Public Health Considerations for a Rapidly Changing World: An Interview with Professor Marcia Castro

June 26, 2018

By Ashley CollinsSão Paulo.

Marcia Castro is a professor of demography in the Department of Global Health and Population at the Harvard T. H. Chan School of Public Health. She was recently promoted to the role of full professor and is the first Brazilian woman to receive tenure at Harvard. Professor Castro’s research focuses on the relationship between urbanization and health, as well as the social and environmental factors that contribute to the spread of vector-borne diseases.

Congratulations on your recent promotion to the role of tenured professor. As far as your research is concerned, what do you hope this new position will allow you to achieve moving forward?

Thanks! My research will continue to address the same broad topics that I have been working on for the past 15 years and will continue to be based in Brazil. Tenure does give me more flexibility to engage in completely new ideas (albeit connected to my broad research interests). It also means that you become more respected and therefore more demanded for leadership roles. Personally, my goal is to continue to conduct high-quality and high-impact work that paves the way to better and new public health policies and to expand even further the connections with Brazil in order to facilitate service learning for Harvard students as well as local capacity building in Brazil.

A great deal of your research focuses on the malaria-poverty vicious cycle. Given the recent outbreak of yellow fever in Brazil, could you please speak more about the relationship between disease and poverty generally? Does the same kind of cycle exist between yellow fever and poverty?

The link between poverty and health has been vastly documented historically, with diseases often striking most severely those living under poor conditions. Lack of or unreliable access to water and sanitation, low education, precarious housing conditions, overcrowding, waste accumulation, limited or no access to health care, food insecurity, exposure to violence, and poor working conditions are some of the factors that contribute to an increased risk of becoming sick among those living under poverty. Although Brazil made significant progress in reducing mortality due to infectious diseases, morbidity persists and outbreaks due to the emergence or re-emergence of diseases continue to occur. Recent examples include the emergence of Zika virus and chikungunya, and the re-emergence of yellow fever and malaria in areas that had been free of the disease for years. The explanation for these recent events does not rest solely on poverty and is not unique either. In the case of yellow fever, specifically, a combination of problems in surveillance for sick or dying monkeys and of vaccine coverage must be considered. Yet, when one measures the burden of the diseases, they do affect disproportionally the poor who lack the means of properly preventing and treating the disease.

On the subject of the factors that contribute to outbreaks, the links between climate change, urbanization, and the spread of diseases have been well established. With this in mind, how can public health considerations be integrated into the creation of sustainable cities? In addition to dealing with the underlying problems related to the infrastructure of rapidly expanding urban areas, what needs to be done in order to curb the spread of disease?

Goal 11 of the Sustainable Development Goals is about making cities inclusive, safe, resilient, and sustainable, and its ten targets make it clear that much more than just infrastructure is needed. Safety, for example, is a major concern. Research that I conducted in collaboration with the Municipal Health Secretariat of Fortaleza has shown that areas with higher homicide rates in Fortaleza have higher prevalence rates of tuberculosis and higher incidence rates of arboviruses – a result of limited access to family health teams and vector control efforts. Also, innovative ways of waste management not only reduce potential foci of diseases (such as mosquito-borne diseases and leptospirosis), but also facilitate community engagement and empowerment. Improving urban mobility and encouraging physical activity – starting with children – is another critical issue that must be addressed to mitigate the growing obesity problem.

What are the consequences of the United States’ backward steps on climate change – its withdrawal from the Paris climate agreement, among other actions – for the public health situation of the rest of the world, in terms of its effects on efforts to mitigate the spread of vector-borne diseases?

The President’s decision to pull out of the Paris agreement sends a message that the administration ignores the evidence that climate change is a real threat. Pollution, for example, was responsible for 1 of 8 deaths globally in 2012 (or about 7 million deaths), as estimated by the World Health Organization. All other countries continue to support the agreement, and even states and cities in the US will continue to take action towards a greener future.

For vector-borne diseases, in particular, it is important to keep in mind that the magnitude of the impact of climate change will depend on many issues, such as: (i) the pattern of variability in temperature; (ii) how countries are planning in anticipation of future changes; (iii) how adaptation strategies are adopted at varied scales (individual, community, institutional); (iv) the combination of control strategies already in place; (v) the extent to which the risk of infection determined by local characteristics can be augmented by climatic changes; and (vi) the level of clinical immunity. Therefore, while an atypically wet/dry or cold/hot year may provide favorable conditions for the spread of vector-borne diseases, there are many other factors that must be taken into account before any prediction is made. The understanding of these other factors is crucial. And accounting for them in anticipation and mitigation of further spread of vector-borne disease must be in the agenda of ministries of health.

Do you have any concluding thoughts to share? What do you believe will be the main challenges to controlling the spread of disease in the future?

Controlling the spread of diseases in a highly connected world is not an easy feat. As humans move, so do pathogens. Vectors can be introduced in new areas through human movement or trade of goods. The threat of a new pandemic is very much real; the uncertainty is when it will happen and what the pathogen will be. To face this reality, solid surveillance systems are needed, strong health systems are imperative, and universal health coverage is absolutely necessary.