Malaria is a disease caused by a parasitic protozoan of the genus Plasmodium. The four most important species, that affect humans, are 1) P.vivax 2) P.falciparum 3) P.ovale and 4) P.malaria. The life cycle of malaria is somewhat complicated. Once injected into the human host it makes it's home within the liver. There it under goes maturation and is then released into the blood stream, where it can invade unsuspecting red blood cells. Within the cell the microbe multiplies until the cell membrane bursts releasing the multiplied versions of it's self back into the humeral regions of the host. This life cycle can last for days and in some cases years (depending on the species). The blood is also the staging ground for transmission between hosts. Infected blood can contaminate other non-infected humans by means of mosquito interaction as well as direct person-to-person contact through emergency transfusions and needle sharing.
Characteristics of malaria include its relation ship with the female anopheles mosquito, incubation period and period of communication. Due to evolutionary reasons the only environment that can support this Plasmodium, for any length of time, is the gut of the anopheles mosquito. Incubation period is another distinctive characteristic that is capable of revealing the identity of the different malaria species. P.falciparum incubates for 7-14 days; P.vivax ranges from 8-14 days, which is also true for P.ovale; and 7-30 days for P.malaria. The period of communicability is highest during the parasitemia stage of the pathogens life cycle, which can last intermittently or remain constant for years. Reservoirs include humans and carriers (6).
Blood smears, chemical tests and DNA testing can be used to identify malaria. Some one suffering from malaria would present the fallowing symptoms. Fever and flu-like issues including the shakes accompanied by chills, headache, muscle aches, and myalgia. Nausea, vomiting and diarrhea could also take place. Jaundice (A yellow coloration of the skin due to toxicity) is a type of anemia that is produced by the malaria parasite and is the result of red blood cell loss. If not treated immediately the P.falciparum species can onset kidney failure, seizures, mental confusion, coma, and death (7). The severity of symptoms is different for each species, which is why it is critical to know which parasite is involved, and at what stage the infection is at, Immunological history of the patient and all other factors possible help in diagnosis.
People that frequent endemic areas are at a greater risk for infection (6). The first consideration in response to malaria is how can it be prevented. Before traveling to a questionable area, one should attain the necessary vaccinations and prescription drugs for treatment of malaria. Oral medicine should be fallowed exactly to the letter; prevent mosquito bites by using DEET insect repellant on exposed skin as well as fumigating the area you are operating in; wear long sleeved pants and shirts during the night hours (this is the most likely time to get bitten by an infected mosquito); and sleep under a mosquito net that has been treated with Permethin insecticide. People residing within an air-conditioned dwelling should not worry (7). However if infection has occurred there are prescription drugs available for treatment. Severity of illness dictates the type of therapy to be administered. Issues that can complicate treatment are: parasite resistance, drug side affects and drug availability. For non-falciparn malaria Chloroquine is the routine drug of choice for curing. On the other hand P.falciparm cases are more complicated due to its resistance to most of the anti Plasmodia agents available. Timely identification is critical with this case because of the potential for accelerated clinical deterioration of the host. Assured success, for remedying, depends on the time the infected individual is admitted into a health care facility. Late stage patients are treated intravenously with Quinidine preferably within an ICU setting (6).
Currently, many different agencies and organizations are searching for a malaria cure. Two of the leading prospects are the United States Army (4) and Oxford University in collaboration with Oxxon Pharmaccines (a biotechnology company) (5). The Army's program focuses on the " Blood-Stage" portion of the infection cycle (the blood stage is the time when the parasite is the most actively causing disease by attacking red blood cells). The key to the Army's vaccine is a malaria surface protein designated as Merozoite surface protein-1 antigen. This protein is a trigger for the human immune system. If successful the Army plans to create vaccines that are composed of multiple antigens that associate the immune system to the target vector, malaria (4). Oxford University and Oxxon Pharmaccines have advanced far enough in their initiative that they are at phase one clinical study that incorporates humans as subjects. Their mission is the development of a vaccine that incorporates what they describe as a "Prime-Boost" technology. Prime-boost elevates the body's natural resistance to malaria via a two-stage regiment. The first stage primes the body's defenses, and then the second stage boosts the response of the immune system in attacking the non-self invader. Both stages of the vaccine contain genes that react to the malaria's antigens. Thus far, animal studies have proven the vaccine to be 100% effective in fighting malarias (5). Hopefully the same results will prove positive for humans.
Malaria is endowed with a very complex virulence mechanism. This mechanism is the ability to undergo a function called antigenic variation. Antigenic variation is a process that continuously changes the surface membrane proteins of the host cell. This changes the antigenic appearance of the infected cell ultimately hiding it from the immune system. This feature is analogous to the cloaking devices the Klingons use in the television series StarTreck. When an infected human's immune system begins to mount an attack, against the invading pathogen, the pathogen switches its surface proteins to express a different characteristic ultimately escaping destruction, which perpetuates the infection. The malaria contains at least fifty different protein characteristics that it can use to deceive the human immune system (3).
The history of Malaria has references that date back to writings that were written in 1600 B.C. (In India). Hippo crates philosophized about the species some 2500 years ago. At one time it was only indigenous to Europe until settlers, about 500 years ago introduced it to the New World (present day America's). The first sighting (via microscopy) of the microbe was in 1880, by an army officer named Charles-Louis-Alphouse Laveran. Not long after that (in 1882) the transmission hypothesis was proposed. This theory stated that the malaria vector was the female Anopheles mosquito. By 1898 this theory was permanently established (1). The first large-scale operation, in order to eradicate this pathogen, began in 1930 and incorporated the use of the airplane. This airborne craft had the ability to dispense pesticide in mass amounts and over large areas (2). In 1974 the WHO (World Health Organization) officially declared that the eradication of malaria would be impossible and that future efforts, up to the present day, would be dedicated to a more preventative scale (1)
References:
(1) Desowitz, Robert S. The Malaria Capers (More Tales of Parasites and People, Research and Reality. 1991. W.W. Norton & Company, New York. 05 May 2002. http://www.idrc.ca/books/reports/1996/01-05e.html
(2) Author unknown. Title unknown. National Library of Medicine. 27 April 1998: p.g. 27, 35, 80, 81, 142. n.p. 5 MAY 2002 http://www.nlm.nih.gov/exhibition/phs_history/82.html
(3) Deitsch, Kirk W. Antigenic Variation and Transcriptional Regulation in Malaria Parasites. 2001. Weill College of Cornell University. 4 May 02. http://www.med.cornell.edu/microbiology/deitsch/index.html
(4) Author unknown. U.S. Army Joins Forces With Malaria Vaccine Initiative to Launch Clinical Trial in Kenya. 25 April 02. n.p. 4 May 02. http://www.malariavaccine.org/files/20020425-USArmy.htm
(5) Author unknown. Malaria Vaccine Initiative, Oxford University, and Oxxon Pharmaccines to Accelerate Clinical Development of Innovative Malaria Vaccine. 22 Oct 01. n.p. 4 May 02. http://www.malariavaccine.org/files/011022-oxford-oxxon.htm
(6) Author unknown. Malaria. 12/00. Oregon Department of Human Services. 4 May 02. http://www.ohd.hr.state.or.us/cdpe/guideln/malaria.pdf
(7) Author unknown. Malaria: General Information. 10/2000. Center for Disease Control (CDC). 3 May 02. http://www.cdc.gov/travel/malinfo.htm