Amendment to the infectious disease control law

The Law Concerning the Prevention of Infectious Diseases and Medical Care for Patients of Infections (the Infectious Diseases Control Law) enacted on April 1, 1999, accompanies an additional rule for reconsideration in five years after putting the law in operation and for taking necessary steps when needed. The responses against bioterrorism involving anthrax and smallpox after the terrorist attacks on September 11, 2001, in the United States of America (a notice on October 11, 2001 by the Tuberculosis and Infectious Diseases Control Division, MHLW) and the response to severe acute respiratory syndrome (SARS), an emerging infectious disease upon which a Global Alert was issued on March 12, 2003, by WHO, were discussed. On November 5, 2003, partial amendment of the Infectious Diseases Control Law and the Quarantine Law was approved and put into operation on. In the present amendment, the following three points were principally reconsidered: 1. strengthening infectious disease control in an emergency, particularly the role of national government, 2. reviewing control strategy of infectious diseases of animal origin, and 3. reviewing target diseases of the Infectious Diseases Control Law and categories of infectious diseases.     

How to estimate the efficacy of periodic control of an infectious plant disease

Certain infectious plant diseases are controlled by inspection and subsequent hand removal of diseased parts. In this paper we give two sets of criteria from which one can conclude whether this control effort is adequate or not. These criteria do not require knowledge of the infection- or detection rate of the disease but only use the structure of the contact matrix. Computer experiments give a feeling of how many inspections are needed in order to draw a conclusion.     

A new method for estimating nonsynonymous substitutions and its applications to detecting positive selection

The standard methods for computing the number of nonsynonymous substitutions (Ka) lump all amino acid changes into one single class, even though their rates of substitution vary by at least 10-fold (Tang et al., 2004). Classifying these changes by their physicochemical properties has not been suitably effective in isolating the fastest evolving classes of changes. We now propose to use the Universal index U of Tang et al. (2004) to classify the 75 elementary amino acid changes (codons differing by 1 bp) by their evolutionary exchangeability. Let Ki denote the Ka value of each class (i = 1, ..., 75 from the most to the least exchangeable). The cumulative Ki for the top 10 classes, denoted Kh (for high-exchangeability types), has two important properties: (1) Kh usually accounts for 25%-30% of total amino acid changes and (2) when the observed number of amino acid substitutions is large, Kh is predictably twice the value of Ka. This shall be referred to as the twofold approximation. The new method for estimating Kh is applied to the comparisons between human and macaque and between mouse and rat. The twofold approximation holds well in these data sets, and the signature of positive selection can be more easily discerned using the Kh statistic than using Ka. Many genes with Ka/Ks > 0.5 can now be shown to have Kh/Ks > 1 and to have evolved adaptively, at least for the high-exchangeability group of amino acid changes.     

A new method for estimating voice sounds transmitted to the chest wall in children and adolescents

A new method for estimating voice sound transmission to the chest wall is proposed. The spectral characteristics of voice-transmitted sounds have been estimated in children and adolescents. A total of 37 subjects aged 7–17 yers were examined. The frequency of the first spectral peak of the voice-transmitted sounds “tree, tree” (M ± SD) is 263.7 ± 7.82 and 253 ± 4.29 Hz at ages of 7–11 and 12–14 years, respectively. In male adolescents aged 15–17 years, this frequency is decreased to 100–150 Hz. The slope of the descending segment of the spectrum on the high-frequency side of the peak steadily increases on moving from the upper to the lower zones of the lungs, which may be related to the increase in the air content of the lung tissue. The difference between the amplitudes of the first and second spectral peaks of voice-transmitted sounds over symmetric regions of the chest on the right and left sides (Me(Q75-Q25)) is ?0.1(11.0) dB and does not depend on age or sex, which can be interpreted as an average statistical symmetry of sound transmission.     

A new method for estimating the effective population size from allele frequency changes

A new procedure is proposed for estimating the effective population size, given that information is available on changes in frequencies of the alleles at one or more independently segregating loci and the population is observed at two or more separate times. Approximate expressions are obtained for the variances of the new statistic, as well as others, also based on allele frequency changes, that have been discussed in the literature. This analysis indicates that the new statistic will generally have a smaller variance than the others. Estimates of effective population sizes and of the standard errors of the estimates are computed for data on two fly populations that have been discussed in earlier papers. In both cases, there is evidence that the effective population size is very much smaller than the minimum census size of the population.     

Empowering African genomics for infectious disease control

At present, African scientists can only participate minimally in the genomics revolution that is transforming the understanding, surveillance and clinical treatment of infectious diseases. We discuss new initiatives to equip African scientists with knowledge of cutting-edge genomics tools, and build a sustainable critical mass of well-trained African infectious diseases genomics scientists.     

A novel method for targeting survey effort to identify new bat roosts using habitat suitability modelling

In the UK, four out of 18 bat species are listed on the EU Habitats Directive, including the lesser horseshoe bat (Rhinolophus hipposideros), and their population status is closely monitored by visiting known roosts. R. hipposideros predominantly form maternity roosts in buildings, but roosts are impermanent features in the landscape and their distribution changes as bats form new roosts and abandon others. Locating new roosts requires intensive surveys which are challenging and inefficient. In this study, we provide a novel model-based strategy to identify potential R. hipposideros maternity roost sites that can be used to monitor bat populations. First, we model potential maternity roost habitat using record centre data on roost locations across Wales, Great Britain. We then constrain the area identified from modelling using record centre data on locations of bats in areas with no known roosts. We used two variable selection methods and three pseudo-absence data sets (random background points, random points in buildings and target group selection of mammal records) to produce six habitat suitability models. The three pseudo-absence data sets produced different habitat suitability maps, demonstrating the influence of pseudo-absence selection on species distribution models. The six models were combined using weighted mean average to produce an ensemble model that performed better than individual models and that indicated high levels of congruence in areas predicted to have high habitat suitability for maternity roosts. Our model revealed an extensive area (6523 km²; 31% of the area of Wales) containing 18,051 buildings in suitable habitat. Using record centre data on bat activity outside commuting range from known roosts reduced the potential survey area to 133 km² (0.6% of the area of Wales) and 207 buildings. Our modelling outputs can be used to direct volunteers and bat surveyors in more targeted and efficient searches.     

Serendipity and new drugs for infectious disease

Serendipity, in various shades of semantic legitimacy, is abundantly evident in the history of the chemotherapy of infectious disease. We may be on the threshold of a new era of rational drug design, but most medications for infectious diseases have arisen, and continue to arise, from chance observation, clinical experience, and the empirical search for substances active against pathogens. Chance does not produce drugs; but where chance has played a pivotal role in drug discovery, the event may be considered serendipitous to a greater or lesser degree. In a deliberate search for new drugs, it is often difficult to assess the degree to which any resulting discovery is serendipitous, and the usefulness of the term becomes debatable. Many therapeutic advances emerge from research involving animals, and a triggering "happy accident" may reside in the most basic aspects of animal care or in the most arcane knowledge of animals. The examples discussed in this article deal mostly with parasitic disease and the use of animal models in the discovery of antiparasitic agents. In this area, as in others, chance has laid the groundwork for scientific advancement and practical benefit. Although the applicability of the word serendipity to drug discovery may often be uncertain, the role played by chance should be recognized and welcomed.     

A new method for estimating population doubling time of vertebrate cells.

Based upon the fact that the amount of DNA doubles after each cycle, a technique was developed in which the population doubling time for cell cultures was determined from the ratio of its DNA content to [3H]thymidine incorporation under conditions in which cell numbers cannot be readily determined. This technique may be useful in determining what proportion the sample is of the total cell population.     

A technique for estimating maximum harvesting effort in a stochastic fishery model

Exploitation of biological resources and the harvest of population species are commonly practiced in fisheries, forestry and wild life management. Estimation of maximum harvesting effort has a great impact on the economics of fisheries and other bio-resources. The present paper deals with the problem of a bioeconomic fishery model under environmental variability. A technique for finding the maximum harvesting effort in fluctuating environment has been developed in a two-species competitive system, which shows that under realistic environmental variability the maximum harvesting effort is less than what is estimated in the deterministic model. This method also enables us to find out the safe regions in the parametric space for which the chance of extinction of the species is minimized. A real life fishery problem has been considered to obtain the inaccessible parameters of the system in a systematic way. Such studies may help resource managers to get an idea for controlling the system.