Malaria And Antimalarial Medications Biology Essay

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Malaria is an insect-borne disease and a critical health issue as it is currently endemic in 100 over countries, and it is accounted for approximately 300 to 500 millions of clinical cases globally1- [8] . It is preventable and treatable, yet approximately one million of people die from this disease each year, most of them live in the impoverished countries (income level are 33% less than similar countries than are free from this disease). What is malaria? It is a dangerous disease that is caused by parasite by the genus Plasmodium that infects our blood circulatory system particularly our red blood cells. [9] . There are only 4 among all the species that can harm the humans- Plasmodium falciparum, P.malariae, P. ovale, and P. vivax. However, P.falciparum is the main cause of high death toll in the world. People who suffered from this disease mostly are from temperate regions or tropical latitudes such as Asians and Africa as they provide the ideal surrounding for Anopheles mosquito to breed and feed. Those who are infected will experience symptoms such as persistent high fever, joint pain, nausea anaemia and convulsions while a more severe repercussion will be coma and eventually death. Children and pregnant women often fall as easy targets are they are more vulnerable towards the superiority of this disease. Although a patient can recover from malaria, unfortunately some of these parasites will remain in our body organ such as liver and will become stronger, causing a relapse without any symptoms within months or years. These parasites will reside in our liver cells and remain dormant for some time. Hence, a patient may suffer from the same sickness again. The problem now protruding on the table is what are the treatments that best eradicate the disease and it's symptoms for good?

Figure 1: Anopheles Mosquito

10http://www.google.com.my/images?hl=en&q=anopheles%20mosquito&um=1&ie=UTF-8&source=og&sa=N&tab=wi

Solutions:

Antimalarial Medications

Currently, antimalarial drugs are the best treatment to alleviate the symptoms, decrease the relapse rate, and the spread of malaria. It is easy to treat as the process requires not more than 3days, but if proper diagnosis and drugs are administered late or wrong, the patient will experience severe ramifications such as comatose and die eventually. [11] The effectiveness of these drugs depends on the factor such as the species of parasites involved and the different stages of life cycle of parasites. Examples of antimalarial drugs available in the market include chloroquine, proguanil, mefloquine, doxycycline, quinine and etc. [12] 

Figure 2: Chemical Structures of selective antimalarial drugs [13] 

(http://www.icp.ucl.ac.be/~opperd/parasites/chemo1.html)

Antimalarial medications are divided into two basic classes-prophylactic drugs and therapy drugs. [14] 

Prophylactic drugs are commonly used as first line treatment for malaria infected patients. How do prophylactic drugs work to suppress the symptoms of malaria? Once parasites of malaria such as P.falciparum reached the erythrocytic cycle of its life, prophylactic drugs such as doxycycline, mefloquine, chloroquine and Malarone are excellent at killing it. These drugs are used as monotherapies to prevent people from contracting the disease even though the presence of the carrier (Anopheles mosquito) of malaria puts them at risk. [15] Chloroquine is given to suspect patients with malaria immediately while waiting for the diagnosis and it is safe with correct dose and no adverse side-effects. For cardiac illness patients, mefloquine are strictly used with extra precaution as it will have the tendency to cause asymptomatic sinus bradycardia and other conduction abnormalities. [16] 

Figure 3: Drug efficacy in western Thailand. CQ = chloroquine; SP= sulfadoxine-pyrimethamine; Q = quinine; QT = quinine and tetracycline; M15= mefloquine, 15 mg/kg; M25= mefloquine, 25 mg/kg. [17] 

(http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=malaria&part=A2011)

On the other hand, combination drugs such as artemisinin act as the second line treatment after the failure of first line treatment in obstructing the parasites from further damage our body system. Combination therapy drugs are administered for patients who have already contacted this disease, require treatment and to enhance remission. What are the advantages on using therapy treatment as compared to the traditional medicine? Parasites such as P.falciparum mutate via natural selection and become increasingly resistance towards prophylactic drugs, thus decreasing their efficacy (Figure 3). So, in order to curb this woe, combination therapy treatment is the latest resort whereby it requires combination of more than one agent requires separate mechanisms of action against the same stage of parasite. The formula works by combining old drug such as chloroquine with new drug such as sulfadoxine-pyrimethamine to perform a combined antimalarial therapy. Table 1 below shows the examples of drugs used in combination therapy treatment currently. This step is vital as it improves the therapeutic efficacy and also delays the development of resistance of parasites towards this treatment. Combination therapy such as artemisinin reduces the percentage of parasite in our body to the extent of 0.00000001%, thus decrease the probability of transmission from one to another. (J.Kevin, 2005)

No.

Drug combination in use or in trials currently.

1.

2.

3.

4.

5.

Artesunate + amodiaquine

Artesunate + sulfadoxine-pyrimethamine

Artemether-lumefantrine

Chloroquine +sulfadoxine-pyrimethamine

Amodiaquine + sulfadoxine-pyrimethamine

Table 1(http://www.malariajournal.com/content/5/1/48/figure/F1?highres=y) [18] 

Artemisinin-based combination therapy (ACT) is being advocated by numerous researcher and medical practitioner as the most reliable treatment and first line therapy in dealing with uncomplicated malaria. In table 2, a study was conducted by Mr.Ikeoluwapo O Ajayi and his fellow colleagues in Sub-Saharan Africa (Nigeria, Ghana and Uganda) over a year length, comprises of 1740 children with malaria symptoms on the effectiveness of ACT used in the context of home management of malaria. From the results obtained below, Uganda had lowered widespread of parasitemia prior to treatment than Nigeria and Ghana (61% vs. 71% and 71% respectively, p < 0.001). The crude parasitological failure rate was highest in Nigeria (41.8%), followed by Ghana (27.8%) and Uganda (3.7%) while the PCR adjusted cure rate was at a healthy level around 90% in all sites, with Nigeria and Ghana each sharing around 91% and Uganda with 97%,indicating the high effectiveness of ACT.

Table 2

Treatment outcome of AL and AS/AQ at D28.

Study site

Drug used

Enrolled

Parasitaemic patients on D0 N (%)

Patients seen at D28 N (%)

Crude parasitological failure (%)

Geometric mean parasite density D28 (p/μl)

PCR adjusted failure rate*

PCR adjusted cure rate

Badeku & Ojoku/Ajia Nigeria

AL

432

306 (70.8%)

C.I. 67%-75%

184 (60.1%)

77/184 (41.8%)

C.I. 35%-49%

2835

14/154 (9.1%)

90.9%

C.I.

86%-95%

Ejisu-Juaben, Ghana

AS/AQ

848

603 (71.1%)

C.I. 68%-74%

205 (34%)

57/205 (27.8%)

C.I. 22%-34%

15080

17/197 (8.6%)

91.4%

C.I.

87%-95%

Bugiri, Uganda

AL

460

280 (60.9%)

C.I. 56%-65%

217 (77.5%)

8/217 (3.7%)

C.I. 1.2%-6.2%

N/A

6/216 (2.8%)

97.2%

C.I.

95%-99%

*= Samples that could not be classified by PCR were excluded from the analysis

AL = artemether-lumefantrine

AS/AQ = artesunate-amodiaquine

(http://www.malariajournal.com/content/7/1/190/table/T1) [19] 

Effects of Malaria on economy, environment and social:

It is treatable and preventable, yet the death toll caused by this diseased reached approximately one million every year. Not only malaria has been a constant threat in terms of social, it has created a chaos economically on some of the poorest nations on every corner of the Earth due to its exorbitant cost. Peoples, who couldn't escape themselves from the clutches of poverty, usually do not have the financial ability to bear the cost incurred by this disease. The average per capita GDP (Gross Domestic Product) of nations where malaria is a constant woe (from 1965 and 1990) only achieved 0.4% per year, 2% lesser than other countries. [20] Dicholorodiphenynlytricholoroethane or DDT is one of the arsenals used to counter the attack of malaria and is highly efficient in reducing the population of Anopheles mosquito to a certain extent (decrease in cases of 78%). Although DDT has proven it's beneficial by its good track records, yet various environment activist proclaimed this chemical weapon will do harm to the humans' health as well. Banning of DDT will result in myriad of deaths and very high economic costs to the extent of US$480 million on nations that can ill afford it. [21] (Tren, R. Economic Costs of Malaria in South Africa)

Figure 4: Factors affecting social vulnerability [22] 

(http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=malaria&part=A1820&rendertype=figure&id=A1834)

From social's perspective, not all people who contract this disease will receive prior treatment due to reasons such as lack of knowledge on the symptoms, local culture, and gender bias and so on(Figure 4). Unlike HIV, there is no stigma attached to uncomplicated malaria. So, less attention will be given to symptoms like fever as the threat is common to the locals and will be brushed off. Moreover, some cultures instill a different level of knowledge which is totally contradict with science in treating the disease and result in mistreatment. [23] Gender bias is a norm as women is treated as lower class, where men are in-charge of their lives. They have limited power or control in making decisions in terms of expenditure (e.g. medical bill), and places themselves in the position of social vulnerability against this disease. Those who are from silver spoon will have the quality treatment, while those who are from the poverty lines will ponder on the availability of meal rather than seeking a quality treatment for themselves [24] .

Figure 5: Antimalarial drug treatment by wealth index in sub-Saharan African children under 5years [25] (http://www.rollbackmalaria.org/cmc_upload/0/000/016/249/SESMalaria_BackgroundPaper.pdf)

In addition, patients need to adhere attentively to the treatment that is chosen for them. ACT is more efficient than traditional cheap drugs such as choloroquine in treating malaria. On the other hand, although ACT is more costly than herbs (choloroquine), yet it will lead the patients to less side-effects and efficacious in handling the disease.

Benefits and risks:

Due to the increasing resistant of malaria parasites toward the drugs, the emergence of ACT has relieved most of the pressure on it. The reliance on ACT has been proven positive as its derivatives wipe out parasites instantly and have lesser side effects as compared to prophylactic therapy. [26] Artemisinin has an advantage where it can be used to treat against severe or uncomplicated malaria and the procedures are faster. One of the reasons why ACT is chosen because it doesn't remain in our bloodstream for long thus limits the chance for parasite to build up resistance against it. This therapy also relieves clinical symptoms such as nausea and fever and brings down the risk of treatment failure. Furthermore, ACT's drugs are always in the form of tablets to make it easier for patients to partake. Optimum dosage and punctuality in taking it will reduce the side-effects and make life easier.

Patients will suffer from some side-effects from the drugs (Table 3). Due to complexity of treatment regimen of two doses daily for days will affect adherence. Most people procrastinate with their treatment once they feel better after two days, and this effects in late relapse of malaria. Mild side-effects are detected during ACT, severe ones are rare. Patients are supposed to adhere to treatment and make sheer decision in switching the treatment to ACT, as delaying will only increase morbidity and mortality.

27Table 3: Safety and Tolerability of antimalarial drugs (J.Kevin, P. (2005). Effectiveness of Antimalarial Drugs. The New England Journal of Medicine .)

Alternative solutions:

Prevention is always better than cure. Below are some alternative solutions offered:

Insecticide treated bed-nets (ITNs)

Bedclothes

Vector Control

Mosquito repellent cream

To curb the disease from further spreading, insecticide treated mosquito bed-nets (ITNs) or bedclothes such as long pyjamas are vital to prevent the biting of Anopheles mosquito. It is proven that the protection it offers is 70% higher compared to no net. The costs of these solutions are far much cheaper and simpler to obtain as it is available in any stores. [28] Moreover, a mobile repellent cream is also recommended as the best preventive from biting of mosquito [29] . Vector control such as fogging must be applied to exposed area of still water such as water reservoir or non-flowing drain by authorities (Ministry of Health) [30] . The methods mentioned above may not eliminate malaria from our life, but at least the threats it posed can be greatly reduced.

Figure 6: Usage of ITNs prevents the biting of mosquito

Evaluation:

Artemisinin based combination Therapy (ACT) is widely advocated by various groups such as researchers and medical practitioners as the best treatment to reduce the growing resistance towards prophylactic drugs and more efficient according to sources (10, http://en.wikipedia.org/wiki/Antimalarial_drug). The content of this site is well supported by another source such as (16, http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=malaria&part=A2011) and some excerpt. 'To counter the threat of resistance of P. falciparum to monotherapies, and to improve treatment outcome, WHO recommends that artemisinin-based combination therapies

be used for the treatment of uncomplicated P. falciparum malaria', By World Health Organization (WHO) 2nd Edition 2006 (http://whqlibdoc.who.int/publications/2010/9789241547925_eng.pdf). This is a manual prepared by the body of United Nations which is a non-profit agency who are responsible in the health issue affecting the world. WHO is a renown body with substantiated status and proven highly reliable.

Besides, (14, http://en.wikipedia.org/wiki/Malaria) is very helpful in providing comprehensive information on treatment, preventive measures and basic information on malaria. This site is updated with latest research by renowned researcher and is used as reference globally. Every journal I read and websites I surfed are referred to this site and this has proven its reliability and trust worth-it.

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