Mosquito-borne viruses - Cord blood

Essential information

Definition/s

Mosquito-borne virus risk areas are shown in the Geographical Disease Risk Index which includes details of the specific viral risks present.

The day that a donor leaves a risk area is defined as Day 0.

Includes
  • Chikungunya Virus, also known as CHIKV
  • Dengue Virus, also known as Dengue Fever
  • Yellow Fever, also known as YF
  • Zika Virus, also known as ZIKV, and Zika Virus Fever
Obligatory

Must not donate if:

  1. A mother has been diagnosed with Chikungunya, Dengue, Yellow Fever or Zika Virus infection whilst in a mosquito-borne virus risk area or following her return to the UK during this pregnancy.

  2. A mother has either had a history of symptoms suggestive of Chikungunya, Dengue, Yellow Fever or Zika Virus infection whilst in a mosquito-borne virus risk area or following her return to the UK during this pregnancy.

  3. In other cases, it is 28 days or less since the mother was last in a mosquito-borne virus risk area.

Supporting information

See if relevant
Additional information

Should a situation arise where a risk assessment is warranted, seek expert virologist advice. Additional laboratory testing may be available and appropriate (e.g. referral to the Porton Down reference laboratory).

Chikungunya, Dengue, Yellow Fever and Zika viruses are spread by the day-flying mosquito species Aedes aegypti and Aedes albopictus.

These mosquitos are typically found in tropical and subtropical regions including the Caribbean, South and Central America, Mexico, Africa, the Pacific Islands, South East Asia, the Indian sub-continent, Hawaii and northern parts of Australia.

The range of Aedes albopictus is increasing into more temperate zones, leading to outbreaks of mosquito-borne virus disease in new areas. This includes seasonal outbreaks of Dengue and Chikungunya in parts of Europe. The GDRI entry for mosquito-borne virus risk areas will indicate whether a risk should be applied all year or can be applied seasonally.

Position statements on mosquito-borne viruses are available.

Chikungunya Virus:

Chikungunya is an alphavirus that can cause a wide spectrum of disease. This may range from no or minimal symptoms to death. Most commonly it causes arthritis (typically in the knee, ankle and small joints of the extremities), high fever and a maculopapular rash.

Chikungunya Virus is found in countries in Asia, Africa, Central and South America, and in the islands of the Caribbean. It is known to be spread by blood in symptomatic cases and on theoretical grounds could be spread by transfusion and transplantation of tissues and organs from people with pre-symptomatic or asymptomatic disease. A number of visitors returning from endemic areas to the UK have been diagnosed with this infection.

Dengue Virus:

Dengue Virus is a flavivirus that typically gives rise to abrupt high fever with a range of accompanying symptoms.

Dengue fever (DF) is the most common insect-borne disease worldwide. Dengue is currently considered endemic in over 140 countries.

Overall, up to 75% of cases are asymptomatic or mild. If symptoms occur, they can range from non-specific acute febrile illness to severe disease including dengue haemorrhagic fever and dengue shock syndrome. Mild cases may be misdiagnosed as other febrile illnesses.

Yellow Fever Virus:

Yellow Fever Virus is a flavivirus which is found in Africa, South America, Central America and parts of the Caribbean.

Symptoms of Yellow Fever include high temperature, headache, nausea and vomiting, muscle pains and backache. One in four individuals may suffer from jaundice and bleeding from the gastrointestinal tract and other sites.

Zika Virus:

Zika virus is a flavivirus which was known to occur in Africa and parts of Southeast Asia. More recently, Zika Virus has been associated with epidemic outbreaks in the Pacific region and in the Americas. As well as mosquito-borne infection, Zika Virus can be spread though sexual transmission.

Infection is usually asymptomatic or presents as a mild self-limiting febrile illness. More severe disease and hospitalisation are rare but infection during pregnancy carries a high risk of congenital abnormalities in the baby. Zika Virus infection may be mistaken for Chikungunya or Dengue infections as these viruses often co-circulate.

Reason for change:
Entry renamed from ‘Tropical viruses’ to ‘Mosquito-borne viruses’ with equivalent changes to terminology throughout the text. Information about seasonal risk has been added to ‘Additional information’.
Version details:

CB-DSG Edition 203 Release 58 (11 August 2026)