Epidemiology of Zika Virus Disease and its Social and Economic Drivers

This study discusses the epidemiology of Zika virus disease, its causality, and social and economic drivers of its emergence. It also covers the implications for future practice of Zika virus disease.

Epidemiology in Public Health
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TABLE OF CONTENT
INTRODUCTION...........................................................................................................................3
Bradford hill criteria in order to discuss causality in the context of Zika virus disease..............3
Epidemiology data with discussion of social and economic drivers of infectious disease
emergence....................................................................................................................................5
Implication for future practice of Zika virus disease...................................................................8
CONCLUSION................................................................................................................................9
REFERENCES..............................................................................................................................10
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INTRODUCTION
Epidemiology is the study of knowing sequence and patterns of public health as it helps out
in determinants of disease within group of people and ways of preventing (Mills, Stefanescu and
He, 2020). This present study is based on Zika virus disease as it will discuss epidemiology on
this disease as when it occurred. In regard to this, it is found that this Zika virus disease that is
uncontrollable was discovered in the year of 1947 and it is named after the Zika forest in
Uganda. In the year of 1952, the first human case of this virus was detected and since then
outbreak of Zika have been reported in Southeast Asia, Pacific Island and tropical Africa. In
addition, it can be said that it is a trigger of Guillain Barre syndrome in adults as well as in
children. This virus causes birth defects in babies that born to infected pregnant women and
babies born with undeveloped head and brain. It is the condition in which the immune system
attacks the nerve (Musso, Ko and Baud, 2019).
Zika virus is single standard RNA virus of the Flaviviridae family, genus Flavivirus. It is
transmitted in humans by the bite of an infected mosquito that is a specie of Aedes. Some
symptoms of this virus include: headache, joint pain, fever, muscle pain and rash. When people
suffer from neurological complications then most of the time it is associated with Zika virus
infections specially in adults and children. Outbreaks of this virus was recorded in Africa,
America, Pacific and Asia. Brazil reported association of Zika virus and microcephaly. On the
basis of current evidence, it is found that ZIKV infection present with no mild clinical features
(Katzelnick and et.al., 2020). It is being estimated by 2018 meta-analysis of 23 studies, Haby and
colleagues that prevalence of asymptomatic ZIKV infection of 62%.
Bradford hill criteria in order to discuss causality in the context of Zika virus disease
Bradford hill viewpoints have been applied in order to identify the relationship between
microcephaly and ZIKV. By comparing secondary data and rates of microcephaly prior to the
Zika virus outbreak. Health agencies have debated on this association between microcephaly and
ZIKV but only few studies have been applied for causation in a systematic way. Increased
incidence of Zika and microcephaly found in pregnancy. Due to time limitation, they stated that
causation was not established. For more knowing, Shepherd’s 6 viewpoints were demonstrated.
Some viewpoints of Bradford hill include:
Strengths of association: In regard to this, it is found that there was around 20-fold
raises in microcephaly cases. In the year of 2013-2014, this virus increased number of cases in
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French Polynesia and there it affected around 66% of population. For knowing its affected rate,
standard criteria were used in which all babies born with head circumference of at least 2
standard deviation of the normal head circumference were considered to have microcephaly.
This study found strong association as well as link between microcephaly and ZIKV because risk
ratio was 20.8. A study on 88 pregnant women was conducted in which around 72-73 women
tested positive with this virus. So, on the basis of this rate, it can be said that there was a strength
of association (Williamson, 2021).
Consistency: By knowing consistency of association between these two, we can know as
whether there was causation or not. Till now 2 strong epidemiological studies have been
investigated and from these studies consistency has been known. Both studies, conducted in the
year of 2013-14 in French Polynesia and Brazil, stated that there was a positive association.
Along with this, Columbia has also stated a total of 601-604 cases of microcephaly between
EW1 and EW41 of 2016. Till date, there is no existing study that has represented negative
association between Zika virus and microcephaly. so, on this basis, it can be said that there is
high consistency.
Specificity: This criteria or viewpoint refers to disclosure that cause 1 disease. If there is
an association in same and specific group of people with the same environment, then it
strengthens the argument for causation. After specific exposure, it is affecting pregnant women
to the great extent. Microcephaly is rare outcome and it is estimated to occur in 2 to 12 babies
per 1000 births in US (Ipekci and et.al., 2021). Outcomes of babies with this virus and
microcephaly suggest that there is specificity exposure to this virus. So, on the basis of studies
conducted so far, it can clearly be said that this association of Zika and microcephaly proves this
viewpoint of Brad ford hill criteria of specificity. It has proved that number of cases of Zika virus
have been seen in pregnant women and the reason behind it can be: exposure severity. At the
time of pregnancy, body of women become sensitive and high exposed to disease.
Temporality: As it is known that this Zika virus was considered as a febrile illness when
it first occurred and identified in Brazil and in April 2015 it was approved by RT PCR following
microcephaly in November 2015. Authors have stated a link between this virus infection in
pregnancy and outcomes of microcephaly via detection of viral RNA in brain as well as
placement tissue of fetus of infected mothers with this virus during their pregnancy period. For
knowing and satisfying this criterion, researchers have conducted some studies in different
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countries and as per the outcome of study, conducted in the state of Paraiba and brazil,
temporality was identified where this virus was detected in amniotic fluid in 2 pregnant women.
For knowing effect of this virus on fetus, ultrasonography was also being done and on the basis
of its result, it is found that this virus had no effect on fetus and their brain in weeks 13,16 and
17.
Biological gradients: This criterion can be defined as the level of exposure to a given
factor. It is believed that by knowing dose response relationship, causation can be reinforced.
Study that was conducted in Brazil, it is found that incidence of babies born with microcephaly
in areas that are affected with this virus is epidemic (Dammann and et.al., 2022). Attack rate in
population have increased the incidence of Zika virus ion pregnant women and it has led to
population burden of congenital malformations.
Plausibility: As it is known that Zika virus caused fever and nonspecific symptoms but
sometimes more severe symptoms and effects have been shown that can affect neurovirulent
ability. for severity and protecting babies from getting affected with this infectious disease,
affected pregnant women needs to abort their child. On the basis of above discussion, it is known
that this virus was isolated in the amniotic fluids of two pregnant women. It shows its ability to
cross the placental barriers.
Coherence: Current study that was conducted in Brazil on Zika virus has stated that
effect of Zika virus on the growing neurosphere as it uses human’s neural cells and it states that
Zika virus has an ability to induce death of human neural cells and impair formation of
neurosphere. On the basis of outcomes of conducted study, it can clearly be said that it is
consistent.
Analogy: These criteria was originally described by Hill as analogous examples of
exposures that may have led to the same outcome. A study that was conducted in Brazil on 151
patients in the year of 2014-2015, it was known that infection from arbovirus autoimmune
disorders in 6 patients among with 4 patients had GBS (Zhu and et.al., 2020).
Epidemiology data with discussion of social and economic drivers of infectious disease
emergence
On the basis of study or epidemiology data, it is found that this virus infection is rare in the
U.S but outbreaks occasionally happen. Travelling is one of the major factor from which people
get high chances of getting affected with infectious disease that spread from one person to other
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and through bite of mosquito. It is being recommended to people that they should take an extra
care when they are travelling as they need to take steps to prevent mosquito bites. People need to
use protections or condoms in order to avoid spreading the infection to sexual partners when they
return. As per the statistical and published data, it is also found that in the U.S, there were around
62 Zika virus infections reported in the year of 2015 then over 5,000 reported in the year of 2016
and only 4 in 2020 (Thézé and et.al., 2018). Since 2018, no Zika infection was reported in the
continental US and around 100 travellers have acquired the disease. As per the data published in
the year of 2021, it is found that there was only 1 case or traveller contacted Zika and there have
been no confirmed cases of Zika that use molecular testing from the U.S territories. On the basis
of this, it can clearly be said that this virus infectious disease has been prevented to the great
extent and it all happened because of efforts of researchers, healthcare providers and scientist.
Before the year of 2006-07, there were only periodic human disease cases from countries
in Africa and Southeast Asia. but in the same year, the first outbreak of ZIKV reported in Yap
state and in the next year, this outbreak began in French Polynesia and this virus spread to other
pacific Islands. In the year of 2015, this outbreak and infectious disease was reported in Brazil.
Till March 2017, there were around 84 countries as well as territories globally had reported
autochthonous mosquito borne ZIKAV transmission that include 61 countries with new
introduction of ZIKAV since January 2015 (Lourenço and et.al., 2018).
Some drivers have also been identified that has caused this infectious disease rather than
specific reason of: through bite of mosquito. Some social drivers that can increase spreading this
infectious disease include: unprotected sexual relations, wearing half sleeves of cloths, not taking
care while travelling to countries where there are cases of this virus. This virus has negative
social impacts as people depression, stress, poor social support and overall family quality of life.
People who got infected from this disease find themselves unable to perform their own daily job
roles because of joint pain, weakness, fever and other causes. It makes them dependent on others
and people on which, infected people depend also become frustrated (Rees and et.al., 2018). If
born babies also get affected with this virus, then it causes them undeveloped brain and head and
for long run they become completely dependent on their parents. Parents also become frustrated
after sometime and they need health care cost. It decreases their quality of life and living
standard as well. It decreases brain tissue with specific pattern of brain damage, it damages to
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eye and congenital contractures. All these make people frustrated and they become self-isolated
(Kapiriri and Ross, 2020).
There are number of other drivers that has also caused this problem. Some economic and
epidemiological drivers of this virus include: inadequate sanitation and poor water supply. It is
stated that there are number of areas where people do not have easier access to healthcare and
pure water and impure water as well as lack of healthcare access is one of the main socio-
economic factor that lead to this problem. Government did not focus on this disease and after
years, when they found that this disease is not controllable then governments of developing
countries invested in this study and preventing measures. This infectious disease has affected
economic condition of countries to the great extent.
For knowing about initial economic impact of this virus for 2016 in the Latin American as
well as Caribbean region, the World Bank group, conducted a study. There is a total of US$3.5
billion or around 0.06% GDP. It has affected economy to the great extent as affected people were
not able to work in an effective and productive manner so, it decreased workers’ productivity,
decreased tourism and public perception (Morgan, Strode and Salcedo-Sora, 2021). In regard to
this, it can be said that travel is one of the main contributor to economic improvement. But due to
this virus, people had fear to travel so, it decreased sales of this sector. On this basis, it can be
said that this infectious disease affected people and economies globally.
Government had invested in prevention, control and response to this Zika virus infection
spread. it has increased economic burden. Due to this, many of people lost their job and family
members were facing problems in taking care of affected people. For measuring or forecasting
actual economic burden of Zika across 6 states in the US, computational model has been
developed. Across six states, an attack rate of 0.01% is estimated to cost around $183.4 million
to society. As per the PAHO, in the year of 2019, Brazil reported around 3,323 cases of Zika.
After Brazil, Peru was the second country in South America that reported 829 cases of Zika
virus. Governments of these countries invested in awareness programs and preventing measures
to the great extent that affected their economic condition but now there are few cases of Zika and
it all happened with efforts of scientists, healthcare providers and researchers (Smith and et.al.,
2019).
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Implication for future practice of Zika virus disease
On the basis of above discussed epidemiology of Zika virus disease, it can be said that it is
an uncontrollable disease. Symptoms, outbreak and associated disease have been identified. It is
important to discuss its future implications and public actions for decreasing its consequences. In
regard to treatment, it is found that for Zika virus infection and its associated diseases, there was
no specific medical treatment. Symptoms of this virus are mild and the only thing that people can
do and they should do is: plenty of rest and drinking fluids. If muscles pain become unbearable
and if symptoms worsen then people should seek medical care as well as advice.
Protection against mosquito bites during the day as well as in early evening is the best way to
prevent from Zika virus infection as people need to use protection cream (Lowe and et.al., 2018).
Some personal protective measures that can be taken by people from getting infected with this
infectious disease include: wearing light coloured and full sleeves of cloths, using physical
barriers such as: closed doors, windows and window screen. Applying insect repellent to
clothing as well as to skin that specially contains IR3535 and DEET can be one of the best
protective measures. Along with these, there is no medical preventing measure of this infectious
disease.
WHO recommended that sexually active women and men need to be counselled correctly
and also need to be offended a full range of contraceptive methods to be able to make an
informed choice about weather. Women need to take counselling about when to become
pregnant in order to prevent adverse pregnancy as well as fetal outcomes. Overall, it can be said
that personal protection and taking self-care is the only measure by which people can protect
themselves from getting infected with this virus (Muniz Junior and et.al., 2019). There are some
WHO response that can also help out people from preventing with this virus such as:
 Advancing research in prevention, surveillance and control of Zika virus infection.
 Strengthening capacity of laboratories to test for Zika virus infection worldwide.
 Development and implementation of integrated surveillance system for Zika virus
infection and associated complications.
 collaboration for improving global efforts to implement as well as monitor vector control
strategies with the main aim of decreasing Aedes mosquito populations.
 Strengthening support and care to affected people and families by complications of Zika
infection.
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This is the pathogen that is poorly studied because it was believed to only cause mild
infection. As per the PubMed, a total number of ZIKV related publications from 117 in 2015 to
3253 in August month of 2017. So, on the basis of this, it can be said that there has been a great
progress. In these publications, number of things have been identified that can help out people
and researchers in identifying vaccines and preventive medical measures. Some new things that
have been found and studied on include: biology of this virus, different disease manifestation in
humans and different routes by which this infectious disease is transmitted in both animals and
humans. Along with this, several efforts have been initiated that can make able to people from
preventing and cured even after getting affected. Study on this virus is being going on and the
main focus is given on development of new diagnostics, vaccines, therapeutic as well as vector
control strategies for better treating, detecting preventing this infectious disease (Lee and Shin,
2019). It is believed that by identifying vaccines for preventing from this disease, scientists can
boost their confidence and they can improve living standard of people.
CONCLUSION
It has been summarised from the above study that Zika virus, uncontrollable and untreatable
disease has affected number of people. It has mild symptoms but people with severe cases need
hospitalisation. It has further discussed Bradford hill criteria of this virus with all its viewpoints
with the main aim of knowing causalities. All elements and viewpoints of Bradford hill criteria
that have been discussed in above study include: strength and consistency of association,
plausibility, specificity, temporality, coherence, experimental evidence, analogy and dose
response relationship. This study has then further shown future implications and public actions
for preventing people against this infectious disease. It has discussed on the statement and topic
as whether Zika virus is a cause of microcephaly or not and it is found that this can be
transmitted from mother to fetus during pregnancy and it can result in microcephaly. Lastly, it
has shown some social, economic and other drivers of this disease so that preventive measures
can be developed in an effective and timely manner.
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REFERENCES
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