Dengue, Influenza and COVID-19 in Brazil: The Perfect Storm

In low and middle-income countries, like Brazil, there are growing pieces of evidence claiming that infectious diseases and socio-economic issues are important. Besides that, most of those countries have serious coexisting diseases, stemming from the historical risk overlap that drives their epidemiological transitions [1].

The Brazilian population had a great achievement, which was the Unified Health System (in Portuguese: Sistema Único de Saúde, SUS), recognized as one of the largest public health systems in the world and used as a model in many other countries. About 20 years ago, this system was challenged by the occurrence of what constituted the first pandemic of this century, the Severe Acute Respiratory Syndrome (SARS), caused by coronavirus, which made Brazil develop and implement a surveillance protocol in a timely manner [2]. These protocols were improved for an eventual influenza pandemic in 2005 [3].

However, today we are facing a spread of the new coronavirus (COVID-19) that is suspected to originate in Wuhan, China, in December 2019 [4]. In the moment that we are writing this article, the number of people infected in the world by the new virus has now surpassed 3.178.000, and authorities have reported 265.000 deaths. Over 211 countries, areas or territories have confirmed cases. The virus spread worldwide in a record time since the first confirmed case, and can be transmitted via close human-to human contact, through respiratory droplets from coughs or sneezes. The World Health Organization declared COVID-19 a Public Health Emergency of International Concern as of February 1, 2020 and indicated that containment of this virus would be particularly challenging [5].

Unfortunately, today in Brazil, we have three simultaneous epidemics: Dengue, Influenza and Coronavirus (COVID-19), the “perfect storm” that alarms our country. Further aggravating this scenario, we can include the deep social inequalities that still exist, which go beyond the capacity of the health sector and determine limits for better effectiveness in the prevention and control of these diseases.

Regarding these epidemics, in a recent systematic review paper, Li and colleagues (2019) [6] have shown us that both influenza virus and respiratory syncytial virus peaks were well aligned with winter months in temperate regions. Corroborating this statement, Alonso et al. (2007) [7] conducted an important study on the pattern of mortality from influenza and pneumonia in Brazil. Their main finding was a pattern of disease peak activity starting earlier in the North of the country in May, with delayed peak activity in the South, in July. The seasonality information of the respiratory virus is key to health services planning, mainly now with the COVID-19 pandemic, the peak cases of which will be precisely in the winter.

The issue of Lancet Global Health, published in February, 2020, comments very precisely on how neglected tropical diseases, among them the dengue, remain a consequence and even a cause of poverty [8]. It is worth it to mention that the Brazilian Ministry of Health warned that dengue remains a serious public health problem and constitutes a threat to the population, also that the dengue endemic is as worrying as the coronavirus, for example, and that the population must continue to fight the transmitting mosquito, preventing the proliferation of Aedes aegypti.

In 2019, some researchers published a very important article on the importance of implementing the Global Virome Project. According to the authors, it would be a pathway to improve the capacity to detect, diagnose, and discover viruses that potentially pose threats to human populations, particularly in low-income and middle-income countries [9]. We should all share this initiative.

There are many uncertainties about the dynamics of viral outbreaks in large populations, but the scenario presented reveals that there has already been an important impact on the profile of morbidity and mortality caused by these diseases in the world. According to the literature, epidemics of emerging pathogens have the potential to disrupt the ecology of other circulating pathogens.

A worrying aspect in the last days about COVID-19 is that there has been reports of patients who had recovered and then tested positive again by the RT-PCR test during the medical observation period that follows discharge. It has been reported that positive test results might happen in about 4 to 17 days later the negative results, and may be associated with the host status, virologic factors and type and degree of immunosuppression [10]. In countries like Brazil, where there is a lack of efficient prevention and control measures, it can be a calamity.

In terms of scope, it is not yet possible to compare COVID-19 with Influenza or even diseases that have plagued the country for years, such as dengue. But, the country can and should follow the guidelines recommended by the Ministry of Health (as for example: clean the backyard, eliminate outbreaks of dengue and mass vaccination against Influenza). Additionally, there is an extreme need to slow the spread of coronavirus, through measures of respiratory etiquette and social isolation. If this strategy is adopted, the new virus will affect fewer people, and, as a consequence of that, fewer patients will arrive at the hospitals and more deaths will be prevented.