Nature Methods
- 4, 887 - 890 (2007)
Published online: 22 October 2007; | doi:10.1038/nmeth1119
Research in situRobert M GrantRobert M. Grant is at the J. David Gladstone Institutes and University of California San Francisco, San Francisco, California 94158, USA. robert.grant@ucsf.edu Research performed where epidemics hit the hardest is necessary to bring solutions to the major health crises that plague poverty-stricken areas. Far from being limited to these areas, 'research in situ' can benefit health management worldwide. There are pressing technological needs to be addressed in order to facilitate such research.Elegant successes in technology and drug development arising from well-funded research do not always have a direct impact on epidemics that rampage the world. The root causes of the disconnect between scientific advances and public health relate to disparities in social justice: while the world's wealth increases by $2.7–3.8 trillion per year1, poverty, violence and lack of education persist. These conditions directly impact health by decreasing access to clean water, adequate nutrition and healthcare for the majority of the world's population. On the individual level, poverty forces people to trade long-term health for short-term safety, food and housing. Although the promotion of social justice is ultimately political, scientific research and technological development are informed by the situation, and can be reformed to provide tools of much greater utility and wider application.
AIDS and tuberculosis are two infectious diseases that account for 4.5 million deaths2,
3 per year, mainly in Africa, Asia and Latin America. Research in situ, conducted where these epidemics hit the hardest, requires the development of laboratory tools that are rapid and robust in the face of microbial and human diversity, and limited technological infrastructure.
AIDS
Human immunodeficiency virus (HIV) infection is the cause of AIDS4. Rapid tests have been developed to allow screening for the presence of antibodies to HIV in a patient at the point of care (reviewed in ref. 5). These tests use unprocessed samples (such as whole blood or oral fluid) and are interpreted visually, requiring no instrumentation.
Although originally intended for use in field situations with limited access to advanced technology, these rapid tests have revolutionized voluntary testing and counseling in all parts of the world. These tests can be less expensive to perform than conventional enzyme-linked immunosorbent assays (ELISAs) and have comparable sensitivity and specificity. Very importantly, these tests allow post-test counseling to be performed the same day, thereby avoiding the anxiety-laden period between the test and the result, and the lack of follow-up. The rapid format also allows testing in emergencies, such as after a needle-stick exposure, or during labor and delivery.
The development of rapid HIV antibody tests is one of the clearest examples of how technology adapted for use in resource-poor settings can benefit everyone. The principles of rapid testing are now being extended to tests for other infections, such as hepatitis B, dengue and sexually transmitted infections.
Similar advances for laboratory tests used to monitor HIV treatment are needed to adapt the technology to public health needs. Periodic measurements of viral RNA levels in plasma and of CD4+ T cell counts are commonly used for monitoring HIV-infected patients treated with antiretroviral therapies in well-resourced settings. The clinical utility of these tests for monitoring therapy, however, has not been formally evaluated, partly because the cost of laboratory monitoring is a small fraction of the total treatment costs in well-resourced regions. Not so in resource-poor areas where, in comparison to prices in developed countries, laboratory reagent prices are frequently higher whereas anti-retroviral drugs are marketed at much lower prices.
The clinical utility of laboratory monitoring during AIDS therapy is being evaluated rigorously for the first time in an Africa-based clinical trial called DART, or Development of Anti-Retroviral Therapy in Africa, which randomizes persons to receive anti-retroviral therapy managed with or without routine use of hematology, chemistry and CD4+ T cell count laboratory test results6. Again, research in Africa leads the way for optimizing care everywhere.
While the utility of CD4+ T cell counts for preventing disease and death during therapy is being investigated, these tests have a defined role in the decision of when to start therapy. For example, CD4+ T cell measurements are used to identify patients who should initiate therapy and to guide the use of chemoprophylaxis for opportunistic infections such as pneumocystis pneumonia and cryptococcal meningitis. CD4+ T counts are also important for selecting therapy because one of the most cost-effective drugs, nevirapine, is not recommended for therapy unless the CD4+ T cell count is below normal. Thus, the development of easy and inexpensive CD4+ T cell tests should be a priority, and progress is being made using manual microscopy7 and microchips8.
Laboratory assays that directly detect the virus can reveal so-called 'virological' drug failure, when a patient's infection is no longer suppressed by medications, as indicated by a significant increase in plasma viral RNA level. Although the utility of these assays for preventing disease and death during treatment is not yet known, there is evidence that continuing therapy in the face of virological drug failure is associated with accumulation of drug resistance9. Timely detection of virological drug failure should prompt assessment of the adherence to or a change in treatment regimen.
Viral detection assays are also used to screen the blood supply and to detect acute HIV infection in persons whose blood is still seronegative. Detection of acute infection is particularly important because as many as 50% of new HIV infections come from partners who are acutely infected (for example, refs. 10,11). Identifying people in the highly infectious phase before seroconversion may prove to be important for stopping the pandemic, one outbreak at a time. Thus, rapid inexpensive tests for detecting the virus are needed. To date, progress has been made based on the detection of viral nucleic acids, reverse transcriptase activity or viral antigens (reviewed in ref. 12).
The utility and cost-effectiveness of assays that detect viral mutations associated with drug resistance (so-called drug resistance genotyping tests) in resource-poor settings remains to be fully evaluated—more sensitive and cost-effective approaches are being developed based on sequence-specific ligation reactions and kinetic PCR13,
14.
HIV prevention is the foundation for sustaining treatment
By December 2006, it was estimated that more than 2 million people living with HIV/AIDS were receiving treatment in low- and middle-income countries, representing 28% of the estimated 7.1 million people in need15. Although the availability of treatment has substantially increased over recent years and these advances are extremely important for the families who have benefited from them, the success of treatment must be compared with the ongoing spread of HIV—4.3 million persons are infected per year. Put in other terms, for every person added to the treatment rolls in 2006, six new people became infected. Development of more effective prevention tools and greater use of existing tools are essential for the sustainability of treatment programs.
Research and use of biomedical prevention tools will require novel and appropriate laboratory tools. A case in point is the study of male circumcision, a recently proven prevention strategy that was shown to decrease HIV acquisition by heterosexual men by approximately 50% in three separate clinical trials, all of which were conducted in Africa16,
17,
18. These pivotal trials have implications for the rest of the world—although applicability to men who have sex with men remains to be evaluated—and were made possible, in part, through the use of rapid HIV tests which could be used at clinical research sites in the field. Widespread implementation of this new prevention strategy will also require devices and procedures that can be safely used in resource-poor settings.
Another promising prevention strategy is chemoprophylaxis, which relies on generally well-tolerated antimicrobial agents to prevent infection or clinical expression of infectious diseases. The concept of chemoprophylaxis is proven for prevention of malaria in travelers, tuberculosis after exposure and the opportunistic infections associated with AIDS.
Chemoprophylaxis for HIV prevention, sometimes called pre-exposure prophylaxis, is in clinical trials in Africa, Asia, Latin America and in the United States19,
20,
21. The trials are conducted in locations where the epidemic is spreading most because the safety and efficacy of this approach will depend on local factors, including human genetics, temperature and humidity, co-infections with hepatitis B virus, gray and black markets, adherence, stigma and other cultural practices. Cost-effective implementation in Africa is feasible if high level efficacy is found22. But minimizing the risk of drug resistance requires careful detection of pre-existing infection before initiating prophylactic regimens. So the trials of HIV chemoprophylaxis are made possible by the advent of rapid HIV antibody tests. Eventually, this prevention strategy may need rapid field tests that detect HIV directly rather than antibodies to HIV, which take some time to appear in an infected individual; such laboratory methods do not exist now.
Tuberculosis
Tuberculosis is identified in an estimated 8.8 million persons per year and causes 1.6 million deaths per year3. In resource-poor settings, tuberculosis is the most common opportunistic infection in HIV-infected patients. After several decades of decline, the epidemic is now on the rise in many places and involves a growing proportion of drug-resistant strains of Mycobacterium tuberculosis. Tuberculosis is more difficult to diagnose in HIV-infected patients because sputum smears are less frequently positive, chest radiographs are frequently normal, and skin tests are almost always falsely negative (reviewed in ref. 23).
Diagnosis and treatment are the mainstays of tuberculosis control. This strategy, however, is hampered by the lack of rapid diagnostic tests and the insensitivity of existing tests in HIV-infected persons. The reluctance to use chemoprophylaxis for tuberculosis prevention in Africa also arises, in part, from the lack of diagnostic tools that convincingly rule out active tuberculosis disease in patients with normal or non-diagnostic chest X-rays—a diagnosis that is essential for preventing tuberculosis resistance during chemoprophylaxis. More rapid tests for multidrug-resistant and extensively-drug-resistant tuberculosis are also needed to monitor these emerging epidemics and to guide treatment.
Findings from high technology studies can foster the development of strategies and techniques that are appropriate for resource-poor settings. For example, the entire genome of M. tuberculosis has been sequenced; as a result new genes and gene families that may be used to develop new diagnostics were identified24. Highly advanced proteomics analysis of serum25 and gas chromatography–mass spectroscopic analysis of volatile components of the breath26 of tuberculosis patients have identified patterns that may be specific markers of disease.
These complex patterns detected using advanced analytical approaches could be translated into low-tech solutions for the field. For example, 'sniffers' or 'electronic noses' are being developed and evaluated, which may detect the volatile fingerprints of tuberculosis patients27. Use of animals to sniff out diagnostic patterns could be even more cost-effective, as suggested by the finding that dogs can identify individuals with bladder cancer by sniffing their urine28 and a recent press report about research to train rats to identify tuberculosis infected sputum29 (Fig. 1). Those with expertise in advanced technologies should be encouraged to team up with clinicians and investigators in resource-poor settings, who will have practical insight into how high-tech science can be translated into low-tech solutions with broad applications to the public's health.
Common problems and solutions
Conducting research in poorly resourced areas presents many technological challenges. As we have seen, there is a need for assays that are sufficiently simple and robust to perform well in the field. When rapid field tests are not available, operating technical equipment in areas in need will be expedited by integrated solutions that facilitate quality assurance, technical support and training. Clinical research requires technical solutions for tracking and retaining research participants through many visits, which can be especially challenging in environments where addresses are not systematically used. Innovative solutions can be found that help.
The World Health Organization Sexually Transmitted Diseases Diagnostics Initiative (SDI) has developed the ASSURED criteria as a benchmark to decide whether tests address disease control needs: affordable, sensitive, specific, user-friendly, rapid and robust, equipment-free, and deliverable to end users30. Robust assays can only be developed taking into account the variety of environments in which they will be used, in terms of laboratory conditions and also human and microbial diversity. Already we see that the most successful diagnostics provide assurance that rare genetic variants will not compromise assay performance. For example, assays for detection of HIV-1 plasma RNA load and drug resistance are frequently promoted based on their capacity to detect non–subtype B viruses, which are prevalent in Africa and Asia.
Integrated laboratory systems are needed to expedite training and minimize costs of medical care in diverse settings. One solution is offered as the Togatainer (Toga, Johannesburg, South Africa), which was first implemented at the Gugulethu clinic of the Desmond Tutu HIV Foundation in Cape Town, South Africa (Fig. 2). This system converts shipping containers into 'portable' HIV laboratories, including a chemistry analyzer, a hematology analyzer, and systems for determining plasma RNA level and CD4+ T cell counts, all integrated together by an information system that is used for quality assurance, specimen tracking, results reporting and inventory management. This solution embodies creative collaborations that provide practical solutions inspired by technological innovation.
 | | |
Effective information management is also essential for clinical and epidemiological research anywhere. Information solutions are increasingly appearing from pioneers in resource-poor settings seeking to exploit the cost-efficiencies of the electronic age.
For example, a dengue epidemiology study in Nicaragua led to the development of integrated systems including fingerprint and bar-code scanning for participant and specimen identification and tracking, personal data assistants (PDAs) for paperless data collection, and geographic information systems for localization of participants' homes to facilitate the study, improve quality control and ensure compliance with Good Clinical Practice and Good Laboratory Practice31.
Similarly, software for scheduling research visits that links to national identification databases in Peru is used to definitively identify research participants in clinical trials and to schedule study visits in advance for the entire study to facilitate retention, help participants plan for adherence and project clinic resources (Peinado, J. et al., abstract presented at Public Health Informatics 2007: Creating a Global Partnership in Public Health Informatics; Seattle; 2007). Collaboration with informatics engineers in resource-poor settings could bring innovation to all clinical research.
Conclusion
Research in situ promises findings that bear directly on problems of global importance and local relevance. Technology developed for diagnosis and management of AIDS and tuberculosis would have an enormous impact on human suffering. Rapid HIV antibody tests showed the way for rapid and robust tests for other diseases. Similarly, control of tuberculosis will require the development of a point-of-care diagnostic test, as needed to guide the use of chemoprophylaxis and curative treatment. In the meantime, integrated systems for implementing laboratory technology and information will greatly expedite training and quality control while minimizing costs.
There is also much to gain for researchers from well-resourced areas who join their collaborators in poorly-resourced places, be it for short trips or prolonged stays. Investigators in Africa, Asia and Latin America are often inspired by necessity, bringing novel ideas and solutions to the collaboration, to say nothing of cross-cultural humor that can bring delight and insight. Children raised outside the busy high-tech and materialistic society often learn respect for time that is well spent with family and friends. Researchers coming to find greater purpose, often stay to enjoy the collaboration, friendship and better living. Genuine collaboration across borders and communities will address ethical challenges and highlight underlying social and political situations that foster disease, and can be changed to promote health. Research in situ brings immediate benefits of funding, jobs and information, and long-term hope that science grown from need will be fruitful.
This article is part of the Global Theme on Poverty and Human Development, organized by the Council of Science Editors. All articles from the Nature Publishing Group are available free at http://www.nature.com/povhumdev. The content from all participating journals can be found at http://www.councilscienceeditors.org/globalthemeissue.cfm.
Published online: 22 October 2007.
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Acknowledgments
I thank E. Harris for critical and creative comments, and for sharing a manuscript in press for my review; L.-G. Bekker for information about the Togatainer; and J. Sanchez and J. Peinado for information about CLIS, the study-scheduling software.
Competing interests statement:
The author declarescompeting financial interests. |
