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What Ebola and HIV/AIDS can teach us about the Zika virus pandemic

The Zika virus continues to spread, with WHO predicting that as many as 4 million people could be infected by the end of the year. As of Feb. 10, there were 52 cases in the U.S. associated with travel abroad, according to the Centers for Disease Control and Prevention. Suspected to be associated with the birth defect microcephaly and the paralyzing Guillain-Barré Syndrome, Zika remains a constant in the news as governments scramble to warn their citizens about the risks.

In this in-depth Q&A, Richard Wamai, assistant professor in the Department of African American Studies and an expert in international global health and development, talks about the Zika virus’s history, puzzling trajectory, and public health interventions that could stem its spread.

 

Both Drs. Wilson Savino, director of a top Brazilian healthcare institution, and Anthony Fauci, director of the National Institutes of Health, have compared the Zika virus crisis to the HIV/AIDS crisis of the 1980s, regarding the speed of the spread and the lack of scientific knowledge about the disease. What similarities and dissimilarities do you see between the two, and how might we use our experience with HIV/AIDS to inform our response to Zika?

My perspective is that there is a greater lack of knowledge about Zika virus than HIV both within the scientific community and the general population. HIV was first reported in the U.S. in a 1981 article by the CDC, but scientists now date the emergence to the 1940s and date the period of ignition and circulation in sub-Saharan Africa to between the 1880s and 1950s. It then left Africa in the 1960s through Haiti. Scientific debate about HIV crystalized in the 1980s, after which generalized knowledge about it spread like fire around the world.

In contrast, most people’s knowledge about Zika virus is probably just about a month old. The Zika virus was discovered in a captive monkey in Uganda in 1947 during studies sponsored by the Rockefeller Foundation on yellow fever, and the first human cases were reported in 1952 in Uganda and Tanzania. While there have been outbreaks in Africa and elsewhere, it is only now that the world is learning about Zika virus.

There are more differences than similarities between these two diseases.

Microcephaly-comparison-5001px

Zika virus has been linked to microcephaly, a birth defect wherein a baby’s head is smaller than expected when compared to babies of the same sex and age. Babies with microcephaly often have smaller, underdeveloped brains. Image by the Centers for Disease Control and Prevention

For starters, the genetic makeup of HIV and Zika virus are different, and thus the diseases they cause follow different trajectories. HIV takes a long time to produce disease and, if not treated, has severe symptoms over time including wasting and death from AIDS. Zika virus has mild symptoms, and deaths due to it are very rare. Zika has been suspected of causing microcephaly and Guillain-Barré syndrome, but there is no definitive proof yet, according to WHO’s latest report. It is puzzling that microcephaly was not a widely associated outcome in past Zika virus outbreaks in Africa or elsewhere. A WHO bulletin being considered for peer-reviewed publication supports earlier research suggesting that the character of the virus in the current outbreak in South America has changed from the African and Asian types.

The mode of transmission of HIV and Zika virus is also different. Unlike HIV, Zika virus is transmitted primarily by an infected mosquito, the Aedes aegypti. HIV is transmitted primarily through blood and unprotected sex; a couple of cases of Zika have been found to be transmitted that way, but they are atypical.

The world has changed so much since the emergence of the HIV epidemic in the 1980s. At that time there was denial and stigma at both the public and governmental levels. Policymakers’ initial reaction to HIV was a disaster in the U.S. and abroad. For example, it took decades, from 1981 to 2000, for sufficient funds to be mobilized for testing and treatment programs in sub-Saharan Africa when millions were dying.

There is no doubt that climate change contributes to the spread of mosquito-borne diseases.
— Richard Wamai, assistant professor

For the Zika virus, in contrast, there has been no denial, though stigma for children with microcephaly and their mothers is no doubt a concern. WHO and the international community reacted strongly to Zika, including designating it an international public health emergency in record time. This may have been an overreaction, with WHO trying to compensate for its slow designation of Ebola as an emergency after widespread criticism in the media and scientific journals.

As for the lesson that stands out from our experience with HIV/AIDS and Ebola: Given that outbreaks may be more common in the future, we need a global health infrastructure capable of a more versatile rapid response than has been the case. This requires investments in outbreak and emerging/emergent disease surveillance, early warning systems, and preparedness programs.

Tropical diseases such as Zika and dengue are migrating northward, including to the United States, as a result of climate change and cheaper, more frequent travel. How do these factors contribute to the spread of these diseases, and what can we do to prevent it?
 
There is no doubt that climate change contributes to the spread of mosquito-borne diseases. Warming weather expands the geographic range of disease carriers that thrive predominantly in the tropics. It also means longer breeding cycles and increased rates of insect survival. A. aegypti had been eliminated in the U.S. in earlier campaigns to eradicate yellow fever in the South; however, a recent report described the persistence of those mosquitoes through low winter temperatures in the neighborhoods of Washington, D.C. A U.N. report notes that the current El Niño event may be contributing to the spread of the Zika virus.

Zika has, once again, brought to the fore the urgent need for WHO, governments, and institutions including universities to invest in research on the basic sciences, epidemiology, and health systems.
— Richard Wamai, assistant professor

Regarding travel, most certainly yes: it is a huge factor. The world has become small, with rapid air- and ground-transportation systems. The cases Zika transmitted through sexual contact and blood transfusion, however, point up the risks of travel for those not even visiting endemic areas. There are a few cases of what is known as Odyssean Malaria, where mosquitoes infected with malaria have been imported from endemic areas; that could happen with Zika-carrying mosquitos as well.

But those are anomalies. The bigger problem is at-risk people traveling to endemic areas. While countries may advise their citizens to avoid certain countries or areas—as the CDC has done—to prevent circulation and migration of disease, surveillance systems, both domestic and global, are needed. Ebola taught us the importance of instituting screening for all travelers—not just for those coming from endemic countries. I remember undergoing screening with thermal technologies that detect high fever when I entered Kenya in the summer of 2015. There was, however, no such screening on my return to Boston.

Why do scientists and the medical community know so little about the Zika virus? Why were we all so unprepared?

Zika has, once again, brought to the fore the urgent need for WHO, governments, and institutions including universities to invest in research on the basic sciences, epidemiology, and health systems, and the value of studies in global health, including surveillance, given the rapidity with which diseases can now travel. Clearly, even after the pre-colonial Zika cases in sub-Saharan Africa and the spread to Micronesia, South Asia, and ultimately the southern part of the Western Hemisphere, not much was ever done.

October 30, 2014 - Assistant Professor of Public Health Richard Wamai researches health systems, HIV/AIDS and neglected tropical diseases (NTDs).

Richard Wamai, assistant professor in the Department of African American Studies, is an expert in international global health and development. Photo by Brooks Canaday/Northeastern University

For many years now, WHO and the CDC have supported a program called Integrated Disease Surveillance and Response in Africa. Unfortunately, many countries with weak health systems in sub-Saharan Africa still do not have robust IDSRs. It is promising that the CDC has signed a memorandum with the African Union to support an African Centres for Disease Control and Prevention. WHO should strengthen its Global Outbreak Alert and Response Network, and African countries should build the Africa Field Epidemiology Network. Academic institutions should increase the available technical expertise by training students in areas like epidemiology; it is notable that many African countries have fewer epidemiologists than are needed for maintaining effective disease vigilance.

From a public health perspective, what recommendations should authorities make regarding the 2016 Summer Olympics in Rio de Janeiro?

These games should go on. Since the symptoms and most outcomes from the Zika virus are mild, the main worry is microcephaly in children and Guillain–Barré syndrome. It is noteworthy that the WHO emergency declaration sprang from suspicion of these two outcomes rather than the Zika-virus infection itself. There are no known severe dangers to the general adult population. Brazil has already deployed about a quarter-million soldiers to help track cases and control the mosquito population. Classic public health measures like these should be continued. Those measures, as well as protecting pregnant women, are the most urgent. The communities affected must be a critical part of the campaign against Zika. A third measure is also crucial but will take time: developing treatments and, better yet, a vaccine. A race is already on regarding both. A dedicated response to Ebola, from basic research to the implementation of surveillance programs, has shown that it is possible to contain, control, and ultimately eliminate a disease.

Infectious diseases like these are a matter of global security, as the Global Health Risk Framework, published by the National Academy of Medicine last month, shows. We are indeed living in interesting times regarding pandemics; it is expected we will see major infectious-disease outbreaks more often. In this, global health is a matter of graver human security concern than nuclear warfare. So it is encouraging to see efforts like the No More Epidemics Campaign emerge. Zika is yet another wake-up call.