Medicine for Africa - Medical Information Service

ALARIA    &                        

Definition:  

Malaria is transmitted to people of all ages and means by the sting of a mosquito – the female Anopheles gambiae mosquito. The mosquito’s sting injects the malaria parasites of the so-called Plasmodium family into the ‘victim’s’ blood stream, thus starting the cycle of parasite growth within the human.

Malaria has been a deadly disease to humans for centuries, dating as far back as to the ancient Chinese, Indian, Greek, and Roman cultures.  However, the malaria parasites have only been identified in 1880 by Dr. Charles Laveran, who also described four distinct forms of malaria parasites present in human blood that later proved to be the malaria parasites in different stages of its life cycle.  Later, in 1897, Ronald Ross, a British officer in the Indian Medical Service demonstrated that the malaria parasites were in fact transmitted from infected patients to mosquitoes and vice versa.

It took another 50 years, until 1948, that the question of where the sporozoites, the parasites which have been inoculated by mosquitoes, undergo early development in the human host, has finally been answered, when the malaria parasites were detected in the infected livers of rhesus monkeys. Subsequently, similar stages were also identified in human livers infected with Plasmodium (P.) vivax and P. falciparum.

In spite of these discoveries and knowledge, malaria continued – and continues – to ravage wide areas of the world, mostly around the Equator in South-East Asia and Latin and South America, but primarily in Sub-Saharan Africa, where also 85% to 90% of worldwide malaria deaths occur. Malaria’s victims are found mainly among young children and pregnant women.

There are four types of human malaria – Plasmodium (P.) falciparum, P. vivax, P. malariae, and P. ovale. P. falciparum and P. vivax are the most common, while P. falciparum is also the most deadly type of malaria infection.

The Anopheles mosquito carries the disease from one human to another, acting as a ‘disease vector’. While the future human host of the malaria parasite will become severely ill and even can die of the disease, the Anopheles mosquito itself neither suffers nor becomes ill from the presence of the malaria parasites.

Malaria transmission can differ widely in both its intensity and regularity, depending on local factors, such as rainfall patterns, humidity, proximity of mosquito breeding sites and mosquito species. Thus, some regions show a fairly constant recurring prevalence of cases throughout the year – these areas are called ‘malaria endemic areas’ – whereas in other regions, there are specific ‘malaria’ seasons, usually coinciding with the local rain season.

Large and devastating epidemics still occur in areas where people have had little contact with the malaria parasite, or where the parasite has developed an immune response to previously favored and successful treatment schedules.

Today, about 40% of the world’s population, most living in the world’s poorest countries, is still at a high risk of contracting malaria. Every year, more than 500 million people become severely ill with malaria, and it is still the most prevalent cause of death in most of sub-Saharan Africa.

Yet, malaria is both preventable and curable!

Symptoms:

When the Anopheles gambiae mosquito feeds on the blood of its victim, it spreads the malaria parasites in its sporozoite stage, which enter the human’s blood stream along with the mosquito's saliva, thus starting the infection in the human.  The transmitted parasites first grow and multiply in the victims’ liver cells, then within their red blood cells, destroying them in the process, and subsequently releasing its ‘daughter parasites’, called ‘merozoites’. These merozoites will then continue their reproductive cycle by invading other red blood cells.

Following the infective bite by the Anopheles mosquito, a certain period of time, called the ‘incubation period’, goes by before the first symptoms appear, usually extending from 7 to 30 days:

• P. falciparum – nine to 14 days, on average;
• P. vivax and P. ovale – 12 to 18 days, on average;
• P. malariae – 18 to 40 days, on average.

First symptoms can already appear after about seven days, but can be longer if preventive medication (chemoprophylaxis) was taken, or if the patient has acquired partial immunity due to a previous infection.

Also, in infections with P. vivax and P. ovale, the time between exposure and signs of active illness can at times be as long as eight to ten months. 

The classic malaria symptoms consist of cyclic periods of sudden coldness followed by rigor (tremor), then fever and sweating lasting for about six hours.

In so-called ‘tertian’ malaria, caused by P. falciparum, P. vivax and P. ovale, these cycles usually repeat themselves every two days. P. falciparum can also present a recurrent fever appearing every 36 to 48 hours, or present a less pronounced, but continuous fever. 

In so-called ‘quartan’ malaria, caused by P. malariae, these cycles repeat themselves every three days. 

'Tertian’ malaria is the classic form of malaria; it usually lasts anywhere between 6 and 10 hours and consists of:

• A cold stage – sensation of cold, shivering;
• A hot stage – fever, headaches, vomiting; seizures in young children; and finally
• A sweating stage – sweats, return to normal temperature, tiredness.

In addition, the patient often presents a combination of any or all of the following symptoms:

• Fever
• Chills
• Sweats
• Headaches
• Nausea and vomiting
• Body aches
• General malaise.

Furthermore, in cases of P. falciparum malaria, the most serious and most often deadly form of malaria, serious multiple organ failures or abnormalities in the patient’s blood and/or metabolism may occur, causing or leading to:

• Severe anemia due to hemolysis (destruction of red blood cells);
• Hepatomegaly (enlarged liver) with/without jaundice;
• Hemoglobinuria (hemoglobin in the urine) due to hemolysis;
• Abnormalities in blood coagulation and thrombocytopenia (decrease in blood platelets);
• Pulmonary edema (fluid within the lungs) or acute respiratory distress syndrome (ARDS), which may even occur after the total parasite count has decreased following treatment;
• Cerebral malaria, causing abnormal behavior, impairment of consciousness, seizures, coma, and/or other neurological abnormalities; and ultimately
• Cardiovascular collapse and shock.

Other equally serious manifestations may include:

• Acute kidney failure;
• Hyperparasitemia (overwhelming growth of parasites within the red blood cells), when more than 5% of the red blood cells are infected by malaria parasites;
• Metabolic acidosis, i.e. excessive acidity in blood and tissue fluids, often in association with hypoglycemia (abnormally low blood glucose levels);
• Hypoglycemia may also occur in pregnant women with uncomplicated malaria, or after treatment with quinine.

The severe form of malaria occurs most often in persons who have no immunity to malaria, or whose immunity has decreased over time, and especially young children and pregnant women in areas with high transmission.

Severe malaria is a medical emergency and needs to be treated immediately and aggressively.

Additional manifestations of malaria may occur during any form of malaria and may include one or more of the following:

• Neurological defects may occasionally persist beyond the acute stage of cerebral malaria, especially in children. Defects may include ataxia (problems with movements), palsies, speech difficulties, deafness, and even blindness.
• Recurrent infections with P. falciparum may result in severe anemia - again, especially in young children, in tropical Africa with frequent infections that are inadequately treated.
• Malaria during pregnancy (especially P. falciparum) may cause severe disease in the mother, and may lead to a miscarriage, premature delivery, or delivery of a low-birth-weight baby.
• On rare occasions, P. vivax malaria can cause the rupture of the spleen.
• Nephrotic syndrome (a chronic, severe kidney disease) can result from chronic or repeated infections with P. malariae.
• The so-called ‘tropical splenomegaly syndrome’ (malaria caused reactive increase of the size of the spleen) is attributed to an abnormal immune response to repeated malarial infections. Characteristic findings include a hugely enlarged spleen and liver (hepatosplenomegaly), abnormal immunologic findings, severe anemia, and a susceptibility to other infections, such as skin infections.

Malaria Relapse

Malaria infections do not result in subsequent immunity to future re-infections. Especially, in P. vivax and P. ovale infections, patients, who recovered from the first episode of their illness, may suffer several additional attacks – relapses – after months or even years without symptoms. Relapses occur, because P. vivax and P. ovale have developed so-called dormant liver stage parasites (‘hypnozoites’) that may become reactivated. Treatment to reduce the chance of such relapses is available and should follow treatment of the first attack.

 
Diagnosis:

It is important to recognize malaria promptly, in order to treat the patient in time and to prevent further spread of infection in the community.

While malaria can often be suspected based upon the patient's symptoms and the physical findings at examination, in order to make a definitive diagnosis, laboratory tests must demonstrate the malaria parasites or their components.  Thus, the ultimate diagnosis of malaria depends on the demonstration of its parasites on a blood smear examined under a microscope. 

Clinical diagnosis is based on the patient's symptoms and on physical findings at examination. However, as mentioned previously, the first symptoms of malaria (most often fever, chills, sweats, headaches, muscle pains, nausea and vomiting) are often not specific and are also found in other diseases (such as the ‘flu’ and other common viral infections), while the physical findings are equally non-specific (elevated temperature, perspiration, tiredness).

In severe malaria, caused by P. falciparum, clinical findings, such as confusion, coma, neurological focal signs, severe anemia, and respiratory difficulties, are more striking and may increase the suspicion index for malaria.

In summary, most cases of early malaria do not represent with ‘typical diagnostic’ clinical findings, and thus need to be confirmed by a laboratory test.

Laboratory / Microscopic Diagnosis

The malaria parasites can be identified by examining a drop of the patient's blood under the microscope. The ‘blood smear’ will be stained, usually with the Giemsa (Wright’s) stain, in order to give the parasites their distinctive appearance. In spite of all the newer, more sophisticated techniques of the last ten-plus years, the staining technique still remains the gold standard for laboratory confirmation of malaria. However, its success depends on the quality of the reagents, of the microscope, and on the experience of the laboratory technicians.

Alternate methods for laboratory diagnosis include:

Over the last decade, a number of various test kits have become available to detect the antigens that are the result of the body’s response reaction to the presence of the malaria parasites. Such immunologic (‘immunochromatographic’) tests most often use a dipstick or are in form of a small cassette, providing results within 2-15 minutes. These ‘Rapid Diagnostic Tests’ – RDTs, otherwise called ‘dipsticks or ‘Malarial Rapid Diagnostic Devices’ (MRDD), offer a very useful alternative to the microscopic diagnosis, especially in situations where reliable microscopic diagnosis is not available. They are also very valuable to make a preliminary diagnosis, if malaria has been suspected, based on clinical findings and physical examination, but microscopic diagnosis is not available or requires considerable time to perform. Furthermore, as these tests become more and more reliable, i.e. more and more sensitive and specific, they can lead to considerable health care cost savings while concurrently ensuring an adequate performance under adverse field conditions.

In June of 2007, the U.S. Food and Drug Administration (FDA) approved the first RDT for use in the United States. This RDT is approved for use by hospitals and commercial laboratories; however, not yet for use by practice physicians or by patients themselves. Obviously, it is still recommended that all RDTs are followed-up by a microscopic examination, in order to confirm the results and if positive, to quantify the proportion of red blood cells that are infected. The use of this RDT may decrease the amount of time that it takes to determine that a patient is infected with malaria.

Molecular Diagnosis

The nucleic acids of the parasite can also be detected by using polymerase chain reaction (PCR). This technique is very sensitive and overall more accurate than microscopy. However, it is expensive, and requires a highly specialized and ‘clean’ laboratory, i.e. the test’s sensitivity may often cause ‘false positive’ results, if the test area is not kept free of any potential contamination problems.

Serology

Serology can detect the antibodies against the malaria parasites, produced by the patient’s immune system, by using techniques such as ‘indirect immunofluorescence’ (IFA) or ‘enzyme-linked immunosorbent assays’ (ELISA). Serology tests do not detect current infection but rather measure past experience.

Drug Resistance Tests

Drug resistance tests can only be performed in specialized laboratories. These tests are able to assess the susceptibility to anti-malarial compounds of parasites collected from a specific patient. There are two major laboratory methods:

• In vitro tests – the parasites are grown in culture in the presence of increasing concentrations of the drugs; the drug concentration that inhibits parasite growth is used as an endpoint;
• Molecular characterization: molecular markers assessed by PCR or gene sequencing allow for some degree of prediction regarding resistance to certain drugs; however, the predictive value of molecular tests is still being evaluated.

Overall, the diagnosis of malaria can be difficult in situations such as:

• In many malaria-endemic countries, lack of resources is a major barrier to achieve a reliable and timely diagnosis. Health personnel are often insufficiently trained, under-equipped and underpaid. In addition, they often face excessive patient loads, and must divide their attention between malaria and other equally severe infectious diseases such as pneumonia, diarrhea, tuberculosis and HIV/AIDS.
• Where malaria is not endemic any more (such as the United States), health care providers are not familiar with the disease. Clinicians seeing a malaria patient may forget to consider malaria among the potential diagnoses and not order the needed diagnostic tests. Laboratory technicians may lack experience with malaria and fail to detect parasites when examining blood smears under the microscope.

The infection of malaria should be considered a potential medical emergency and be treated accordingly. Any delay in diagnosis and subsequent treatment often results in the death of the patient.

 
Therapy:

Early diagnosis and prompt treatment are the most important objectives, in order to be able to achieve an effective malaria control. If the appropriate treatment is started as soon as possible after identification of the malaria parasite, the disease will shorten its duration and prevent the development of complications, as well as the majority of deaths from malaria.  Access to proper disease management should be seen not only as a component of malaria control but as a fundamental right of all people and populations at risk. Malaria control has to be an essential part of any successful health care management.
                
The two most important currently used anti-malarial drugs are derived from plants whose medicinal values have been known for centuries – artemisinin derived from the Qinghao plant in China, and quinine derived from the cinchona tree in South America.

Quinine was introduced to Europe in the 1600s from Peru, and soon became the favorite form of treatment for ‘intermittent fever’ worldwide. Up to today, quinine has remained a major and effective treatment form for malaria; however, over the decades, the Plasmodium parasites have developed an increasing resistance to quinine.  This resistance has led to an alarming increase of malaria outbreaks in the malaria infected regions around and south of the Equator, and especially in Western, Central and Southern Africa.

Chloroquine, a ‘substitute’ drug for quinine, was developed in 1934 in Germany, adding Resochin (chloroquine) and Sontochin, a chloroquine derivative, to the treatment schedule for malaria. These compounds were so-called four-amino quinolines.

Following World War II, chloroquine and DDT (Dichloro-Diphenyl-Trichloroethane) became the World Health Organization’s (WHO) ‘weapons of first choice’ in the fight of worldwide eradication of malaria.  Subsequently, chloroquine resistant P. falciparum developed first in Asia in the 1950s, in South America around 1960 and finally in Kenya in 1978, spreading east and south to Uganda, Tanzania, Malawi, and beyond.

Other drugs that emerged for anti-malarial treatment included proguanil, a pyrimidine derivative, leading to the development of the even more effective drug, called pyrimethamine.  As resistance to these two drugs developed almost ‘over night’ (within one year for proguanil), sulfones and sulfonamides were added to create a so-called ‘combination therapy’.

Mefloquine was developed by the US Army Medical Research, the WHO/TDR and Hoffman-La Roche in the early 1970s. However, by the time that mefloquine became widely available in 1985, the first reports of resistance appeared already in Asia.

Artemisinin, the latest development drug in the fight against malaria, has been known by practitioners of the Traditional Chinese Medicine for more than 2000 years as ‘Qinghao’.  In the early 1970s, Chinese scientists showed that artemisinin was as effective against malaria as quinine and chloroquine, however, without the development of resistance.  Thus, today, artemisinin and related drugs of the artemether-drug group are considered the major line of defense against drug-resistant malaria in Asia and Africa.  In 2001, the WHO declared artemisinin to be the treatment of choice for uncomplicated P. falciparum malaria.  Especially in combination with other anti-malaria drugs, the so-called ACTs (artemisinin-based combination therapies), artemisinin is considered to be the most effective drug against malaria at this point in time.

Drug Resistance

The development of resistance to malaria drugs poses one of the greatest threats to its control, and has been linked to recent increases in malaria morbidity and mortality.  Thus, WHO has called for a continuous monitoring of the efficacy of the recently implemented artemisinin combination therapy (ACT). Furthermore, WHO has also recommended abandoning the use of oral artemisinin mono-therapies, in order to prevent the early development of drug resistance.

Drug-resistant P. falciparum

Chloroquine resistant P. falciparum first developed in the early 1960s; since then, chloroquine resistance has spread to nearly all areas of the world where P. falciparum malaria is present.  Furthermore, P. falciparum has also developed resistance to nearly all of the other currently available anti-malarial drugs, such as sulfadoxine/ pyrimethamine, mefloquine, halofantrine, and quinine. Although resistance to these drugs tends to be much less widespread geographically, in some areas of the world, the impact of multi-drug resistant malaria can be extensive.

Drug-resistant P. vivax

Chloroquine resistant P. vivax (CRPV) malaria was first identified in 1989 in certain Australian travelers. Thereafter, CRPV has also been identified in Southeast Asia, on the Indian subcontinent, and in South America. Vivax malaria, particularly from Oceania, exhibits decreased susceptibility to primaquine.

Tests for Drug Resistance

There are four basic tests for identifying drug resistance by the malaria parasite:

• in vivo tests,
• in vitro tests,
• molecular characterization, and
• animal models.

Only the first three are routinely performed.

In vivo tests: Patients with clinical malaria are given a treatment dose of an anti-malarial drug under observation, and then monitored for either their failure to clear parasites or for the reappearance of parasites.

In vitro tests: In these tests, blood samples are taken from malaria patients, and the malaria parasites are exposed to different concentrations of anti-malarial drugs in the laboratory.

Molecular characterization: For certain drugs (chloroquine and similar drugs, such as atovaquone), molecular markers have been identified that confer resistance. Molecular techniques, such as PCR or gene sequencing can identify these markers from blood samples, taken from malaria-infected patients.

 
Prevention:

There are two ways of preventing a malarial infection – by taking anti-malarial preventive medication and by protecting yourself against mosquito bites to the best of available possibilities.

Preventive drug treatment against malaria is absolutely required and recommended, if you travel to a malaria-prone country/region for a short period of time.  However, the available drug regimens are both too expensive and too compromising to one’s health, if taken over a long-term/indefinitely.  Thus, people who decide to reside in malaria infested countries for a longer period of time need to concentrate on non-drug preventive measures, which include:

• Limit your outdoor activity between dusk and dawn; stay in screened or air-conditioned rooms.
• Wear protective clothing (long [white] pants and long-sleeved shirts).
• Use insect repellent with DEET (N,N-diethylmetatoluamide; the repellent is available in varying strengths of up to 100%.
• Use bed nets (mosquito netting) – probably the most important and least expensive way of preventing malaria – especially, if the nets are sprayed with or soaked in an insecticide such as permethrin or deltamethrin.
• Use flying-insect spray indoors around sleeping areas.
• Avoid areas where malaria and mosquitoes are present - whether or not, you are a member of the very high risk group, such as for example, if you are pregnant, very young, or very old.
• If using a bed net treated with insecticide, and using insect repellents on one’s clothes, one will be able to reduce one’s risk of becoming infected with malaria.  Other steps that may be helpful in reducing the risk of malaria include using air conditioning and electric fans, wearing protective clothing, using aerosol insecticides in the house, and taking certain anti-malarial medications.

As a tourist or temporary visitor, it is advisable to take preventive medications if you travel to malaria-prone countries/regions, such as:

• atovaquone/proguanil,
• doxycycline,
• mefloquine,
• primaquine (in special circumstances).

Atovaquone/proguanil (brand name: Malarone ™)

Atovaquone/proguanil is a combination of two drugs, atovaquone and proguanil, combined in one single tablet; it is now available in the United States under the brand name ‘Malarone’.

Doxycycline (many brand names and generic drugs are available)

Doxycycline is related to the antibiotic tetracycline - directions for usage include:

• The adult dosage normally is 100 mg once a day (OD).
• Take the first dose one or two days prior to arriving in the malaria-risk area.
• Take the prescribed dosage once a day, at the same time each day, while in the risk area.
• Take your dose once a day for four (4) weeks after leaving the risk area.

Mefloquine (brand name Lariam ™ and generics)

• The adult dosage is 250 mg (one tablet) once a week.
• Take the first dose 1 week before arrival in the malaria-risk area.
• Take your dose once a week, on the same day of the week, while in the risk area.
• Take your dose once a week for 4 weeks after leaving the risk area.
• Take the drug on a full stomach with a full glass of liquid.

Primaquine

In special situations when other anti-malarial drugs cannot be taken, and in consultation with malaria experts, primaquine may be used to prevent malaria while the traveler is in the malaria-risk area (primary prophylaxis); however, primaquine can cause hemolysis in G6PD-deficient people, which can become fatal.

Chloroquine phosphate (brand name Aralen ™ and generics)

Travelers to high malaria-risk areas such as Mexico, Haiti, the Dominican Republic, and certain countries in Central America, the Middle East, and Eastern Europe, as well as most of southern Africa, should take chloroquine as their anti-malarial drug of choice.Most travelers who take chloroquine as a preventive drug treatment, do not have side effects serious enough to stop taking the drug.  The most common side effects that have been reported by patients under chloroquine therapy, included nausea and vomiting, headache, dizziness, blurred vision, and itching.  Chloroquine may also worsen the symptoms of a previously present psoriasis syndrome. For other anti-malarial drugs that are available, please see your health care provider.

Hydroxychloroquine sulfate (brand name: Plaquenil ™)

Hydroxychloroquine sulfate is an alternative although less effective treatment to chloroquine phosphate:

• The adult dosage is 400 mg once a week.
• Take the first dose 1 week prior to traveling to the hih-risk malaria area.
• Take your dose once a week, on the same day of the week, while in the risk area.
• Take the dose once a week for four (4) weeks after leaving the risk area.

Protect Yourself from Mosquito BitesMalaria is transmitted by the bite of the infected Anopheles mosquito – while these mosquitoes usually bite between dusk and dawn, avoid being bitten and remain indoors in a screened or air-conditioned area during the peak biting period. If out-of-doors, wear long-sleeved shirts, long pants, and hats. Apply insect repellent (bug spray) to exposed skin.

Other recommended anti-mosquito measures:

• Travelers who are going to visit high-risk malaria countries/regions, should take a flying insect spray on their trip to help clear rooms of mosquitoes.  This product should contain a pyrethroid insecticide which usually kills flying insects quickly, including mosquitoes.
• Travelers who cannot stay in well-screened or air-conditioned rooms, should sleep under bed nets (mosquito nets), preferably nets treated with the insecticide permethrin. Permethrin both repels and kills mosquitoes as well as other biting insects and ticks. In the United States, permethrin is available as a spray or a liquid (e.g. Permanone™). Pre-treated nets, permethrin or another insecticide deltamethrin, are available overseas.
• Protect infants, especially babies that are younger than two (2) months of age, and thus cannot wear insect repellent, by using a carrier draped with mosquito netting with an elastic edge for a tight fit.
• Be aware that all clothing, shoes, and camping gear, can also be treated with permethrin. Treated clothing can be repeatedly washed and still repel insects. Some commercial products (clothing) are now available in the United States that have been pretreated with permethrin.

The main objective of malaria vector control is to significantly reduce both the number and rate of parasite infection and clinical malaria by controlling the malaria-bearing mosquito and thereby reducing and/or interrupting transmission. Currently, there are two main operational interventions for malaria vector control available: Indoor Residual Spraying of long-acting insecticide (IRS), and Long-Lasting Insecticidal Nets (LLINs).

Insecticide-treated nets (ITNs) are a form of effective vector control, when coverage rates are high and a large proportion of human-biting by local vectors takes place after people have gone to sleep. It can also be used for personal protection. Their use has repeatedly been shown to reduce severe disease and mortality due to malaria in endemic regions. In community-wide trials in several African settings, ITNs have been shown to reduce overall mortality by about 20%.These two core interventions can locally be complemented by additional methods (e.g. larval control or environmental management) in the context of Integrated Vector Management (IVM).  Vector control remains the most generally effective measure to prevent malaria transmission, and the principal objective of vector control is the reduction of malaria morbidity and mortality by reducing the levels of transmission. Vector control methods vary considerably in their applicability, cost and sustainability of their results. The choice of local appropriate vector control depends on the extent of the malaria threat, the feasibility of timely and correct application of necessary interventions, and the possibility of sustaining this situation. WHO recommends a systematic approach to vector control based on evidence and knowledge of the local situation.

Integrated Vector Management is a decision-making process for the management of vector populations, in order to reduce or interrupt transmission of vector-borne diseases, its characteristic features include:

• Selection of methods depending on local vector biology, disease transmission and morbidity;
• Utilization of various interventions, in combination and synergistically;
• Collaboration within the health sector, and with other public and private sectors;
• Engagement of local communities and other stakeholders;
• A public health regulatory and legislative framework;
• Rational use of insecticides;
• Good management practices.

The IVM approach takes into account the available health infrastructure and resources, and integrates all available and effective measures, whether chemical, biological, or environmental; it also encourages an integrated approach to disease control. Effective and sustained implementation of malaria vector control interventions – IRS or LLINs – also requires clear political commitment and engagement from national authorities as well as long-term financial support.

Insecticide Resistance

As in drug resistance, the resistance of the mosquitoes to insecticides is increasing steadily, putting a serious challenge on the task of preventive efforts to the disease.   There are currently no alternatives to DDT and pyrethroids, while the development of new insecticides will be an expensive long-term endeavor. As recent evidence from Africa indicates, pyrethroid and DDT resistance is already more widespread than anticipated, and it is believed that the same level of resistance will have a more detrimental impact on the efficacy of IRS than on that of LLINs.

How People Living in Africa Conduct Prevention

Obviously, drug preventive treatment is not an option for people who live in Africa, because of two reasons – (1) one cannot take preventive anti-malarial drugs for ever without serious physiological side effects, and (2) at about US-$ 6 to 7 per pill per day per person, these drugs could not be purchased by 99% of all people living in Africa.  So how do Africans protect themselves?  There are some fairly effective methods which are equally simple and cheap to use, such as:

• Since Anopheles mosquitoes are usually low flying insects, and most active at dawn and dusk, it is recommended to wear long trousers, socks and shoes (no sandals) at these times of day.
• Do not sleep on the floor, if possible, and spray insecticides under the bed in the evenings – a simple but effective protective measurement.
• After the morning shower, many Africans cream their legs and feet with a mixture of ‘Aquis’ – a water based cream, mixed with a high dose of citronella oil.
• “Bat Hotels” – a little wooden house on a pillar (similar to bird feeding houses) with a wire mesh under the roof, where bats can ‘hang around’ and sleep during the day, while feeding themselves on mosquitoes during the evening and night.  As bats eat about three times their weight in mosquitoes every night, they can certainly provide some protection to their ‘neighborhood’.   
• An African mosquito trap can be made out of an empty 2 liter soda bottle, 50 gram of (brown) sugar and one gram of yeast. It works like a charm for about two weeks, and every African family can afford one. The mixture produces small amounts of CO2 that attract the mosquitoes – away from the CO2 that we exhale, which otherwise would have attracted their interest.

Future Preventive Methods

To-date, there is no vaccine available for preventing malaria infections.  However, recent research in the genetic make-up of the Anopheles gambiae mosquito has opened up some interesting future potentials on how to combat malaria at some point in time.  These include the identification of the mosquito susceptibility to the malaria parasite and its adaptation mechanism.  Thus, if future research can create Anopheles mosquitoes that will not host the Plasmodium parasite anymore, the cycle of malaria infection and re-infection by and via the mosquito could one day be broken. Until the above mentioned ‘futuristic’ gene therapy will be available, key interventions to control malaria nowadays should include the prompt and effective treatment with artemisinin-based combination therapies, the use of insecticidal nets by people at risk, and the indoor residual spraying with insecticides to control the vector mosquitoes.

In the meantime – it is adamant that preventive anti-malarial drugs should be taken by travelers to endemic areas. Concomitantly, it is of utmost importance to promote local preventive anti-malarial procedures in high risk countries and regions, including insecticide-sprayed nets, window and door screening, as well as a ‘clean’ (air-conditioned) environment.  Most of the malaria afflicted countries cannot afford to finance this broad range of preventive malaria procedures, although they are the countries and people who suffer the most under this ‘plague’.  Thus, it is up to the ‘Western’, economically potent world to help and support efforts to prevent and hopefully eradicate malaria at some time in the future.  If this help will be withheld or be insufficient to regional needs, the result may very well be that malaria, and recently developed drug-resistant malaria, may spread worldwide into regions that are not at all adapted to handle this disease in an epidemic-like extent.
  

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