|More illness: malaria in Vermont?
Comments to pages 92 - 102 in Cool it.
Page 93 top: ". . a headline like `Climate change death toll put at
150,000´ sells a lot of newspapers"
Lomborg does not mention that due caveats are mentioned in the press
release, for instance this: "But he acknowledged
global deaths from climate change were minuscule compared with the
total number of deaths a year, which the WHO puts at 56 million. About
10 times more people die each year from tobacco-linked illness, he
Note to page 93: "The analysis was redone in 2005 . . . "
The reference from 2005 is not a remake of the analysis, but a review
dealing with the WHO analysis as well as with many other studies. It
does, however, contain some information that was not included in the
chapter in the WHO report.
Note to page 93: "They only have old and very limited surveys for these
results. . ."
This is not true. The surveys for hot climates are completely new. It
is true that for Europe they only use Kunst et al. (1993). Between the
lines, Lomborg suggests that this study is old
and hence outdated and not so reliable as newer studies. On the
contrary, the WHO report argues why exactly this study is
better and more reliable than others. In any case, the changes in death
rates are mainly in warm climates, and therefore the finer details
concerning deaths in Europe are of little importance.
Note on page 93: " However, there are no `reasons described
anywhere . . "
The source gives many reasons why the data are of
doubtful value on its page 142.
Page 93 and note: " . . they simply left
out cold and heat deaths . . ." In the note: "In the 2005 update
. . they equally leave them out of the total (Patz et al. . .)"
is directly wrong. The net effect of cold and heat on cardiovasular
disease is actually included in the table referred to by Lomborg on
page 312 in the 2005 paper. When Lomborg tells his readers that Patz et
al. left out the data, and they clearly did not, this is deliberately misleading.
Page 93: " . . leading to the total death toll of 153,000."
primary source, Campbell-Lendrum et al., does not give any total death
toll. The secondary source, Patz et al. 2005, gives a total death toll
of 166,000. It seems that Lomborg has subtracted the figure of the
death toll due to cardiovascular disease of 12,000, although the result
of this (completely unjustified) subtraction is 154,000 rather than
Page 93: " . . . we get about 620,000 avoided cold deaths and
130,000 extra heat deaths."
This calculation is made on the basis of Bosello et al. (2006). As
on Lomborg-errors, the data go back to Martens (1998), which has a
flawed treatment of the data. In the original data, the increase of
heat-related deaths more than outweigh the decrease in cold-related
deaths, but on the basis of these data, regression formulae are made
which give just the opposite result.
Page 93 bottom: ". . there are actually almost 200,000 more people
surviving each year. "
First, Lomborg´s calculation
is wrong. If we use the figures that he mentions in his text,
we obtain the following net change in number of deaths per year:
-153,000 + 620,000 - 130,000 = 337,000. Second, the figure cited by
Lomborg is just the outcome of one calculation,
based on the misuse of original data in Martens (1998). The alternative
data in Patz (2005) is that the net effect of cold and heat is an
increase in cardiovascular deaths of 12,000 per year. So, one
calculation, which is probabaly flawed, gives a net result of +200,000,
whereas another gives -12,000. Considering the uncertainty indicated by
the difference between these two estimates, it is very misleading to
use the word "actually", as if this were well-established fact.
Page 94 top: "Had all the relevant data been included, it would more
likely have shown the very opposite picture."
is completely wrong. All the relevant data have indeed been included,
and the result is 166,000 extra annual deaths. Lomborg knows this (he
has studied the relevant table in Patz et al. 2005), so his text is delibearately misleading, and
very grossly so.
SOME GENERAL COMMENTS:
Lomborg uses several pages (pp. 94 -97) to explain that the
distribution of malaria is mainly governed by socioeconomic conditions,
whereas climate causes no serious restriction. Indeed, malaria may
very cold climates, such as Finland and Siberia, but one should not
exaggerate the ability for malaria to thrive in cold climates.
There are several species of malaria parasites. The
most deadly is Plasmodium falciparum, which is widespread in the
tropics. Another species, Plasmodium vivax, is more widespread in
temperate climates and is of little concern in Africa, because most
tribes/races of Africans are resistant to it. P. plasmodium can hardly
develop in its mosquito host at temperatures below 18° C, whereas
the corresponding limit for P. vivax is 16° C.
Details concerning the climatic conditions limiting
P. falciparum in Africa are given on this
page in Lomborg-errors. As described there, the number of
months with temperatures above 18° is crucial. When every month is
above this temperature, the parasite may infect at any time of the
year. Children will be permanently exposed, and they will gradually
develop immunity. However, if some months are too cold, infections
occur only seasonally. And if temperatures are not high enough every
year, infections will occur only in certain years. Contrary to what you
might expect, the latter situation is the most dangerous, because then
children will not have developed immunity. Malaria will then occur as
epidemics in certain years, and in these years it will kill thousands
Similar situations may arise in northern Europe or
Asia with Plasmodium vivax. This parasite species exists in several
forms; the northernmost form does not become infective until it has
spent about 8 months in its human host. That is, when people are
infected in late summer, the parasite survives in them during winter,
and become infective only in the next spring. The life cyclus may be
completed if only summer temperatures remain above 16° C for at
least one month. But in some years, summer temperatures may become much
higher. For instance, temperatures at Arkhangelsk in the summer of 1935
were up to 35° C, which means that during the season when the
parasite is in the mosquitoes, it may be subject to "tropical"
temperatures, and the development within the mosquito host will be
extremely rapid, allowing very fast reinfection of humans. If there are
two or three hot summers in a row, the parasite may multiply
enormously. Under these conditions, most people have not previously
been exposed to the parasite, and have developed no immunity. When
there is a sudden mass infection with malaria parasites, they will
therefore become very ill, and if they are not treated, many will die.
This is the explanation why we hear that mass mortality due to malaria
has occurred in northern climates.
If the climate warms generally, the risk to have
series of such hot summers increases, and epidemics may become more
At intermediate latitudes, there may be a spreading
of other forms of P. vivax which develop fast in their human host and
are able to reinfest mosquitoes already after 3 or 4 days. This allows
them to have several generations during a summer, and thus to have
multiplied considerably by the end of the summer. There may then be a
trend towards seasonal increase in malaria infections every year.
It is therefore much too simple to claim that
malaria may occur in the tropics as well as in Finland and Siberia, as
if changes in temperature would have little consequence. Even small
temperature changes would easily lead to large differences in the
prevalence of malaria.
All this concerns a situation when no chemicals are
available to fight the malaria parasite or its mosquito host. It is not
possible to eradicate the host - only to decimate its numbers
temporarily. On a short term, however, this is enough to break the life
cycle of the parasite and thus to eradicate it. For instance, in the
years following the Second World War, spraying with DDT eradicated
malaria in the Soviet Union. USSR was declared free of malaria in
There is always a risk that the parasite may return,
however, because the Anopheles mosquitoes will survive, and because
people travelling around may carry the parasite with them. Local
mosquitoes will become infested when feeding on migrants, and thereby a
local cycle of transmission to resident people will be initiated. This
is happening to an increasing extent. In Russia, especially around
Moscow, the number of cases of local origin has been growing. Thus in
1998 there were 1,019 "imported" cases and 63 of local origin, while in
2002 the corresponding figures were 764 and 134. Malaria has been
imported mainly from Tajikistan, where the disruption of civil war
combined with an influx of malaria-carrying refugees from Afghanistan
has generated the first post-Soviet malaria epidemic (source: this
If a local cycle of infections starts e.g. at Moscow, it
will be interrupted by finding all infected people and treating them
with anti-malaria drugs. However, malaria strains resistant to the
commonly used drugs are becoming more widespread in South Asia, and may
be carried to Russia with immigrants or tourists.
A similar situation may arise in USA if tourists or
migrants import drug-resistant forms of the malaria parasite, e.g. from
Mexico or other Central American countries.
Historically, the malaria parasite has developed
resistance to anti-malaria
drugs, first to quinine, then to chloroquinine, then to pyrimethamine,
and now the very first examples of resistance to
artemisinin-derivatives are being reported (for instance this link).
A new cheap anti-malaria drug seems to be underway now (link),
but in the end the question is: who wins the race between man and
parasite: will the parasite develop resistance faster than man can find
new drugs? Once resistance to artemisinin becomes widespread in future
very well happen), there may remain no efficient anti-malaria drugs,
and if man becomes the loser of the race, there may come a time when
malaria cases in highly developed
countries will no more be treatable.
Page 98 top: ". . . DDT, which is still the most cost-effective
insecticide against mosquitoes . . "
Comment: Rosenberg (2004) says: "Both bed
nets and house spraying can be effective, and studies comparing costs
differ on which is cheaper." Schapira (2006) Says: "Few trials have
compared insecticide-treated nets [impregnated with pyrethroids] and
indoor residual spraying [with DDT], but results so far suggest that
the methods are more or less equal in efficacy." Walker (2000) says: ".
. the prices of pyrethroids are declining, making some only slightly
more expensive than DDT at low application dosages."
Page 98: ". . . which has made it easy to claim that global
warming is the culprit."
Comment: This is not a fair summary of the
references by Epstein and Patz noted for page 98. Especially the paper
by Patz et al. (2005) does
not make easy,
general assertions. Rather, it says that several studies "have not
found a link to temperature trends, emphasizing instead the importance
of including other key determinants of malaria risk such as drug
resistance, human migration and immune status . . ". See also the
Lomborg-errors page on malaria in Africa here.
Page 98 bottom : ". . . the malaria parasite is becoming resistant to
it. There are
new and effective combination treatments based on artemisinin available
. . . "
Comment: Optimism concerning the
possibility to reduce malaria or to keep it away where it does not
occur now is corrupted by the development of resistance to anti-malaria
drugs. The very first examples of resistance to
artemisinin-derivatives are being reported (for instance this link).
Once resistance to artemisinin becomes widespread in future (which may
very well happen), there may remain no efficient anti-malaria drugs.
Page 99: " . . researchers tried to see whether more people at
risk would actually lead to
more malaria. "
Flaw: The paper cited by Lomborg (Rogers
and Randolph 2000) states in its abstract: "These results were applied
climate scenarios to predict future distributions, which showed
remarkably few changes, even under the most extreme scenarios."
Therefore, what is referred to here is predictions of the geographic
distribution of malaria parasites in the future, which by their very
nature are uncertain. And no measures of society´s ability to
fight malaria e.g. by drug treatment is included in that paper. It is
therefore wrong to postulate that the paper investigates whether there
will actually be more
Page 101: " . . . it seems likely that the continent [Africa] will
cross the $ 3,100
threshold around 2080. "
$ 3,100 threshold is taken from Tol & Dowlatabadi (2001) and is
extremely uncertain. The figure is obtained by excluding regions that
do not fit into the general pattern, especially Africa. So it is not
valid for Africa.
Page 102: "The problem is that often the climate argument is virtually
the only one offered."
Flaw: The press article referred to is no
longer on the net. However, one may
search the archives of that source, chron.com, which gives access to
many newspapers. Searching for the period 2001-2007 for articles with
titles containing the word `malaria´ in combination with either
`climate´, `CO2´ or `rising temperatures´ gives just
one hit, from the same date and with the same author as the article
cited by Lomborg. Also, in scientific articles referred to by Lomborg,
for instance the paper by Patz et al. (2005) referred to above, the
climate argument is certainly not the only one offered, contrary to
Page 102: "However, WHO finds that the real reason for the reemergence
of malaria in Kenya is not climate change . . . "
The WHO report does not say that. It refers to a number of studies
a possible relationship between changing climate and changing
prevalence of malaria. It goes on to say that these studies have
"garnered popular interest among the wider scientitific fraternity",
which in turn has stimulated the tendency to link all phenomena to
popular scientific themes. And it criticises this tendency. But it does
not claim that the studies referred to had made wrong conclusions.
Instead, it says that the genesis of epidemics is multifactorial, and
that in a number of cases, climate does affect malaria incidence. For
instance, El Nino rains have had such effects. The text then proceeds
to discuss the cyclical pattern of epidemics occurring at intervals of
a few years, and concludes that temperature data cannot explain this
cyclicity. Lomborg misreads this part of the text and gets the
impression that temperature is without importance for the incidence of