Epidemiological update: outbreak of Zika virus in French Polynesia

Epidemiological update

​On 6 November 2013, Public Health Authorities in French Polynesia reported of an outbreak of sub-febrile and eruptive syndrome due to Zika virus spreading across the archipelago since week 41 of 2013. An outbreak of dengue type 1 and 3 is on-going in the archipelago since February 2013.

Over 400 clinical cases of Zika virus infection have been reported up to 30 October 2013 from three archipelagos of French Polynesia (Society, Tuamotu and Marquesas islands). All the reported cases are mild. Laboratory confirmation was performed by sequencing of the virus on three cases. The infection is spreading rapidly within all age-groups and both genders are affected.
In light of the risk of further spread of the epidemic in the area, clinical surveillance of febrile eruptive syndrome is being reinforced across the community and hospital care settings of the archipelagos. The epidemiological surveillance has been strengthened by local health authorities together with re-enforcement of vector control measures.

Zika viral infection is a mild and short-lasting febrile illness with conjunctivitis and a maculo-papular rash without haemorrhagic symptoms [1,2]. The treatment is only symptomatic. Zika virus is a flavivirus likely transmitted by Aedes mosquitoes similar as the ones transmitting dengue [2]. Aedes aegypti and Ae. albopictus have been recently demonstrated as competent vectors for Zika virus [3,4].
The laboratory diagnosis is done by molecular testing (PCR amplification and genetic sequencing) during the early phase of the disease and/or serological assay (detection of specific IgM antibodies) with possible cross-reactivity with others flavivirus [5,6].
After the first isolation of the virus in the Zika forest in Uganda from a sentinel monkey in 1947, sporadic cases or limited outbreaks have been reported in tropical Africa and in Southeast Asia [2].In 2007, a large outbreak has been recorded in Yap island (Micronesia) as well as a case confirmed in Cambodia in 2010 [1,5]. Two geographically distinct lineages of Zika virus are circulating, one in Africa and one in south eastern Asia and the Pacific region [7]. The 2013 outbreak in French Polynesia is the second outbreak of Zika virus identified in the Pacific region.
The prevention is based on vector control campaigns at community level and individual protection measures to minimise the exposure to mosquito bites as for dengue fever prevention (use of anti-mosquito devices and wearing long sleeves and clothes with long legs, especially during the hours of highest mosquito activity (morning and late afternoon).
Although parts of French Polynesia are touristic areas, the potential risk of importation to the EU by travellers is limited due to the limited number of cases. However, returning travellers from the area experiencing dengue-like clinical symptoms are advised to seek medical care. In absence of Ae. albopictus mosquito activity in Europe during late autumn and winter months, there is presently no risk of spread of the virus and onwards transmission in continental Europe.
1. InVS. Bulletin hebdomadaire international n°424 30-oct to 5-nov 2013: Institut de Veille Sanitaire; 2013 [13/11/2013]. 2]. Available from: http://www.invs.sante.fr/Publications-et-outils/Bulletin-hebdomadaire-international/Tous-les-numeros/2013/Bulletin-hebdomadaire-international-du-30-octobre-au-5-novembre-2013.-N-424.2. Heang V, Yasuda CY, Sovann L, Haddow AD, Travassos da Rosa AP, Tesh RB, et al. Zika virus infection, cambodia, 2010. Emerging infectious diseases. 2012 Feb;18(2):349-51. PubMed PMID: 22305269. Pubmed Central PMCID: 3310457.3. Hayes EB. Zika virus outside africa. Emerging infectious diseases. 2009 Sep;15(9):1347-50. PubMed PMID: 19788800. Pubmed Central PMCID: 2819875.4. Li MI, Wong PS, Ng LC, Tan CH. Oral susceptibility of singapore aedes (stegomyia) aegypti (linnaeus) to zika virus. PLoS neglected tropical diseases. 2012;6(8):e1792. PubMed PMID: 22953014. Pubmed Central PMCID: 3429392.5. Wong PS, Li MZ, Chong CS, Ng LC, Tan CH. Aedes (stegomyia) albopictus (skuse): A potential vector of zika virus in singapore. PLoS neglected tropical diseases. 2013 Aug;7(8):e2348. PubMed PMID: 23936579. Pubmed Central PMCID: 3731215.6. Duffy MR, Chen TH, Hancock WT, Powers AM, Kool JL, Lanciotti RS, et al. Zika virus outbreak on yap island, federated states of micronesia. The New England journal of medicine. 2009 Jun 11;360(24):2536-43. PubMed PMID: 19516034.7. Lanciotti RS, Kosoy OL, Laven JJ, Velez JO, Lambert AJ, Johnson AJ, et al. Genetic and serologic properties of zika virus associated with an epidemic, yap state, micronesia, 2007. Emerging infectious diseases. 2008 Aug;14(8):1232-9. PubMed PMID: 18680646. Pubmed Central PMCID: 2600394.8. Haddow AD, Schuh AJ, Yasuda CY, Kasper MR, Heang V, Huy R, et al. Genetic characterization of zika virus strains: Geographic expansion of the asian lineage. PLoS neglected tropical diseases. 2012;6(2):e1477. PubMed PMID: 22389730. Pubmed Central PMCID: 3289602.