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University of Toronto Scarborough
Health Studies
Caroline Barakat

HLTC07: Patterns of Health, Disease, and Injury Lecture 9: Patterns of Infectious Disease/Tuberculosis and Influenza Lecture Outline  Introduction to TB o Burden (of morbidity and mortality) o TB / HIV o Drug-Resistant o Economic Burden  Introduction to Influenza o Epidemiology o Influenza control Introduction to TB  Currently, the 2 most infectious disease that kills worldwide o Figure 1: gives an indication what are the different types of infectious diseases (based on 2007 data)  # 1 most infectious: respiratory illness followed by TB (as #2)  These number do change  Graph shows 2007 data, with 3.1 million global death from TB  Current death rate: has gone down to: 1.6 million global deaths from TB  4,400 individuals per day die from tuberculosis  It's estimate that in the past 2 centuries TB has accounted for approximately one billion deaths  Industrialization and urbanization - colonization o The disease became very common as cities began to industrializing and urbanizing in Europe, essentially in Asia o These processes began extending into colonization and spread from Europe and Asia to N. America and Africa  Indth & China - TB reached epidemic levels at the turn of the 20 century o Both of these are top countries in terms of incidence of TB worldwide TB trends and Determinants  TB used to be very prevalent in the 1800s, and sanatorium flourished in the 16th and 17th centuries to reduce the rates of TB  1940s - TB death rates began a steep decline in Europe and North America o Largely due to the use of antibiotics o Specifically, antibiotics that were very effective in treating TB were Streptomycin and isoniazid  Resurgence as economic inequalities increased o Since the 1940s-1950s, income inequalities were very small o As time progressed to 1980s and 1990s, income inequalities and changes in terms of social disparities increased (bigger gap between income and inequalities) worldwide o Increase in economic inequalities occurred later in the 20th century also led to the resurgence of TB in some developed countries such as the US o Income inequalities increased , gaps between the social disparity increases the resurgence of TB 1980s and 1990s became a reality  Rates of TB - indicators of wealth or poverty, and particularly of resource disparities o Economic factors led to certain people becoming poor o Differences in terms of poverty and urban settings, have large prevalence of TB, when it comes to people with low SES, homeless people, immigrants, and crowded housing o TB known as crowding disease because people are very likely to get TB when they live in small-density homes with large number of people occupying the space leading to higher incidence of TB o About a century ago, we know that TB ravaged everyone equally, whether they were rich or poor o Now TB is more of an indicator of a country's poverty level or wealth or an indicator for disparity or the inequalities within a specific country Examples of specific countries that show that their poverty, wealth, or disparities led to the resurgence/increase in incidence of TB Figure 1  Map of estimated TB incidence rates in 2011  Darker the colour gets, we know that TB cases increases  Sub-Saharan Africa – resources scarce - TB incidence rates are highest in this region Figure 2  In countries, where TB therapy was available for some time, but may have been improperly prescribed, or frequent drug shortages of multi-drug resistance TB  The darker colours show more increase in MDR resistance  More prevalent in Asia an USSR  This is probably due to improper drug use or shortage of drugs which have led to multidrug-resistant TB  In areas, where there were programs, but the findings of those programs was cut and the political support for eradicating or decreasing TB incidence were cut away in the years  Shows there is an increase in TB and an increase in multi-drug resistance TB  So if you put these two maps together, shows that there were programs at one time, but they were defunded, and led to the increase of TB  We need to acknowledge the understanding of social inequality is essential to our understanding the persistence and the resurgence of TB, as well as increase of MDR-TB Figure 3  Study took place in Brazil  This study aimed to evaluate the epidemiological status of Tuberculosis regarding to the socioeconomic characteristics of São José do Rio Preto between 1998 and 2004  Indexes estimated for 432 urban census tracts from the demographic census of 2000  Divided them into 4 socioeconomic levels  Clear differences between TB cases in each level between both year of occurrence  Level 4 shows less TB cases and higher SES  Two programs may have led to TB control levels that took place to decrease of TB cases  In socioeconomic level 1, TB cases went down from 51.7 to 37.7 cases per 100 000  The overall pattern is that higher the SES of an individual, the lower incidence of TB occurring throughout the years Figure 4  National report from WHO from 2000  Maps TB incidence from 100 000 population against the GDP  Trend: as GDP increases (higher income for a country), the TB incidence decreases worldwide and vice versa  Outlier in the graph show high HIV/AIDS levels, so what does that mean? o TB and HIV are connected, both are syndemic disease, where, being exposed to TB can result in developing HIV (or vice versa) o Lower immunity due to HIV can result in latent TB to become active, therefore incidence rates tend to be higher Burden of TB Morbidity and Mortality  According to WHO 2007 report, approximately 1/3 of the world’s population is infected with TB  Among the new cases of death from TB, more than 95% are thought to occur in developing countries  In different trends, developed countries have treatment and quality of health care  Preventative actions to prevent new cases of TB  In developing countries, these actions do not exist or they are not used effectively  Imbalance in this disease burden is due to: 1. Underfunding of public health (in developing countries) 2. Higher prevalence of HIV/AIDS (in certain developing countries) 3. Emergence of drug-resistant TB Figure 5: WHO (2005)  Funding in TB in developed vs. developing  Depicts funding of TB among 5 WHO regions in the world  Higher funding in South-east Asia, Western Pacific, and then Africa  For Africa, the budget tends to be higher and funding is low  In Americas, the budget, available funding, and expenditures are at the same level  Not seen in this graph is funding within North and South America, where in the South there is a larger gap in funding How are data on the burden of TB collected?  Largely based on case notification, where each country will notify the WHO of the cases that they have  Each notification is also dependent on several factors  Case notification versus True incidence o In many cases, case notification may be significantly different than the true incidence of the disease  Each notification depends on: 1. Health service coverage  In those countries, where there is existing health service coverage that's widely available where the case notification tends to be very close to the true incidence rate  e.g. Canada and its universal health care for its citizens 2. Efficiency of case-finding  Is extremely important  Different countries may have different levels of efficiency when it comes to case-finding  e.g. Canada and its universal health care for its citizens provides efficiency 3. Reporting activities  Is there a system that translates this information?  If someone is diagnosed with TB, what does the system do?  WHO uses case notifications and modeling methods to estimate the global TB disease burden o In most developing countries, this is not the case o Case notification tends to be only a fraction of the true incidence o And so, WHO, to come up with number of TB cases will use case notifications, but also use other modelling methods to estimate the global TB disease burden Recent trends in case notifications (NOT GLOBAL BURDEN)  Case notifications of TB has been steadily falling in SE Asia and Western Pacific regions, in Western and Central Europe, and North and Latin America o Are showing that there is less cases of TB reported to WHO  Case reports have been increasing in Eastern Europe ( former Soviet Union) since 1990, and Sub-saharan Africa since 1980s and it continues  In some places, case notification are steadily decreasing and increasing slightly, although the rate of increase (seen in the former Soviet Union) and Sub-Saharan Africa is little bit lower and slower in the past few years  Why is there an increase in resurgence of TB in Europe (such as the former Soviet Union) since the 1990s ? 1. Economic decline 2. Poor TB control 3. Poor general infrastructure (poor medical care, poverty, increased inequalities)  Elevated drug resistance TB in this region is also there, but it's probably a by-product of this increase in poor economic decline and poor TB control and not a cause of the larger incidence of TB cases  1990s – now there is still an increase of TB in former soviet union, whereas there is a decrease of TB in central and eastern Europe  Figure 6: Trends in TB incidence in eastern European and central Asian countries, 1990–2005. Former Soviet Union (FSU) countries include Armenia, Azerbaijan, Belarus, Estonia, Georgia, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Moldova, Russia, Turkmenistan, Ukraine, Uzbekistan; Central and Eastern European non-FSU countries include Albania, Bosnia, Bulgaria, Croatia, Czech Republic, Hungary, Macedonia, Poland, Romania, Slovakia, and Slovenia [WHO Global Tuberculosis Database 2007 (5)]. Estimated incidence and mortality  Report by the WHO indicates that TB incidence rate were stable or in decline in all the 6 WHO regions  In general, we're looking at the regional level, there is a trend moving towards stability  Country-level burden of TB; there are 5 countries with the highest levels of TB 1. India 2. China 3. South Africa 4. Indonesia 5. Pakistan  N and S Americas and Europe accounts for 9% of the world’s TB burden o In North America and Europe, more than 50 % of TB cases are reported tend to come from people who are not born in the country (born somewhere else and they immigrate to the countries) o The TB tends to be active after they immigrate to this region Figure 7  TB cases in 2011 shows 22 high-burden countries in terms of b
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