Sunday, November 28, 2010

Key Determinants of MDR-TB in Tomsk, Russia

Multidrug-resistant tuberculosis in Tomsk, Russia has several key determinants, some of which are surprising. 

There are biological determinants including immune status (HIV status) and psychological disorders (depression).  Co-infection of HIV and TB, along with the development of MDR-TB in HIV positive persons has been reported globally.  In Russia, the dual epidemic of HIV and TB has already arrived; the risk of developing TB in HIV positive persons is 10% per year, leading to the threat of increased MDR-TB incidence. [1]  Additionally, 85% of HIV positive persons are injection-drug users, indicating a behavior determinant that could also contribute. [1] 

Psychological disorders, especially depression, are also a key determinants.  The odds ratio for having depression and developing drug resistant TB is 3.3, indicating the necessity of metal health therapies. [2] 

There are also social determinants that contribute to developing MDR-TB in Tomsk.  Several organizations have pointed out that social stigma exists against tuberculosis patients in prisons or tuberculosis patients who are ex-prisoners; being in prison, or aving history of imprisonment has also been shown to be a determinant.  Being an ex-prisoner has an OR of 1.4 for developing MDR-TB, and this population is a contributor to the population of those who don’t finish drug therapies (a risk for developing MDR-TB, as will be shown later) [2,3].  The social stigma can affect the resource pool for DOT staff. 

Perhaps the biggest social determinant is poverty.  Approximately 26% of the Tomsk population is below the poverty line. [4]  Poverty provides the ideal condition for the acceleration of TB (unsanitary housing, overcrowding, etc), and also significantly contributes to the development of MDR-TB.   Substandard treatment (interrupted treatments, insufficient medications leading to short treatment times, and poor adherence) along with MDR-TB transmission from previously infected persons (overcrowding) are cited as contributors [4].   

Environmental determinants also exist.  Hospital crowding contributes by creating reservoirs of MDR-TB.  Even in populations adherent to drug therapies, hospitalization became a significant contributor to MDR-TB development, with a hazard ratio of 6. [5]  Hospital-acquired MDR-TB may indicate pre-existing MDR-TB or re-infection with MDR-TB; infection-control actions may be needed. 

Several behavior determinants have significant effect.  With a 26% default rate, not adhering to TB treatment has an OR of 6.7 on MDR-TB development. [2]  Substance abuse is strongly associated with nonadherence, having an OR of 7.3, indicating that substance abuse is also a major behavior determinant. [5]  Indeed, alcohol abuse causes an eight-fold increase in drug resistance, and is a major predictor of MDR-TB. [6,7] 

Inadequate labs (a political determinant) is still a contributor to increased MDR-TB and TB rates [8].  Several suggestions have been made as to how they can be improved [9], so we can extrapolate to say that inadequate training, technology and staffing have contributed to inadequate laboratory diagnosis services. 

So in summary, the most important determinants that I can address:
Psychological disorders and alcohol abuse
Adherence to treatment
Poverty (substandard treatments and overcrowding)
Hospital-acquired MDR-TB
Inadequate labs  

[1] Implications of the growing HIV-1 epidemic for tuberculosis control in Russia
[2] The risk of MDR-TB and polyresistant tuberculosis among the civilian population of Tomsk city, Siberia, 1999
[3] Alcohol and drug use disorders, HIV status and drug resistance in a sample of Russian TB patients
[4] Treating Multidrug-Resistant Tuberculosis in Tomsk, Russia: Developing Programs That Address the Linkage between Poverty and Disease
[5] Barriers to successful tuberculosis treatment in Tomsk, Russian Federation: non-adherence, default and the acquisition of multidrug resistance
[6] Alcohol and drug use disorders, HIV status and drug resistance in a sample of Russian TB patients
[7] Treatment outcomes in an integrated civilian and prison MDR-TB treatment program in Russia.
 [8] Reform of tuberculosis control and DOTS within Russian public health systems: an ecological study
[9] The state-of-the-art of Russia's Laboratory Tuberculosis Diagnosis Service: basic problems and ways of their overcoming

Friday, November 19, 2010

The Magnitude of MDR-TB in Russia.

After much thought and research into several cities, I have decided to focus in on Tomsk, Russia.  Preliminary research didn’t reveal much data about MDR-TB in HIV patients in Tomsk, but more data was available for MDR-TB in new and re-treatment tuberculosis patients in Tomsk.  Therefore, I have revised my problem statement to: 

High Incidence of MDR-TB in New and Re-treatment Tuberculosis Patients in Tomsk, Russia from 1990 to Present Day. 

The role of surveillance of MDR-TB in Tomsk is given to the Tomsk City Tuberculosis Services (TCTS), which “oversees diagnosis, treatment and reporting of adult patients with TB,” following WHO guidelines [1].  Further research into the TCTS didn’t reveal much, other than the impression that there was a comprehensive network of tuberculosis facilities involved in surveillance [2], including tuberculosis laboratories that report all drug-susceptibility testing results accompanied by various other data (“new case” vs “previously treated case,” age, sex, HIV status, etc) [3]  

The WHO has a project called the Global Project (on Anti-Tuberculosis Drug Resistance Surveillance), which collects and analyzes drug-resistance, mortality and budget data from population surveys and national surveillance systems around the world.  It uses the data to help countries scale-up MDR-TB management, including standardized surveillance systems like patient surveys and drug susceptibility testing [3]. 

Interestingly, the WHO compiles country-specific data into country-specific “profiles.”  These profiles outline various surveillance parameters, some of which are indicators such as mortality, incidence and prevalence, finances.  Let’s just focus on a few of these indicators, and how they present the public health impact of the problem.  Rates such as morality, incidence and prevalence are direct indicators.   

In Russia, MDR-TB accounts for 13% of new TB cases and 49% of retreatment TB cases, as of 2007 [4].  In Tomsk, MDR-TB accounts for 11.2% of all new TB cases and 42.2% of all retreatment cases by 2003 estimates. [5] Together, the prevalence data show that Tomsk has a significant MDR-TB burden similar to Russia’s as a whole; strikingly, MDR-TB occurs a huge portion of previously-treated TB cases.  With TB incidence rates increasing by 2.1% in Russia [4], I would predict that these numbers would increase without good public health measures. 

Mortality data for MDR-TB is lacking; what I found was that in 2003, TB in general caused 17.6 deaths per 100,000 in Tomsk [5]; and since 2007, TB has caused 18 deaths per 100,000 per year in Russia as a whole [4].  Steady mortality rates may indicate that treatment protocols aren’t being largely beneficial across the board. 

TB budget expenditures of Russia [4] are an indirect indicator of the MDR-TB problem in Russia.  In 2009, the largest budget component (36%) was for staff dedicated to TB control, 28% for TB hospitals and 11% for MDR-TB, indicating that MDR-TB is recognized as a significant problem in Russia. 

A systematic weakness in most of these data from Russia is that this is reported data from facilities such as labs and hospitals.  For those in the rural areas or without access to such facilities, they may not be represented in these statistics.  For example, this could be reflected in the statistics taken from source 5, since the data is reported to be collected by the Tomsk Oblast Tuberculosis Services or TCTS. 

[1] http://www.who.int/bulletin/volumes/85/9/06-038331/en/
[2] http://eurpub.oxfordjournals.org/content/17/1/98.full
[3] “Guidelines for surveillance of drug resistance in tuberculosis” Fourth edition
[4] “Global Tuberculosis Control WHO Report 2009”
[5] “Treating Multidrug-Resistant Tuberculosis in Tomsk, Russia”

Friday, November 12, 2010

Tuberculosis: A Resilient Killer

The tuberculosis bacterium is a nasty organism to deal with.  It has all sorts of tricks, like having a very thick outer coating that enables it to survive inside the body for long periods of time.  Tuberculosis has also developed the ability to resist drugs that are typically used against it. 

The bacterium is causing an annual global burden of twelve billion [1] while infecting one third of the world’s population [2].  A population that is especially threatened by tuberculosis is HIV positive people; for them, developing tuberculosis is a much higher possibility than if they were HIV negative.  In fact, research indicates that HIV and TB facilitate each other’s attack on our immune system.  Interestingly, in HIV positive people, multi-drug-resistant tuberculosis (MDR-TB) is twice as common than in HIV negative people [3]. 

These observations indicate that HIV and TB must be addressed together, and that MDR-TB among HIV positive persons is a significant emerging issue.  I would like to base my paper on the topic of MDR-TB in HIV positive persons.   

I find this topic interesting because of so many factors that contribute to tuberculosis and the emergence of MDR-TB.  Tuberculosis and poverty form a cycle of disaster.  Because poverty correlates with hunger, lack of sanitation and poor housing conditions, poverty forms a friendly breeding ground for tuberculosis.  Tuberculosis then worsens the situation by decreasing people’s capacity to work, makes them poorer due to expensive treatments, and generally exacerbates poverty. 

It is also interesting that poverty correlates with high incidence of HIV in inner cities.  So it would be possible that the topic can be focused on MDR-TB in HIV positive persons in inner cities.   

I think this is an important topic to investigate because biomedical research still has to make major improvements in the realm of MDR-TB and effective tuberculosis vaccinations.  MDR-TB is something that would only be exacerbated if treated with more drugs, so the most effective approach would be a public health approach.  There are some novel ideas coming out from research, like using antimicrobial pigments from Antarctic bacteria to treat TB, but that could take years to develop and test. 

I hypothesize that by focusing on MDR-TB in HIV positive persons, we can tailor MDR-TB or TB prevention programs specifically to HIV positive persons.  By using models from various existing inner-city programs that work, MDR-TB/TB prevention programs for HIV positive persons can be targeted to HIV positive persons living in inner cities. 

I am already eying Partners in Health and their community-based programs in Boston as a good source of information, and certainly a model to consider. 

[1] http://www.who.int/trade/distance_learning/gpgh/gpgh3/en/index7.html

[2] http://www.who.int/mediacentre/factsheets/fs104/en/

[3] http://www.unaids.org/en/KnowledgeCentre/Resources/FeatureStories/archive/2008/20080227_MDR_rprt_for_UNAIDS.asp

Sunday, November 7, 2010

The Half-way Point

It’s astounding how much was covered in the first half of Intro to Public Health!  We’ve covered the science, the economics, and even the environmental aspects behind public health (and that’s not even the full list.)

The design of the class makes it easy for us to understand this wide variety of topics.  I enjoyed how there were different lectures each class, and each lecture used the textbook for background information.  This combination helped to identify the most pertinent concepts being taught in each topic.  The weekly blog posts are also contributing to my understanding of each topic.  Because the posts require some reflection, concepts are reinforced and applied in sample scenarios.  But of course, it also matters how much I enjoy the topics.

The topics in which I felt most engaged include epidemiology, infectious disease and history of public health.  I enjoyed epidemiology not only because I had background in epi, but also because Dr. Alexander dissected into its definition; that epi is the study of distribution and determinants of disease frequencies was subtly taught to me previously, but not explicitly said.  In the context of this definition, epi began to make more and more sense, and because the strongest/clearest part of public health for me.

Infectious disease was also interesting to me because of the many possibilities for intervention, and because of the recent vaccine-fear issues.  Since vaccination is one method to break the chain of infection, fear about vaccines can undermine the goal of prevention.  To me this was particularly interesting because whereas one might think that an intervention in the chain of infection would be foolproof, human qualities can cause an intervention to fail or be weaker than designed.

I don’t think I ever intended on taking interest in the history of public health, but the lecture surprised and convinced me otherwise.  Public health was described as the “promise of control,” but sometimes public health falls short.  This is where history of public health comes in and investigates to learn from public health’s successes and failures; and to determine how societal and governmental functions can affect public health programs.  I especially enjoyed learning about cholera and how John Snow’s study shifted the paradigm from “treat to prevent.”  In the context of the modern world, I feel that this is important because often we address issues with treatments rather than preventions (take food contamination and swine flu as examples).

My first post described how I wanted “this course [to] change all my preconceptions and inspire me to think cleverly about future public health.”  I feel that so far, it has done so; I got exposed to areas I never even knew were involved in public health (e.g. health services research).  And where I used to think of public health as unnecessarily involving too much politics and economics, I now know that these two areas have significant impact on public health.  I would say that my interests in public health have broadened and now, I can see the relevance of several topics.

I am looking forward to learning more about some specific topics, and slowly narrowing down.

Eric

Friday, October 29, 2010

Protecting the Community by Limiting Rights

The spread of infectious disease can wreak havoc on a society’s organization and economy.  For example, the economic impact of a flu pandemic in the US would be at minimum $71 billion. [1]  It follows that in order to ensure a society’s function and economy, the public must be protected from infectious disease.  However, defensive measures, and the extent to which public health can use them, are debatable issues.

When health officials think an infectious disease is present in a population, they can either quarantine or isolate individuals.  Though in everyday terms quarantine and isolate seem interchangeable, they are actually distinct.  Quarantine applies to those who have been exposed to an infectious disease but are not yet sick; isolation applies to those who are already sick.

For example, if during a flight someone has a particularly contagious infectious disease, then those around him would be quarantined (probably asked to stay indoors, treated and observed for early signs of illness.)  The sick person would be isolated and given special care, and his caregivers would be protected to prevent infection by the disease.  In general, the idea with quarantine and isolation is to “prevent further potential spread of the illness.”[2]  However, these methods require restricting the freedoms of people, putting the safety of the community above freedoms of an individual.

What becomes hot debate, then, is who has the power to decide whether an individual’s freedoms should be restricted (or whether this individual should be quarantined.)  The legislative branch dictates laws, and public health law is warranted under the police power of a state, which must take measures to protect the general welfare and health of the state.  Public health laws set up agencies that make regulations to achieve a well and healthy state; these regulations have the force of law.

Sometimes these regulations state that an infected person must be quarantined and isolated from society.  The health agency, doctors and the patient are involved in deciding whether such actions must be taken.  However, it is complex when one considers questions such as to where? and is this necessary to protect public health?, questions that could involve judicial review.  An example is the 1909 case Kirk v. Board of Health, in which Miss Kirk, a sufferer of leprosy, fought the board (the agency) that ordered her to vacate her home and temporarily move into a “pesthouse,” awaiting construction of a “comfortable cottage outside of the city” for her.

It was decided that the pesthouse was a health hazard in itself, and that “even temporary isolation…would be a serious affliction and peril to [Miss Kirk].”  Instead, the court preferred to wait for the cottage to be built.  The court also addressed the necessity of sending Miss Kirk to the pesthouse.  Since Miss Kirk’s form of leprosy was found to be hardly dangerous, the court deemed the pesthouse as an unnecessary measure.  So, even though public health laws guarantee the health of a state, and agencies go about to ensure these laws are met, courts can become involved in checking to make sure agency actions are rational.

I feel that judicial review, given accurate and adequate evidence, should balance the individual’s rights against the community’s rights.  The only exception would be when a disease is clearly contagious/dangerous and requires immediate action.  This would favor the community’s rights in the worst-case situation; this is exactly what is needed because in a worst-case situation, one mistake could be deadly for the community.

Friday, October 22, 2010

Global Health: Can it continue?

Global health takes on big issues that are often complex and multifaceted.  To tackle these issues, more than simply money is required, as Laurie Garrett’s The Challenge of Global Health explains.

Garrett’s article discusses several issues that prevent global health efforts from being effective.  To begin, she talks about aid being “tied to short-term numerical targets,” which means that aid often focuses more on particular diseases than on broad measures that would address general well-being.  Garrett argues that narrowly focused programs are unsustainable, and that agencies/donors should “integrate their infectious-disease programs into general public health systems.”  Such integration would allow for treatment and prevention to be addressed, making aid programs more effective.

But how would one distinguish the effectiveness of healthcare systems?  Garrett proposes two important markers that are telling: maternal mortality and life expectancy.  Maternal mortality data would reflect the “overall status of healthcare systems:” the conditions of facilities, along with the training and amount of personnel.  Life expectancy data tells about “child survival and essential public health services,” essentially the broad-spectrum services that allow for survival through childhood (e.g. safe water, mosquito control and immunization).  These markers are critical because they can contribute to a feedback loop where weaknesses of systems (issues that a system doesn’t address) are identified and improved upon.

Garrett also argues that despite the enormous monetary aid, global health continues to decline.  There are several reasons including narrow spending and corruption and bureaucracy trapping money.  Corruption and bureaucracy seem to be common among developing countries.  The World Bank estimated that “about half of all funds” for sub-Saharan Africa never reached the clinics and hospitals they were intended for.  Instead, the funds were misspent and even involved in the black market and sale of counterfeit medications.  But even following legal routes, funding still gets lost in the maze of “financing bureaucracy,” severely hampering health-delivery systems by a least 15%.  However, even if aid does reach a program, the narrowly defined goals can prove detrimental to global health.

Referred to as “stovepiping,” these goals tend to reflect the interests of the donors instead of those of the recipients- the people in need of help.  This causes phenomena that we see every month: a disaster or epidemic breaks out, and massive donations are made.  These diseases and health conditions bask in “a temporary spotlight,” which draws attention away from other broader and more statistically important killers (i.e. maternal death during childbirth and pediatric respiratory and intestinal infections.)  Garrett points out that stovepiping also causes a shift in the interests of health-care workers, as more move towards the money and abandon other programs that “lack activist constituencies.”

Therefore, there is a strong need for integrated programs that can “prevent, recognize, control, and treat infectious diseases.”  The beauty of such a model, as Garrett proposes, is that the ideal model can be generalized to include chronic diseases.  Initially, steady funding and lasting support are needed, but attention to execution is also important.

Current donor practices need to be improved; faulty programs that lack effectiveness and sustainability are likely to be detrimental to public health.  For example, failed tuberculosis programs that poorly handled tuberculosis treatment (the majority of patients did not complete antibiotic therapy) led to the emergence of XDR-TB.  Other examples include mass vaccination campaigns gone wrong when lack of funding forced health-care workers to reuse needles, leading to a spread of HIV.

There’s enormous opportunity in this era to make a difference in global health, and Garrett’s got the right idea.  If we can make smart programs that provide local infrastructure and address the big picture, instead of focusing on narrow goals and relying on donor support, then we can make sustainable programs.

Eric Wan

Friday, October 15, 2010

Vaccinations: Necessary or just a hassle?

A month ago, I blogged about the controversy surrounding vaccines, specifically the MMR vaccine which was wrongly accused of causing autism.  A couple weeks later, the Washington Post published an article about whooping cough and its vaccines, the histories thereof, and whether people should get immunized.

Whooping cough is caused by the Pertussis bacterium, which attacks the cells in our lungs.  Before vaccines were available, the number of cases was near 150,000 people annually.  However, when vaccinations became widely used, the number of cases dropped to a low of 1,000 in 1976.  Since then, the number of cases has increased to a peak of 25,000 in 2005.  The article addresses several reasons why this might be case.

In some states like California, it is “legal and quite easy” to refuse being vaccinated or getting your child vaccinated.  This forms groups of unvaccinated people throughout communities, and these clusters undermine a fundamental purpose of vaccinations: herd immunity.  Herd immunity works by diluting the number of cases in a community by giving a large population within the community resistance to disease.  It is a method to protect the whole population from disease, by simply protecting a majority.

However, it only works when there is an immunized “herd,” meaning people have to get immunized for herd immunity to work.  But there always seems to be reasons why people aren’t getting immunized.  Reasons might include a patient or parent’s fear of side effects from the vaccine (see MMR-Autism post), or their ignorance of the dangers of the disease.  Since whooping cough rarely occurred several decades ago, young parents might not remember the threat it poses.

Reasons could also have nothing to do with patients; their doctors could be foregoing vaccination because it is perceived as “a disease of the past,” or because they feel that evidence for a vaccine’s effectiveness is lacking.  Reasons could also orginate from the healthcare system itself; if the healthcare system doesn’t feel that immunizations are an effective intervention, then it is likely that more emphasis will be placed on treatment (which of course doesn’t help to prevent disease.)  Also, pharmaceutical companies are hugely important to the healthcare system, and may be reluctant to develop vaccines because of low cost-effectiveness.  All of these reasons may attribute to a lack of immunization in the community, but they do not fully explain why whooping cough cases are increasing.

Other contributing factors discussed by the article include mutation of Pertussis and the low effectiveness of the new vaccine compared to the old one.  There’s quite a bit of science behind each of these, and for vaccines, different types can have different efficacies.

However, in the grand scheme of things, this doesn’t mean that one shouldn’t get vaccinated.  Vaccinations won’t protect you fully but certainly it will offer a significant degree of protection (compared to having no protection).  But in order to increase vaccination, I think a few priorities have to be tackled: firstly, there must be better campaigns for vaccination for diseases that are re-emerging (emerging diseases are new, but re-emerging diseases are often forgotten by the public).  Secondly, I feel strongly that states should mandate vaccinations for all eligible.  Since not everyone is eligible (e.g. newborns often aren’t), herd immunity has already been impaired to a degree.  Having those eligible but not vaccinated is weakening herd immunity more.  Thirdly, I feel that more emphasis should be placed on federal vaccine research.  Pharmaceuticals tend not to share their data, even if it is good data that could help the population.  So if they deem a good vaccine as not cost-effective based on a poor (low profit) market for a certain vaccine, then the federal government can provide those vaccines.

Eric Wan