromes suggest the possibility that they are caused by mutations at homologous loci.     

Prevalence of 2009 pandemic influenza A (H1N1) virus antibodies, Tampa Bay Florida--November-December, 2009

Background

In 2009, a novel influenza virus (2009 pandemic influenza A (H1N1) virus (pH1N1)) caused significant disease in the United States. Most states, including Florida, experienced a large fall wave of disease from September through November, after which disease activity decreased substantially. We determined the prevalence of antibodies due to the pH1N1 virus in Florida after influenza activity had peaked and estimated the proportion of the population infected with pH1N1 virus during the pandemic.

Methods

During November-December 2009, we collected leftover serum from a blood bank, a pediatric children''s hospital and a pediatric outpatient clinic in Tampa Bay Florida. Serum was tested for pH1N1 virus antibodies using the hemagglutination-inhibition (HI) assay. HI titers ≥40 were considered seropositive. We adjusted seroprevalence results to account for previously established HI assay specificity and sensitivity and employed a simple statistical model to estimate the proportion of seropositivity due to pH1N1 virus infection and vaccination.

Results

During the study time period, the overall seroprevalence in Tampa Bay, Florida was 25%, increasing to 30% after adjusting for HI assay sensitivity and specificity. We estimated that 5.9% of the population had vaccine-induced seropositivity while 25% had seropositivity secondary to pH1N1 virus infection. The highest cumulative incidence of pH1N1 virus infection was among children aged 5–17 years (53%) and young adults aged 18–24 years (47%), while adults aged ≥50 years had the lowest cumulative incidence (11–13%) of pH1N1 virus infection.

Conclusions

After the peak of the fall wave of the pandemic, an estimated one quarter of the Tampa Bay population had been infected with the pH1N1 virus. Consistent with epidemiologic trends observed during the pandemic, the highest burdens of disease were among school-aged children and young adults.     

Estimation of the incubation period of influenza A (H1N1-2009) among imported cases: addressing censoring using outbreak data at the origin of importation

Empirical estimates of the incubation period of influenza A (H1N1-2009) have been limited. We estimated the incubation period among confirmed imported cases who traveled to Japan from Hawaii during the early phase of the 2009 pandemic (n=72). We addressed censoring and employed an infection-age structured argument to explicitly model the daily frequency of illness onset after departure. We assumed uniform and exponential distributions for the frequency of exposure in Hawaii, and the hazard rate of infection for the latter assumption was retrieved, in Hawaii, from local outbreak data. The maximum likelihood estimates of the median incubation period range from 1.43 to 1.64 days according to different modeling assumptions, consistent with a published estimate based on a New York school outbreak. The likelihood values of the different modeling assumptions do not differ greatly from each other, although models with the exponential assumption yield slightly shorter incubation periods than those with the uniform exposure assumption. Differences between our proposed approach and a published method for doubly interval-censored analysis highlight the importance of accounting for the dependence of the frequency of exposure on the survival function of incubating individuals among imported cases. A truncation of the density function of the incubation period due to an absence of illness onset during the exposure period also needs to be considered. When the data generating process is similar to that among imported cases, and when the incubation period is close to or shorter than the length of exposure, accounting for these aspects is critical for long exposure times.     

Early outbreak of 2009 influenza A (H1N1) in Mexico prior to identification of pH1N1 virus

Background

In the aftermath of the global spread of 2009 influenza A (pH1N1) virus, still very little is known of the early stages of the outbreak in Mexico during the early months of the year, before the virus was identified.

Methodology/Main Findings

We fit a simple mathematical model, the Richards model, to the number of excess laboratory-confirmed influenza cases in Mexico and Mexico City during the first 15 weeks in 2009 over the average influenza case number of the previous five baseline years of 2004-2008 during the same period to ascertain the turning point (or the peak incidence) of a wave of early influenza infections, and to estimate the transmissibility of the virus during these early months in terms of its basic reproduction number. The results indicate that there may have been an early epidemic in Mexico City as well as in all of Mexico during February/March. Based on excess influenza cases, the estimated basic reproduction number R₀ for the early outbreak was 1.59 (0.55 to 2.62) for Mexico City during weeks 5–9, and 1.25 (0.76, 1.74) for all of Mexico during weeks 5–14.

Conclusions

We established the existence of an early epidemic in Mexico City and in all of Mexico during February/March utilizing the routine influenza surveillance data, although the location of seeding is unknown. Moreover, estimates of R₀ as well as the time of peak incidence (the turning point) for Mexico City and all of Mexico indicate that the early epidemic in Mexico City in February/March had been more transmissible (larger R₀) and peaked earlier than the rest of the country. Our conclusion lends support to the possibility that the virus could have already spread to other continents prior to the identification of the virus and the reporting of lab-confirmed pH1N1 cases in North America in April.     

A report on the artificial fertilization of the smallmouth yellowfish, Barbus holubi (Steindachner, 1894)

Artificial fertilization was successfully applied in the culture of Barbus holubi . By this method the fertilization potential was raised considerably and the mortality rate under normal conditions during the incubation period was less than 5 %. The handling and transferring of larvae to fertilized rearing ponds was simplified and an estimation of the seasonal production could be made without waiting for the fish to attain the fingerling stage. Normal breeding activities were not disturbed by frequent handling and natural breeding took place in ponds where the fish were kept.     

Biochemical switching device: how to turn on (off) the switch

We previously showed with computer simulations that cyclic enzyme systems have the reliability of ON-OFF types of operation (McCulloch-Pitts' neuronic equation) and the applicability for a switching circuit in a biocomputer. The switching time was inevitably determined in accordance with the difference in amount between two inputs of the system. This characteristic is, however, a disadvantage for practical use of a switching device; we need to improve the system in order for the switching time to optionally be changed. We shall present here how to turn on (off) the switch independently of the modes of two inputs. By introducing pulse perturbation, we could optionally set up the switching time of a cyclic enzyme system (biochemical switching device).     

多腺巨伪蝎(伪蝎目:苦伪蝎科)的雌性新发现（英文）

首次报道了采自中国贵州宽阔水国家级自然保护区一洞穴的多腺巨伪蝎Megachernes glandulosus Mahnert,2009雌性,并对其形态特征进行了详细描述。标本保存于河北大学博物馆(MHBU)。多腺巨伪蝎Megachernes glandulosus Mahnert,2009(图1~3)鉴别特征:该种触肢非常粗短,触肢膝节中央明显具1突起,腿节和膝节着生大量浓密的长羽状刚毛;背甲刚毛正常;基节、第Ⅳ~Ⅸ每半个腹板和触肢螯固定指基部内侧面具大量腺体刚毛,第三步足和第四步足腿节和膝节腹面着生有大量腺体微刚毛。     

Smart phone, smart science: how the use of smartphones can revolutionize research in cognitive science

Investigating human cognitive faculties such as language, attention, and memory most often relies on testing small and homogeneous groups of volunteers coming to research facilities where they are asked to participate in behavioral experiments. We show that this limitation and sampling bias can be overcome by using smartphone technology to collect data in cognitive science experiments from thousands of subjects from all over the world. This mass coordinated use of smartphones creates a novel and powerful scientific "instrument" that yields the data necessary to test universal theories of cognition. This increase in power represents a potential revolution in cognitive science.     

第二届国际牙形刺会议(ICOS,2009)简介

第二届国际牙形刺会议(ICOS,2009)于2009年7月12-17日在加拿大Alberta省Calgary大学举行.参加会议的有来 自17个国家的82名代表,向会议提交了75篇论文提要.4天的学术会议,共安排了56个学术报告和18个墙展(poster).     

A spontaneous outbreak of polycholorinated biphenyl (PCB) toxicity in rhesus monkeys (Macaca mulatta): toxicopathology.

Polychlorinated biphenyls (PCBs) were shown to be the cause of a wasting syndrome and reproductive dysfunction in a group of rhesus monkeys (Macaca mulatta). The polychlorinated biphenyls were found by gas chromatographic analysis in high amounts in the superficial layers of concrete slab floors in the housing facility. The concrete sealant was suspected as the original source although it is not known whether it contained polychlorinated biphenyls before it was applied or if it was contaminated later. Histopathologic findings for the most part were confined to epithelial tissues where squamous metaplasia of several glandular tissues was observed. A striking finding was severe hypertrophy of the glandular stomach and a similar but less severe lesion in the colon. The lesions may be related in part to impaired vitamin A metabolism, but not to a dietary deficiency.