Arbovirus and coronavirus: announced tragedies in Brazilian health
And the whole world asks, what will be the next epidemic caused by arboviruses and how will it affect public health?11/04/2020
The world in recent decades has experienced the occurrence of major epidemics caused by zoonotic viruses or viral agents that normally had a restricted and limited distribution within certain countries or continents. Many of these epidemics were caused by arboviruses (acronym for arthropod-borne virus). In fact, in the present 21st century, arbovirus epidemics have become very frequent and, generally, they occurred in several countries on more than one continent, most of them in developing countries in the so-called “tropical world”, where the impact was tremendous in the face of social inequalities, poverty, lack of education and the neglect of authorities in most affected countries.
Virologist Dr. Pedro Fernando da Costa Vasconcelos, president of the Brazilian Society of Tropical Medicine (BSTM) explains that this was the case with dengue, which currently affects stratospheric numbers of cases and deaths; it was followed by chikungunya from 2005 and then by Zika, which has affected many countries since 2015. The last was responsible for the first international public health emergency decreed by the World Health Organization (WHO) due to the outbreak of microcephaly and other congenital malformations. It was followed by the yellow fever epidemics in Africa (Angola and Democratic Republic of Congo) and South America (Brazil). “And the whole world asks, what will be the next epidemic caused by arboviruses and how will it affect public health?”, he inquires.
On the other hand, we have also been experiencing a series of epidemics by other zoonotic viruses that are not arboviruses, therefore, transmission does not depend on an arthropod vector. “Here we can find those of the Henipavirus genus (family Paramixoviridae) – Hendra virus in Australia that affects humans and horses and that results in significant losses in herds, and Nipah, in Southeast Asia, which has been associated with outbreaks of acute encephalitis with important lethality. The Nipah virus, incidentally, also leads to neurological sequelae in survivors and, more recently, studies have shown that many of these survivors have developed dementia with extreme speed and severity”, adds Dr. Vasconcelos, who is also part of the Department of Pathology at the State University of Pará (UEPA); Arbovirology and Hemorrhagic Fevers Section.
In addition to these in this century we have members of the genus Coronavirus (family Coronaviridae) and that are associated with respiratory conditions. In 2002, the SARS virus (Severe Acute Respiratory Syndrome) was described, which started in China and spread to several countries with a lethality of about 10%; in 2012 the MERS (Middle East Respiratory Syndrome) was recognized, which presented lethality in humans of about 30%, but which remained restricted in the Middle East region, but also affected camels. In December 2019, the new coronavirus (SARS-COV2) responsible for the conditions of Coronavirus Disease 2019 (COVID-19) was diagnosed.
Dr. Vasconcelos, who is also part of the Evandro Chagas Institute (IEC) and the Ministry of Healths Health Surveillance Secretariat (SvS/MS), clarifies that when analyzing the situation of arboviruses with other zoonotic viruses, especially coronaviruses, which emerged in the present 21st Century, we see that with the exception of dengue (whose transmission is direct in urban environments between humans and the Aedes aegypti mosquito), all other arboviruses initially emerged in wild zoonotic cycles and later adapted in urban environments, facilitated by the unique vectoral capacity of the Aedes aegypti mosquito. “On the other hand, the coronaviruses associated with SARS, MERS and COVID-19 were zoonotic viruses, whose transmitters are different species of bats, a class of mammals that are eclectic in their ability to harbor viruses, and which are abundant on the planet. Incidentally, the Hendra and Nipah viruses are also from bats, as is the case with Ebola and Marburg (Filoviruses), which had defined that the primary hosts would also be bats, as well as rabies and other lyssaviruses”, he adds.
Also according to the virologist, the approach to studies of these viruses must include the One Health initiative, or the only health, the more humans invade natural ecosystems (for the exploitation of natural wealth or for occupations with housing and development projects), for millennia inhabited by these and other wild vertebrates, we increase the risks that some of these viral pathogens will be able to adapt and multiply in humans, which can result in epidemics or even pandemics as currently observed with COVID-19. Therefore, according to him, only with the interaction between the different medical and veterinary sciences, ecology and epidemiology, will we be able to understand the eco-epidemiology of arboviruses and zoonotic viruses a little better, as humans will not fail to invade natural ecosystems.
“And so, using scientific information, we can get a rough idea of how viruses make the jump between species, and build mechanisms to try to contain the spread or minimize their effects on populations around the world. Finally, it is necessary to emphasize that national and international health authorities and politicians in general must learn to trust science and the scientifically obtained information. Only with scientific information will we be able to build mechanisms for the prevention and control of these viruses, as well as to develop diagnostic, therapeutic, vaccine methods and also to understand the mechanisms of disease. Scientific information is essential for us to be able to predict and prevent zoonotic viruses present and in balance in nature, from becoming a new health problem as we currently experience with COVID-19”, concludes Dr. Vasconcelos who is also a Full Member of the Brazilian Academy of Sciences (ABC).