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The World Health Organisation says 39,000 people have contracted dengue fever in the Pacific region over the past eighteen months.
The Team Coordinator, of Health Security and Communicable Diseases, Dr Angela Merianos, told Jenny Meyer outbreaks of dengue, which is spread by mosquitos, have been widespread affecting many Pacific nations.
ANGELA MERIANOS: Since about the beginning of 2017 dengue serotype 2 has actually spread quite widely throughout the Pacific. But in fact three of the serotypes of dengue are co-circulating in the Pacific at the moment. We've had over 39,000 cases of dengue reported since that time, most of that has been dengue 2 but we have had some countries also reporting dengue type 1 and dengue type 4. So the outbreaks that we have had reported so us since 2017 have been from American Samoa, Fiji, Nauru, Palau, Samoa, Solomon Islands, Tonga, and Vanuatu in 2017. Some of those were actually continuing since 2016. We've also heard from Wallis and Futuna, which has experienced a dengue type 1 outbreak, while French Polynesia and New Caledonia have reported both intercurrent outbreaks of serotypes 1 and 2. Niue reported serotypes 2 and 4 and most recently you've heard of the dengue type 2 in Kiribati.
JENNY MEYER: So have you got any idea how many people have died of dengue over that period? You're talking about over the past year and a half, is that right?
AM: That's correct.
JM: How many fatalities have there been in that time?
AM: I don't have absolute numbers. But fortunately the number of fatalities have been relatively low. So although any fatality is obviously a tragedy for that individual and their family and community, in terms of international comparisons for example, a dengue programme and the case management of dengue is considered to be good if the case fatality rate, so that's the number of deaths per total number of cases rather, is under one per cent. And certainly in the Pacific the numbers are well and truly under one per cent.
JM: What is the World Health Organisation doing to try and help Pacific governments deal with this problem. I guess it's a known issue, it's perhaps related to climate change, it does seem like quite an extended outbreak, what's being done to help people deal with this problem?
AM: First of all can I just say that it's actually a very complex inter relationship between the vectors, temperature, climate, and population immunities. So it's actually difficult to be able to definitively say that outbreaks of dengue are associated with climate change or climate variability. One of the most important factors in determining how big or small a dengue outbreak will be is the circulation of serotypes. Because they have this ability to disappear from a population for a period of time. And so we've been seeing these large outbreaks of dengue 2 in some countries because they hadn't actually had dengue 2 circulating for over twenty years in some of these countries. This means that there is a large population of people who have not been previously exposed to dengue type 2 and therefore it can spread very rapidly in that population. When you have a situation where the population has got high immunity overall against that particular type of dengue, even if the virus is circulating we don't see these large outbreaks. Temperature can effect the capacity of the dengue vector to carry the virus and the density of the population of the mosquitos in terms of breeding sites. But the bottom line is that if the population is immune because they have been previously exposed, even in the presence of the virus, it doesn't mean we'll see large outbreaks.