Epidemic Mortality Research Articles

Special Challenges in the Prevention and Treatment of Malaria in Children.

Malaria is a devastating disease, inflicting epidemic morbidity and mortality with an estimated 500 million cases and 2.5 million deaths annually. Children suffer the most severe morbidity; one child dies of malaria every 30 seconds, accounting for over 1 million of the deaths annually. There continues to be a tremendous increase in human migration and travel between malaria endemic and nonendemic areas, with approximately 20% of imported malaria cases to Europe and the United States occurring in children. Although many recent advances in the prevention, diagnosis, and treatment of malaria have been made, the emergence of drug resistance and changes in the disease's epidemiology present new challenges. This article discusses the special considerations encountered in the prevention and treatment of malaria in children.

Using an age-structured model to simulate the recovery of the Australian pilchard ( Sardinops sagax) population following epidemic mass mortality

An age-structured model of the Australian pilchard’s population has been adapted to simulate recovery from the mass mortality suffered during the herpesvirus epidemics of 1995 and 1998/1999. The model generates a vigorous recovery even when levels of mortality are very high, which accords with observations. In spite of this strong recovery, the model indicates that stock is sensitive to increased fishing pressure. Healthy stocks of juvenile pilchards play a key role in the vigorous post-epidemic recovery.

Red Oak Borer, Enaphalodes rufulus (Coleoptera: Cerambycidae), in the Ozark Mountains of Arkansas, U.S.A.: An Unexpected and Remarkable Forest Disturbance

A complex interaction of multiple factors has resulted in an oak decline event in oak-hickory forests of the Ozark Mountains of Arkansas and Missouri, U.S.A. The most striking feature of this situation is an unprecedented population explosion of red oak borer, a species of cerambycid beetle, Enaphalodes rufulus (Haldeman), which appears to be causing extensive mortality to mature red oaks (Quercus, subgenus Erythrobalanus). The insect is a native species, historically a minor pest of oaks, found throughout the eastern United States. Beetles normally reproduce in living oaks, as larvae initially feed in phloem tissue and subsequently bore into xylem where pupation occurs. The life cycle is two years in length and synchronous adult emergence occurs in odd-numbered years. Data from previous research indicate average attack densities of less than four per tree with a high of 71 on a single tree. Historical emergence densities are similarly low and the highest reported was 15 adults from one tree. Our research is concerned with understanding factors contributing to this outbreak; developing sampling methods for red oak borer; assessing oak mortality; and evaluating site and stand conditions associated with the current outbreak. Results of our initial sampling reveal dramatically higher average attack densities of 244 per m2 and emergence densities of 18 per m2 of bark surface area. We confirm a three-week period of adult emergence and activity during mid-June to early July. We also report on possible management responses by federal and state agencies to this remarkable epidemic and oak mortality crisis.

THE MORTALITY OF MIDWESTERN OVERSTORY OAKS AS A BIOINDICATOR OF ENVIRONMENTAL STRESS

Tree mortality rates are potential indicators of the impact of environmental stresses on forests. But the relationship between environmental stress and tree mortality is poorly understood, particularly in forests not experiencing epidemic mortality. To determine whether there is a sufficiently direct link between stress and tree mortality to allow mortality rate to serve as a stress bioindicator, I addressed the question: Are trees more likely to die during years when environmental stress is more intense? Subject trees were 62 overstory oaks (Quercus spp. L., '20 cm diameter at breast height) that died during 1968-1987. These trees were from seven oak-hickory forests in the midwestern USA that were ex- periencing low rates of tree mortality. A previous study had found these oaks to be growing more slowly than surviving oaks from the same forests, suggesting that these now-dead trees may have been physiologically compromised and particularly vulnerable to stress. Based on two Monte Carlo method-based tests, there was no consistent positive association between the likelihood of tree death in a year and the intensity of stress during that year or the previous year, where stress was represented by the growth rates of surviving neighbor trees (mean chronologies), growing season precipitation, or the mean Palmer drought se- verity index during the growing season. An evaluation of the statistical power of one of the two tests found a low probability of failing to detect a modest positive association between year of tree death and stress intensity. The results indicate the need for additional research on the link between stress and tree mortality if overstory tree mortality rates are to serve effectively as a bioindicator of environmental stresses.

Age Distributions of Hominid Samples at Atapuerca (SH) and Krapina Could Indicate Accumulation by Catastrophe

Age distributions of the Atapuerca (SH) (MNI=32) and Krapina (average MNI=23·5) hominid assemblages differ markedly from that of the pooled Neanderthals. Three out of six statistical tests imply both assemblages resulted from catastrophe while for the remaining three no decision can be made due to the very small size of the age samples in the age-class 5–14 years. It is improbable that the human bones accumulation be the result of an attritional mortality via, either a regular lion predation, or a kind of primitive cemetery. However, there is either a marked underrepresentation of the individuals aged 5–14 years or an overrepresentation of those aged 15–24 years, along with an underrepresentation of the younger (below 5 years) and older individuals (25 years and above). The mortality distribution corresponds neither to a shortage nor an epidemic mortality profile. The curious age distribution of both hominid samples may be best explained as a result of a demographic crisis of a local group for a meta-population in nature, caused by severe environmental fluctuation.

Ebola in Western Australia: fears and facts

Ebola virus causes haemorrhagic fever and has resulted in vast mortality in several epidemics. Most outbreaks have occurred in Africa but, due to international travel and commerce, it is not impossible that a case could occur in Australia. Few healthcare workers, let alone the public, have an understanding of Ebola. One can only imagine the panic and terror that a potential outbreak – with the accompanying, exaggerated media reports of an impending mass epidemic and death – could bring.This article provides information about Ebola and its containment. Should a potential Ebola case arise in Western Australia (WA), are there procedures in place to cope with this disease or would it lead to massive fatalities, as in previous epidemics? The authors have investigated and here outline the contingency plans and guidelines for Ebola.The authors found that, theoretically, WA could maintain and control public health in relation to this deadly virus. It is hoped, however, that it will never be necessary to put theory into practice.

Women's health--a global challenge

The global challenge in the 21st century concerns a new world trade order environmental threat and the problem of world health. Primary problems of the global health in the next decades have to do with the growth of population and family planning the HIV epidemic maternal and child mortality and morbidity drinking water hygiene nutrition classical infection and tropical diseases and multiple drug resistance migration from the land suburbanization and their effects on health. In this context the health of women is of primary importance since more than 50% of the worlds population are women. They perform 65% of all work yet their share of total income is only 10% and they possess only 1% of all property. In the developing world they are responsible for household chores caring for the sick the raising of children fetching water and firewood religious rites contraception and work in the fields. The health of women in a medical sense is connected to their life cycle from birth and childhood through adolescence the reproductive life phase and to menopause with the conclusion of old age. In childhood under- and malnutrition are a risk. In adolescence the protection from unwanted pregnancies the avoidance of sexually transmitted diseases (STDs) and female genital mutilation which affects 80 million women worldwide are vital issues. Young women are often exposed to sexual harassment rape and domestic violence. During the reproductive age women in developing countries face the possibility of STDs with the consequence of pelvic peritonitis infertility chronic lower abdominal ailments and avoidable operations. In postmenopause deficient diagnosis and treatment often result in late detection of cancer. The strategy for the improvement of womens health in these countries requires elevation of womens socioeconomic status the betterment of their physical health the training of health personnel and comprehensive reproductive health care.

Jack Fisher's' flu’: a virus still virulent

t is pleasing that Zell has been stimulated by my attempt at revisionism. However, I did not 're-assert Fisher's claim that as much as one-fifth of England's population died as a result of harvest failures and epidemics between I556 and I560'.1 My own calculation of overall population decline was i5.9 per cent (explicitly termed 'speculative'), and I described Fisher's estimate of 'around 20 per cent' as 'unintentionally exaggerated'.2 Zell in fact refers to 'Moore's more cautious estimate of I2 to i8 per cent',3 though my estimate of i8 per cent resulted from the application of Fisher's estimated vital rates to my new data, and that of I2.5 per cent resulted from the application to the new data of Wrigley and Schofield's 'normal' birth rate and my revised death rate. Both these calculations assumed no change in birth rates during the crisis years, which is improbable: substituting a lower 'crisis' birth rate raises my estimated overall drop in mortality to I5.9 per cent.4 Zell is of course correct in ascribing to me the view that Wrigley and Schofield's figure for mortality, 5.5 per cent, 'has to be rejected as a substantial under-estimate'. Zell also states that I believe in the existence of '404 pre-Elizabethan registers in the Cambridge Group's sample'.' I think he means 'preRestoration', not 'pre-Elizabethan'; but, in any event, of course I do not believe in the sample of 404 registers being fully in observation before i662. The real issue, on which I suspect Zell and I will continue to disagree, is whether '8o or go registers are a large enough sample from which to derive estimates of national population movements'. It may well be, as he further suggests, that 'the full impact of epidemic mortality will be under-represented by any parish register sample', but I would feel more confidence in that conclusion if a much larger number of registers than the '8o or go' from the mid-I55os actually used by Wrigley and Schofield had been examined.6 On my own calculations there are likely to be about 700-800 parish registers, out of just over I,400 registers beginning (or stated to begin-none of the existing lists of parish registers is infallible) in or before I550, which are usable for continuous chronological analysis before, during, and after the crisis years of I557-9. Of these possibly useful I,400 registers, to date I have tabulated 220 and rejected, after examination, 340. Nevertheless the

Chehalis River Disease: A Unique Gill Disease of Salmonids

Epidemic mortalities of chinook salmon alevins (Oncorhynchus tshawytscha) have occurred annually at a freshwater hatchery at the Chehalis River, British Columbia, Canada, since 1982. Previous work has identified branchial epithelial hyperplasia as the predominant pathological change. Our initial work lead us to test the hypothesis that Chehalis River disease (CRD) was actually a novel form of bacterial gill disease (BGD). Histological and ultrastructural observations indicated that CRD-affected gills harboured a bacterial biofilm apparently complexed with particulate iron prior to and during clinical CRD. In one instance, extracellular viruslike particles were observed. Large numbers of a mixed bacterial population were recovered from diseased gills. Flavobacterium sp. and Pseudomonas fluorescens were considered the predominant isolates from the 1990–91 outbreak. However, indirect immunofluorescence of gills with anti-Flavobacterium branchophila serum failed to detect antigenically similar bacteria on the gills of CRD-affected fish. Chemotherapeutic treatment of both naturally and experimentally infected fish was successful, thereby confirming the infectious nature of the disease. We conclude that CRD is a form of BGD, but the significance of the branchial viruslike particles and the presence of particulate iron has not yet been established.

Influenza: Relation of Mortality to Morbidity Parameters-Netherlands, 1970—1989

The purpose of this study is to investigate the relationship between the number of influenza-like illness (ILI), weekly registered by the general practitioners (sentinel stations), and the monthly overall influenza mortality in people over 60 years of age, provided by the Dutch Statistical Bureau during the period July 1970 to June 1989. The quantitative impact of influenza-morbidity is expressed by three summary parameters, calculated from the 52 (53) weekly ILI-figures per season-year, (i) their sum (i.e. global extent of an epidemic), (ii) their standard deviation, and (iii) their maximum (i.e. peak number of ILI during an epidemic). In the analysis influenza A subtype is also included. These four parameters are mutually compared with respect to their predictability for yearly total influenza mortality in the 19 season-years available. In most cases, the standard deviation and the peak number of ILI are more powerful for prediction of mortality, than the global extent of the epidemic. The peak number of ILI is of special interest. It is particularly useful for estimating the effect on current influenza mortality during an ongoing epidemic. From the model it is possible to calculate a threshold (of weekly ILI) beyond which mortality increases proportionately more than the number of illness episodes. By using the peak value of morbidity it is possible to calculate the minimal impact of epidemic mortality. This study indicates that the weekly number of influenza-like illnesses has a certain prognostic value for the real impact of influenza. An electronic surveillance system could detect immediately the threshold above which influenza mortality increases more than proportionally.(ABSTRACT TRUNCATED AT 250 WORDS)

Demographic Change in Northwestern New Spain

The process of Spanish colonization in Northwestern New Spain, here roughly defined as Sonora and the Californias, set into motion a complex set of factors that contributed to demographic change; absolute population decline among the Indian groups involved, the growth of a largely mestizo settler population, and a number of different types of social and economic interactions between the two populations. Scholars in recent years have debated the causes and the nature of change. Alfred Crosby established a framework for the debate in his provocative book entitledThe Columbian Exchange, which discusses, as the sub-title implies, the consequences of interaction between the Old and New Worlds after 1492. In a recent study Henry Dobyns elaborated on one of Crosby's principal themes, the introduction and impact of Euro-Asiatic diseases, and prepared a chronology of epidemics between the sixteenth and early twentieth centuries that affected Native American populations. Dobyns applied his “epidemic mortality” model to Florida and calculated both a high contact population and the rate of population loss due to each of the major epidemics. The model when applied to all of North America has major implications for our understanding of the course of Native American history. In a recent bibliographic article historical demographer Shelia Johansson cast doubt on the high contact population estimates and the degree of demographic collapse.

Excess mortality from influenza in a large urban population, Rome, Italy, 1956--76.

Influenza activity was studied in the Rome population from 1956 to 1976 by analysis of mortality from respiratory causes and from all causes. During cold weather months, type A influenza virus was associated, as a rule, with epidemic excess deaths at two year intervals while type B virus was prevalent twice during isolation data were also compared with epidemic excess mortality during four consecutive years. The evidence obtained indicated that influenza virus isolation alone does not represent a reliable index of epidemic influenza activity in this population. The proportion of deaths attributed to respiratory causes consistently increased in every epidemic, the most pronounced increases occurring during large epidemics. The break-down by age of deaths from respiratory causes in the course of two epidemic periods showed that the percentage distribution of deaths was essentially the same as in non-epidemic periods. This evidence indicates that the same factors influencing the age-related distribution of mortality from respiratory causes during non-epidemic periods, probably affect the fatal outcome of influenza during epidemics.

The meteorological analysis on the epidemic mortality of pine trees, with special reference to the effective accumulated temperature

The meteorological analysis on the epidemic mortality of pine trees, with special reference to the effective accumulated temperature

Population Studies on the Toheroa, Amphidesma ventricosum Gray (Eulamellibranchiata)

The ecology, distribution, and commercial importance of the toheroa, Amphidesma ventricosum Gray, are discussed. The habitat favoured by that portion of the population at present known is a beach fully exposed to heavy surf, with a fine sand and sufficient residual moisture to prevent desiccation at low tide. Frequent dense blooms of phytoplankton are necessary to provide an adequate food supply. Estimates of numerical abundance for various beaches are given, showing that violent fluctuations in numbers may occur, sometimes, but not always, with epidemic mortalities. The sampling technique for estimat- ing numerical abundance is described and discussed. The growth rate has been estimated for several different beaches, both by interpreting the annual growth-rings of the shell, and by analysis of length frequency data. The South Island toheroa have a significantly lower growth rate than those in the North Island. It is shown that the distribution of age classes on the beach is inconsistent with the assumption that the species is confined to the littoral region. In particular, the younger toheroa are almost invariably fewer in numbers than would be expected in a self-contained popula- tion. From this, and from the extreme fluctuations in numbers which occur from time to time, it is concluded that some part of the population is located in the sublittoral. The spatial distribution of the beach toheroa shows a high degree of over-dispersion (or aggregation) which is mainly attributable to variations in environmental conditions. Vertical and horizontal zonation of size groups may sometimes occur, but the contributing factors are obscure. Statistical aspects are discussed in appendices.

Feeding and Control of Toheroa (Amphidesma ventricosum Gray) (Eulamellibranchiata) Populations in New Zealand.

Surveys of toheroa stocks on the North Island beaches of New Zealand are described and the causes of natural and epidemic mortality discussed. The evidence for previous resurgent populations of tuatua (Amphidesma subtriangulatum Wood) alternating with toheroa is given. Analyses of water samples show that a source of sea-water rich in nutrient salts produces the great quantities of diatoms on which the shellfish populations feed. A quantitative estimation is made of the littoral phytoplankton and the dominant species are given for each beach. Chaetoceros armatus is found on all beaches and, in the cold months, when blooming occurs, comprises in some places 100 per cent. of the diatoms. The greatest quantity recorded is 1500 g dry weight per cu. m. of water. Each beach has a characteristic flora. The rate at which toheroa feed is determined from the diatom consumption. Methods are suggested by which more stable toheroa stocks might be developed and consequently a greater production achieved.

Double enteric infection ('la fièvre typhoide intriquée'); an account of an epidemic.

1. A double enteric infection is defined as the simultaneous infection of an individual or group of individuals with two organisms of the enteric group. The literature of the previously recorded cases and epidemics, in which the diagnosis of double enteric infection has been established by cultural methods, is reviewed.2. An account is given of a double enteric outbreak of seventy–six cases which occurred amongst British troops and police at Acre, Palestine, in 1948. The infection is thought to have been due to contamination of the water supply with sewage during the civil disturbances. The diagnosis was established bacteriologi–cally in seventy-four cases (93.3%);Salm. typhiwas isolated in forty–three cases,Salm. paratyphiB in three, and bothSalm. typhiandSalm. paratyphi Bfrom twenty–eight cases. There were three fatal cases in the epidemic (mortality rate = 3·94%).3. The morbidity rate from enteric fever among the infantry unit was 60%, and among the Palestine police, 17%. The possible reasons for this difference is discussed, and the conclusion drawn that it was probably due to the Palestine policemen being older men, with longer overseas service and more 'seasoned' to life in subtropical conditions.4. Thirteen cases were treated with polymyxin B (15 mg. 4-hourly for 4-day periods); with this small dose no beneficial therapeutic effects were observed, and ten cases showed evidence of renal damage while under treatment.5. The bacteriology, epidemiology and clinical aspects of double enteric infections are discussed. The diagnosis of a double enteric infection may be established with the greatest certainty by blood culture. Such infections are usually water-borne or milk-borne, and tend to occur when there has been a severe breach of hygiene, e.g. in the contamination of a water supply by sewage. The claim that the prognosis in instances of double enteric infection is worse than with single infections is not supported by the experiences at Acre where the three fatal cases occurred in cases infected withSalm. typhialone.

Mexico's Vital Statistics

DR. RICARDO GRANILLO, head of the Mexican Department of Statistics and Demography, states that his Department is a part of the Secretariat of National Economy (Bol. Of. San. Panamericana, 23, 419; 1944). It collects and publishes statistics, takes a national census, makes special studies, represents the country at international congresses, and has jurisdiction over population, public education, social welfare, industrial economy and vital statistics. The principal, functions of the Vital Statistics Office of the Secretariat of Health and Welfare include keeping Federal and State health authorities informed of the general mortality and that from contagious disease and other important causes; reporting on epidemics in areas where there are no practitioners and regular reports of contagious diseases cannot be obtained; the study of the geographical and seasonal distribution of general, infant, endemic and epidemic disease mortality; reporting to the Panamerican Sanitary Bureau and other international offices and neighbouring health authorities on the general health conditions of Mexico; and keeping a record of public health activity throughout the Republic.