Special Report
Arboviruses and Pacific Islands: Zika in Polynesia, Chikungunya in Micronesia, Dengue in Melanesia
By Stan Deresinski, MD, FACP, FIDSA
Clinical Professor of Medicine, Stanford University, Hospital Epidemiologist, Sequoia Hospital, Redwood City, CA, Editor of Infectious Disease Alert
SYNOPSIS: Arbovirus infections, including Zika, are currently a prominent cause of febrile illness in Pacific Islands nations.
Zika virus is a mosquito-borne flavivirus first identified in 1947 in a sentinel rhesus monkey stationed on a tree platform in the Zika forest, near Entebbe, Uganda.1 The virus was subsequently isolated from a pool of Aedes africanus mosquitoes collected in 1948 from the same area of the forest. At the same time, a serosurvey found that 6.1% of the residents in nearby regions had specific antibodies to Zika virus.
In December 2013, the French Polynesia Department of Health confirmed an outbreak of Zika fever in the islands of Tahiti, Moorea, Raiatea, Tahaa, Bora Bora, Huahine, Nuku Hiva, Hiva Oa, Ua Pou, Hao, Rangiroa, Fakarava, Tikehau, Takaroa Ahe and Arutua.2 By December 3, 2013, 99 laboratory confirmed cases and 35,000 suspected cases had been reported. No hospitalizations or deaths have been reported. It is estimated that 7.6% of the total population have had symptomatic infection that lasted, on average, 3-6 days. Rash was present in 95%, fever in 73%, arthralgia in 70%, and conjunctivitis in 43%. There has, at the same time, been a marked increase in cases of Guillian-Barre syndrome, approximately 8 times higher than expected, and each case had a previous illness compatible with Zika. However, no one was tested, so a link has not been demonstrated.
Only one previous large outbreak of Zika has been reported. In 2007, a relatively mild febrile illness with rash, conjunctivitis and arthralgia was recognized to be affecting residents of Yap, one of the Carolina islands of the Federated States of Micronesia. A total of 108 cases (49 proven, 59 probable) were identified. Although many patients had IgM antibody to dengue virus, the infection proved to be due to another flavivirus, Zika, which had previously only been reported in 14 individuals.1,3 There were no hemorrhagic manifestations, hospitalizations, or deaths identified.
Chikungunya virus (which has recently made its first appearance in the Caribbean,4 is now causing an ongoing outbreak of infection in Yap. As of November 29, 2013, there had been more than 1,000 suspected cases of infection with this alphavirus. No deaths had been reported. Dengue has been undergoing ongoing transmission in many areas of the Pacific, including Micronesia and the Solomon Islands, which is part of Melanesia.5,6
Dengue has been active in tropical and subtropical regions for many years and has recently extended its reach into areas of southern France and in Florida. Chikungunya has continued to be transmitted in vast areas surrounding the Indian Ocean, including southeast Asia, but has also extended its presence into places such as Italy and, now, the Pacfiic Islands. The outbreak of Zika virus infection in French Polynesia raises the profile of this obscure virus.
References
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Deresinski S. Zika in Yap. Infect Dis Alert 2007:26[12]134-35
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Mallet, HP. Zika virus - French Polynesia (02) Jan. 9, 2013; Archive Number: 20140110.2165365 http://www.promedmail.org
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Duffy MR, et al. Zika virus outbreak on Yap Island, Federated States of Micronesia. N Engl J Med 2009;360(24):2536-43.
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CDC issues Health Advisory Alert on Chikungunya Virus Infections Infect Dis Alert 2014;33[4]43-4
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Centers for Disease Control and Prevention. Dengue outbreak—Federated States of Micronesia, 2012-2013. MMWR 2013; 62(28);570-573.
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Nagareda F, et al. Ongoing outbreak of dengue serotype-3 in Solomon Islands, January to May 2013. WPSAR 2013;4(3):28-32. doi:10.5365/wpsar.2013.4.2.013
