Authored by Claudio Cesar Cirne Santos
Arthropod-borne viruses (known as arboviruses) are widely
circulated throughout the world, causing numerous episodes of
emergence and resurgence of epidemic outbreaks with serious
consequences to public health [1,2]. The arboviruses most
frequently responsible for causing important outbreaks are
distributed in the genera Alphavirus (family Togaviridae) including
Chikungunya, Semliki Forest, Ross River, Mayaro virus and Sindbis
virus [3]. Flavivirus (Flaviviridae family) such as Dengue, West Nile
and Japanese encephalitis viruses are important to public health
as well. Other viruses of consequence to human health are also
reported, although less frequently. These include the Bunyaviridae,
Reoviridae, and Rhabdoviridae.
Most arboviruses that cause human diseases have RNA genomes
and are zoonoses that depend on wildlife or domestic animals for
maintenance in nature; however, humans may be targets of these
viruses. The identification of infections caused by such viruses
can be determined by molecular techniques such as polymerase
chain reaction (PCR), mainly in cases of acute febrile diseases
[4], although many groups are having difficulty implementing
techniques that are capable of differentiating infections [5] and
considering possible co-infections between ZIKV and DENV and
CHIKV [6,7].
Although molecular detection is possible, the availability of
these methodologies to the population at large during times of
outbreak makes it impossible to determine precisely which virus
is affecting an individual. Clinical manifestations are highly variable
and may present from mild to more complex conditions with
neurological complications, hemorrhage, and severe joint changes;
causing a significant increase in the morbidity and mortality of
these conditions [8]. The association between ZIKV infection
with microcephaly and Guillain-Barré syndrome in 2015 brought
fear and insecurity primarily to pregnant women, although it has
caused concern among all people. In the same way, both DENV and
CHIKV infection showed signs of worsening, although many people
had been treated empirically because they manifested symptoms
that are similar among different arboviruses; especially symptoms
associated with dengue virus, Mayaro, Zika and Chikungunya such
as fever, rash, muscular pains, joint pains, and headache, among
others, and may only vary in intensity.
Our group, in collaboration with clinical care services, observed
a great deal of confusion in the clinical diagnosis of arboviruses. This
is due to numerous cases where patients presented characteristics
of ZIKV infection, but it was not possible to confirm this infection
by observation of signs and symptoms alone. In our studies of 25
patients with a clinical diagnosis of ZIKV infection were evaluated
during the ZIKV and CHIKV outbreak in the period from January to
August 2016. However, we did not obtain a positive result for the
isolation of arboviruses in all analyzed samples, only concluding
the isolation of CHIKV in 3 of the 25 collected samples. As can be
observed in Figure 1, the same person may present symptoms
characteristic of more than one arboviroses, demonstrating that
even with the use of diagnosis may not be possible. This situation has occurred for both CHIKV and DENV infection, although
symptoms caused by viruses such as Mayaro may be unknown by
some health professionals as they are not common (Figure 1).
Cheap diagnostic methods with high reliability are long awaited
and their availability would be very timely. Many groups have been
working intensively to develop new strategies in the control and
treatment of viral infection to reduce the risk of more severe clinical
forms since there are no antivirals or vaccines available for clinical
use [9]. We believe that more accurate diagnoses and better clinical
knowledge of arboviruses can contribute to a significant reduction
of more severe outbreaks or offer better control of sporadic
outbreaks of these diseases.
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