Vaccines And The Eradication Of Malaria

Malaria has been a major life-threatening disease for thousands of years, and continues to threaten millions of lives around the world. It infects approximately 219 million people each year, mostly poor women and children. What is striking about malaria is the fact that it has the worse effect on those with the least ability to fight the disease. The Republic of Cuba believes that malaria prevention, treatment, and research efforts must be accelerated to eliminate the burden of this disease across Africa, Asia, the Americas, and any country or territory at risk of malaria transmissions.

The illness associated with the malaria parasite was first thought to be a result of poisonous mists drifting from marshes hence its name meaning “bad air” in Italian. Of course it was unbeknownst back then that it was actually caused by the female anopheles mosquito which tends to live near still water such as marshes.2 Although it was unknown what actually caused the symptoms of malaria,

Between 1998-2004, the malaria cases in Panama quadrupled. And globally, the malaria death toll has grown inescapably since 1981. In 1995, Europe suffered 90,000 cases of malaria. Today, eight times more malaria patients arrive at the clinics and hospitals across Europe than they did in the 1970’s. Mosquitoes infect between 250 million and 500 million people with malaria every year and close to 1 million perish. Human beings have suffered the disease for more than 500,000 years. This plague is very deadly.

Malaria. Our 130 million year old enemy. Malaria has been around since the dawn of time and just like the evolution of humans, the disease evolved over time (Malaria.com, 2011). Malaria is a life-threatening disease caused by a specific parasite called Plasmodium, and it is transmitted to people through the bites of an infected female Anopheles mosquito. Plasmodium is a unique parasite because of its structure-it is a single celled organism that multiples in our red blood cells (Canada.com, 2016). The Plasmodium parasite has 4 species which are known to cause the disease in humans, these being: P. Vivax, P. Falciparum, P. Ovale, and P. Malariae. Specifically, P. Vivax, and P. Falciparum are the 2 most common types of parasites to cause the

Plasmodium falciparium belongs to the family Plasmodidae and is one of four different Plasmodium species that infect humans (7). Plasmodium species are obligate intracellular parasitic protozoa that are unicellular, eukaryotic and chemoheterotrophic and as a result, need a host for nutrition and reproduction (5). Plasmodium falciparium along with Plasmodium malariae, Plasmodium ovale and Plasmodium vivax are usually seen as human parasites (10). P. falciparium is one of the two protozoan parasites that is responsible for most cases of malaria, the other being Plasmodium vivax (6). P. falciparium is usually found in the tropics and subtropics but has also spread to temperate zones (11). Blood smears are usually used to differentiate between the four species because at the blood stage, they tend to modify the host erythrocyte differently and exhibit differences in their morphology (6, 7). P. falciparium is usually characterized with young rings in the absence of mature rings and schizonts (9). These ring stages tend to be slightly smaller and more numerous than those of the other species. Other distinguishable characteristics of P. falciparum are its high level of parasitemia and its banana shaped gametocytes (7). The genome size of P. falciparum ranges between 1x107 and 4x108 base pairs and its cell cycle takes place in two stages: asexual and sexual (10).

Malaria, a mosquito-borne infectious disease of humans, is a global burden which is commonly seen in sub-Saharan Africa and South- East Asian regions. It affects people living in the malaria-prone areas and lower socio-economic statuses. However, children under 5 years old are particularly susceptible to malarial illness and its complications. In 2015, an estimated rate of 438,000 mortality rates was reported due to malaria.3 Thus, the recent rise in malarial disease is a global concern that needs to be addressed. More effective vector control methods and increase availability of anti-malarial drugs for malaria- prone regions must be implemented.

There are currently five distinct protozoan vertebrate Plasmodium species identified as causal agents of malaria in humans: P. falciparum, P. vivax, P. ovalae, P. malariae, and P. knowlesi, with the most common, P. falciparum, accounting for approximately seventy percent of all cases. The female Anopheles gambiae is a vector for all plasmodia of malaria, as observed by Ronald Ross in 1897 (Nobel Media, 2014) , and acquires the Plasmodium by feeding on the blood of an already infected human. Subsequently, the Plasmodium multiplies, and migrates from the midgut of the insect to the oesophagus, ready to be regurgitated into the bloodstream when the mosquito obtains a blood meal from a human (NIH, 2017) . Ultimately, once inoculated by the

Most of us have heard of the disease Malaria and are familiar with the fact that it is transmitted by mosquitos. We also all know that it occurs mainly in third-world, poverty-stricken areas, such as Africa and South America. However, there is a great deal of microbiology behind these deadly, microscopic diseases that makes them particularly fascinating and opens the reader’s eyes and to just how complex these organisms can be, as well as the havoc they can wreak on one’s internal body systems. Malaria infects an estimated 219 million people a year, while it claims about 660,000

The main mode of transmission is when a mosquito bites an infected person and bites an un-infected person next; the un-infected person will also get it. The people most capable of getting the disease include young children who have not yet developed a good immune system, pregnant women and travellers going from healthy communities to areas where malaria is common. What are/were the etiological factors? Different organisms have different modes of nutrition and the mode that parasites use is that they benefit on the expense of the host. Malaria gets spread when people travel to and from areas where many people are infected with the disease. An etiological factor of Malaria includes the lack of access to health care and poverty because people who get infected and are poor are not able to afford treatment and are more likely to be causes for the spread of the disease(Worrall E, Basu S, Hanson K. (2005)). Another etiological factor is that people who travel to places where malaria is wide spread and travel back to their healthy home country; they can play a part in spreading the disease across the different countries as well(Houston S. Houston A. (2015)). Although this is not a factor of the acquisition of the disease, it plays a major role in its spread.

As discussed, because the malaria parasite is not a virus or bacterium, it differs quite a bit from regular pathogens. Thus, explanation is needed about the complex morphology of this organism. Depending on the developmental stage and species, malaria parasites can be spherical, ring-shaped, elongated, or crescent shaped, and can range of 1-20 microns in diameter (Desowitz 89). Because P. falciparum is the most common and deadly species in the genus, it is highly emphasized in research as it will be discussed exclusively in this paper. Falciparum has several important

Effective malaria treatment is fraught with challenges. Resistance is seemingly around the corner for every previously superlative drug, while being deeply entrenched among those medications that a few decades ago were vital to chemotherapy. For artemisinin, the first signs of resistance were observed in a 2008 study of parasite clearance times following monotherapy with artesunate. Clearance was slower among patients from the Eastern Thai-Cambodian border than that of patients from the Thai-Myanmar border to the West (Dondorp et al., 2009). Though an alarming fact on its own, when coupled with the proportional increase of such slow-clearing infections from 0.6% in 2001 to 20% in 2010 with rates approaching 42% in Cambodia one must conclude that there is cause for alarm (Flannery et al., 2013). Resistance is not only emerging but also spreading.

Infectious diseases are the leading cause of death all over the world [1]. Malaria, also called plasmodium infection, is one of the most important human infectious diseases threatening the lives of millions of people every year. According to WHO malaria report, globally, an estimated 3.2 billion people in 97 countries and territories are at risk of being infected with malaria and developing disease, and 1.2 billion are at high risk [2]. Although the disease has been eradicated in most areas, it’s still widespread in some regions [2]. The biggest challenges in controlling malaria disease are the emergence of anti-malarial drug resistance and insecticide resistance in parasite and mosquito, respectively [3-5]. Therefore, there is an urgent need to develop novel intervention strategies such as vaccines to reduce the burden of malaria morbidity and mortality. Malaria is commonly associated with poverty and has a major negative effect on economic development [6]. Oral vaccines offer exciting possibilities for reducing the burden of diseases especially in developing regions of the world. Oral vaccines are inexpensive, easily administered (needle-free) and capable of being stored and transported without refrigeration [7]. In contrast to injected vaccines, oral vaccines are mucosal-targeted, which cause stimulation of systemic as well as mucosal

There are four species in the Plasmodium Genus that affect humans: P. falciparum, P. vivax, P. ovale, and P. malariae. What people did not know then, was how the protozoan got from

becoming resistant to insecticides and so again we must look to a vaccine as a

Natural immunity against asexual stage parasites develops with repetitive exposure to malaria parasites and thus forms the basis of clinical immunity against malaria (Baird, Jones et al. 1991, Day and Marsh 1991, Trape, Rogier et al. 1994, Baird 1995, Baird 1998, Hviid 2005). Though clinical immunity to malaria has been shown to develop in individuals, it does not prevent reinfection due to several factors including the complex life-cycle of the parasite and insufficiency of the magnitude of effective antibodies. Susceptibility to P. falciparum was shown to be independent of the number of years of exposure to the parasite, and age-dependent protective immunity developed over a two-year period of repeated