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  • Writer's pictureThe Paladins

The decrease in prevalence of Malaria and other tropical diseases

Malaria is a human (and animal) parasite transmitted by anopheles, or marsh mosquitos, and historically it has been one of the most deadly afflictions known to human kind. Malaria occurs only in the tropics. There is a specific geographical band across the equatorial and sub-equatorial regions where malaria is a risk, and travellers to these territories have traditionally had to take heightened precautions to prevent themselves from contracting malaria. Here is a diagram showing the tropical band across the globe in which malaria is traditionally perceived as a risk.

Once transmitted to a human, malaria is often fatal, absent treatment. According to UNICEF, in 2021 there were 247 million cases of malaria globally, that led to some 619,000 deaths. This is a mean death rate of approximately 2.5%; but these statistics are too crude because the mortality rate for malaria depends upon a number of critical factors, including the availability of treatment; the age of the victim; and the state of their health. UNICEF points out that of the 619,000 deaths in 2021, some 77% were under the age of five; but this does not help us considerably, because UNICEF does not tell us, according to their figures, what proportion of the 247 million cases were in children under five. However what we do know and can be reasonably certain of is that malaria disproportionately affects infant children and it is a substantially greater killer of infant children and a greater threat to them than it is of older children or of adults.

Deaths from malaria are in the same order of magnitude as deaths from COVID-19, albeit that malaria is an annual problem whereas COVID-19 lasted just a few years. The global death toll for COVID-19 to the end of December 2020 (including 2019) has been recorded by the World Health Organization as slightly in excess of 1.8 million, although there are some figures available that place the death toll at 50% higher than this figure or even slightly more. There is also a complex debate about the difference between deaths caused by COVID-19 and so-called "excess mortality": that is to say, the number of people who died globally in the COVID-19 years in excess of the number of people one would statistically expect to die in such years. Statistical analyses of this kind are complex and controversial and they are premised upon the intuitive assumption that a contagious and debilitating disease such as COVID-19 accelerates other causes of death; and/or the fact that people dying from COVID-19 are not having that fact recorded upon their death certificates. Of course both these things are also true of malaria. So there is an "excess deaths" figure from malaria but we do not know what it is.

One very important distinction between measuring deaths from malaria and those from COVID-19 is that COVID-19 deaths were more prevalent in medically and industrially developed parts of the world (at least the deaths that were recorded are; it is virtually a truism that it be so) whereas malaria is traditionally more prevalent in societies in which healthcare infrastructure may be wanting and/or people may not be able to afford the treatment or medicines due to poverty. Therefore calculating malaria deaths may be a more rough and ready process. However the tropical and subtropical environments in which malaria is prevalent have in may cases, in recent years, seen increases in healthcare standards and improved access to medicines. So that distinction may be gradually erased. Further study is necessary in this area.

Nevertheless we must accept, if we are to adopt a globalist outlook in which the welfare of all humankind is important to us as policymakers, that malaria is a virulent and deadly disease and over the years it has killed far more people than COVID-19 ever did. It is by far the greater health emergency than COVID-19, yet the international reaction to the hundreds of thousands of entirely preventible deaths (unlike COVID-19, where in many cases the deaths are not preventible) from malaria each year is paltry. Consider the following graph:

Courtesy of The Lancet

This graph reveals that from 1980 until 2010 there were well over one million people a year dying of malaria, most of them in Africa and under five years of age. Malaria is a far greater killer than COVID-19 and it has been killing vulnerable people in tropical and subtropical environments over many decades without adequate resources being put into treatment and prevention.

However since 2010 annual global deaths from malaria have been decreasing. Nobody is entirely certain why this is but it is an undoubted pronounced trend. The figure of 619,000 for 2021 represents a near-constant trend in reduction of fatal cases of malaria. Undoubtedly one reason for this is increasing quality of prophylaxis. The traditional treatments for malaria, of chloroquine and paludrine, were not always easy to obtain in tropical environments and without treatment the mortality rate for malaria stands at almost 100%. So treatment is essential. Then a medicine called mefloquine (the usual brand name is Lariam) become popular; but it turned out to have a range of unpleasant side effects including psychoactive properties. Also malaria variants became resistant to all of chloroquine, paludrine and mefloquine. It was then discovered the a relatively simple antibiotic, doxycycline, which is cheap to manufacture even in tropical environments, could be used both as a malaria prophylactic and for treatment. Because it is cheap and straightforward to manufacture, access to malaria treatment became more widely available across the tropics and without doubt the discovery of doxycycline as a treatment for malaria was a real breakthrough. Now all of chloroquine, paludrine and mefloquine have fallen into disuse. For the most part it appears that malaria variants cannot acquire significant resistance to doxycycline although this remains to be seen.

So the advent of doxycycline as a form of malaria prophylaxis and treatment surely is a significant contributor to the decline in mortality rates from malaria. Nevertheless, some would argue, a mortality rate of 15-20% is still too high and greater international development funding ought to be spent in rolling out malaria awareness courses and ensuring the availability of cheap doxycycline treatment along with the essential paramedic advice and assistance that needs to be on hand to encourage people to finish the course of medications. Many deaths from malaria occur when patients start taking the doxycycline, start to feel better, and then stop taking the pills. It is imperative to take doxycycline for several weeks; when used as a prophylactic the standard advice is to take the pill for at least four weeks after leaving the malarial area. Malaria is a stubborn and tenacious parasite and not a lot of people realise just how tenacious it is. The antibiotics are needed in an extended course to eradicate the presence of the parasite in the body altogether, or it will just start re-multiplying.

Compared to malaria, other tropical diseases kill in relatively small numbers. Here are some global mortality figures for a variety of virulent tropical diseases, together with the year in question, to illustrate that compared to malaria the risk of dying from another tropical disease is really rather paltry.

Visceral leishmaniasis: 51,600, 2010

Rabies: 26,400, 2010

Dengue fever: 14,700, 2010

Schistosomiasis: 11,700, 2010

Chagas disease:10,300, 2010

African trypanosomiasis: 9,100, 2010

Ebola: 6,000-7,000, 2014

Intestinal nematode infections: 2,700, 2014

Cysticercosis: 1,200, 2014

E. Coli: 1,200, 2014

In general, mortality rates from tropical diseases are reducing across the tropics, although malaria is the big one and the fact that hundreds of thousands fewer people per year are dying from malaria than used to be the case is palpably a cause for celebration. However it is not all medicines. One of the major causes may be the increased prevalence of air conditioning in the tropics. Each year, larger proportions of people are living in air conditioned residential and working premises and these sealed environments have the advantage that the insects that carry tropical diseases do not like air conditioning and cannot enter air conditioned rooms. Those of us who have lived in hot humid sub-tropical environments, particularly near large bodies of water, may have returned home to our hotel rooms or houses to finds scenes such as the following on the front door, windows or surrounding the air conditioning units:

The reason things like this occur is because insects like the contrast between the warm air generated by air conditioning units as they cool inside rooms, and the cooler air in the rooms. The insects stay outside, while you sleep inside. The net result is that you do not need a fan, you do not need hordes of insecticide of different kinds, you do not need a mosquito net and you are far less likely to be bitten and therefore to contract either malaria or any of the other insect born diseases this article has briefly mentioned.

The number of lives saved by air conditioning decreasing contraction and mortality rates for tropical diseases carried by insects may not be a politically fashionable thing to discuss in the current environment of climate change science, in which the increasing prevalence of air conditioning is seen as carbon-wasteful in that air conditioners require electricity and hence (for the most part) the burning of hydrocarbons to sustain their operation. This, it is argued, increases global warming. Some of the issues are intelligently discussed in a Washington Post article from September 2022. However in deciding whether we should campaign for an increase or decrease in the number of air conditioning units and the general prevalence of air conditioning across both developing and developed world, it may be important to take into account the number of lives saved by reason of the fact that air conditioning reduces mortality from tropical diseases. We are not aware of any research that has been undertaken to try to assess the extent to which air conditioning is reducing morality rates from tropical diseases, but it is surely an area worthy of further study.

The matter may come down to a very straightforward calculus in principle, although a hard one to measure in practice. How many hundreds of thousands of lives are being saved each year through reduction in mortality rates by reason of the increased prevalence of air conditioning in the tropics, and how many lives are being lost by reason of the marginal increase in global warming caused by the increased use of air conditioners? There is also a more philosophical, or equitable, question: if in the West we consider ourselves entitled to use air conditioning, then on what grounds can we properly issue moral prescriptions to those living in the developing world not to use air conditioners when in the latter case it might be a matter of life and death?

Finally, the thing most likely to kill you in a tropical environment is travellers' diarrhoea, by virtue of dehydration and loss of essential salts. So if and when you contract diarrhoea, which may not be the result of a microbe, parasite or virus but just due to a change of diet, then treat it with loperamide (an agent that causes constipation through bowel contractions); rehydrate (fizzy drinks); and consume fruit with high levels of potassium (bananas and oranges are best).


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