Zika Virus Information For Travel – December 2016

Zika Virus Information

If you are travelling to an area which is affected by Zika, travel precautions are recommended.

What is the Zika virus?

Zika virus is from the same family as dengue, West Nile, yellow fever and Japanese encephalitis viruses.

It also belongs to a larger category (arboviruses) capable of spreading from one human (or animal host) to another via the bites of insects and other arthropods.

Zika Virus Image

How is it spread?

  • Zika MosquitoBy mosquitoes: Zika is spread by two species of mosquito: Aedes aegypti and Aedes albopictus (note these mosquitoes’ characteristic biting posture and striped markings). Transmission occurs when mosquitoes bite an infected person, and then go on to bite a susceptible individual
  • By blood, body fluids and sex: Zika can also behave as a blood-borne virus, with the potential for spread by blood and body fluids. Out of the first 600 travel-related cases that were imported into the USA, 11 were sexually transmitted
  • Male-to-female as well as male-to-male sexual transmission can occur. Female-to-male sexual transmission occurs, but is much less common. Infectious virus is most commonly detected in semen for less than 24 days after the start of symptoms, but has been documented for as long as 69 days following onset, and studies on the duration of excretion of the virus continue. Zika virus has been detected in breast milk, but transmission by breastfeeding has not been reported.
  • Non-infective traces of virus can be detected in blood, urine, saliva, semen and breast milk following infection – the presence of viral genetic material in tests does not indicate infectivity; viral RNA can be found in the urine and blood for a variable period following onset of symptoms – the record currently stands at 91 days for urine and 81 days for whole blood (rather than serum).

The current outbreak

  • Since the beginning of 2015, local transmission has been reported in 69 countries (48 in Latin America and Caribbean). Brazil has seen the largest number of cases, 97% occurring in the northeast of the country. The second highest number of cases has been in Colombia. Cases (caused by the same strain) have occurred in Cape Verde, raising fears that the virus will soon spread to Africa. By the end of November 2016, the USA had reported 4250 cases in returning travellers, and local transmission in Florida had become established. During the last week of August, local transmission was documented in Singapore for the first time, with over 120 cases recorded, and with travel-related spread to neighbouring Malaysia, and cases of microcephaly in Thailand and Vietnam associated with congenital Zika infection have been reported.
  • There are many facts about the current outbreak that are still unknown – why the WHO declared this outbreak to be a public health emergency of international concern in February 2016 (its status as an emergency ended in November 2016 and it will now be managed in the same way as other health threats).

Worldwide map of Zika Virus Zika in Pacific Islands

Countries with active Zika transmission (CDC 12 December 2016)

The latest maps can be found here

Global cases of Zika

Global Distribution of Aedes aegypti and Aedes albopictus (2015)

Aedes mosquitoes are found throughout Africa and Asia, so the future potential for the Zika virus to spread is very alarming.

Travel to areas with a high risk of Zika transmission

As in any other outbreak situation, it is important to do everything possible to reduce the risk of infections that might possibly be confused with Zika. Vaccine precautions against other travel-related infections are important: see separate travel health advice. Of special note is the need to be vaccinated against flu.

Insect bites cannot be avoided completely, but travellers should do everything possible to reduce the numbers of bites.

  • Cover up as much of the body as possible – preferably with light-coloured clothes
  • Using plenty of DEET insect repellent
  • Wear clothing impregnated with permethrin when working outdoors
  • Using mosquito nets or plug-in mosquito killers in your room at night
  • Choose screened, air-conditioned accommodation if available and keep windows and doors closed
  • Ensure any obvious mosquito breeding sites close to your work or accommodation are reported and properly dealt with

What illness does the Zika virus cause?

After an incubation period of 3 to 14 days following exposure, the most common symptoms are:

  • Rash (lasting 5 to 6 days)
  • Itching
  • Headache
  • Joint and muscle aches
  • Conjunctivitis
  • Mild fever (occurs in only 50% of cases, often lasting less than a day).

Symptoms persist between 4 and 7 days. In early stages, the Zika illness is indistinguishable from dengue and chikungunya (two other arbovirus infections that occur in exactly the same parts of the world, and that are currently more frequent than Zika). Only 20% of Zika infections cause symptoms.

A person who has been infected with Zika is likely to be protected from future infections.

Treatment/What to do if you suspect infection

  • No specific anti-viral treatment is available. Most symptoms are mild. People with symptoms of Zika should get plenty of rest, drink sufficiently, treat any pain and/or fever with paracetamol and should seek medical advice if symptoms worsen. For conjunctivitis, apply in-eye lubricants, stop wearing contact lenses, and seek ophthalmological advice if symptoms are severe.
  • It may be helpful to document infection. RT-PCR blood and urine testing (see below) for Zika (and other arboviruses) is available in many of the places where Zika occurs, so seek local medical advice if you think you have been infected. Testing at the time (or shortly after) infection is more likely to yield conclusive results.

What complications can follow infection?

Foetal harm

  • Damage to the developing nervous system of the foetus during pregnancy is the greatest concern. The malformations include: microcephaly, calcification, structural abnormalities of grey and white matter, and enlargement of the brain’s ventricles (internal fluid-filled spaces). Other foetal abnormalities affect the eyes and limbs (club foot and limb contractures).  Zika virus can be detected in blood, brain tissue, and cerebrospinal fluid of foetuses following miscarriage, stillbirth or termination of pregnancy. In cell culture, the virus has been demonstrated to multiply in neural cells and cause cell death.
  • The exact frequency of microcephaly and malformation in foetuses of pregnant women who have been infected with the virus is still under investigation; the risk is highest during the first trimester (three months) of pregnancy, remains present during the middle trimester, and appears to be reduced but still present during the third. A study of women in Rio de Janeiro who experienced symptoms of infection during pregnancy found foetal malformation in 22%. Microcephaly following symptomless Zika infection during pregnancy has been shown in at least 4 cases. In the US, of 1110 pregnant women with travel exposure to Zika and positive test results, microcephaly occurred in 6% of pregnancies.

Post-infection syndromes

  • Zika infection has also been associated with Guillain-Barré syndrome, also called GBS. This is a rare autoimmune condition that can follow a variety of viral infections. It consists of weakness, paralysis and a spectrum of neurological complications ranging from mild to life threatening. Most people with GBS recover fully. Although Zika-affected countries have seen an increase in the number of GBS cases, it remains infrequent. Preliminary data suggest that GBS follows approximately one in 5000 cases of infection. In the current outbreak, no deaths from GBS been reported.

Sexual transmission

In the recovery phase of a viral infection, the immune system produces antibodies that inactivate and eliminate the cause. Live Zika virus is capable of surviving in semen following infection: for a variable period afterwards, semen can temporarily protect Zika virus from inactivation by immune defences, making it a possible source of delayed infection.

Any traveller who develops symptoms of Zika infection should seek medical advice, ask for testing, and abstain from sex in the meantime. Men who have travelled to risk areas should abstain from sex or use barrier contraception on returning, for six months afterwards or for the duration of pregnancy if their partner is pregnant. Note: this recommendation is subject to change in the light of evolving evidence.

Concerns about pregnancy and conception

Live Zika virus remains present in the blood of an infected person for about 10 days. There is no evidence that the virus can cause infection in a baby conceived after the virus has been cleared from the blood.

Advice for women

  • Avoid travel to affected areas if you are pregnant or trying to conceive; otherwise, seek expert medical advice
  • If you or your partner has travelled to a risk area, use barrier contraception for six months afterwards
  • If you or your partner has travelled to a risk area, wait 6 months before trying to conceive

Advice for men

  • If you or your partner has travelled to a risk area, use barrier contraception for six months afterwards
  • If you or your partner has travelled to a risk area, wait 6 months before trying to conceive
  • If you have travelled to a risk area and your partner is pregnant, you should abstain from sex or use a condom on returning for at least the remainder of the pregnancy

If you become pregnant following travel

  • Current UK guidelines advise that women who have experienced symptoms of possible infection should be tested for Zika virus, and have a baseline ultrasound examination.
  • All other pregnant women who have travelled to an area with active Zika virus transmission during pregnancy but who have not reported clinical illness should be offered a baseline ultrasound scan; consideration of storing a serum sample locally is also advised.

Progress towards a vaccine and control

  • Vaccine development is ongoing. Promising recent developments include a combined vaccine that would also include protection against dengue. The earliest practicable timeline for introduction of a vaccine into clinical use is 2020. 

Testing for Zika virus infection or exposure

  • Routine testing in non-symptomatic travellers returning from tourist areas is not considered necessary
  • Testing may be recommended for pregnant women who have been symptomatic during travel, who have recently returned from risk areas, or who have had possible sexual exposure to a person who has travelled to a risk area

Two kinds of tests are available:

  • Tests for traces of viral genetic material (called RT-PCR tests) – can be used on serum (within 7 days of the start of symptoms) or urine (within 14 days of the start of symptoms)
  • After this period, antibody tests should be used. They may turn positive as early as Day 4 (usually 5-7 days), and remain positive for several months

Fleet Street Clinic offers PCR and Antibody Tests, read here for more information 

Testing is not straightforward:

  • Positive RT-PCR tests confirm infection, but negative RT-PCR and antibody tests do not completely rule it out.
  • Positive antibody tests may also need additional tests for confirmation, because of similarities (cross-reactivity) to other viruses from the same family (e.g. dengue, yellow fever vaccine virus)
  • Negative antibody tests may not completely rule out infection (and therefore ongoing risk) since asymptomatic infection may be associated with reduced viral load: we simply don’t know.
  • New commercial tests and instant tests are also currently in development that may make the process faster and more straightforward.
  • Dengue and chikungunya cause similar symptoms to Zika, so tests for these may also be needed to clarify a diagnosis: PCR and antibody tests are available for dengue; antibody tests are available for chikungunya.

Staying up-to-date

All travellers to regions with Zika should seek up to date travel health advice before they go.

Check these sources for latest news:

World Health Organization

Pan American Health Organization (PAHO)

Centers for Disease Control & Prevention (US advice)

National Travel Health Network & Centre (NATHNAC) UK

Consultation with Fleet Street Clinic

Fleet Street Clinic offers advice for travellers visiting Zika-infected areas and provides Zika testing following travel abroad. Fleet Street Clinic is an independent medical practice with over 20 years experience in travel health. Our experienced medical staff can provide expert help tailored to your own individual circumstances.

Zika Testing Prices: 

Zika PCR Test -£300

Zika Antibodies Test – £195

Price includes the GP consultation fee.

To book a travel consultation, vaccines or post-travel tests with Fleet Street Clinic call 020 7353 5678, email info@fleetstreetclinic.com or book an appointment here

Richard Dawood: 12th December 2016

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