Climate not enough to explain (vector-borne) disease emergence

[Shiloh]

Source: http://www.eht-forum.org/news.html?fileId=news100423030931&from=home&id=0

Friday 23 April 2010
Climate not enough to explain disease emergence
Using maps to direct surveillance the ?best first line of defence? against new vector-borne disease risks

Global climate change and the spread of viruses like dengue and chikungunya have fuelled warnings over the emergence of infectious diseases in new areas. With questions lingering over what drives changes in disease patterns, Sarah Randolph, of the University of Oxford in the UK, cautions against blaming climate change alone.

In a review published in the May issue of Nature Reviews Microbiology Randolph and colleague David Rogers examined what determines whether or not pathogens move into new areas, take hold, and spread. Looking at changes in the distribution of six vector-borne diseases as examples they considered the influence of human activities, environmental conditions, and socio-economic factors.

?So far there is not a single case of a vector-borne disease whose recent emergence has been convincingly shown to be due to climate change,? comments Randolph for EHTF News. ?At best there is a loose coincidence in time, of course, as climate change is the backdrop for everything that has happened in the past few decades.?

Randolph explains that even where climatic conditions have been favourable ? with changes having occurred in the right place, at the right time and in the right ways ? they leave ?large gaps? in the understanding of vector-borne disease patterns. Human activities like travel and trade are at least as important, she says.

Complex dynamics

The spread of dengue and chikungunya viruses are good examples of how human activities come into play, according to the review....

 

[Sally Furniss]

Re: Climate not enough to explain (vector-borne) disease emergence

Yellow Fever and Dengue: A Threat to Europe?

P Reiter (paul.reiter@pasteur.fr)1
1. Insects and Infectious Disease Unit, Institut Pasteur, Paris, France


...

Aedes albopictus

In its original range, Ae. albopictus was present from
Beijing and northern Japan to tropical Asia [25]. In
1983, however, the mosquito was found in Memphis,
Tennessee [26], and, two years later, a survey revealed
that it was widely distributed, often common, in the
southern United States. Investigation revealed a glo-
bal trade in used tyres that were frequently infested
with eggs and larvae of the species [27]. Japan was the
principal exporter, and a study of winter diapause at
various latitudes in Asia confirmed that the day-length
that triggered diapause was identical in the southern
United States and in southern Japan [28]. The mosquito
is now widespread in the United States, and is a major
nuisance species as far north as Nebraska and Illinois,
where winter snowfall can be well above 200 cm, aver-
age January night-time temperatures are -10ºC, and
temperatures as low as -33ºC have been recorded. It
is also established in Mexico and all the countries of
Central and South America except Chile. In Africa it is
well established in Nigeria, Gabon, Equatorial Guinea
and Cameroon [29,30], and in Europe it has been
reported from 16 countries [8]. Recent infestations in
the Netherlands have been traced to imports of ‘lucky
bamboo’ from sub-tropical China [31], but these mos-
quitoes do not appear to have survived the winter, per-
haps because they have no winter diapause.

http://www.eurosurveillance.org/images/dynamic/EE/V15N10/art19509.pdf