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PubMedDate not supplied

The developmental cycle of a drug epidemic: the cocaine smoking epidemic of 1981-1991.

Although Americans have experienced many drug epidemics, the majority of which have ended within ten years of onset, they nevertheless believed that the use of smokable cocaine, which took the popular form of crack cocaine in 1984, would grow exponentially throughout the 1990s unless it was vigorously combated. However, in 1991 it appears that crack use is in decline even in the inner-city neighborhoods where it had been most entrenched, and that the decline is due more to natural controls than to the War on Drugs. The cyclical nature of drug epidemics, as well as their progression through regular stages, was again affirmed. The cocaine-smoking epidemic of 1981-1991 (which included crack) afforded the opportunity to research it in its entirety. In this article, the advantages of recognizing the developmental cycles of drug epidemics are outlined, the most important of which concerns the future. In the terminal stage of the developmental cycle of a drug epidemic, remaining abusers play a pivotal role. If humanely treated, they may serve as deterrents to future drug use: frustrated in current drug use, however, yet insensitively treated by the wider society, they may author the next epidemic.

Adolescent↗

PubMed2002

When is an epidemic an epidemic?

BACKGROUND: The large number of cases of West Nile fever diagnosed in Israel in 2000 once again brought into focus the confusion that frequently accompanies the use of the term "epidemic." OBJECTIVES: To examine the different definitions of the term "epidemic" and to propose ways in which it can be used to both improve communication among professionals and provide the public with a better sense of the associated risks. METHODS: The literature was reviewed for the various definitions of the terms "epidemic" and "outbreak." Sources included popular and medical dictionaries, ancient documents, epidemiology texts, legal texts, and the medical literature. RESULTS: The term epidemic is variously defined. The broad definition given by epidemiologists--namely, more disease than is anticipated by previous experience--is less meaningful to the general public. In some ways it conflicts with the definitions found in the popular literature, which generally imply danger to the public and a very large number of victims. CONCLUSIONS: The interpretation of the term epidemic may vary according to the context in which it is used. For risk communication, we suggest that every effort be made to add descriptive terms that characterize the epidemic.

Communication↗

PubMed1986

[The duality of the qualitative determinacy of the epidemic process in anthroponoses as the main trait distinguishing them from the epidemic manifestations of zoonotic diseases in man].

The present article substantiates the necessity of defining more accurately the notion "epidemic process" and using this term only in reference to anthroponotic diseases. Proceeding from the philosophical concept of the qualitative definiteness of material objects and phenomena, the author proposes to distinguish the epidemic process in anthroponoses from mass spread of zoonotic diseases among humans on the basis of using the systemic qualities of the epidemic process, and in particular the principle of the dual character of the qualitative definiteness of objects and phenomena as the distinctive feature of the epidemic process of anthroponoses. Distinction, based on this principle, between anthroponotic diseases and zoonotic diseases in groups of humans must be reflected in the definitions of these phenomena. The application of the term "epidemic process" only in reference to anthroponotic diseases is proposed, while zoonotic diseases in groups of humans should be considered as epidemic manifestations of zoonotic infections.

Animals↗

PubMedDate not supplied

Empirical decompositions of overall AIDS epidemics in local epidemics using generalized neural networks.

A generalized neural network was adapted for the simulation of processes strongly dependent upon the history, imposed by the inner own history of an individual neuronal activation. This involves the dependence of the neural network parameters upon the cumulated values of the corresponding neuron activations. When in the neural network weakly coupled blocks with strong inner couplings can be identified, the activation wave on the entire network (associated with the overall epidemic) can be decomposed into quasi-independent intra-block local activation waves, with characteristic delays between them (corresponding to the simultaneous and successive local epidemics). Special simulations on strongly connex neural network determine the typical local activation waves for various block parameters and the mentioned delays between two such successive activation waves in two coupled blocks. Another type of neural network is used to achieve the empirical decomposition of the overall epidemic into simultaneous (corresponding to a layer) and successive local epidemics (corresponding to the various epidemic waves, associated with different layers). A simpler approximative algorithm for the estimation of the number of the mentioned simultaneous local typical epidemics is also presented.

Acquired Immunodeficiency Syndrome↗

PubMed2006

Transmissibility and mortality impact of epidemic and pandemic influenza, with emphasis on the unusually deadly 1951 epidemic.

There are important gaps in our current understanding of the influenza virus behavior. In particular, it remains unclear why some inter-pandemic seasons are associated with unusually high mortality impact, sometimes comparable to that of pandemics. Here we compare the epidemiological patterns of the unusually deadly 1951 influenza epidemic (A/H1N1) in England and Wales and Canada with those of surrounding epidemic and pandemic seasons, in terms of overall mortality impact and transmissibility. Based on the statistical and mathematical analysis of vital statistics and morbidity epidemic curves in these two countries, we show that the 1951 epidemic was associated with both higher mortality impact and higher transmissibility than the 1957 and 1968 pandemics. Surprisingly in Liverpool, considered the 'epicenter' of the severe 1951 epidemic, the mortality impact and transmissibility even surpassed the 1918 pandemic.

Communicable Disease Control↗

PubMed2006

An improved technique for isolation of environmental Vibrio cholerae with epidemic potential: monitoring the emergence of a multiple-antibiotic-resistant epidemic strain in Bangladesh.

Predicting cholera epidemics through monitoring the environment for the presence of pathogenic Vibrio cholerae is complicated by the presence in water of a large number of mostly nonpathogenic V. cholerae strains. V. cholerae strains causing recent cholera epidemics in Bangladesh carry the sulfamethoxazole-trimethoprim (SXT) element, which encodes resistance to several antibiotics. Here, we show that the use of a culture medium containing streptomycin, sulfamethoxazole, and trimethoprim (the antibiotic selection technique [AST]) can significantly enhance the isolation of environmental V. cholerae O1 with epidemic potential (P<.001). The AST was also used to monitor the recent emergence and spread of a new multiple-antibiotic-resistant strain of V. cholerae in Bangladesh. The results of this study support the hypothesis that pre-epidemic amplification of pathogenic V. cholerae occurs in the human host and leads to the start of an epidemic cycle dominated by a single clone of V. cholerae that spreads rapidly through environmental waters.

Anti-Bacterial Agents↗

PubMed1999

[Study on the risk factors influencing the epidemicity of epidemic cerebrospinal meningitis].

Based on a 8-year surveillance data, a factor analysis theory was used to analyze the 12 risk factors influencing the epidemicity of epidemic cerebrospinal meningitis. The results showed that the first sixth risk factors were the rate of carrying meningococci A and B in the population, relative air humidity in January, morbidity rate in January, vaccination rate before epidemic, and the titre of antibody. Although the incidences of epidemic cerebrospinal meningitis are scattered, the risk factors influencing the epidemicity did not disappear. It is important to use meningococci A vaccine continuously and widely to strengthen the surveillance among migrated population and population at high risk.

Carrier State↗

PubMedDate not supplied

[Specific features of the epidemic process of measles and epidemic parotitis in territories with ecologically unfavorable conditions].

Differences in the epidemic process of measles and epidemic parotitis in cities situated at territories with ecologically unfavorable conditions have been established. The intensity of the epidemic process of measles and epidemic parotitis is higher in those cities where a higher total level of pollution has been established. A high level of morbidity in these infections is due to disturbances in the immunological resistance of children living in such cities and, as a consequence, having insufficient postvaccinal immunity. A higher percentage of seronegative children among those immunized against the corresponding infections and a higher morbidity level among this category of the population have been established. To decrease morbidity in measles and epidemic parotitis to the level, sporadic for such cities, a greater coverage of children with immunization (up to 99-99.5%) is necessary.

Air Pollutants↗

PubMed2004

The burden of malaria epidemics and cost-effectiveness of interventions in epidemic situations in Africa.

Attempts to quantify the epidemiologic and economic burden of malaria have so far neglected to specifically address the burden of epidemic malaria. Moreover, the data on the effectiveness and cost-effectiveness of interventions in epidemics is extremely limited. Answering such key questions in an epidemic prone context is more challenging than doing so in endemic areas. Using the limited data available, we estimate that in Africa, there are more than 12 million malaria episodes and 155,000-310,000 malaria deaths per year attributable to epidemics if control options are not implemented or well timed, which is equivalent to some 4% of estimated annual malaria cases worldwide and 12-25% of estimated annual worldwide malaria deaths, including up to 50% of the estimated annual worldwide malaria mortality in persons > 15 years of age. The possible economic impact of malaria epidemics is described and the limited evidence on the effectiveness and cost-effectiveness of interventions in areas of low or seasonal transmission is reviewed.

Africa↗

PubMed1993

[Changes in epidemic features of epidemic cerebrospinal meningitis after vaccination with purified meningococcal polysaccharide vaccine group A in Zhengzhou].

The authors studied the epidemic features of epidemic cerebrospinal meningitis before and after mass vaccination with Purified meningococcal polysaccharide vaccine group A. After the mass vaccination, the morbidity rate of epidemic cerebrospinal meningitis fell considerably year after year. The epidemic cycle changed for the first time. The ratio of the number of cases in the city to those in the countryside was reduced. The phenomenon that the infectious disease spread along traffic lines from city to countryside disappeared. The cases mainly occurred in the remote mountain village. The morbidity rate in the group of 0-3 years relatively increased. The level of antibody titers in population obviously increased. The carrier rate of meningococci and constituent ratio of group A reduced. The epidemic group was group A, but cases of group C occurred for the first time.

Adolescent↗

PubMed1998

The South African HIV epidemic, reflected by nine provincial epidemics, 1990-1996.

OBJECTIVES: To determine by serological examination the annual point prevalence rates of infection with the human immunodeficiency virus (HIV) in representative samples of subjects in the nine provinces of South Africa, 1990-1996. DESIGN: Annual cross-sectional point prevalence surveys conducted in October/November of each year. SETTING: South Africa, including areas that used to be known as self-governing and independent National States. SUBJECTS: Pregnant women in the age group 15-49 years who attend antenatal clinic services provided by the public health services, and who act as an indicator group of the HIV epidemic among the heterosexually active population. OUTCOME MEASURES: HIV positivity as determined serologically; done consistently over several years, this serves to monitor the distribution and trend of the HIV epidemic in each of the nine provinces of South Africa. RESULTS: Empirical data gained from seven annual, consecutive countrywide surveys demonstrate a wide geographical variation in the point prevalence rates of HIV infection. In October/November 1996 the point prevalence rates (%) were as follows: Western Cape 3.09, Northern Cape 6.57, Northern Province 7.96, Eastern Cape 8.10, Gauteng 15.49, Mpumalanga 15.77, Free State 17.49, KwaZulu-Natal 19.90 and North West 25.13. The weighted national average was 14.17%. There are indications that some of the provinces (KwaZulu-Natal and possibly Mpumalanga) might have passed a point of inflection suggesting deceleration in their specific rates of increase. These results are, however, counterbalanced by the exponential growth still being experienced in provinces with large populations such as Gauteng and the Eastern Cape. It is concluded that the net effect of these divergent trends currently affects the national figure only marginally. A major deflection from the exponential growth patterns seen hitherto can be anticipated only once all or most of the highly populated provinces have traversed their respective points of inflection. The exponential model significantly explains the HIV epidemics in the provinces. The combination of these provincial epidemics describes the initial exponential phase of the epidemic.

Adolescent↗

PubMed1994

Epidemic of herpes zoster following HIV epidemic in Manipur, India.

Since 1989, injecting drug use (IDU) related HIV infection has affected thousands of young adults in Manipur, a north eastern state of India bordering Myanmar following a similar kind of epidemic in adjoining countries like Thailand and Myanmar. During a clinical surveillance of a group of HIV positive IDUs for a natural history study at Manipur, herpes zoster (HZ) emerged as the most specific early HIV related illness (positive predictive value of 100%) in patients belonging to the age group of 12-45 years. Data collected from the dermatology departments of the two main hospitals of the state revealed that there had been an epidemic of HZ since 1990 (rate of 1990 being 11.3/1000 compared to 6.5/1000 in 1989, P value < 0.0001) among males of 12-45 years. The epidemic of HZ has been attributed to the preceding epidemic of IDU related HIV in the same age and gender group occurring 1 year earlier. HZ should be recognised as a marker condition similar to tuberculosis indicating the necessity of screening for HIV in regions where the dual problem of IDU and HIV exist in young adults.

AIDS-Related Opportunistic Infections↗

PubMed2002

Epidemic crack cocaine use linked with epidemics of genital ulcer disease and heterosexual HIV infection in the Bahamas: evidence of impact of prevention and control measures.

BACKGROUND: Epidemic freebase/crack cocaine use began in the Bahamas in 1982, closely followed by epidemics of genital ulcer disease (GUD) and HIV infection. Numbers of new clients receiving ambulatory treatment for cocaine use in Nassau peaked in 1984. GOAL: To assess interrelations among epidemics of crack use, GUD, and HIV infection. STUDY DESIGN: The study was designed for review and comparison of temporal trends in ambulatory and inpatient treatment of cocaine users and in numbers of cases of sexually transmitted disease (STD) and HIV infection in the Bahamas. A retrospective case-control study of cocaine use and STDs was performed at the Comprehensive Dermatovenereology Clinic in Nassau. RESULTS: Ambulatory visits and inpatient admissions for cocaine use peaked in 1984 and 1987, respectively. GUD cases increased 12-fold in the Bahamas from 1983 to the period of 1985-1987 and then declined. At the Comprehensive Dermatovenereology Clinic, gonorrhea cases outnumbered bacterial GUD cases approximately 10:1 in 1982 and 1983, but the latter increased to outnumber gonorrhea cases in 1985 and 1987-1988. Annual HIV seroprevalences at new-problem visits rose from less than 0.3% in 1986 to 12.9% by 1994 and then leveled off. Cocaine use among patients seen with STD from 1985 through 1990 was significantly associated with GUD (odds ratio [OR], 3.3; 95% CI, 2.1-5.1), secondary syphilis (OR 5.5; 95% CI, 2.4-12.6), and HIV infection (OR, 8.1; 95% CI, 4.3-15.2). CONCLUSIONS: In temporally linked successive epidemics of cocaine use, GUD, and HIV infection, case-control analyses confirmed the association of cocaine use with GUD and with HIV infection. Declining GUD and HIV seroprevalence stabilization followed declines in cocaine use and implementation of syndromic management of GUD, as well as intensified partner-notification efforts.

Adult↗

PubMed2006

Expanding ICU facilities in an epidemic: recommendations based on experience from the SARS epidemic in Hong Kong and Singapore.

Epidemics have the potential to severely strain intensive care resources and may require an increase in intensive care capability. Few intensivists have direct experience of rapidly expanding intensive care services in response to an epidemic. This contribution presents the recommendations of an expert group from Hong Kong and Singapore who had direct experience of expanding intensive care services in response to the epidemic of severe acute respiratory syndrome. These recommendations cover training, infection control, staffing, communication and ethical issues. The issue of what equipment to purchase is not addressed. Early preparations should include fit testing of negative pressure respirators, training of reserve staff, sourcing of material for physical modifications to the ICU, development of infection control policies and training programmes, and discussion of triage and quarantine issues.

Counseling↗

PubMed2006

Age-structured homogeneous epidemic systems with application to the MSEIR epidemic model.

In this paper, we develop a new approach to deal with asymptotic behavior of the age-structured homogeneous epidemic systems and discuss its application to the MSEIR epidemic model. For the homogeneous system, there is no attracting nontrivial equilibrium, instead we have to examine existence and stability of persistent solutions. Assuming that the host population dynamics can be described by the stable population model, we rewrite the basic system into the system of ratio age distribution, which is the age profile divided by the stable age profile. If the host population has the stable age profile, the ratio age distribution system is reduced to the normalized system. Then we prove the stability principle that the local stability or instability of steady states of the normalized system implies that of the corresponding persistent solutions of the original homogeneous system. In the latter half of this paper, we prove the threshold and stability results for the normalized system of the age-structured MSEIR epidemic model.

Age Factors↗

PubMed1996

Epidemic cholera in Guatemala, 1993: transmission of a newly introduced epidemic strain by street vendors.

Epidemic cholera reached Guatemala in July 1991. By mid-1993, Guatemala ranked third in the hemisphere in reported cases of cholera. We conducted a case-control study with two age-, sex-, and neighbourhood-matched controls per patient in periurban Guatemala City. Twenty-six patients hospitalized for cholera and 52 controls were enrolled. Seven (47%) of 15 stool cultures obtained after admission yielded toxigenic Vibrio cholerae O1. All seven were resistant to furazolidone, sulfisoxazole, and streptomycin, and differed substantially by pulsed-field gel electrophoresis from the Latin American epidemic strain dominant in the hemisphere since 1991. In univariate analysis, illness was associated with consumption of left-over rice (odds ratio [OR] = 7.0, 95% confidence interval [CI] = 1.4-36), flavored ices (-helados') (OR = 3.6, CI = 1.1 - 12), and street-vended non-carbonated beverages (OR = 3.8, CI = 1.2-12) and food items (OR = 11.0, CI = 2.3-54). Street-vended food items remained significantly associated with illness in multivariate analysis (OR = 6.5, CI = 1.4-31). Illness was not associated with drinking municipal tap water. Maintaining water safety is important, but slowing the epidemic in Guatemala City and elsewhere may also require improvement in street vendor food handling and hygiene.

Adolescent↗

PubMed1993

Age-specific efficacy of pertussis vaccine during epidemic and non-epidemic periods.

A national survey was conducted of 3150 notified cases of whooping cough in order to determine age-specific pertussis vaccine efficacy by the 'screening' method. The cases were collected over two periods, one just prior to the start and one at the first peak of the whooping cough epidemic of 1989-90. Vaccination status was determined by a postal questionnaire to the reporting doctor and clinical data were also collected to provide efficacy estimates according to standardized case definitions. Overall, observed vaccine efficacy was high but differed between epidemic (87%) and non-epidemic (93%) periods (P = 0.03). Efficacy estimates were generally higher for typical or severe cases than for children with an atypical illness. Vaccine efficacy declined with age (P < 0.01) but estimates remained high up to the age of 8 years. This study will provide baseline data for comparison with efficacy observed from similar studies of children immunized at an accelerated schedule and from phase III studies of acellular pertussis vaccines performed elsewhere.

Age Factors↗

PubMed1999

An epidemic of enterovirus 71 infection in Taiwan. Taiwan Enterovirus Epidemic Working Group.

BACKGROUND: Enteroviruses can cause outbreaks of hand-foot-and-mouth disease (characterized by vesicular lesions on the hands, feet, and oral mucosa) or herpangina, usually without life-threatening manifestations. In 1998 an epidemic of enterovirus 71 infection caused hand-foot-and-mouth disease and herpangina in thousands of people in Taiwan, some of whom died. METHODS: We assessed the epidemiologic aspects of this outbreak. Cases of hand-foot-and-mouth disease or herpangina in ambulatory patients were reported to the Taiwan Department of Health by a mean of 818 sentinel physicians. Severe cases in hospitalized patients were reported by 40 medical centers and regional hospitals. Viruses were isolated by 10 hospital laboratories and the department of health. RESULTS: The sentinel physicians reported 129,106 cases of hand-foot-and-mouth disease or herpangina in two waves of the epidemic, which probably represents less than 10 percent of the estimated total number of cases. There were 405 patients with severe disease, most of whom were five years old or younger; severe disease was seen in all regions of the island. Complications included encephalitis, aseptic meningitis, pulmonary edema or hemorrhage, acute flaccid paralysis, and myocarditis. Seventy-eight patients died, 71 of whom (91 percent) were five years of age or younger. Of the patients who died, 65 (83 percent) had pulmonary edema or pulmonary hemorrhage. Among patients from whom a virus was isolated, enterovirus 71 was present in 48.7 percent of outpatients with uncomplicated hand-foot-and-mouth disease or herpangina, 75 percent of hospitalized patients who survived, and 92 percent of patients who died. CONCLUSIONS: Although several enteroviruses were circulating in Taiwan during the 1998 epidemic, enterovirus 71 infection was associated with most of the serious clinical manifestations and with nearly all the deaths. Most of those who died were young, and the majority died of pulmonary edema and pulmonary hemorrhage.

Child, Preschool↗