The Zika Virus | Need to Know FactsPosted May 13, 2016
Dr. Scott Mann shares with us the implications of The Zika Virus on eye health, vision, overall health, and our communities.
Zika virus stories are everywhere in the news these days. However, there are still many questions about this virus including its short term and long term effects on eyes and vision. The story of Zika and eye involvement is still evolving. As an eye doctor my goal is provide helpful information to the public, our patients and friends about the Zika virus and its affect on the eyes and vision. I have a personal interest in this story. My family and I have friends in Puerto Cabezas, Nicaragua from mission trips to a school, church and orphanage complex there. We encounter many women of child bearing age who live in less ideal socioeconomic conditions.Background of The Zika Virus
- Why is Zika such a big story recently? The Zika virus is new and it is spreading rapidly in many countries. Unfortunately, the US Center for Disease control (CDC) has determined that the Zika virus causes birth defects, including microcephaly and blindness in newborns.
- What is the Zika virus? Zika is an “Arbovirus” in the “Flaviviridae” family – which also includes dengue fever and chikungunka.
- Where did it come from? Zika virus is an emerging mosquito-borne virus that was first identified in Uganda in 1947 in rhesus monkeys through a monitoring network of yellow fever.
- How long has it been around? It was identified in humans in 1952 in Uganda and the United Republic of Tanzania.
- Is the Virus spreading? Yes. Outbreaks of Zika virus disease have been recorded in Africa, the Americas, Asia and the Pacific. Brazil was the epicenter of a large outbreak in 2015. Many other countries in the Americas have reported infections which suggests a rapid spread of the Virus.
- How is it spread? According to the World Health Organization (WHO) the Zika virus is spread by the bite of the Aedes aegypti mosquito, which also can carry denque fever, chikungunka and yellow fever. The mosquito acquires the virus by biting an infected person. It can then transmit the virus to others.The Aedes albopictus mosquito species is also suspected of transmitted Zika. As of May 2016 there have also been dozens of suspected cases of sexual transmission. This typically results from males returning from effected areas.
- Can I catch Zika from someone like I catch a cold or “pink eye”? No. The virus is spread primarily by the bite of an infected Aedes aegypti mosquito.
- How far north can it travel? The Aedes mosquito can be found in the warmer regions of the United states and has been identified in 30 different states. Some of the northern most locations the virus has been found include San Francisco and Washington, DC. and New York State. This information is still evolving as more is understood about this invasive species.
- Do all mosquitoes carry Zika? No, there are over 3,000 species of mosquitoes. The primary mosquito species that has been identified as a carrier of Zika is Aedes aegypti.
- What makes the Aedes aegypti mosquito unique? It is an invasive species originating in Africa. Only the females bite, as they need blood to reproduce. This species is unusual in that they are “day-time biters” so mosquito night-time bed nets are less helpful. They travel only 150 to 200 yards in their lifetime which means they thrive in areas where people are densely populated. As a result, this enables the virus to be spread more easily from person to person by the mosquito.Zika Symptoms & Effects On Eyes And Vision
- What at the most common symptoms? Only 1 in 5 with the Zika virus will actually have symptoms. The time from being infected to the onset of symptoms is uncertain but likely occurs within a few days. The symptoms are mild and last 2 to 7 days. The most common symptoms are fever, headache, rash, conjunctivitis (pink eye), muscle and joint pain. There is no specific treatment beyond rest, fluids and OTC remedies.
- What are the short term effects on eyes & vision? The Zika virus can cause mild conjunctivitis in the symptomatic phase. This includes redness, irritation, light sensitivity and watery eyes. It is self limiting but the symptoms can be lessened with steroid eye drops. There appears to be no long term damage from this acute phase of Zika.
- Is there a link between the Zika Virus & Microcephaly? Zika appears to have an affinity for nervous system tissue. It appears to be strongly linked to microcephaly and other birth defects in newborns and to a lesser extent Gillian-Barre syndrome, which can result in partial paralysis that last for months, in adults.
- What is microcephaly? Microcephaly is a condition where a baby’s head is smaller than those of other babies of the same age and sex. Microcephaly happens when there is either a problem during pregnancy, causing the baby’s brain to stop growing properly, or after birth when the head stops growing properly. Children born with microcephaly often have developmental challenges as they grow older.
- How does Microcephaly effect the eyes & vision? The eyes and optic nerves that connect the eyes to the brain are part of the nervous system. When microcephaly effects the nervous system it can have a profound effect on vision. Unfortunately, the Zika virus has an affinity for nervous system tissue.
- What are the long term effects on eyes & vision? One 2015 study conducted in Brazil involving children with microcephaly, thought to be caused by Zika, resulted in findings that 30% had occular symptoms (10 of 29). Additionally, 7 of 10 children in the study had occular symptoms involving both eyes. There was atrophy of the retina, macula and optic nerves evident. This type of ocular involvement can have sight threatening implications for these children.Social Implications of Zika
- Are poorer countries effected more by Zika? Based on my personal observation – the answer is yes. The gap between “Haves” & “Have Nots” is evident in the United States but even more evident in many of the recently effected countries. The income disparity in Central America, South America and the Caribbean is readily apparent.
- Three areas in which income disparity makes a difference include air conditioning, window screens and standing water. Air conditioning is considered the norm for US citizens that are within the middle class or higher. Lower income families often can not afford this amenity. As a consequence the windows are open and often window screens are not present. In a literal sense, this is an open invitation for
mosquitoes. Window screens with gaps, holes and tears allow mosquitoes inside.
- Lower income areas typically have more standing water and standing water yields more mosquitoes. This is due to poor drainage and debris in the general area. A small soda bottle cap can be the breeding ground for hundreds of mosquito eggs. Old tires are also a fertile breeding ground.
- To compound matters, countries with less resources may be less prepared to help families with Zika related birth defects.
Treatment | Prevention | Cure
- Is there treatment or cure? No.
- Is there a vaccine? There currently is no vaccine although much work is being done in this area.
- How do I prevent infection by Zika? The best prevention is to avoid mosquito bites.
- What can science & technology do to help? Currently there are vaccine studies underway. There are also genetically modified mosquitoes using the “Sterile Insect Technique” to reduce local populations. Insecticides are used but poor effectivity, species resistance and unintended targets (like bees, butterflies and “good” insects) are problematic.
To Travel or Not?
- Should I travel to the countries that are effected? This decision should only made be in consultation with your physician and your family. The CDC recommends that pregnant women should not travel to areas where the Zika virus is epidemic. If their partners travel to those areas CDC cautions should be followed.
References: Dr. Mann and the optometrists at Invision recommend US and international citizens start here:
http://www.cdc.gov/zika/ (US Centers for Disease Control)
CDC Concludes Zika Causes Microcephaly and Other Birth Defects
CDC Travel page
WHO Fact sheet : Zika (World Health Organization)
‘Scarier than we initially thought’: CDC sounds warning on Zika virus
news/politics/2016/04/11/ scarier-than-we-initially- thought-cdc-sounds-warning- zika-virus/82894878/
Zika Virus in the Americas — Yet Another Arbovirus Threat
Surveillance and Control of Aedes aegypti and Aedes albopictus in the United States
CDC encourages following guidance to prevent sexual transmission of Zika virus
Wikipedia: Zika Virus
How far north is the Zika-spreading mosquito?
Zika virus and potential complications: Questions and answers (WHO)
Zika Is Proving to Also Be Dangerous to Adults
Ocular Findings in Infants With Microcephaly Associated With Presumed Zika Virus Congenital Infection in Salvador, Brazil
CDC: help control Mosquitos
com/article/how-a-tiny- bacterium-called-wolbachia- could-defeat-dengue/