Zika virus disease is caused by the Zika virus, which is spread to people primarily through the bite of infected mosquitos of the species Aedes aegypti and Aedes albopictus.
Please find more information on this disease in the text below or watch the expert interview:
How dangerous is Zika?
Infected people usually don’t need to go to the hospital and they very rarely die of Zika. Once a person has been infected with Zika, they are likely to be protected from future infections.
Nevertheless, Zika infection during pregnancy can cause a birth defect of the brain called microcephaly and other severe brain defects in newborns. It is also linked to problems such as miscarriage, still-birth, and other birth defects.
Increased reports of Guillain-Barré syndrome, an uncommon sickness of the nervous system, coincide with Zika infection rates.
Who is at risk?
Anybody living in or travelling to an area where a Zika outbreak occurred.
Pregnant women should not travel to any area with risk of Zika be-cause infection during pregnancy can cause microcephaly and other severe brain defects in newborns.
According to a study published in The Lancet1:
An estimated 2·6 billion people live in areas of Africa and the Asia-Pacific region where the presence of competent mosquito vectors and suitable climatic conditions could support local transmission of Zika virus.
Countries with large volumes of travelers arriving from Zika virus-affected areas of the Americas and large populations at risk of mosquito-borne Zika virus infection include India with 67 422 travellers arriving per year and 1·2 billion residents in potential Zika transmission areas, China with 238 415 travelers and 242 million residents, Indonesia with 13 865 travelers and 197 million residents, Philippines with 35 635 travelers and 70 million residents as well as Thailand with 29 241 travelers and 59 million residents.
How many people are affected by Zika?
85 countries and territories had reported mosquito-borne Zika virus transmission as of November 16, 2017, to the WHO.
In 2014 147 cases of microcephaly were reported in Brazil. In 2015, the number of cases rose dramatically to 3,530 suspected cases.
Where is Zika found?
Local transmission of Zika virus by Aedes mosquitoes has been reported on the continents of Africa, the Americas, South-East Asia and the Western Pacific.
There are two types of Aedes mosquito known to be capable of transmitting Zika virus. In most cases, Zika is spread through the Aedes aegypti mosquito in tropical and subtropical regions. The Aedes albopictus mosquito can also transmit the virus and can hibernate to survive regions with cooler temperatures.
How do people get Zika?
Zika is spread mostly by the bite of infected Aedes species mosquito namely Ae. aegypti and Ae. albopictus. These mosquitoes bite during the day and night.
Additionally, Zika can be passed from a pregnant woman to her fetus.
Furthermore, Zika can be transferred through sex.
Very likely but not confirmed is that Zika can be passed on through blood transfusion.
What are the signs and symptoms of Zika?
Many people infected with Zika virus won’t have symptoms or will only have mild symptoms. The most common symptoms of Zika are:
- joint pain
- red eyes
- muscle pain
These symptoms normally last for two to seven days.
How is the disease developing?
Symptoms can last for several days to a week. People usually don’t get sick enough to go to the hospital, and they very rarely die of Zika. Once a person has been infected with Zika, they are likely to be protected from future infections.
How is Zika diagnosed?
A blood or urine test can confirm a Zika infection.
Symptoms of Zika are similar to other illnesses spread through mosquito bites, like dengue and Zika.
How is Zika treated?
There is no specific medicine or vaccine for Zika virus. Treat the symptoms:
- get plenty of rest
- drink fluids to prevent dehydration
- take medicine to reduce fever and pain
- if you are taking medicine for another medical condition, talk to your healthcare provider before taking additional medication
How can I prevent infection?
There is no vaccine to prevent Zika.
The most effective way to avoid Zika virus infection is to prevent mosquito bites.
Scroll down for recommendations how to prevent Zika virus infection through sexual intercourse
The mosquitoes that spread the Zika bite during the day and at night.
- Use insect repellent1 in strict accordance with product label instructions. Repellents should contain DEET, IR3535 or icaridin.
- Wear long sleeves and pants, and stay in places with air conditioning or that use window and door screens.
- Treat items, such as boots, pants, socks, and tents, with permethrin2 or buy permethrin-treated clothing and gear.
- Dress your child in clothing that covers arms and legs.
- Cover crib, stroller, and baby carrier with mosquito netting.
- Use screens on windows and doors.
- Repair holes in screens to keep mosquitoes outside.
- Use air conditioning when available.
- Sleep under a mosquito net
- Because mosquitoes lay eggs near water, empty and scrub, turn over, cover, or throw out items that hold water, such as tires, buck-ets, planters, toys, pools, birdbaths, flowerpots, or trash containers once a week.
1 The CDC recommends to:
- use Environmental Protection Agency (EPA)-registered insect repellents (https://www.epa.gov/insect- repellents) with the active ingredients DEET, IR3535. When used as directed, EPA-registered insect repellents are proven safe and effective, even for pregnant and breastfeeding women.
- follow these tips for everyone:
Always follow the product label instructions. Reapply insect repellent as directed.
Do not spray repellent on the skin under clothing.
If you are also using sunscreen, apply sunscreen first and insect repellent second.
- follow these tips for Babies & Children:
Always follow instructions when applying insect repellent to children.
Do not use insect repellent on babies younger than two months old. Do not apply insect repellent onto a child’s hands, eyes, mouth, and cut or irritated skin.
Adults: Spray insect repellent onto your hands and then apply
to a child’s face.
Do not use products containing oil of lemon eucalyptus (OLE) or para-menthane-diol (PMD) on children under 3 years old.
2 In some places, such as Puerto Rico, where permethrin products have been used for years in mosquito control efforts, mosquitoes have become resistant to it. In areas with high levels of resistance, use of permethrin is not likely to be effective.
Zika can be spread by a person infected with Zika to his or her sex partners. Condoms can reduce the chance of getting Zika from sex. Condoms include male and female condoms. To be effective, condoms should be used from start to finish, every time during vaginal, anal, and oral sex and the sharing of sex toys. Not having sex eliminates the risk of getting Zika from sex. Pregnant couples with a partner who traveled to or lives in an area with risk of Zika should use condoms every time they have sex or refrain from having sex during the pregnancy.
How is Zika transmitted?
Zika virus is primarily transmitted to people through the bite of an infected mosquito from the Aedes genus, mainly Aedes aegypti in tropical regions. Aedes mosquitoes usually bite during the day, peaking during early morning and late afternoon and evening. This is the same mosquito that transmits dengue, Zika and yellow fever.
Sexual transmission of Zika virus is also possible.
Other modes of transmission such as blood transfusion are being investigated.
How can the vector be controlled?
Anti-mosquito efforts can target the destruction of eggs, larval or pupae in water containers, or can target the adult mosquitoes where they fly, feed or rest.
It is important to cover, empty or clean potential mosquito breeding sites in and around houses such as buckets, drums, pots, gutters, and used tires.
Communities should support local government efforts to reduce mosquitoes in their locality.
Health authorities may also advise that spraying of insecticides be carried out.
For rapid impact, surveillance and control should build on existing national structures rather than seeking to establish new or parallel structures. In many countries of Africa these are existing malaria control programs. In some countries of the Americas, South-East Asia and the Western Pacific existing dengue control programs can be built on.
More information on the vector:
Ae. aegypti are day-biting mosquitoes while Ae. albopictus usually bite in the early morning and late afternoon.
Ae. aegypti typically rest indoors and fly short distances up to 80 meters. Eggs are usually laid in artificial containers found in and around homes such as those used for domestic water storage and decorative plants as well as rain-filled habitats like used tires, dis-carded food and beverage containers and blocked gutters.
Ae. albopictus tend to rest outdoors and inhabit both domestic and peri-domestic artificial containers e.g. rubber tapping cups filled with rain water, roof gutters etc. as well as natural receptacles such as tree holes and plants.
Ground pools and other stagnant water bodies are not usually pre-ferred for egg laying by either species.
Eggs hatch into immature larvae which develop into pupae and then emerge out of the water as adult mosquitoes.
What are the difficulties and challenges in combating Zika?
The proximity of mosquito vector breeding sites to human habitation is a significant risk factor for Zika as well as for other diseases that these species transmit.
It is very difficult to control or eliminate Ae. aegypti mosquitoes because of adaptations to the environment that make them highly resilient. Additionally they have the ability to rapidly bounce back to initial numbers after natural phenomena like droughts or human control measures.
One such adaptation is the ability of the eggs to withstand desicca-tion (drying) and to survive without water for several months. If, for instance, all larvae, pupae, and adult Ae. aegypti were eliminated at once from a site, its population could recover two weeks later as a result of egg hatching following rainfall or the addition of water to containers harboring eggs.
Ae.aegypti seem to continually adapt to environmental change. For example, it was recently found that Ae. aegypti is able to undergo immature development in broken or open septic tanks, resulting in the production of hundreds or thousands of Ae.aegypti adults per day.
In general, it is expected that control interventions will change the spatial and temporal dispersal of Ae. aegypti and perhaps the pattern of habitat utilization.
For these reasons, entomological studies should be included to give support before and throughout vector control operations.
Aedes albopictus, a secondary Zika vector, has spread to North America and more than 25 countries in the European Region, largely due to the international trade in used tires, which are a breeding habitat, and other goods e.g. lucky bamboo.
Ae. albopictus is highly adaptive and, therefore, can survive in cooler temperate regions of Europe. Its spread is due to its tolerance to temperatures below freezing, hibernation, and ability to shelter in microhabitats.
What programs exist against Zika?
WHO responds to Zika by:
- formulating evidence-based outbreak management plans
- providing technical support and guidance to countries for the effective management of cases and outbreaks
- supporting countries to improve their reporting systems
- providing training on clinical management, diagnosis and vector control at the regional level with some of its collaborating centres
- publishing guidelines and handbooks on case management and vector control for Member States
- encouraging countries to develop and maintain the capacity to detect and confirm cases, manage patients and implement social communication strategies to reduce the presence of the mosquito vectors
CDC’s response to Zika includes developing laboratory tests to diagnose Zika, conducting studies to learn more about Zika, publishing reports about Zika, monitoring and reporting cases of Zika, providing guidance to travelers and Americans living in areas with outbreaks, providing on-the-ground support in countries and US territories with current Zika outbreaks, and more.
What does Bayer contribute to the fight against Zika?
- Bayer has been successfully developing vector control products for decades (see below).
- Currently, the two most relevant Vector Control methods for fighting Chikungunya outbreak are Space Spray applications and breeding sites management. Bayer is a major supplier of Space Spray products since decades.
- A major issue is the build-up of mosquito resistance to the different active ingredient they have been exposed to. Most products used since many years are now facing this situation.
During the last six years Bayer researchers have developed an innovative approach for fighting resistance build-up. They are bringing to market a range of mosquito insecticides that combine two different modes of action, In particular, the new Fludora™ Co-Max Space Spray includes also a new chemistry family. This solution will associate robustness to resistance build up as well as excellent efficacy.
- Thanks to an innovative polymere formulation, Bayer has also launched a totally new type of intervention, Targeted Outdoor Residual Spray (TORS) . This type of application rolled out is South East Asia id particularly adapted to urban environment where Chikungunya, dengue and Zika strive. The product is marketed under the brand KOthrne™ Polyzone.
Additionally Bayer has devised an education tool – Mosquito Con-trol Learning Lab – an online learning platform that explains which diseases are transmitted by mosquitos, how they spread and how individuals can protect themselves against mosquito bites. The platform is interactive, testing users in their knowledge and skills in real life scenarios.
Bayer Mosquito Control Learning Lab can be accessed on any computer or tablet and is found here: https://www.environmentalscience.bayer.ph/Fight-Dengue
Besides this Bayer can look back on products that are still supplied in many parts of the world where resistance to pyrethroid insecticides is not yet established:
- Since 1990s: Aqua K-Othrine™ and Aqua Reslin™ Super are launched. These are the first space sprays to employ a new technology, Film Forming Aqueous Spray Technology (FFAST), and are used to combat adult mosquitoes in flight outdoors without releasing volatile hydrocarbons.
- Since 2015: DeltaGard™ launched in the United States. The space spray can be used at 80 times lower doses than comparable products. DeltaGard™ is currently the only product in its class that does not contain volatile organic compounds (VOCs) and is water-based. It was awarded the rarely conferred reduced-risk product classification by the U.S. Environmental Protection Agency (EPA).
What is the societal burden of Zika?
The social and economic cost of the recent spread of the Zika virus in Latin America and the Caribbean may have totaled an estimated US$7-18 billion between 2015 and 2017, according to an impact assessment by the United Nations Development Programme (UNDP), in partnership with the International Federation of Red Cross and Red Crescent Societies (IFRC).
The Zika epidemic will have significant short and long-term impacts in the economic and socials spheres in the Americas because of tangible losses to GDP and to economies heavily dependent on tourism, stresses on health care systems, and potential undermining decades of social development and health gains as well as slowing down progress towards the Sustainable Development Goals.
The Caribbean is the most affected, with an impact five times that of South America. More than 80 percent of the potential losses over three years are due to reduced revenues from international tourism, with the potential to reach a total of $9 billion over three years or 0.06 percent of GDP annually.
Larger economies such as Brazil are expected to bear the greatest share of the absolute cost, but the severest impacts will be felt among the poorest countries. Haiti and Belize stand to lose as much as 1.13 and 1.19 percent respectively of GDP annually in the high infection scenario. Indirect costs could be substantial. Estimates suggest lost income due to new child-care obligations will potentially reach between half a billion and $5 billion for the region.
How did the history of the disease proceed?
- in 1947 the Zika virus was first identified in Uganda in monkeys through a network that monitored yellow fever. The disease is named after the Zika Forest in Uganda
- in 1952, the first human cases of Zika were detected in Uganda and the United Republic of Tanzania
Outbreaks of Zika virus disease have been recorded in Africa, the Americas, Asia and the Pacific
- from the 1960s to 1980s, human infections were found across Africa and Asia, typically accompanied by mild illness
- in 2007 the first large outbreak of disease caused by Zika infection was reported from the Island of Yap (Federated States of Micronesia)
- in July 2015 Brazil reported an association between Zika virus infection and Guillain-Barré syndrome
- in October 2015 Brazil reported an association between Zika virus infection and microcephaly
Please find a more detailed timeline put together by CNN here: