Emerging Infections of International Public Health Importance

Objectives:

Understand the emergence of the HIV global epidemic and contributing factors
Understand the impact of the HIV epidemic on health and society
Understand the strategies for reducing illness and death due to HIV and current impediments in implementing these strategies.

I have been working in HIV/AIDS both domestically and internationally for a fair amount of time and it is always interesting for me to see the interface between the domestic US situation and what is going on globally. How it contrasts and how there are similarities and how there are trends between all of them that are important.

I am going to use HIV as an example about the emergence of an epidemic. HIV is the only disease in our generation that has emerged suddenly to become a major global health problem.

First, in 1981 HIV began as a syndrome seen among 5 young men who had sex with men, who were treated for PCP, pneumocystis carinii pneumonia, which is very rare pneumonia and never seen before among healthy young men. In September 1982, AIDS was defined as an acquired immunodeficiency syndrome. In 1993 the Centers for Diseases Control did an investigation in Kinshasa, Zaire and noted that a similar immunedeficiency illness was present in Africa but with a different epidemiologic pattern. It was happening to heterosexuals, not just gay men or intravenous drug users. In 1995, Rock Hudson died of AIDS, the same year a test for the virus became available. In1986-1987 the World Health Organization AIDS program began which was an important hallmark because that was the first time an international body came together to focus on this problem and that a whole program was actually devoted to it. Zidovudine (AZT) the first drug for HIV was introduced in1987. By 1996, there were 3 classes of antiretroviral medication including the protease inhibitors and for the first time saw the mortality rates declining in the United States.

Here we are today where HIV is now the leading cause of infectious death and the fourth leading cause of death worldwide. It accounts for about 5% of death world wide, but if you look at infectious causes it is the single leading specific infectious cause preceded only by acute respiratory infections which are a variety of different infections.

Currently the largest burden of this disease is in sub-Saharan Africa which accounts for almost 70% of current infections. Ninety five percent of new infections are occurring in the developing world with Southeast Asia beginning to have rapid spread of HIV.

The human impact of this is emphasized by the huge increase in orphans as a result of the deaths from HIV/AIDS which may likely reach over 40 million by 2010. This is clearly an epidemic that has shaped our world and will continue to do so in this 21st century. Another perspective is this:

This table gives a sense of an ever expanding epidemic and one that is going in different phases throughout the world. This table summarizes the current epidemic trends of infection with HIV/AIDS and the mode of transmission for different parts of the world.

The trend in the US for those affected with HIV/AIDS is showing a decline among the Caucasian population and a persistent increasing slope among African Americans and Hispanics. If we look at infection rates by risk behavior we see an increasing trend of infection among heterosexual contacts and an increase among women. The epidemic is now disproportionably impacting minority populations and the number of women infected is steadily growing.

In the United States the number of new infections has remained relatively stable with about 40,000 new cases annually. From a public health perspective this is an unacceptably high number. There are currently approximately 900,000 persons infected. The epidemic is spreading to more diverse populations. The good news is we have very effective antiviral therapies so people are living longer.

This also means that we have more people living with the disease and continued new infections so the burden of disease becomes greater over time. The other success is the reduction of perinatal transmission of HIV by using antiretroviral therapy. The ACTG study 076 led to the discovery that use of AZT reduced mother to child transmission by two-thirds. Currently in the United States the risk of perinatal transmission can be less than 2% with each birth.

Ninety five percent of people living with HIV/AIDS reside in developing countries.

Main causes of death between higher income countries and lower income countries show that infectious diseases account for almost 50% of mortality in low income countries compared to approximately 5% in higher income countries.

This slide shows that among infectious disease AIDS is the largest single killer. It is important to remember that HIV/AIDS affects persons most in the 15-49 years of age, the segment of society that shapes its economy and working force. This has economic, security, and public health consequences.

This slide emphasizes that sub-Saharan Africa has the greatest impact of disease with a steep continued increase over time. Looking in the later 1990’s Asia and Eastern Europe are beginning to expand and will likely grow most rapidly over the next decade.
There are approximately 14,000 new infections daily worldwide. Twelve thousand are in persons aged 15-49 and 2000 in children younger than 15. Fifty percent of the new infections are in women.

[Figure: Africa - HIV Seroprevalence in Pregnant Women]

[Figure: Africa - AIDS Estimated Impact on Child Mortality Rates]

These 3 slides show that the HIV/AIDS epidemic has different trends for different regions but the general trends are for increasing infection rates and decreasing life expectancy. Botswana has some of the highest seroprevalence as well as the most significant change in life expectancy. In the under 5 mortality we see that there is a 4 fold increase in death due to the HIV/AIDS epidemic. Extending out to 2010 this will likely continue to rise.

[Figure: Lifetime Risk of AIDS Death]

This slide looks at the lifetime risk of AIDS death for 15yo boys both assuming no change in the epidemic and assuming a reduction of 1/2 the cases. In either scenario a 15 year old boy has anywhere from a 20-80% chance of dying from HIV depending on the specific country epidemic. This number is still significantly high even if the infection is reduced by half.

[Figure: Seroprevalence of Pregnant Women]

Surveillance can sometimes be difficult for this disease but one way to look at trends is to use the sentinel population of pregnant women and the HIV seroprevalence in this group.
We can see that from the early 1990’s to 2000 the rates have increased to as high as 35%.

This slide shows the current seroprevalence in this portion of SE Asia with increasing rates in most countries especially Cambodia which has the highest prevalence rate among adults.

[Figure: HIV/AIDS in India]

India is now second only to South Africa in the number of people infected with HIV.
The overall rate of infection may only be 1% but this translates into at least 4 million persons.

[Figure: HIV/AIDS in China]

This slide shows the chronology of HIV/AIDS epidemic over time. With now every province of China reporting cases of HIV/AIDS.

This slide is showing the dissemination of the epidemic in Latin America and Caribbean from 1984 to 1999.

[Figure: Trends]

This slide emphasizes the new AIDS cases per year with the highest increasing rates in the Caribbean.

This rise of HIV parallels the increase in syphilis rates in Russia during this same time period.

On the household level there is personal grief, breakdown of families, interruption of schooling, reduced production, lost income, and increased health care expenditures.

On the institutional level there are increased health care costs, industry absenteeism, staff replacement, loss of professionals, and skilled staff workers.

The macro effects of this disease can lead to a decrease in the gross domestic product and its sequelae.

[Figure: Expected AIDS Rx Costs and Economic Impact]

These 2 slides show the type of economic impact HIV/AIDS has on the government health spending and on the decline of the gross national product depending on the burden of the disease.
For example, by 2014 it is estimated that almost 40% of the Ministry of Health budget in Ethiopia will be spend on AIDS care. This does not include the needs from other diseases.
The decline of the gross national product has a huge toll on a country being able to finance their health budget among other responsibilities.

This slide emphasizes that Uganda had a huge prevalence of HIV in the early 1990’s and through a series of steps was able to reduce its prevalence from 30% down to 12%. In order for this to be successful they needed strong political commitment, donor support, a comprehensive national AIDS plan and community involvement. Their willingness and commitment to making a difference has been very visible and effective.

[Figure: Prevalence by Age Group and Year]

This slide shows the reduction of HIV seroprevalence among Thai army conscripts from 1989-2000. They were able to reduce the prevalence by a series of steps including government sponsored condom campaigns, treating sexually transmitted diseases, and enhancing public information.

[Figure: Cambodia and Sex Workers]

These slides show that with increasing condom use among commercial sex workers the prevalence of HIV among the police declines.

The second slide has shown a small decline in HIV seroprevalence. Hopefully with continued condom use this trend will also continue to decline.

[Figure: India - Use of Condoms]

This shows that condom use with commercial sex partners demonstrated an increase.

[Figure: AIDS in Brazil]

Brazil took the strategy of aggressive antiretroviral treatment of their HIV infected persons along with a prevention campaign. There was increased testing and treatment since they made treatment available to anyone infected.

Some of the global strategies that have been established for control of HIV/AIDS are:

This graph shows by region the estimated coverage of those infected with HIV by use of HAART (highly active antiretroviral therapy)

Some of the issues with geographic discrepancy and constraints are multifactorial but include the following;

The things that should be available to all the population going up the ladder if you will to more and more sophisticated levels of care. And that is just one way of looking at how you would build the appropriate level of services given the stage of the epidemic that you may be facing.

Estimated that in the United States we will need approximately 9.2 billion dollars for prevention and care support by 2005 for HIV/AIDS.

[Figure: Resources Needed]

If we look at this slide for just HIV/AIDS care the additional resources needed will be 7-10 billion dollars annually, which would include 3 billion for prevention and 4 billion for care.

The Commission on Macroeconomics and Health in their 2001 report came out with the following conclusions:

Official development assistance (ODA) is what rich governments provide financially to poor governments. The first slide looks at net ODA shows that the United States is second to Japan in terms of our assistance.

However in the second slide if we look at this in relation to what the countries gross national income, the United States ranks at the bottom of the list. With countries such as Denmark and others giving a far greater percentage of GNP than larger and wealthier countries. The United Nations has suggested a target of 0.7% of the gross domestic product to be fair and equitable and reasonable for countries to give.

In conclusion, HIV/AIDS will continue to be a global public health problem which will require continued efforts at both treatment strategies and prevention/control strategies. The use of public/government and private partnerships will be important to turn the current trend of this disease.

Study Questions:

Name 2 factors that have led to the spread of HIV/AIDS and describe how.
Describe why HIV/AIDS is a global security problem.
Describe some of the difficulties with implementing the global AIDS, malaria and TB fund.