Malaria is a life-threatening but preventable and curable disease. Despite the wide palette of global efforts, every minute a child dies from malaria. Mostly in Sub-Saharan Africa. Every fourteenth person on Earth carries the evidence of an evolutionary change due to malaria in their genes. Not only has the disease influenced our biology, but also the political map of the world: malaria was piling up colonialists and missioners when they were stepping on new lands without bringing along their immunity against malaria. An illustrative example of how the disease ruined the dreams of Scotts for becoming a strong independent country is given in the book of Sonia Shah "The Fever", which I highly recommend to curious minds.
Malaria is a parasitic vector-borne disease caused by the plasmodium parasite. It is transmitted to humans via the bites of infected female mosquitoes. One of the parasite’s human species, plasmodium falciparum, is listed among the most severe causes of morbidity and mortality in Africa.
At the beginning of the 20th century very few countries on the planet were malaria free. The burden of the disease has not been monotone through the last century world-wide, but particularly in Sub-Saharan Africa: after the Second World War it experienced a substantial decline, which continued for about four decades, until, in the late 1980s it returned to the pre-1940s level. Since 2000, due to multiple undertaken measures, malaria incidence shows declining trends in many areas again.
Anyhow, nowadays nearly half of the global population is at risk of malaria and the challenges are many. They include complexity of the parasite’s life cycle, its genetic diversity and acquisition of immunity, sensitivity of diagnostics methods, movements of the population including importation and displacement, leading, in some cases, to resurgence of the disease.
Here is a selection of facts that I recently learnt through books, courses and conversations, summarised in a naive but hopefully clear way.
1). Little but fierce: are we blaming the right killer?
According to the data of the Bill Gates Foundation, the deadiest animal in the World in terms of killing humans is not a scary crocodile or even a human himself. But a mosquito! Still, it is not the final truth. The truth is that mosquitos do not murder themselves, but only serve as transport to real killers - viruses and parasites such as malaria, yellow fever, dengue, zika, etc.
2). Up to a holiday romance with a parasite? It may last longer than you wish.
Dependence of the transmission on mosquitos makes malaria an environmental disease. Mosquitos like it in warm moist regions - precisely where people from the upper half of the northern hemisphere love going on vacation. Beware of the sneaky admirer - this one may take your sleep away for too long.
3). All cats are black at night: what may fever be a sign of?
Malaria becomes symptomatic with a delay: it takes from 10 to 15 days after a mosquito bite for the symptoms such as fever, headache, muscular aching, vomiting, cough and diarrhea, to appear. As an ensemble, they indicate a malaria case. But it is not rare, that an infected person only has fever and no other symptoms. High temperature may be caused by any other infection or inflammation. What a puzzle for a clinician!
4). Professional hide-and-seeker: losing the game may cost a life.
There are several malaria diagnostic tools available such as microscopy, rapid diagnostic test and PCR (polymerase chain reaction). These methods differ in sensitivity and cost and are also related to further obstacles for precise diagnosis. For instance, the quality of microscopy highly depends on the experience of a person performing it. However, if the microscope is old and rusty, which is frequently the case in poor countries, no proficiency can compensate it. Another ill luck is that plasmodium is a professional hide-and-seeker: its concentration in human blood drastically varies over time having peaks around 15th, 25th, 50th days after infection and almost vanishes in-between. This means, that if a blood smear was taken in the low-concentration phase, results of the diagnostics may be false.
6). A one-cell parasite outsmarts the humanity: resistance detected.
There is a series of interventions that we invented to protect ourselves from the devastating disease. The strongest among them are ITNs (insecticide-treated mosquito nets), indoor residual spraying (IRS) with insecticide and antimalarial drugs. This natural-history-quest would be too easy if those measures solved the problem.
As a lyrical and personal remark I would like to say, that the more I learn about malaria, the more I think, that the mutual agreement on what intelligence is, should be reconsidered. That is why: plasmodium is a single-celled eukaryotic parasite; it does not have limbs to move around by itself, but found a way to travel with mosquitos; it does not have a brain, but outsmarted the entire humanity and developed resistance against both insecticides and antimalarials.
7). Back to the future: genetically engineered mosquitos.
Modern history knows several success stories of defeating diseases by genetically modifying vectors. For dengue eradication, for instance, the genes of mosquitos were edited in such a way that the next generation would not have female progenies. Similarly, there has been created a mosquito that is incapable of transmitting malaria to humans with this trait being inherited by its offsprings. For the concept to work scientist also need to ensure, that wild female mosquitos will pick the genetically modified mates. Researchers from Perugia conjecture that the sound of the wings and the speed at which male mosquitos are moving defines female mosquitos' choices. This and other examples can be found in the book "The Deadly Air: Genetically modified mosquito" by Christian Jennings.
8). When networking becomes harmful: importation.
In the setting of low local transmission importation becomes the main threat. Investigating local climatic conditions and focusing on vector control will not be fruitful. Instead, discovering social networks could be of great help. This can be done either through surveys or, as the world is becoming digitalized, through analysis of digital communication data.
There is much more to write and read and learn and question about malaria. But what is the conclusion so far? The war is far from over!
New global goals to achieve by 2030 have been recently determined and it is truly exciting to be working in a place with a lot of malaria research going on and espetially being part of it. On the 25th April, Swiss Tropical and Public Health Institute, member of the Swiss Malaria Group, takes us on a short trip to Bern for the Malaria Day 2016.
Traditionally I close the post with a TED-talk. Sonia Shah, mentioned above, names 3 reasons we still haven't got rid of malaria. How can this be changed within the coming 14 years?
Malaria is a parasitic vector-borne disease caused by the plasmodium parasite. It is transmitted to humans via the bites of infected female mosquitoes. One of the parasite’s human species, plasmodium falciparum, is listed among the most severe causes of morbidity and mortality in Africa.
At the beginning of the 20th century very few countries on the planet were malaria free. The burden of the disease has not been monotone through the last century world-wide, but particularly in Sub-Saharan Africa: after the Second World War it experienced a substantial decline, which continued for about four decades, until, in the late 1980s it returned to the pre-1940s level. Since 2000, due to multiple undertaken measures, malaria incidence shows declining trends in many areas again.
Anyhow, nowadays nearly half of the global population is at risk of malaria and the challenges are many. They include complexity of the parasite’s life cycle, its genetic diversity and acquisition of immunity, sensitivity of diagnostics methods, movements of the population including importation and displacement, leading, in some cases, to resurgence of the disease.
Here is a selection of facts that I recently learnt through books, courses and conversations, summarised in a naive but hopefully clear way.
1). Little but fierce: are we blaming the right killer?
According to the data of the Bill Gates Foundation, the deadiest animal in the World in terms of killing humans is not a scary crocodile or even a human himself. But a mosquito! Still, it is not the final truth. The truth is that mosquitos do not murder themselves, but only serve as transport to real killers - viruses and parasites such as malaria, yellow fever, dengue, zika, etc.
2). Up to a holiday romance with a parasite? It may last longer than you wish.
Dependence of the transmission on mosquitos makes malaria an environmental disease. Mosquitos like it in warm moist regions - precisely where people from the upper half of the northern hemisphere love going on vacation. Beware of the sneaky admirer - this one may take your sleep away for too long.
3). All cats are black at night: what may fever be a sign of?
Malaria becomes symptomatic with a delay: it takes from 10 to 15 days after a mosquito bite for the symptoms such as fever, headache, muscular aching, vomiting, cough and diarrhea, to appear. As an ensemble, they indicate a malaria case. But it is not rare, that an infected person only has fever and no other symptoms. High temperature may be caused by any other infection or inflammation. What a puzzle for a clinician!
4). Professional hide-and-seeker: losing the game may cost a life.
There are several malaria diagnostic tools available such as microscopy, rapid diagnostic test and PCR (polymerase chain reaction). These methods differ in sensitivity and cost and are also related to further obstacles for precise diagnosis. For instance, the quality of microscopy highly depends on the experience of a person performing it. However, if the microscope is old and rusty, which is frequently the case in poor countries, no proficiency can compensate it. Another ill luck is that plasmodium is a professional hide-and-seeker: its concentration in human blood drastically varies over time having peaks around 15th, 25th, 50th days after infection and almost vanishes in-between. This means, that if a blood smear was taken in the low-concentration phase, results of the diagnostics may be false.
6). A one-cell parasite outsmarts the humanity: resistance detected.
There is a series of interventions that we invented to protect ourselves from the devastating disease. The strongest among them are ITNs (insecticide-treated mosquito nets), indoor residual spraying (IRS) with insecticide and antimalarial drugs. This natural-history-quest would be too easy if those measures solved the problem.
As a lyrical and personal remark I would like to say, that the more I learn about malaria, the more I think, that the mutual agreement on what intelligence is, should be reconsidered. That is why: plasmodium is a single-celled eukaryotic parasite; it does not have limbs to move around by itself, but found a way to travel with mosquitos; it does not have a brain, but outsmarted the entire humanity and developed resistance against both insecticides and antimalarials.
7). Back to the future: genetically engineered mosquitos.
Modern history knows several success stories of defeating diseases by genetically modifying vectors. For dengue eradication, for instance, the genes of mosquitos were edited in such a way that the next generation would not have female progenies. Similarly, there has been created a mosquito that is incapable of transmitting malaria to humans with this trait being inherited by its offsprings. For the concept to work scientist also need to ensure, that wild female mosquitos will pick the genetically modified mates. Researchers from Perugia conjecture that the sound of the wings and the speed at which male mosquitos are moving defines female mosquitos' choices. This and other examples can be found in the book "The Deadly Air: Genetically modified mosquito" by Christian Jennings.
8). When networking becomes harmful: importation.
In the setting of low local transmission importation becomes the main threat. Investigating local climatic conditions and focusing on vector control will not be fruitful. Instead, discovering social networks could be of great help. This can be done either through surveys or, as the world is becoming digitalized, through analysis of digital communication data.
There is much more to write and read and learn and question about malaria. But what is the conclusion so far? The war is far from over!
New global goals to achieve by 2030 have been recently determined and it is truly exciting to be working in a place with a lot of malaria research going on and espetially being part of it. On the 25th April, Swiss Tropical and Public Health Institute, member of the Swiss Malaria Group, takes us on a short trip to Bern for the Malaria Day 2016.
Traditionally I close the post with a TED-talk. Sonia Shah, mentioned above, names 3 reasons we still haven't got rid of malaria. How can this be changed within the coming 14 years?
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