This guidance provides practical advice for clinicians caring for immunocompromised persons who wish to travel or who have travelled to Zika affected areas.
Zika virus, travel and the immunocompromised patient
Published experience of Zika virus infection in immunocompromised or immunosuppressed individuals is very limited and knowledge about the pathogenesis of Zika virus infection continues to evolve.
Since Zika virus is a flavivirus, it is likely that both innate and adaptive responses are required to halt Zika viral replication and clear the virus, so medical conditions or interventions that influence innate and/or adaptive immune responses could alter the course of clinical illness, including the symptoms, severity and duration of infection.
Case reports describing Zika virus infection in patients with conditions associated with compromised immune systems are limited. In Colombia, an adult and a child with confirmed Zika virus infection had severe illness with fatal outcomes. Post mortem examinations suggested probable lymphoblastic leukaemia and myeloid leukaemia, respectively. The role of Zika virus infection in these fatal outcomes is unclear.
As an interim measure, and until data from case control studies and large observational studies appear (note these may not be forthcoming), some extrapolation from experience of infections caused by the related flavivirus, dengue virus, is reasonable.
Published data on dengue virus infection and immunocompromised patients come from case reports or small case series, often with mixed patient populations (for example variability in underlying conditions or interventions, differing degrees of immunocompromised, different ethnic and geographical backgrounds).
From the limited data available, overall clinical outcomes for dengue virus infection in immunocompromised patients appear to be similar to those for dengue virus infection in immunocompetent patients. Based on experience with acute RNA virus infections in general, immunocompromised patients could have atypical presentations, including absence of fever.
There is a theoretical risk of prolonged dengue viraemia in profoundly immunocompromised patients (using Green Book definitions), and it is not clear whether dengue virus could persist in certain organs after becoming undetectable in serum or plasma. The same theories may be applied to Zika virus and immunocompromised patients in the absence of data from specific studies.
There are no reliable data available from any patient group to assess duration of viral RNA detection in blood, semen or other compartments in immunocompromised patients. It is possible that severe immunosuppression could be associated with more severe illness following flavivirus infections, but conclusive data are lacking; close clinical monitoring is recommended for severely immunosuppressed patients with Zika virus infection.
HIV infection and Zika virus
To date, several case reports of Zika virus infection in HIV-infected individuals have been published, all describing mild Zika illness with recovery. Since experience is limited and detailed background clinical information was not provided for all published cases, it is difficult to assess the impact of HIV infection on Zika virus illness or on the likelihood of sexual transmission of Zika virus.
It is possible that HIV-infected patients with severe immunosuppression (over 6 years of age and CD4 cell count of less than 200 cells per mm3, or an AIDS-defining illness at any age) might have an increased risk of complicated Zika illness. Travel advice should consider the degree of immunosuppression, and HIV-infected patients with Zika virus infection should be monitored closely, especially if they have severe immunosuppression.
Practical advice for immunocompromised patients
Since risks are likely to vary according to the immunosuppression or immunocompromise involved, travel advice will need to be tailored to the individual, with the strongest recommendations being made for severely immunocompromised patients (as per Green Book definitions).
The following advice could be provided to patients by their clinicians:
Consider whether travel to an area with high or moderate Zika virus risk is necessary. Your GP or specialist can help you to assess the potential risks of Zika virus infection and other travel-associated infections. The National Travel Health Network and Centre (NaTHNaC) also offers advice online.
Ensure you have adequate and appropriate travel insurance prior to travel and that you have a plan of what to do should you become ill whilst travelling; support groups for your condition may be able to advise you on where to obtain specialist travel insurance, if it is required for your particular condition.
Seek advice on vaccination requirements for travel and malaria prophylaxis. Information is available from NaTHNaC, or contact your GP or specialist.
Zika virus infection in women who are pregnant or who are planning to get pregnant can result in serious birth defects, regardless of whether the mother underlying immune problems or not. Contact your GP or specialist for further advice before you travel.
If you are pregnant and have travelled to an area with a high or moderate risk of Zika virus transmission, seek advice from your GP or midwife on return to the UK, even if you have not been unwell.
All women are advised to avoid becoming pregnant while travelling in an area with high or moderate Zika virus risk, and for 8 weeks after their return (or 6 months if the male partner has travelled). See guidance on preventing infection by sexual transmission where a male partner has travelled to an area with active Zika virus transmission.
Notify your GP, and specialist if necessary, if within 2 weeks of returning to the UK from an area with risk of Zika virus transmission, you have any new symptoms, particularly symptoms that can be associated with Zika virus infection. These include:
- joint pain
- muscle pain
- lower back pain
- pain behind the eyes
There have been cases of likely sexual transmission of Zika virus infection (mainly male-to-female, but also male-to-male and female-to-male). The overall risk of sexual transmission is considered to be low, but it is not known whether the risk of sexual transmission of Zika virus is different in people with immune problems.
Contact your GP or specialist if you have concerns about potential sexual transmission after visiting an area with high or moderate Zika virus risk or following Zika virus infection. See advice on preventing sexual transmission of Zika virus.
Travel medicine services: patients with complex medical problems
Hospital for Tropical Diseases
The Hospital for Tropical Diseases, University College London Hospitals NHS Foundation Trust, operates a consultant-led clinic that offers pre-departure travel medicine service to patients with complex medical problems, including immunocompromised patients. This is an NHS-commissioned service (GP referral required). Private appointments are also available.
NaTHNaC telephone advice line for health professionals
Monday to Friday: 9am to 11am
Monday and Friday: 1pm to 2pm
Tuesday, Wednesday and Thursday: 1pm to 3pm
Telephone: +44 (0)845 602 6712