Tuesday August 30, 2016
As the Olympics of 2016 come to an end, thousands of Team GB spectators, athletes, coaches and team-members alike will soon be journeying back across the Atlantic to the UK. And something on the forefront of many of their minds will be Zika.
Since this current outbreak is relatively recent, the guidelines and recommendations with regard to Zika virus testing are changing almost weekly. At London Doctors Clinic, we are striving to keep our patients informed with the most up-to-date information possible. Our doctors have been scouring the web for the most recent Zika guidance from a variety of healthcare authorities, including the American Centers for Disease Control and Prevention (CDC) – who are playing an instrumental role in providing reliable, up-to-date information on the outbreak – as are Public Health England, the NHS’s health authority. Scientists around the world are working around the clock to gather more data and statistics on the virus and its effects.
Here, we lay out what we’re currently advising for patients concerned about Zika.
A reminder on the Zika virus:
Scientists have been aware of the Zika virus since the 1940’s; it’s not a new virus. Zika is a member of the Flavivirus family, similar to the West Nile, Dengue and Yellow Fever viruses. Zika is transmitted by the Aedes aegypti mosquito, which can also be found in other hot and tropical climates, such as parts of Central and Southern Americas, parts of the US, India, South-East Asia and Northern Australia.
Distribution of the Aedes aegypti mosquito, responsible for Zika transmission.
Despite the very wide distribution of the Aedes aegypti mosquito, the current Zika virus outbreak is mainly focused around Central and South America, although is spreading further afield with movement infected travellers. To date, there have been approximately 2,000 Zika diagnoses in the USA over the last few months, 500 of which were in Florida.
There is currently no evidence to suggest that other types of mosquito, such as those found across parts of Europe, are capable of transmitting the Zika virus.
The distribution of the Aedes aegypti mosquito across Europe.
According to the above map, the only country in Europe with an established population of the Aedes aegypti mosquito (responsible for Zika transmission) is in red. Green represents where the mosquito is ABSENT; grey represents countries for which there is no data.
Zika symptoms are very non-specific, and hard to distinguish from other everyday illnesses such as common flu. They include fever, headache, rash, vomiting, joint and muscle pain. They are usually only mild, passing within a few days. Some sources suggest that only 20% of people infected with Zika go on to develop symptoms, meaning 80% of Zika cases are actually asymptomatic.
Diagram demonstrating the potential symptoms of Zika in the estimated 20% of symptomatic cases.
So DO YOU NEED TO BE TESTED?
First things first, are you pregnant or trying to conceive?
This is possibly the most important question regarding the Zika outbreak. There is currently little evidence to suggest that the Zika virus is harmful to humans, other than to unborn babies.
The British Government’s Department of Health will generally only facilitate testing for pregnant women and their partners, with non-pregnant patients considered a lower priority. Due to the potentially devastating effects of Zika on unborn babies, Public Health England advises pregnant women “to postpone non-essential travel to areas with active Zika virus transmission”. This currently includes many parts of South and Central America, and the Caribbean – but areas of active transmission appear to be gradually expanding. It’s worth checking up-to-date guidelines before considering travelling to a destination near the current Zika-affected areas.
As a private GP Clinic, however, we are able to facilitate testing for a wider range of people should our doctors deem your request reasonable. We do not test exclusively ‘higher priority groups', as other healthcare providers do. Private doctors offer patients a choice, as to whether they want to get tested or not.
How does Zika virus affect unborn babies?
There is a strong link between pregnant women infected with the Zika virus, and the incidence of babies born with foetal abnormalities, namely microcephaly. This is a condition whereby the foetus’ brain does not fully develop throughout the pregnancy, resulting in a smaller than average brain, and therefore head. This may lead to disorders including poor brain function, intellectual disability, poor movement and seizures. There is no treatment available, and babies born with microcephaly have a reduced life expectancy. Microcephaly can be due to genetic mutations, or as a result of Zika infection of the mother while in utero.
If you are currently pregnant or trying to conceive, and have recently visited a Zika-affected area, we would strongly recommend you get tested for the Zika virus. Similarly, if you are pregnant and your sexual partner has visited a Zika-affected area, you may have been exposed to the Zika virus by unprotected sex. Although it was initially thought that the virus is only transmitted via the Aedes mosquito, there is an increasing amount of evidence to suggest it can also be transmitted sexually.
A few months ago, it was reported that Zika virus had been detected in sperm as long as 62 days after Zika infection. However more recently, the Zika virus been detected in the sperm as long as six months after Zika infection. This is why all men returning from a Zika-affected area are strongly advised to use condoms during sexual intercourse, to prevent the potential transmission of Zika.
We offer three different tests for the Zika virus. Depending on your risk factors for Zika infection – including exposure, travel location and duration – as well as pregnancy status, our GP may recommend one, or a combination of tests at specific intervals.
The first two test available is a Zika virus urine and blood PCR test. These tests are advised to be done in the first 7 days (using blood) or 14 days (using urine) of exposure to Zika virus. There is some evidence to suggest that the urine test is more sensitive than the blood test, although neither are completely sensitive.
One limitation of this test, is the definition of ‘exposure’, since during a 3-week trip to a Zika-affected area, travelers likely will receive a number of mosquito bites, any one of which may have transmitted the Zika virus. Therefore, if you’re bitten on day one of the holiday, and visit the doctor immediate upon returning home, you may have missed the appropriate window for testing. However, for patients who attend London Doctors Clinic within 14 days of first entering a Zika-affected area, our doctors may still recommend this PCR test.
However, due to this uncertain window, a negative PCR result does not guarantee that the patient never had Zika virus infection – we could have just missed the testing window. That’s why it’s strongly recommended that any patients who undergo PCR testing are also strongly advised to undergo antibody testing at a later date, for a more reliable result.
This Zika PCR test costs £306.40, with results available in 7-10 days. The Centers for Disease Control and Prevention (CDC), recommend that the PCR test should be performed on both urine and blood specimens together, for the most reliable result.
The third of our three tests is a Zika antibodies test. This tests for previous infections, and looks for Zika-specific antibodies. Different authorities and clinic have slightly different recommendations as to the appropriate window for testing. Our doctors at LDC have decided that within 3-12 weeks post-exposure is the accurate time-frame for antibody testing.
We recommend patients wait 3 weeks after returning from a Zika-affected area, since the virus has an incubation period of 3-14 days, whereby no or few antibodies are made. Then, after this viral incubation period, it takes the body’s immune system up to 7 days to produce antibody levels sufficient for detection. Testing any sooner than 21-days post exposure is possible, but may not be reliably sensitive.
Testing can be facilitated up to 12 weeks post-exposure, however there is some evidence to suggest that anti-Zika antibodies may dip below a sufficient level for detection after 12 weeks, thus making the test less sensitive.
Since this Zika outbreak is relatively recent, the lab tests for the virus (both PCR and antibodies) are also very new. This means that unfortunately, we don’t have reliable statistics as to the sensitivity and specificity. However, at LDC we strive to keep our all of our patients well informed with reliable, up-to-date information so soon as we receive it!
For the most comprehensive screening possible, we would recommend choosing all three testing options. As per the CDC’s Zika testing guidelines, a PCR test is best performed on both blood and urine samples. Even if this result returns as negative, to be as certain of this as possible, we would then recommend a follow-up antibody test, 3 weeks after returning from a Zika-affected area. This Zika testing protocol is especially important for anyone pregnant or trying to conceive, and who has had significant exposure to the Zika virus.
If you are not pregnant or trying to conceive, but believe you have been exposed to the Zika virus, then we would recommend the antibodies test, since this is the test with the clearer time-frame for testing. This can be accompanied with either the PCR urine test (more sensitive), or both the PCR urine and blood tests, depending on your choice.
For patients who believe they may have been exposed to Zika via unprotected sex with a person at-risk of Zika infection, the testing options may vary are are probably best to be discussed in person with a GP.
All blood tests at London Doctors Clinic require at least one 15-minute private GP consultation, costing £55, during which you can discuss your Zika concerns and testing options with the doctor. For any further queries, please do get in contact with us at LDC, and one of our team will be able to advise.
So if you have any concerns about the Zika virus, or would like to be tested for Zika, book a GP appointment now. Or consult our infographic if you are still wondering "Should I get tested for the Zika virus?"
Click here for an Zika Update