Zika Book Fourth Final Draft

Zika Virus Molly Metz Semester Project

Table of Contents 1. Overview ...................................................4 2. Classification...............................................6 3. Aedes Aegypti ..........................................8 4. History of Transmission............................10 5. Types of Transmission .............................15 6. Symptoms, Diagnosis and Treatment.......18 7. Prevention................................................24 8. Current Research......................................26 9. Climate Change.......................................28 10. Conditions of poverty..............................30 11. What’s next?............................................30 12. Bibliography ............................................31

Science & Politics of Infectious Diseases LSCI 2840 Professor Davida Smyth Fall 2018 Final Project December 17, 2018 2

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1. Overview

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Zika Virus

World Health Organization

Zika is a mosquito-borne virus that infects humans which was originally found in Uganda in 1947 and later became a global epidemic in the late 2000s and mid 2010s. The Zika virus is most commonly transmitted through the bite of an Aedes Aegypti mosquito although it has been known to be carried by other Aedes mosquitoes as well. In February of 2016 the Zika virus was declared a Public Health Emergency by the World Health Organization after an increasing amount of cases were reported in Brazil along with the rest of South and Central America and areas in tropical and subtropical climates. The virus, although only asymptomatic in 80% of those infected, can to lead to the development of microcephaly in newborn babies as well as Guillain-Barre Syndrome, both which are extremely serious conditions [1]. Zika has quickly become a global health phenomenon due to the neurotrophic nature, or the affect of the growth of nervous tissue, and its rapid spread across the globe. With the climate of the earth changing drastically, the potential for the virus to become endemic in an increasing amount of countries is high. With no

vaccine currently available and prevention most often being unreliable, Zika has potential to infect a lot of people across the world. One of the biggest issues facing Zika is that because 80% of those infected don’t show symptoms, they often go undiagnosed and play a big role in infecting even more people. In the U.S. in 2015, 62 cases were reported from travelers returning home with the infection. That number increased significantly in 2016 to 5,168 symptomatic cases made up of infected travelers returning home, mosquito-borne transmission in Florida and Texas, as well as sexual transmission, laboratory transmission and other person-to-person transmission. By 2017, the number of reported cases significantly decreased with 452 symptomatic cases and this year so far only 58 cases were reported from travelers [2]. In comparison to the rest of the places where Zika is endemic, these numbers are extremely minute. This booklet will talk about the various socio-political and scientific factors of Zika and how we can move forward to address the quickly spreading virus. 5

2. Classification Zika comes from a family of viruses call the flavivirus genus. The genus is composed over over 70 viruses including Dengue, West Nile, Yellow Fever and Chikungunya. They share a genetic makeup with positive sense single stranded RNA that stretches 11kb in length [3]. Having a positive-sense single strand RNA, means that the RNA can be read as messenger RNA (mRNA) and the virus doesn’t need to go through extra steps to create mRNA [4]. Similar to others in the Flavivirus family, Zika is enveloped, icosahedral (20 sided). Zika also falls under the classification of an arbovirus meaning that it is transmitted by an arthropod vector. Mosquitos are arthropod vectors along with flies, sand flies, lice, fleas, ticks, and mites which all transmit a large number of pathogens. Zika also belongs to a small group of viruses called the Spondweni serogroup. The two viruses, Zika and Spondweni present with very similar signs and symptoms of infection. The only way to distinguish between the two is by the monotypic reaction to

Zika Virus

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Aedes Aegypti 6

a serologic assay, virus isolation or detection of viral nucleic acids by PCR (polymerase chain reaction). This only really becomes an issue in sub-Saharan Africa where both viruses are present because Spondweni has only been detected there as well [5]. The main symptoms of Dengue are high fever, severe headache, severe pain behind the eyes, joint pain, muscle and bone pain, rash, and mild bleeding oftentimes in the nose or gums. [6].The main symptoms of Chikungunya are fever and joint pain as well as headache, muscle pain, joint swelling, or rash. Like Zika, aside from those cases that lead to GBS or microcephaly, most infected people feel better in about a week. So all three viruses: Zika, Chikungunya and Dengue have really similar symptoms and are most of the time occurring in the same place, given that they have the same species of vector.

Yellow Fever

Chikungunya

Dengue Virus

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3. Aedes Aegypti

The Aedes Aegypti mosquito is originally from Africa but has now spread globally in tropical and subtropical regions due to the mass migration of humans. They spread to the New World during the Atlantic slave trade during the 15th to 19th centuries and then went on to spread to Asia via trade. Because of the rapid growth in cities, or urbanization, people more frequently moved into substandard housing with an inadequate water supply, sewage and drainage systems which resulted in more reservoirs for the Aedes breeding sites. It’s also important to remember that mosquitoes don’t naturally carry viruses and it’s because of their cohabitation with people that they’ve become vectors [7]. The Aedes Aegypti mosquito is known for its black and white striped markings on its legs and body. The Aedes genus is largely known as a vector for various mosquito-borne viruses. Mosquito-borne means that the virus is transmitted by the vector, not that they are the source of the virus, they are simply an intermediate host for the virus and are not affected but the virus at all. It’s extremely difficult to control the Aedes mosquitoes because they are very adaptive to their environment and can become highly resistant to insecticides, bug re8

pellants and more. They have also adapted the ability of their eggs to survive drying out and sustain themselves without access to water for weeks to months and still be able to grow into larvae once they get water again once rainfall or another source of water becomes present [8]. The average lifespan of an Aedes mosquito is about two weeks. During that lifetime a mosquito can lay eggs about three times, each time laying 100 eggs. Additionally, eggs can lay dormant for about nine months in the right conditions and remain just as viable with proper water and food [9]. The Aedes Aegypti mosquitoes often stay near shaded places and often hide inside the home under furniture, in closed spaces and near laundry areas. They are really quick and hard to catch. The mosquitoes often bite peoples feet and ankles and sometimes more than once, though the bit is mostly painless and people sometimes may not even notice they are being bit [7]. Life Cycle of Aedes Aegypti Mosquitoes

Adult

Pupa Eggs Larva

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4. History of Transmission

Entebbe, Uganda

Zika dates back 1947 when it was first discovered in the blood of a sentinel rhesus monkey from the Zika forest in Uganda, where the virus gets its name from [10]. A year later the virus was found in an Aedes africanus mosquito on a tree in the same forest [11]. But it wasn’t until four years later that the first cases were reported in a humans in 1952 in Uganda and the United Republic of Tanzania [4][11]. Later, in 1954, Zika was isolated in a young girl in Eastern Nigeria [11]. In 1964, a researcher in Uganda contracted the virus while working with the strands. He developed a rash that lasted about five days that covered most of his body, but he never experienced any severe symptoms or even symptoms like bone pain which is common with the Dengue and Chikungun10

ya infections [11]. Between the 60s and 80s Zika was isolated in more than 20 species of mosquitoes, most of which from the Aedes genus. Although sporadic cases of human infection were identified during this time the disease was still regarded as benign and there weren’t any deaths nor hospitalizations. According to to seroprevalence studies, it showed widespread exposure of the virus to humans [11]. In 2007, the first known major outbreak of Zika took place on the Yap Islands , a collection of small islands in the Pacific. In this outbreak, approximately 73% of the population of the island was suspected to have Zika and revealed the epidemic potential of the virus [4]. Even though mosquitoes can travel long distances in the wind and even across open ocean, they found that the introduction of the virus to the islands was because of travel and trade and subsequent infected people because there weren’t any monkeys on the island at the time [11]. In 2008, shortly after the outbreak in the Yap Islands, one of the first known cases of sexually transmitted Zika was documented. The man was a U.S. scientist who’d returned from Senegal to Colorado and infected his wife [11]. A few years later in 2013, a large outbreak occured in French Polynesia where it proved how virulent the virus was.

Yap Islands 11

Brazil French Polynesia Zika spread rapidly throughout the islands and affected nearly 11% of the population which at the time was about 28,000 people [4]. Before this outbreak, only 14 cases of Zika had been documented world wide [11].Amongst those infected, one person was reported to have Guillain-Barre Syndrome, commonly known as GBS. Following this outbreak, the European Centre for Disease control revealed that there had been a significant increase in the incidence of GBS during and following an outbreak of Zika in the French Polynesian islands [4]. It was also during this outbreak that two mothers and their newborn babies were found with Zika. The infection was confirmed by PCR and it appears that the babies were infected by transplacental transmission or during delivery [11]. By 2015, Zika had become epidemic in Brazil and more and more cases of microcephaly in infants were popping up at an extremely high rate for the rare condition. By the latter half of 2015 in Brazil, 739 cases of suspected microcephaly were recorded being investigated. By early 2016 the World Health Organization (WHO) had declared it a public health emergency and the Pan American Health Organization (PAHO) issued

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an epidemiological alert. By this time, the virus had spread to more than 19 other countries and territories across South and Central America [4] [11]. In Puerto Rico the first cases were being confirmed by PCR in December of 2015. During this time researchers, who were focused on finding a link between Zika and microcephaly, found the virus in amniotic fluid of two women whose fetuses were diagnosed with microcephaly [11]. From 2015 to the present day there have been detailed reports of Zika infections as well as cases of Microcephaly and GBS and researchers continue to look into their connections. 13

Because of this, in 2016 The U.S. issued a travel warning for pregnant women to advise them not to travel to places where Zika is endemic in order to prevent the transmission of Zika, and the subsequent risk of Microcephaly, from mother to fetus [11]. And by early 2016, Brazilian health officials confirmed that Zika can be transmitted through blood transfusion from the infected donor. At this point it is confirmed that Zika can be transmitted from the Aedes Aeygpti mosquito, vertically (from mother to fetus), through sexual contact, as well as blood transfusions.

5. Process and Cycle of Infection The Aedes genus of mosquitoes is the main vector, also known as an intermediary host, for transmitting the virus to humans. They are extremely active during the daylight from dawn to dusk. The female Aedes Aegypti mosquitoes which thrive in tropical and subtropical regions, look for a healthy host to obtain a blood meal from so that can get the protein they for their eggs so they can develop. To identify a healthy host, the Aedes mosquitoes are drawn towards hosts that emit chemicals like Carbon Dioxide (CO2), Ammonia (NH3), and Lactic Acid [12]. The mosquito transmits the virus into the blood when the proboscis, which is the long sucking mouth of the mosquito, pierces the skin of the host. The proboscis passes through the epidermis and into the dermis of the skin where there is vascularization and the virus can access the bloodstream.

CO2 NH3 Lactic Acid The keratinocytes which are found in the epidermis and produce keratin, fibroblasts which are found in connective tissue, and dendritic cells which present antigens) are more welcoming to the virus and allow the virus to bind and enter the cell. Once inside the cell, the Zika virus injects its single strand positive RNA, which is already to messenger RNA. Using the host cells resources the RNA is translated and then the virus begins to replicate and the host cell eventually breaks apart and dies, which releases the virus cells to go and find more cells to infect. 14

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Zika Virus Recepters 1. Attachment 2. Entry

With a mild case of Zika, the infection will stay in the bloodstream for about seven days, which is called the incubation period. During this time the host can still pass the virus to another host if another mosquito were to come along and bite them. With most other viruses a host would be considered a dead-end host and they wouldn’t be able to reinfect anyone else. During this time the virus can also be spread through sexual contact. When an aedes mosquito bites someone who is already infected with Zika it will become infective approximately seven days afterwards. It’s during this time, called the incubation period, in which the virus replicates itself and goes to the salivary glands.

Host Cell

3. Replication & Gene Expression

4. Reassembly

5. Release

Zika Virus Transmission via Aedes Aegypti

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6. Symptoms, Outcomes & Treatment Symptoms After being infected by Zika, symptoms may include red eyes (also known as conjunctivitis), fever, skin rash, joint pain, muscle pain and headaches [13].

Skin Rash

Muscle Pain

Red Eyes/ Conjunctivitus

Joint Pain

Headache Fever

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Microcephaly

The most common condition that has been linked to Zika is the development of microcephaly in newborn babies whose mother was infected with Zika during pregnancy. Zika is able to basically trick the immune system into letting its defense system down and welcoming the virus into the body. Zika specifically targets the white blood cells and because a pregnant woman’s immune system is already compromised during pregnancy and and when zika enters the bloodstream and it tricks the immune system, suppresses it even more and begins to spread really quickly. In a non-pregnant person the immune system would be able to send the macrophages to the scene and attack and kill the virus because it 20

knows it’s a an invader in the body. In pregnant women, their bodies have sent a lot of M2 macrophages, which are activated by exposure to certain cytokines and are associated with healing wounds and tissue repair, to the infection site which tell the immune system to calm down. The immune system of a pregnant women creates even more m2 macrophages and so rather than attack the Zika virus, it allows it to propagate (or grow). At this point the virus is spreading throughout the body and passes through the placental barrier and infects the fetus [14]. Microcephaly makes the size of the head and brain substantially smaller and underdeveloped compared to the normal development of the brain. Because of this condition, there are serious neurological and intellectual deficits, lead to vision, hearing and speech impairments and seizures. 21

Guillan-Barre Syndrome As mentioned previously in this paper, Guillain-Barre Syndrome (GBS) is rare neurological disorder which causes progressive paralysis of the entire peripheral nervous system. Progressive paralysis starts in the feet and moves upward throughout the person’s body. The cause of this paralysis is the body’s immune system mistakenly attacks its own peripheral nerves. The peripheral nerves are those that are located outside of the brain and spinal cord [15]. The cause of GBS aren’t fully understood but has been known to follow after infection with viruses (like zika) or bacterial infections. It is thought that the disease mechanism by which GBS develops is related to an abnormal immune system response or other immune stimulation for example, a vaccination [16]. The onset of GBS symptoms most often develop within 6-8 weeks but with exposure to a virus like Zika, it could be just 10-14 days after exposure [16]. According to the Center for Disease Control (CDC) about 3,000 to 6,000 people develop GBS each year. Most people recover from GBS but age plays a large factor into the recovery rate 22

Nerve

and extent of recovery. Some patients suffer from permanent nerve damage. GBS can fall on a spectrum of severity, some cases are pretty mild with just a brief weakness and some result in devastating paralysis leaving patients unable to break independently [17].

Treatment

Healthy Nerve

To be diagnosed with Zika, you can be given a blood or urine test [13]. But the treatment is not very advanced. At the moment the only treatment for Zika is to simply treat the symptoms that arise. This includes getting a lot of rest, drinking lots of fluids and taking pain medications like acetaminophen.

Damaged Nerve

Central & Peripheral Nervous System

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7. Prevention

Vaccine

At this point there is no vaccine for Zika, but researchers are working hard to create one. The best ways to avoid getting infected with Zika are to take precautionary measures, especially if you’re pregnant. Unfortunately, the only ways you can really prevent getting Zika is to avoid getting bit by the Aedes mosquitoes and make sure that you are having protected sex so it can’t spread through sexual contact. It’s important to focus on the educational aspects of prevention, addressing safe sex and using protection so as to not spread the virus to your partner. To avoid getting bit by the mosquitoes it’s best practice to keep your skin as covered up as possible by wearing long sleeves and pants as well as using natural mosquito repellant sprays, making sure to be wary of spraying young children and infants. It’s also best to sleep under a net to make sure you’re not bitten while you’re asleep, though the mosquitos are usually only out during sunlight. Another precaution is to make it harder for mosquitoes to breed. They often breed near still water, so you should do the 24

mozzie wipe out of your potted plants and any container that catches water. That wipeout includes turning the pail, tip the vase, flip the flower pot, loosen hardened soil and clear the gutters and spray with pesticide. All of these prevention methods can only do so much. If you live in place with Aedes mosquitoes there’s no one prevention strategy to guarantee prevention from the virus. Even these small steps like clothing, repellant and destroying breeding grounds are costly (both financially and otherwise) for impoverished communities. Some water supply is very small and wasting it to prevent mosquito breeding isn’t a reality. For those that don’t yet live in a region where Zika is endemic, it’s advised to think about the measures you need to take if you plan on traveling to somewhere where it’s endemic and if it’s worth the risk.

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8. Current Research In order to stop the spread of the Zika viruses and others transmitted by the Aedes Aegypti mosquitoes, there are many approaches that researchers are exploring. Some are working to make the mosquitoes unable to pick up the disease and some are working to control the mosquito population altogether through gene modification and bacteria. In one study done by Oxitec, a british biotechnology company, scientists worked to genetically modify Aedes Aegypti mosquitoes in an effort to reduce the spread of disease in Brazil. The scientists developed what they call the “lethality gene” which makes the mosquitoes dependent on tetracycline, an antibiotic. They also created a fluorescent marker gene so that they would be able to track the mosquitoes by examining them under a certain light. In this experiment the male mosquitoes were raised from their pupae stage to become dependent on tetracycline and when released into the wild they would breed and create offspring who would be unable to survive because they’d be dependent on tetracycline which is not available in nature. Male mosquitoes were chosen because they do not bite people, only females do (in order to feed their babies with the blood), and the males would be able to then pass the gene onto their offspring. The key to this is that the lab raised male mosquitoes carry two copies of the lethality gene so there’s a 100% chance that the offspring will inherit one of them [18]. In order for this method of controlling the mosquito populations to work, thousands of the male mosquitoes must be released regularly. Their reports have shown that with repeated and regular distribution the population of the mosquitoes in the village has shrunk by 95%. If this method remains safe and effective, it could potentially lead to eliminating extremely large populations of mosquitoes contributing to the spread of many harmful diseases [18]. Professor Scott O’Neill at Monash University in Australia has been working to stop the transmission of mosqui26

Wolbachia to-borne viruses amongst the Aedes Aegypti mosquitoes since 2011. He noticed that other species of mosquitoes that carry a naturally occurring bacteria called, Wolbachia, do not transmit illnesses like the Aedes genus does. O’Neill and his team of researchers at the World Mosquito Program (WMP) conducted an experiment to implant Wolbachia into Aedes Aegypti mosquitoes and see what happened to the transmission of disease once they were released back into the wild. The important thing about using the Wolbachia method is that the mosquitoes will spread the bacteria on for generations, making the growing population of mosquitoes unable to transmit disease. Although a formal epidemiological trial has not been done yet in the area where O’Neill and his team released the Wolbachia-infected mosquitoes, he says that local Dengue transmission hasn’t occurred where they’ve been released for the last seven years [19]. Release Period

Wild Mosquito Population

Mosquito without Wolbachia

Mosquitoes with Wolbachia released

Wolbachia established in mosquito population

Mosquito with Wolbachia

Other advancements in CRISPR technology, or Clustered Regularly Interspaced Palindromic Repeats, Cas-9 are showing a new ways of editing the genetic makeup of Ae. Aegypti mosquitoes. CRISPR is a revolutionary technique to alter an organism’s genome by delivering a DNA-cutting enzyme, Cas9, to a specific region of the DNA. This results in a mutation that can delete or replace DNA pieces which can promote or disable certain traits [20]. 27

9. Climate Change

global warming It’s also important to keep in mind that just because it’s mostly affecting tropical or subtropical climate right now, it won’t necessarily always be that way. With the rise in the earth’s overall temperature, weather patterns are becoming more extreme and the climate is changing which makes a larger number of countries more susceptible to becoming endemic with more infectious and neglected tropical diseases, including Zika. In the past few years we’ve already seen Zika spread to the Southern U.S. In a study done in Ecuador, researchers focused on the 7.7 magnitude earthquake that struck the coastline in April 2016 that coincided what a strong El Nino event. Cecilia Sorensen, a clinical instructor in emergency medicine at CU Anschutz, said, “We were seeing all of these viral symptoms in the wake 28

of the quake … We noticed a huge spike in Zika cases where the earthquake occurred. Prior to this, there were only a handful of Zika cases in the whole country.” Researchers concluded that the number of Zika cases had increased 12-fold in the area of the quake [21][22]. “We saw so many people affected by the earthquake that were sleeping outside without any shelter from mosquitoes, so we were worrying that the region’s changing climate could facilitate the spread of diseases...Natural disasters can create a niche for emerging diseases to come out and affect more people,” Sorenson says [23]. Natural disasters like this earthquake cause significant damage to the infrastructure of homes, especially in an urban environment. This leaves people more exposed to mosquitoes, creates new breeding grounds, and makes health care services much more difficult to obtain. The unpredictability of these weather events makes controlling mosquito-borne illnesses and other NTDs extremely difficult, so we must not forget that they are closely associated. Living in a place like the U.S. with a President who denies Climate Change is extremely detrimental to our planet and humanity, especially since the U.S. has the resources to fund research and development of vaccines, treatment and make a significant impact on the earth if we were to acknowledge and correct the behaviors and practices that are detrimental to the earth and are accelerating global warming. Since the industrial revolution our planet has already changed in ways that the climate has never changed before. The climate of the earth is constantly changing, it has fluxes in temperature and weather patterns, but what we are seeing today is unlike anything that’s been documented in a really long time. Although Zika is no longer a Neglected Tropical Disease, we can’t forget to think about NTDs because although they haven’t become global health phenomenons like Zika, the impact that NTDs can be horrid. And in places where there is one NTD, there are often multiple. 29

10. Conditions of Poverty

12. Bibliography

A major factor to think about is that most tropical and subtropical countries are also low-income. Low-income countries face a variety of negative health and social impacts. With little job availability and job skills, limited access to education, poor or inadequate housing, little access to healthcare or unaffordable health care and lack of governmental support, diagnosing, treating and preventing tropical diseases becomes extremely difficult. Living in these low income tropical regions makes sustaining a job and staying healthy almost impossible and it’s a never ending cycle of poverty. When you need a job to pay for you medication but you can’t make it to work because of your illness, you become stuck in limbo and the systems and services in place aren’t able to support you, so you don’t get the aid that you need. This is why we must address the sustainable development goals and build up physical, social and service infrastructure because it’s such a connected web that creates cycles like this.

1. Elliott, R., Banerjee, T., & Santra, S. (2018). Zika: An emerging disease requiring prevention and awareness. PLOS Neglected Tropical Diseases, 12(6). doi:10.1371/journal.pntd.0006486 2. Zika Virus. (2018, December 07). Retrieved from https://www. cdc.gov/zika/reporting/2018-case-counts.html 3. Huang, Y., Higgs, S., Horne, K., & Vanlandingham, D. (2014). Flavivirus-Mosquito Interactions. Viruses, 6(11), 4703-4730. doi:10.3390/v6114703 4. Schirmer, D., & Kawwass, J. (2016). Epidemiology, Virology, and Pathogenesis of the Zika Virus: From Neglected Tropical Disease to a Focal Point of International Attention. Seminars in Reproductive Medicine, 34(05), 261-265. doi:10.1055/s-0036-1592069 5. Distinguishing between Zika and Spondweni viruses. (2017, December 08). Retrieved from https://www.who.int/bulletin/ volumes/94/10/16-181503/en/ 6. Dengue. (2012, September 27). Retrieved from https://www. cdc.gov/dengue/faqfacts/index.html 7. Aedes aegypti mosquitoes. (n.d.). Retrieved from http://www. eliminatedengue.com/our-research/aedes-aegypti 8. Dengue. (2018, May 31). Retrieved from https://www.cdc.gov/ dengue/entomologyecology/index.html 9. Zika. (n.d.). Retrieved from https://www.nea.gov.sg/denguezika/zika 10. Harris, A. A. (2016). History, Epidemiology, and Clinical Manifestations of Zika: A Systematic Review. The Journal of Emergency Medicine, 51(2), 216. doi:10.1016/j. jemermed.2016.06.035 11. Zika: The origin and spread of a mosquito-borne virus. (2016, May 23). Retrieved from https://www.who.int/bulletin/online_ first/16-171082/en/ 12. Kistler, K., Vosshall, L., & Matthews, B. (2015). Genome Engineering with CRISPR-Cas9 in the Mosquito Aedes aegypti. Cell Reports, 11(1), 51-60. doi:10.1016/j.celrep.2015.03.009 13. Zika Virus. (2018, October 31). Retrieved from https://www.cdc. gov/zika/index.html 14. Southern California Public Radio. (2017, November 11). Zika, HIV attack the immune system in similar ways. Retrieved from

11. What’s Next? In order to address the crisis of the spreading Zika Virus as well as other viruses spread via mosquito transmission, it’s important to keep in mind that we’ll have to take extra precautions and act quickly because of the changing climate and its weather events will only bring about more infectious diseases, worse conditions and perpetuate conditions of poverty. This can’t be another situation where people who live in places where it’s not endemic jsut disregard the impacts of the virus because it’s not affecting them. In the US we’ve already documented hundreds of cases from local mosquito populations, not just from travelers returning home. Tackling mosquito-borne illnesses is going to be extremely difficut to do on a macro scale, especially since they are highly adaptive. We must address conditions of poverty that sustain the spread of NTDs and find a solution to control the mosquito population in one way or another. , 30

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https://www.scpr.org/news/2017/08/25/74954/the-zika-virusundermines-immune-system/ 15. Guillain-Barré Syndrome - Causes, Symptoms, Treatment, Diagnosis. (n.d.). Retrieved from https://medbroadcast.com/ condition/getcondition/guillain-barre-syndrome 16. Araujo, L. M., Ferreira, M. L., & Nascimento, O. J. (2016). Guillain-Barré syndrome associated with the Zika virus outbreak in Brazil. Arquivos De Neuro-Psiquiatria, 74(3), 253255. doi:10.1590/0004-282x20160035 17. Guillain-Barré Syndrome Fact Sheet. (n.d.). Retrieved from https://www.ninds.nih.gov/Disorders/Patient-CaregiverEducation/Fact-Sheets/Guillain-Barré-Syndrome-Fact-Sheet 18. Genetically Modified Mosquitoes. (n.d.). Retrieved from https://www.hhmi.org/biointeractive/genetically-modifiedmosquitoes 19. A self-defeating success story. (2018, November 22). Retrieved from https://lens.monash.edu/2018/04/11/1345939/fightingmosquito-spread-viruses-from-the-inside-out 20. New technology improves CRISPR-Cas9 gene editing in mosquitoes, other species. (n.d.). Retrieved from https://phys. org/news/2018-08-technology-crispr-cas9-gene-mosquitoesspecies.html#jCp 21. Caminade et al., Global risk model for vector-borne transmission of Zika virus reveals the role of El Niño 2015. (2017). Proceedings of the National Academy of Sciences, 114(7). doi:10.1073/pnas.1700746114 22. University of Colorado Anschutz Medical Campus. (2017, October 12). Climate change may accelerate infectious disease outbreaks, say researchers: Study of natural disaster in Ecuador showed 12-fold increase in Zika cases. ScienceDaily. Retrieved November 24, 2018 from www.sciencedaily.com/ releases/2017/10/171012122835.html 23. Climate change may accelerate infectious disease outbreaks, say researchers. (2017, October 12). Retrieved from https:// www.sciencedaily.com/releases/2017/10/171012122835.htm