Dengue on the Big Island

There's been a recent small outbreak (15 19 23 27 33 56 65 72 79 88 92 101 cases in the past month) of dengue on the Kona (west) side of the Big Island here in Hawaii. Dengue is a public health problem in much of the tropics. It is seldom fatal, but can cause hospitalizations. Occasional neurological complications include encephalitis, brachial neuritis, and Guillain-Barre.

Dengue is not transmitted from person to person: it requires a mosquito (Aedes aegypti or less often Aedes albopictus) as an obligate intermediate host. If a mosquito bites a person with the dengue virus from about 1.5 days before the onset of fever to about 8 days after fever onset, the mosquito can become infected with the virus (yes, this virus infects insects and humans alike). The infection starts in the mosquito's gut, and after about 10 days spreads up to the salivary glands, at which point the mosquito can transmit the infection to a human that is bitten. The female mosquito bites during a 20 to 50 day period of its tropical life cycle, so a typical mosquito can spread the virus for a month, if it bites for that duration, rather than stopping after its first meal. On the other hand, people with dengue can only infect mosquitoes for about 12 days at most. Unfortunately, that probably includes short periods of time where there is no sign of infection in the human, yet a mosquito can contract the virus from biting the asymptomatic individual.

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ABSTRACT

Front Immunol. 2014; 5: 290.

Published online 2014 Jun 17. doi: 10.3389/fimmu.2014.00290

PMCID: PMC4060056

Human to Mosquito Transmission of Dengue Viruses

Lauren B. Carrington and Cameron P. Simmons

The successful transmission of dengue virus from a human host to a mosquito vector requires a complex set of factors to align. It is becoming increasingly important to improve our understanding of the parameters that shape the human to mosquito component of the transmission cycle so that vaccines and therapeutic antivirals can be fully evaluated and epidemiological models refined. Here we describe these factors, and discuss the biological and environmental impacts and demographic changes that are influencing these dynamics. Specifically, we examine features of the human infection required for the mosquito to acquire the virus via natural blood feeding, as well as the biological and environmental factors that influence a mosquito’s susceptibility to infection, up to the point that they are capable of transmitting the virus to a new host.

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