Plasmodium falciparum in Cambodia: Difference between revisions
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==Why is this disease a problem in Cambodia?== | ==Why is this disease a problem in Cambodia?== | ||
Cambodia is one of a few countries in Southeast Asia that have been struck by the malaria epidemic. It is home to the world’s most drug-resistant strain of malaria and continues to fear that of its growing resistance to malaria drugs. Plasmodium falciparum, one of the most common and deadliest strands of malaria has been a major problem in Cambodia due to numerous factors. | |||
More than 60% of Cambodia’s landmass is comprised of forests and plains (PRB). Coupled with the Monsoon-dominated weather making Cambodia’s climate very moist and landscape shady and wooded making it the perfect home for mosquitoes to survive and breed. Most of the population in Cambodia lives in these dense and moist forests where mosquitoes can transmit malaria to humans. Forest regions bordering Thailand and rubber plantations found in the East and Northwest are where malaria is likely to be found. About 15% of Cambodians are at medium to high risk of malaria infection, of these forest inhabitants, migrant and border workers, pregnant women, and infants and children are mostly contract the disease (PRB). | |||
Poor health infrastructure and poor communication systems are also major contributing factors to the malaria epidemic in Cambodia. In high transmission areas such as forests, the facilities such as hospitals are lacking, and transportations systems are deficient or nonexistent. Poor road conditions, lack of suitable vehicles, and a lack of telephone facilities lead to treatment delays for the infected in remote areas. Many of the affected areas are inaccessible. | |||
In addition, the inadequate health care adds to the problem of malaria in Cambodia. There are often shortages of diagnostic kits and appropriate drugs, as well as a lack of qualified private practitioners. Many unqualified doctors and pharmacies do not follow the national treatment guidelines. There are also a large number of fake drugs available in the market, which does nothing to solve the problem. | |||
==What is being done to address this problem== | ==What is being done to address this problem== | ||
Revision as of 20:02, 26 August 2009
Introduction to Malaria
Malaria is fatal disease that infects about 515 million people worldwide and kills nearly a million people annually (1). Malaria is widespread in mostly tropical and subtropical countries because of their conditions allow the Anopheles mosquitoes to thrive.
Malaria infected individuals have symptoms such as fever, abdominal pain, chills, headaches, nausea, diarrhea, vomiting which can appear after couple of days or weeks after the infection. Also, very often malaria can lead to severe anemia, seizures, kidney failure, confusion and death if not treated on time (5).
As a result of its devastating effects on the human population, many organizations (Gates Foundation) and countries (Global Fund) have banded together to find preventative measures and treatments for this global epidemic.
Description of Malaria
In Cambodia, the specific species (Anopheles dirus, A. minimus, and A. sundaicus) transmit the malaria-causing parasites (Plasmodium falciparum and P. vivax) to the host during feeding with the bite, transmitting the parasite through their saliva.
The parasite initially enters the liver, where it multiplies and then infects the red blood cells. Here parasites still continue to multiply until eventually the red blood cells burst and the parasite appears in the plasma. Now, the parasites are free in the plasma and will infect any mosquito that bites and feeds on the host’s blood. Once the parasites enter the mosquito, they are also found in its saliva and are ready to be transferred to another individual and repeats the cycle after biting another host.
The number of infected people observed in Cambodia each year exceeds more than a million out of which about 10-15% die (5). Victims of malaria are mostly children, infants, and pregnant women because of their weaker immune system (3). Forest inhabitants, border workers and migrants are also in high risk in getting the disease because of their increased exposure to mosquito vectors. Due to global warming, the increasing temperatures, humidity, and rains may all favor the spread of malaria as mosquito habitats spread (4).
Description of the Plasmodium falciparum
Plasmodium falciparum is species of the genus Plasmodium, which of the Eukaryote domain and Plasmodiidae family. Plasmodium are much more complex than simple bacteria because of a “genetic complexity five times greater” (1). Their complex genome allows them more flexibility in various environments where simple bacteria can’t survive. Aside from having a complex genome, Plasmodium possesses various invasive stages for targeting specific host.
Infection/Polymorphism/Cycle
Plasmodium possesses various forms, the most prominent being sporozoite, merozoite, and ookinete. These various forms of a plasmodium are directly tied to the cycle of infection. Sporozoite enters the human body via the saliva of mosquitoes during a blood meal. Sporozoites infect the hepatocytes (liver cell) within 30 minutes. From the hepatocyte, the parasite reproduces asexually into merozoites until they are released from the liver and enter the bloodstream. Merozoites then invade the erythrocytes (red blood cells) within 10 minutes. The merozoites continue proliferation in infected erythrocytes and also infect other uninfected erythrozytes. In an erythrocyte, merozoite can also differentiate to become gametocyte where they can be carried off by female mosquitoes after a blood meal. The gametocytes travel to the mosquitoes’ guts where they differentiate into male and female cells for fertilization. A zygote or ookinete is ultimately formed. The ookinete develops into sporozoites and venture into the saliva of the mosquitoes where they can further infect other human (7).
This cycle ties human and mosquitoes directly in the transmission and infection of malaria. In this relation, anopheline mosquitoes act as a vector and aid in spreading the infection. However, not all mosquitoes can be vectors. Only 68 out of 460 Anopheles can be vectors. Moreover, only female mosquitoes can take up gametocytes and transmit sporozoites as they are the only mosquitoes that bite.
Reasons for Symptoms
Symptoms of malaria are caused by the effects of merozoites interfering with the red blood cells' ability to carry oxygen. In infected erythrocytes, the cells are found to be deformed and stiff. Hemoglobins also function as food and nutrients for the merozoites. Infected red blood cells are more prone to rosetting and sequestration. Rosetting is when red blood cells attached to other red blood cell. With malaria, this occurs at a higher rate to allow for further infection of other red blood cells. Sequestration is the attachment of infected blood cells to the endothelial layer by rolling. The site of sequestration also prompts more infected cells to attach resulting in a buildup. Sequestration hinders oxygen delivery to organs and tissues. The effects of sequestration can lead to coma symptoms in severe cases of malaria. The combined effect of rosetting, sequestration, and consumption of hemoglobin by merozoites play a strong role in hindrance of oxygen delivery. This leads to the flu like symptoms of malaria (8).
Prevention
Malaria preventive measures can be approached in various ways. Simple preventative measures can be vector control or protection from mosquitoes bites via mosquito nets or the use of bug sprays containing DEET. Anti-malaria drugs can be combined with vector control or bit prevention to lower the risk of infection. Unlike typical diseases, vaccination is not a viable solution due to the disease's complexity.
Hey, let me know; does this qualify as prevention? "Cambodia recommends prophylaxis for all areas. Other medicines are mefloquine (Lariam, doxycycline, and atovaquone (Malarone), Mefloquine should be taken once a week, and this should be started two weeks prior to arriving in Cambodia. Mefloquine may cause mild neuropsychiatric symptoms, such as nausea, vomiting, dizziness, insomnia, and nightmares. Other severe reactions occur: “depression, anxiety, psychosis, hallucinations, and seizures.” However, in the cities near Thai border, mefloquine is not recommended because there is mefloquine-resistant malaria in the forested areas. Atovaquone/proguanil (Malarone) should be taken once a day with food, from two weeks before arrival and also seven days after departure. Atovauqone can cause mild symptoms like “abdominal pain, nausea, vomiting, headache, diarrhea, or dizziness.”
Why is this disease a problem in Cambodia?
Cambodia is one of a few countries in Southeast Asia that have been struck by the malaria epidemic. It is home to the world’s most drug-resistant strain of malaria and continues to fear that of its growing resistance to malaria drugs. Plasmodium falciparum, one of the most common and deadliest strands of malaria has been a major problem in Cambodia due to numerous factors.
More than 60% of Cambodia’s landmass is comprised of forests and plains (PRB). Coupled with the Monsoon-dominated weather making Cambodia’s climate very moist and landscape shady and wooded making it the perfect home for mosquitoes to survive and breed. Most of the population in Cambodia lives in these dense and moist forests where mosquitoes can transmit malaria to humans. Forest regions bordering Thailand and rubber plantations found in the East and Northwest are where malaria is likely to be found. About 15% of Cambodians are at medium to high risk of malaria infection, of these forest inhabitants, migrant and border workers, pregnant women, and infants and children are mostly contract the disease (PRB).
Poor health infrastructure and poor communication systems are also major contributing factors to the malaria epidemic in Cambodia. In high transmission areas such as forests, the facilities such as hospitals are lacking, and transportations systems are deficient or nonexistent. Poor road conditions, lack of suitable vehicles, and a lack of telephone facilities lead to treatment delays for the infected in remote areas. Many of the affected areas are inaccessible.
In addition, the inadequate health care adds to the problem of malaria in Cambodia. There are often shortages of diagnostic kits and appropriate drugs, as well as a lack of qualified private practitioners. Many unqualified doctors and pharmacies do not follow the national treatment guidelines. There are also a large number of fake drugs available in the market, which does nothing to solve the problem.
What is being done to address this problem
The government of Cambodia believes that the increase of infections was because of the early rains. So the government distributed mosquito net, which cause malaria by injecting parasites into the bloodstream (9). Also, the government provided Rapid Diagnostic Tests (RDT), and Blister packaging. Rapid Diagnostic Tests assists, also known as dipstick, the diagnosis of malaria by detecting the parasites in blood stream. This improves the quality of management for malaria infections. Blister packaging contains one dose of sulphadoxine/pyrimethamine and three doses of artesunate. This provides high quality and effective treatments for malaria. This will be sold cheaper than other drug combinations.
Over the past few years, many counterfeit antimalarial drugs have been distributed in Cambodia. The counterfeit antimalarial drugs cause mutation of resistant strains of the parasites that cause malaria, which makes the real drug to lose its effectiveness. However, Malaria Workers (VMW) distribute the proper medication and dipstick test, which confirms P. Falsiparum. Their efforts huge changes in Cambodia; it slows down the drug resistance, and it also prevents the spread of malaria. MOT (Malaria Outreach Teams) reaches out to remote areas and provide diagnosis and treatment services at public and private facilities. This is extremely helpful for children who are in rural area because they have weak immune system.
The Health Education Department of Cambodia works hard to morbidity and mortality rates of illness. In this program, they inform malarial prevention techniques and urge them to” initiate behavioral change regarding illness and prevention techniques within the community” (10). Also, there had been many awareness campaigns for people to realize the danger of malaria. Due to the awareness efforts, the number of malarial infections and deaths have decreased in recent years because of education and mosquito net distribution. The rate has “decreased from 2.81 percent to 1.68 percent for every 100,000 people” (11).
What else could be done to address this problem
Are there solutions that could be successful but haven't been implemented due to political or economic reasons? Are there successful efforts in other countries? Are there reasons why these efforts may or may not be successful in the country you've focused on? etc. etc.
References
1. “Genome of Parasite that Causes Relapsing Malaria Decoded.” 2009. ScienceDaily. 9 Oct. 2008.
2. Pierce, Susan K., Miller, Louis H. World Malaria Day 2009: What Malaria Knows about the Immune System that Immunologists Still Do Not. 2009. The Journal of Immunology. 5 March, 2009.
3. “Drug-Resistant Malaria Has Emerged in Cambodia.” 2009. Science Daily. 13 Aug. 2009.
4. “Is Global Warming Likely to Cause an Increase Incidence of Malaria?” 2009. Libyan Journal of Medicine. 13 Feb. 2009.
5. "Fewer Malaria Cases in Cambodia.” 2009. Population Reference Bureau. Dec. 2002.
6. "Epidemiological Profile of Cambodia" World Malaria Report 2008. Geneva : World Health Organization , ©2008. p.51-54.
7. http://www.impact-malaria.com
8. Molecular aspect of malaria.
9. http://news.xinhuanet.com/english/2009-08/17/content_11896491.htm
10. http://news.xinhuanet.com/english/2009-08/17/content_11896491.htm
11. http://news.xinhuanet.com/english/2009-08/17/content_11896491.htm
Edited by [Betsy Chiem, Ben Cho, Chuong Do, Katherina Leu, Albert Luong and Lusine Minasyan], students of Rachel Larsen
