Parasitic Parasites - Essay Example

Parasitic Parasites s
Miotto,O. et al. (2013). Multiple populations of artemisinin-resistant Plasmodium
falciparum in Cambodia.Nature Genetics, 45 (6),648-655. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3807790/.
In the warm tropical regions malaria remains one of the most deadly diseases resulting in high rates of morbidity and mortality. Each year millions of people fall prey to the disease and therefore Malaria is of immense public health concern. Malaria maybe caused by one of the four species of Plamodium parasites-Plasmodium falciparum, P.vivax. P.ovale and P.malariae. However, Plasmodium falciparum is found all around the world especially in the tropics and kills more than 1 million African children each year (Gardner et al, 2002).The infectivity of the parasite has been extensively studied. P.falciparum infected females mosquitoes transmit the sporozoites into human blood stream when they suck blood. The spoprozoites enter the blood stream and infects hepatic cells where they mature and produce merozoites which subsequently become trophozoites while some merozoites become sexual gametocytes. The infection causes shivering and persistent fever. These gametocytes are primarily responsible for transmission of the parasite from the infected human to the vector mosquito (Bousema and Drakeley). Presently Artemisinin is one of the most widely used drugs to treat Plasmodium falciparum infections such as malaria which helps in prevention of spread of malaria. However recent studies have shown that some mutants of P.falciparum have developed resistance to the drug especially along the Thailand-Cambodia border (Witkowski et al,2010).
Miotto et al conducted an experiment to understand the pattern of genome variation in the parasites. The genome of the parasite has been already sequenced. The genome is a23 megabase genome with 14 chromosomes that code for 5,300 genes. Most of these genes are involved in the regulation of host-parasite interaction (Gardner et al, 2002). Previous studies have already established that higher rates of inbreeding and greater population structure occurred in regions where transmission of the pathogen was less (Anderson et al,2000).The researchers obtained blood samples from 825 patients infected with the parasite in the regions of Cambodia, Ghana, Mali, The Gambia, Thailand, Vietnam and Burkina Faso. The population structure of the genomes of the parasites obtained from different regions was analyzed and neighbour-joining trees were constructed. The result of this showed that African and Vietnamese samples of the parasites showed higher similarity than samples from Thailand. However, western Cambodia parasites showed higher genetic variations which meant that within the population of parasites in Cambodia, sub-population also existed. The different sub-populations were identified using chromosomal painting-KH1, KH2, KH3 and KH4.genetic studies showed that the genetic difference between KH2, KH3 and KH4 were primarily because of Founder’s effect and therefore showed lesser haplotype diversity as obtained from allele frequency analysis. Next the researchers investigated the efficacy of the anti-malarial drug on all the 4 kinds of sub-population of the parasite. The results highlighted the fact that the parasite had the capability to develop resistance against the drug through evolution. The study showed that in high genetic variation of the parasite existed in Cambodian regions. The researchers inferred that the drug exerted a pressure on the genetic makeup of the parasite which induced mutation in the genome. This led to production of parasites that differed genotypically. Sexual recombination of genotypes that show resistance produces offsprings who show greater resistance with more biological fitness. Therefore the study established that in Cambodia the emergence of drug-resistant parasite was a result of out-crossing of resistant strains and maintenance of the particular combination of alleles.
The study focussed on the genetic evolution of the parasite P.falciparum. Cambodia is known to be hot-spot for development of anti-malarial drug resistance and this study helps in understanding how exactly genetic mutations taking place within the parasite increase chances of development of resistance. This study helps in understanding the genetic evolutionary pattern of the parasite and hence is important to design management strategies to control multiple forms of resistance. The study would also help in generating genetic markers which may be used for characterization and distribution of the sub-populations of the parasites. Moreover, the study would help in understanding the disease pathology of mutant strains and derive anti-malarial drugs that will effective on the mutants as well.
Reference
Anderson TJ, et al.(2000). Microsatellite markers reveal a spectrum of population structures
in the malaria parasite Plasmodium falciparum. Mol Biol Evol.17:1467–82
Bousema,T., and Drakeley,G.(2011). Epidemiology and Infectivity of Plasmodium
falciparum andPlasmodium vivax Gametocytes in Relation to Malaria Control and Elimination. Clinical microbiology reviews, 24 (2), 377-410.
Gardner,M.J., et al.(2002). Genome sequence of the human malaria parasite Plasmodium
falciparum. Nature, ;419(6906):498-511
Miotto,O. et al. (2013). Multiple populations of artemisinin-resistant Plasmodium
falciparum in Cambodia.Nature Genetics, 45 (6),648-655. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3807790/.
Witkowski, B. Et al.(2000).Increased Tolerance to Artemisinin in Plasmodium falciparum Is
Mediated by a Quiescence Mechanism. Antibacterial Agents and Chemotherapy, 54 (5), 1872-1875. Read More