A P R E V E N T A T I V E A P P R O A C H TO M A L A R I A : Some Preliminary Considerations EM I LY H. ROH F O R T Y - O N E PERCENT OF T H E W O R L D ' S P O P U L A T I O N IS C U R R E N T L Y AT RISK FOR M A L A R I A . T H I S D I S E A S E , SPREAD V I A M O S Q U I T O S , IS ESPECIALLY P R O M I N E N T I N DE- V E L O P I N G C O U N T R I E S . ALT H O U G H WE H A V E C O M E A L O N G WAY I N O U R K N O W L E D G E OF M A L A R I A A N D A T T E M P T S TO F I N D DRUGS TO C O M B A T IT, T H E A B I L I T Y OF T H E M A L A R I A PLASMODIUM TO A D A P T TO T R E A T M E N T IS P R O B L E M A T I C . C H L O R O Q U I N E A N D D D T , T W O F O R M E R L Y EFFECTIVE C O M P O U N D S , H A V E A L R E A D Y BEEN R E N D E R E D USELESS. T H I S M A K E S P R E V E N T I T I V E A P P R O A C H E S , S U C H AS E D U C A T I O N , ESPECIALLY I M P O R T A N T . I N T R O D U C T I O N Epidemics like malaria strike on a large and seemingly un- controllable scale. While it is often difficult to comprehend the notion of eradicating such widespread diseases, recog- nizing the connection between humans, nature, and the diseases themselves is an essential first step. Like many other infectious diseases, malaria has had devastating ef- fects on both public health and the economy. Because of the incredible adaptability of the mosquito and its anthro- pophilic tendencies, methods for slowing the spread of the disease should not only include treatments with drugs and pesticides but also involve the education of those at risk as well as of those treating the disease. It is not enough to sim- ply address the biological mechanisms of malaria, of the mosquitoes that spread it , or of its victims. Humans, mos- quitoes, their respective natural and social environments, and the interaction among all of these factors must also be strongly considered. T H E O R G A N I S M B E H I N D I T A L L Malaria is caused by plasmodia (single-celled and usually microscopic) parasites. There are hundreds of species of Plasmodium parasites each of which infects specific verte- brate hosts. Among these, four particular species infect human beings: Plasmodium vivax (P. vivax), Plasmodium malariae (P. malariae), Plasmodium ovale (P. ovale), and Plasmodium falciparum (P. falciparum). Of these four species, Plasmodium falciparum is responsible for most deaths, whereas other species of the parasite, although not as fatal, cause high morbidity and affect national economies. The less deadly species have an impact on economies for logical reasons: the presence of the vector i n the population may not k i l l nearly as many people as P. falciparum does, but i t does damage the health of the working population. Not being able to work means less production which dis- courages trade and business both locally and internation- ally. I N S I D E T H E H U M A N B O D Y The malaria parasite enters the human host when an in- fected mosquito takes her blood meal. The parasite inside the mosquito is transmitted into the human blood through her saliva, which she injects into the flesh as she sucks her meal. The parasite, as a sporozoite, reaches the liver where it invades liver cells. Inside the liver cells it changes into round forms called merozoites, which are released into the blood to invade red blood cells. Inside the red blood cells they multiply into more merozoites and are finally released. The cyclical development and release of the parasite in blood cells causes the disease malaria. The falciparum malaria makes the infected red blood cell sticky, causing them aggregate to the endothelial wall of the blood vessels. This can block blood flow in small capillaries and can cause cerebral thrombosis, which essentially is the formation of a blood clot in an artery supplying the brain with blood. This gradually cuts off the blood supply to that particular area of the brain and causes a stroke, often leading to death. Sometimes, some parasites in humans can go on to trans- form i n a sexual stage and become a gametocyte. When a mosquito then feeds on the infested blood of the in- fected individual, the parasite enters the mosquito as a ga- metocyte. Gametocytes live inside the red blood cells of a mosquito and emerge from it. Here, sexual fertilization oc- curs, and the union of two gametes forms a zygote. The zy- gote transforms into a slug-like structure called an ookinete. The ookinete then egresses from a mass of blood called the bolus and crosses the mosquito's intestinal wall. It remains attached to the intestine and grows as a cyst, now becoming an oocyst. Inside the oocyst the parasite multi- plies a thousand-fold of sporozoites. The sporozoite is the form into which the parasite develops to invade the salivary glands. P H Y S I C A L S Y M P T O M S The release of the parasite from the red blood cells coin- cides with the violent rises in body temperature during the fever attacks commonly seen in malaria. The body temper- E L E M E N T S S P R I N G 06 ature can reach an astonishing 106 degrees Fahrenheit. However, this massive fever is preceded first by a series of other unmistakable symptoms. Andrew Spielman's book, Mosquito, gives a very vivid account of the body under attack by this debilitating disease: Seven to fourteen days after an infecting bite, malaria be- gins with a chill that spreads like jack Frost on a window- pane. The victim's skin becomes pallid, and shaking begins. Then the cold plunges to the body's core and deep tremors - called rigors - come in waves. Though weakened by the dis- ease, a man who feels the ice of malaria will shake with a vi- olence that can propel an iron bed across the floor. Completely out of the victim's conscious control, the spasms are the body's vain attempt to generate the heat. Of course, the man, woman, or child who lies in the parasite's grip soon comes to understand that fever will inevitably follow the chill, and bring the next stage of suffering. The fever from malaria...brings a sweat so profuse that doc- tors can almost see the droplets forming on the patient's fore- head. They certainly see the rivulets that run down the tem- ples and onto the pillow. The bedclothes and sheets of the malaria victim become soaked with salty perspiration that is the by-product of the body's valiant effort to cool and pro- tect the vital organs. Death is usually unavoidable for those who are physically weakened by age or previous illnesses. The dying decay physically while their red blood cells, made sticky by the parasite, form into a plaque that clogs the vascular system and starves the brain. Most cases usually follow the com- mon pattern of lethargy, delirium, and then coma. Unfortunately, those who have survived the initial episode of malaria are not necessarily cured of it; the progeny of the original parasites can remain in the body for months or years. They are usually held under control by the body's im- mune system, but any cause of decline of the immune function can trigger the disease to return in all its virulence. TRANS M I T T A N C E Malaria was originally thought to have originated i n rancid marshes; hence mal aria is an Italian phrase meaning "bad air." Contrary to early understanding, however, it was actu- ally a result of little creatures in the air which had been no more than an outdoor nuisance. I n fact, many people did not realize that this minute insect was responsible for a worldwide epidemic. Malaria is transmitted to humans by the bite of the female Anopheles mosquito, which i n turn needs human blood to nurture her eggs. Anopheles mosquitoes mainly hunt for blood between dusk and dawn. Though some may feed at other times of the night, rarely are they around during the bright, sunny parts of the day. This is an immense benefit to the mosquitoes, especially in countries like Africa, be- cause it gets cooler between dusk and dawn. People usually sit outside and rest or eat after a long day of work in the sun, making a buffet of human blood available to the mosqui- toes. However, these insects are not only found in hot, dry climates like that of Africa because they can thrive any- where from temperate to tropical climates, from Europe to South Africa. They can breed in any area with high humid- ity where there is warmth and a relatively permanent source of water. Distinguishing an uninfected mosquito from an infected mosquito cannot be done easily,1 but now there are molecular techniques available to detect malaria- infected mosquitoes within a population. A P R E V E N T A T I V E A P P R O A C H TO M A L A R I A : S O M E P R E L I M I N A R Y C O N S I D E R A T I O N S A S P R E A D I N G T H R E A T Malaria has had an effect on human history since ancient times. In ancient China, men would arrange for the remar- riage of their wives i f they ever planned to travel to malari- ous areas; Alexander the Great is thought to have died in 323 B.C. as a victim of malaria; the city of Carthage was known to be plagued by malaria during the time of Christ; malaria probably defended Western Europe from falling into the hands of Genghis Khan. Despite its profound ex- istence since the very first human beings, malaria was car- ried, undetectedly, by mosquitoes unti l the 1890s. Today, approximately 41 percent of the world's population, mostly those living i n the world's poorest countries, is at risk of contracting malaria. 1 1 "Developed countries are likely to stay malaria-free," said Professor Andrew Haines of the London School of Hygiene and Tropical Medicine. Any outbreaks would be scattered cases, from insects un- wittingly stowed away on airplanes. Countries currently most at risk are i n the Third World or at the fringes where healthcare systems are weak. Some studies say malaria may reach higher altitudes i n mountainous areas of devel- oping countries. 1 1 However, the malaria epidemic could easily become an international issue. While the improve- ment and success of many national economies is a result of globalization, the fading of geographical barriers intro- duces malaria vectors to vulnerable areas and drains those national economies. When malaria hits, it leaves the region's economy dam- aged. Sick people are unable to work; crops and other goods are ruined and left abandoned for fear that they are swarming with the parasites and wi l l affect the remaining healthy population. The community may be forced to evac- uate the area and populate other regions originally free of malaria. Unfortunately, those displaced introduce the para- site to more unprotected people. Human carriers of the dis- ease often show no symptoms, and when they move into previously malaria-free areas, the mosquitoes that bite them can pick up the parasite and go on to transmit it to other people. The chain of events can lead to a debilitating drop in the region's economy, which makes it difficult for the residents to afford the proper medication and treat- ment, which then leads to more sickness and death. The cycle continues as malaria spreads, ultimately becoming an international economic issue in this age of globalization. Malaria is also spread to unprotected communities through the increasing popularity and ease of overseas travel. Infected mosquitoes may be introduced to new areas by being transported in planes or ships, or the parasite can be introduced to a new area via infected but asymptomatic re- turning travelers and foreign visitors. This is similar to how many of the immune African slaves unknowingly brought yellow fever to the West, or how the Europeans in- troduced foreign diseases that wiped out entire indigenous populations in the New World. It illustrates human means of transportation as an aide to the longer-distance journeys of the mosquito across borders and over oceans. Malaria made its way to the United States through the im- portation and exportation of certain materials. These mate- rials were then redistributed to other formerly non-malari- ous parts of the world, thus continuing the spread of malaria. The journey of Aedes albopictus (the Asian tiger mosquito) is an example of how a species of mosquito, though non-malarious, can come into the United States. Anopheles mosquitoes that carry malaria may have made their way to the United States in a similar manner. The Asian tiger mosquito arrived i n the U.S. in the late 1970s because the U.S. began to import many used tires from Asia, where recapping worn tires and reusing them is illegal. However, reusing tires is not illegal in U.S. The tires were shipped to Houston, the tire recapping capital of the world, along with their unwelcome guests. Mosquito larvae were present in water that had pooled in these tires, while their eggs adhered to the inside walls of the tire. This type of mosquito usually breeds i n water-filled cavities, like rot holes i n trees. Thus, when humans began to save used tires, mosquitoes found the most ideally textured and the most perfectly simulated tree hole. Since it is difficult to E L E M E N T S S P R I N G 0 6 empty used tires of the water inside them, they make the perfect mosquito maternity wards. Roughly four billion old tires are piled up on the American landscape today, with millions more being added every year. Due to the fact that many of the tires that arrive in Houston are redistributed worldwide, there is no stopping the spread of the Asian tiger mosquito. Fortunately, malaria i n the United States was only a close call, although that does not mean that malaria wi l l not be able to strike again with worse consequences. The largest single factor that allowed the defeat of malaria in the United States seems to be the Tennessee Valley Authority (TVA), which designed every water project to l imit mos- quito breeding. Dams, irrigation networks, power systems, and drainage projects were built i n the most malarious parts of the South. Where standing water could not be avoided, it was monitored for anopheline larvae, and larvi- cides, which are insecticides that float just on or under the fi lm on the water's surface, were applied. These larvicides destroy anopheline larvae easily because an Anopheles mos- quito feeds on material that is directly associated with the surface and breathes through two pores located at the end of its abdomen, which is kept in close contact with the water surface. As shown by the TVA, civilization and the productive use of land can be beneficial not only to the health and wealth of the inhabitants, but also an effective way to keep the malaria epidemics at bay. However, other cases show that mosquitoes, no matter what the circumstances, malarial or not, constantly adapt to new environments. This poses an incredibly difficult challenge to overcoming malaria. The introduction of artificial containers to the environment was a great benefit to the tree-hole mosquito. These insects prefer any small openings in which water can be collected. In our throwaway society, discarded food containers that ac- cumulate near houses can serve as tree-hole replicas where a mature female mosquito can readily find sources of blood needed for egg production. Ultimately, people supply the mosquito with all she needs: artificial, water-collecting tree holes and a blood supply. Although this particular case does not involve the Anopheles species in particular, it in- dicates how mosquitoes have learned to survive among us. In the early 1880s, the French attempted a canal project to connect the Atlantic and Pacific. The failure of this project unlocked some of the mosquitoes' secrets: The camps built to house the Panama Canal workers were probably the best in the tropics. But because mosquitoes were considered nothing more than a nuisance, screens were one luxury that was not indulged. In time, the bar- racks and even the hospitals built for construction workers became feeding areas for local mosquitoes. The French aided the insects' breeding as well, by decorating their com- pounds with lavish gardens where pottery rings filled with water were used to protect hundreds of trees from ants. These rings teemed with mosquito larvae.w A P R E V E N T A T I V E A P P R O A C H TO M A L A R I A : S O M E P R E L I M I N A R Y C O N S I D E R A T I O N S Another example of precautions to be considered in hous- ing appears i n parts of Africa. Andrew Spielman, a leading malariologist at the Harvard School of Public Health, ex- plained in a conversation that maize fields around African homes serve as locations for mosquitoes to be closer to their human feed. Mosquitoes use the maize pollen as their food and lay their larvae in the mud, which is used to build the houses. Furthermore, there are usually mud ditches close to the homes for convenience. Many of these ditches are left open after the mud has been dug out, leav- ing ideal breeding sites for mosquitoes when they are filled with water. Clearly, it is important to assess the housing sit- uations for places that are threatened by malarial mosqui- toes for indirect relationships to malaria transmittance. Futhermore, U.N. reports say rising temperatures linked to human burning of fossil fuels are likely to widen malaria's range in the tropics because mosquitoes and the malaria parasite they pass on (when sucking human blood) thrive best i n hot, wet climates. Paul Reiter, professor of medical entomology at the Pasteur Institute in Paris, admits mos- quitoes and plasmodia parasites reproduce faster in hot, damp climates but says that, on the other hand, higher tem- peratures might trigger floods that wash away stagnant pools in which malaria larva breed or spread deserts to dry up the waters. "More rainfall sometimes means more malaria, it sometimes means less," he said. A l l experts agree that there is slight risk that clouds of malaria-bearing mosquitoes wi l l eventually make their way north to make the disease again endemic in nations from the United States to Russia.v F I G H T I N G M A L A R I A Although medicines were developed to mitigate the vic- tim's suffering, the evolution of drug-resistant malaria par- asites soon followed. The compound known as chloro- quine was developed after World War I I and was thought to be the ultimate cure for malaria—not only was it highly ef- fective with fewer side effects, but it was also inexpensive, costing no more than a few cents compared to today's cost of approximately eight dollars a p i l l . v l Chloroquine's mirac- ulous abilities, however, were short-lived after its popular- ity led to widespread drug resistant malaria parasites, which were first seen in South American mosquitoes i n i 9 6 0 but later spread around the world. After the creation of the controversial DDT, the United States was able to stay malaria-free, Europe eradicated malaria. Believing that DDT was the ultimate weapon for mass destruction of the mosquito, many other countries jumped on board with DDT; for a while, it was very effec- tive. Australia began to spray their tire shipments, and other countries began to fumigate the cabins of aircrafts ar- riving from abroad, even with passengers in them. Because of DDT's reputation as the "end all, be all" solution, re- search grants for DDT disappeared overnight. There was no need for further research because it was assumed that the battle had been won. Soon enough, the hype of DDT caused an unnecessary overuse of the chemical, allowing the mosquitoes to quickly build resistance. Moreover, Rachel Carson showed that, among many other hazards, DDT was found in mother's milk and could accumulate in babies, illustrating the chem- ical's ability to reach and harm the public. Consequently, the federal Food and Drug Administration announced that, "It's extremely likely that the potential hazard of DDT has been underestimated."™ Workers who handled the chem- ical developed health problems, and liver cancer was found in exposed fish. To make matters worse, malaria had begun its return. Some recent developments in medicinal treatments in- clude the use of a fungus fatal to the mosquito™ 1 and tests with the ancient Chinese plant Artemesia. However, as new drugs come and go as a consequence of the parasite's ever- increasing resistance, and as there is a continuous chase to remain ahead of mosquitoes' resistance to man-made chemicals designed to ki l l them, it becomes increasingly imperative to stress the importance of making changes in our daily habits and in our surroundings as the most effec- tive protection from malaria-transmitting mosquitoes. ELEM ENTS S P R I N G 06 C O N C L U S I O N In some ways, it seems that the refinements modern soci- ety continually brings have worsened the malaria epidemic. Both the industrial progress of mankind and the ever-evolv- ing nature of the mosquito make fighting malaria a difficult and exhausting battle. However, there is no doubt that our knowledge of malaria and the behavior of the mosquito car- riers have progressed immensely since it was first ob- served. Instead of pouring money into more and more pills and shots, it is now evident that investing in proper education about the mosquito and malaria can lead us to effective pre- vention methods. This is especially important to countries that do not have the medical resources or other proper means of protection. A simple change i n habit or lifestyle can dramatically decrease the number of bites that an indi- vidual gets in a day. Most malaria vectors bite at night; some like A. gambiae generally bite predominantly indoor late at night, while others such as A. albimanus in Central America attack outdoors early in the evenings. The time of biting and whether it occurs indoor or outside are both epi- demiologically important and relevant to control strategies. The on-going and uphill battle against malaria needs to uti- lize all viable methods, after the many previous failures in the search for a way to eradicate malaria. F U R T H E R STUDY I n light of trying to present the power that anthropological and environmental factors have over infectious diseases, I would like this project to continue into an exploration of the cultural beliefs held by endemic regions that influence the population's response to the disease's presence. This in- cludes the general attitude to Western medicine and treat- ment. Ultimately, the objective is to encourage Western medical practices to work with a region's culture and its tra- ditions instead of blindly implementing their own method- ologies. This wi l l not only show respect for tradition, but wi l l also be a more effective solution to the issue. A friend mentioned an interesting belief that lies around the river Ganga (pronounced Ganges i n the West) in India. The Ganga River is testable for mercury, arsenic, and dozens of other poisons, along with various parasites and bacteria. Some of this is due to the ritual of interring the dead in the river. Yet, i f one asks a traditional, spiritual Indian about the river, he wi l l insist that it is the purest water in the world. To them it is, after all, holy. l x To the West, however, it is clearly unsanitary. And i f the Ganga ever became a cause for an endemic disease like malaria, Westerners would react very differently than Indians would. From my observation, Westerners seem make it a priority to put the safety of people before cultural beliefs, whereas Indians may find prefer to endure the dis- ease rather than to disregard tradition. I hope to ameliorate the situation without infringing on anyone's cultural be- liefs, but it is questionable i f this is completely possible. E N D N O T E S i . Beier et al., 1990 i i . Center for Disease Control i i i . Doyle, Alister. PlanetArk.com, July 29, 2004 iv. Spielman v. Doyle v i . Spielman v i i . Spielman v i i i . New York Times article: June 10, 2005 ix. This is an anecdotal tribute to my friend Wesley Saavedr, although I am unsure where the story originated. REFERENCES Alzate, Alberto; Spielman, Andrew. "A Sustainable Antimalaria Strategy for a Region of Intense Transmission." i986(?) Beier, et.al. "Malaria Transmission i n Urban Sub-Saharan Africa." The American Society of Tropical Medicine and Hygiene 2003, pp. 169-176 Doyle, Allister. "Global Warming Effect on Malaria." 2005, PlanetArk.com Hoffman, Stephen L. Malaria Vaccine Development: A Mul t i - Immune Response Approach. i996American Society for Microbiology, Washington D.C. A P R E V E N T A T I V E A P P R O A C H TO M A L A R I A : S O M E P R E L I M I N A R Y C O N S I D E R A T I O N S http://PlanetArk.com http://PlanetArk.com Lane, Richard P., Crosskey, Roger W. Medical Insects and Arachnids.1993, Chapman & Hall , Cambridge, UK. Lehane, M.J. Biology of Blood-Sucking Insects. 1991 Harper Collins Academic, London, UK. Lipowsky, Renate, et.al. "Sociomedical Aspects of Malaria Control i n Colombia." Social Science Medicine Magazine, Vol. 34, No. 6, pp. 625-637. 1992, Great Britain, UK. Spielman, Andrew, DAntonio , Michael. Mosquito: The Story of Man's Deadliest Foe. 2001 Hyperion, New York, New York. Yamin, Gavey. "Malaria Drug Politics." May 8, 2000. EssentialDrugs.org World Health Organization (www.WHO.int) Center for Disease Control (www.cdc.gov) Net Doctor (www.netdoctor.co.uk) www.RaintreeNutrition.com, 2005 www.MalariaFoundation.com. May 17,1998 www.SeniorHealth.com www.CancerWEB.com. Online Medical Dictionary, 2004. New York Times article, June 10, 2005 http://EssentialDrugs.org http://www.WHO.int http://www.cdc.gov http://www.netdoctor.co.uk http://www.RaintreeNutrition.com http://www.MalariaFoundation.com http://www.SeniorHealth.com http://www.CancerWEB.com