Malaria Falciparum: Microbiology, Host Response, Epidemiology and Treatment

This essay discusses the microbiology, host response, epidemiology and treatment of Malaria Falciparum. It covers the life cycle of the Plasmodium parasite, the innate and adaptive immune response of the host, and the global epidemiology of the disease. It also touches on current and future treatments for the disease.

Running head: MALARIA FALCIPARUM
Malaria Falciparum
Name of the Student
Name of the University
Author Note

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Introduction
Malaria is counted as one of the most killer disease in the world and every year a huge
number of people is died due to the outbreak of this disease. It is assumed that. Almost 250
million people in this world has been infected by this disease every year and along with this,
World Health Organization (WHO) also declared that every year 800,000 people die due to the
malaria disease. The number also depict that a child is dying in every 45 seconds by malaria
infection. Malaria is completely a vector-borne disease and the reason behind this disease is a
single-celled protozoan parasite named Plasmodium and the female mosquitoes are the carriers
of this parasites. Five species of the plasmodium family can cause the disease malaria in the
human body. Plasmodium falciparum or P.falciparum is one of the dominant species of this
family which can be a cause for this disease. The disease has a common flu like symptoms that is
headache, vomiting, shivering, fever. However, due to such common symptoms, it is often
observed that, the disease cannot be diagnosed in a proper way. Due to this, WHO recommended
that, before starting the treatment of malaria, all the cases should be judged in a proper way to be
confirm about the disease ( WHO 2018). The disease is mainly transmitted by the female
mosquitoes of certain species of mosquitoes that is anopheles mosquitoes. The female of this
species can transmit malaria disease as they are capable of sucking blood from the human bodies
as they require high levels of protein in their meals due to development of the eggs. They sucks
the human blood as they are attracted to the human body by vision and smell. While sucking the
blood, the mosquitoes transfers their saliva and due to the anti-clotting property of the saliva the
sucked blood is not clotted. After that, the life cycle of the parasites take place inside the human
body. In this essay, the microbiology of the malaria falciparum, the host response against the

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disease, epidemiology of the disease and current and future treatment of the disease are described
under a few points in a brief manner.
Microbiology of the Disease
Malaria is the disease that is caused by the single celled protozoan parasite Plasmodium.
There are five species that can cause the disease and they are Plasmodium falciparum,
Plasmodium vivax, Plasmodium ovale, Plasmodium malaria and Plasmodium knowlesi. Among
the five sub types, the malaria caused by the Plasmodium falciparum, is referred to as malaria
falciparum. The parasite enters the human body by the mosquito bites. When the female
anopheles mosquito bites a human being in order to sucks the blood, the process of infection is
started. When the mosquito bites a human being, the female mosquito transfers its saliva into the
human body. The saliva of the mosquitoes contains a special type of anti-clotting element and as
a result the blood is not clotted (Angchaisuksiri 2014). The Plasmodium parasite in their
complex life style, completes the sexual and asexual reproduction. The sexual reproduction
takes place in the body of the mosquito and on the other hand the, asexual reproduction is
occurred in the red blood cells and liver cells of the human body. The whole life cycle of a
plasmodium life cycle is dependent on two hosts When an infected female anopheles mosquitoes
bite a human being, the sporozoites of the parasites are transferred to the body of the human.
After entering into the blood stream of the human being, they are transferred into the hepatic
cells of the human body within 30 minutes (CDC 2019). The sporozoites survive in the human
body as they are fed on the cells and gradually grow to enter the next stage of their life cycle that
is formation of schizonts. After that, within the 5-8 days, the schizonts goes through the process
of cell cycle and divides in a rapid manner. After the cellular multiplication, thousands of
merozoites are produced. Theses merozoites then invade into the blood stream of the human

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being and in the blood stream they invade the red blood cells of the body. However, during this
time, when the parasite is present in the liver of the human body, the person has no symptoms of
any disease and the person don’t even feel any sickness. Therefore, in the host body, the parasite
is not destroyed by the antibodies of host’s body. After invading the RBC, the merozoites is
converted into trophozoites and finally into the merozoites that may contain up to 32 merozoites.
After the 2-3 days of the rupture of the RBC, the released merozoites from that RBC, comes into
the blood stream of the human body. After that, these the uninfected RBCs are also infected by
those merozoites as they invade new RBCs and the process is again repeated. During the
rupturing of the RBCs, the toxins produced by the merozoites are released and it is assumed that,
this toxins stimulate the immune system of the host and a complex immune response is initiated
in the body of the host. Due to this toxic response, symptoms like fever, sweating can be
observed. The blood stage of the parasite is responsible for the clinical manifestation of the
disease (World Health Organization 2019). The trophozoites are converted into female and male
gametocytes. The male gametocytes are called microgametocytes and on the other hand the
female gametocytes are called macro gametocytes. The sexual stages of the parasites are
continued by the activity of a female mosquitoes during their blood meal. When a female
mosquito sucks blood from an infected person, the merozoites are also transferred into the body
of the mosquito and the converted merozoites then enter the stomach of the mosquito. The
parasites’ life cycle inside the mosquitos’ body is referred to as sporogonic cycle (Chen et al.
2016). In the stomach, the gametocytes form gametes. After the fertilization, the formation of
the zygotes takes place. After 24 hours of the zygote formation, motile ookinetes are formed
from the newly formed zygotes and those ookinetes are burrowed into the wall of the stomach.
After that, ookinetes are transformed into oocysts and each of the oocysts produces 1000

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sporozoites after cell division. The grown oocytes release the sporozoites through the process of
rupture and then the sporozoites make their way towards the salivary gland of the mosquito
(World Health Organization 2019). From the salivary glands the sporozoites enter into a new
human host to perpetuate a new malaria life cycle ( Richie et al. 2015).
Host Response
A host response refers to the defense mechanism against a host that is exogenous in
nature. In case of P. falciparum infection in the human body there are two type of responsive
immunity system. First one is the innate or natural immunity and the second one is the adaptive
or acquired immunity. During the complex life cycle of the malaria parasite, different types of
immune response is produced by the host. The innate immunity refers to the inherent
refractoriness of the host that initially produce a defense mechanism against the malaria
infection. There are a very specific diseases such as sickle cell anaemia, certain type of
thalassemias can produce protection against the malaria disease. In addition, people who carries
homozygte hemoglobin C ,is also protected from the infection (Tewari et al. 2015). The innate of
the host is naturally present in the host’s body and whenever a foreign body, enters in the body,
this immunity is activated inside and it is not dependent on any other previous infection at all. An
acute malarial infection causes an immediate and non-specific immune response that partially
prevents the progression of the disease. However, this defense mechanism is very weak in
nature as it is very non-specific in nature. Primordial cells, Natural killer cells (NK Cells),
intermediate TCR cells and autoantibody producing cells that is B-1 cells are counted as primary
defense producing cells (Gazzinelli et al. 2014). The NK cells are generally present in the bloods,
secondary lymphoid organs and also in non-lymphoid tissues. In investigation, it is observed
that, the NK cells are capable of destroying the falciparum infected erythrocytes in an in vitro

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condition. NK cells can also produce, interferon gama in response to falciparum infection in the
erythrocytes and as result activation of the parasiticidal macrophages take place. This
macrophages are assumed to play a crucial role in lysing the infected erythrocytes in the human
body. Moreover, it is also observed that, these cells take a crucial part in developing adaptive
immunity in the human body in response to an infection. In addition, the production of
proinflammatorry cytokines such as Interleukin 8 (IL-8) is also initiated by the NK cells (Olivier
et al. 2014). It is observed that, the IL-8, is associated with the activation of the other cells that
can provide protection during the malaria infection. Therefore, there are other types of
immunogenic cells that can participate in the protection mechanism against the malaria infection
in the human body and those cells are dendritic cells, macrophages, gamma delta T cells
and NKT cells (Belachew 2018). It is observed in a mouse model that, the NKT cells are
one of the primary inhibitors of liver stage of parasite’s life cycle. Another important
immunogenic cell is the NK 1.1 CD4 murine T cells as they are involved in the regulation of IgG
antibody responses to glycosylphosphatidyl inositol-anchored P. falciparum protein. This
response ultimately causes rapid and specific MHC unrestricted parasite control in the infected
person. Moreover, the activation of CD+4 T cells with the help of mature dendritic cells results
in activation of the macrophages. The activated CD+4 T cells can initiate the process of
phagocytosis of the infected RBCs and small inflammatory molecules is also activated by the
CD+4 T cells (Belachew 2018).
Adaptive immunity against the malaria refers to the protective efficacy against the
specific infection with the help of any vaccination. After the infection of malaria, an individual
generally experiences acute clinical illness along with a very low level of parasitemia. However,
this .low level of infection may cause severe infections. It is observed that, after a couple of

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infection, an anti-disease immunity is formed against the disease as a result clinical symptoms of
the disease is suppressed although, high amount of parasitemia is present in the human body.
Moreover, it is observed that multiple infections can cause development of anti-parasite
immunity in the body (Belachew 2018). The innate immunity in response to malaria response is
associated with the immunity induced by the cytokines are activated by the cells of innate
immunity. Whenever, the parasites enter into the body, it is recognized by the pattern recognition
receptors (PRRs) and those PRRs include CD36 , Toll like receptors ( TLRs), inflammatory
cytokines such as dendritic cells (DCs), interferon- gama (IFN-γ). S these cells are then migrated
to spleen which is the primary site of immune response against plasmodium parasites. The up
regulation of MHC-II molecules, CD86, CD80, CD 40 and adhesion molecules are associated
with the maturation of the DC cells. The production of various cytokines such as IL12 is
associated with the activation of NK cells in order to produce the IFN-γ and the differentiation
process of TH1 cells are also induced by them. The production of NK cells, cytokines cause DC
maturations and increase the clonal expansion of antigen-specific naive CD4+ T cells. IL-2.
However, the cytokine IL10 and Transforming growth factor -β (TGF-β), negatively regulate the
adaptive and innate immunity responses against the disease (Belachew 2018).
Epidemiology
According to WHO, in every year, a huge number of people are suffering from the
P.falciparum infection and as a result, a significant number of deaths are also contributed by this
infection among the people of various region of the world. As per the report of WHO, in
AFR200 region almost 99.7% cases of malaria infection due to falciparum infection has been
reported. In SEAR region the amount is 62.8%, in EMR region 69.0%, in WPR region 71.9%
and in AMR region 25.9% falciparum infection cases were reported. It is reported by WHO that,

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almost 80% of malaria cases were reported in the African countries and India. Among the total
cases of malaria, 25% is reported from Nigeria, 11% is reported from the Republic of Congo and
4% is reported from India. Among the total 87 countries, that had indigenous malaria cases in
2017, 20 countries had faced almost 20 % rise in the reported cases in comparison with the
previous year. The countries which faced a rise in the malaria cases are Batswana, Namibia,
South Africa and Zimbabwe, Costa Rica, Mexico, Brazil, Bolivarian Republic, Cambodia and
Solomon Islands. In 2017, there are a few countries which reported more than 300,000 cases and
they are Nigeria, Mali, Niger, Venezuela, Senegal, Madagascar (World Health Organization
2018). However, in this same time period, a few countries such as India, Ethiopia, Rwanda,
Pakistan has reported reduction in the malaria infection cases. Only in India, 24% reduction was
observed. Although, in few African countries, the number of reported cases increase, the overall
prevalence rate in the world decreases in between 2010 to 2017 (World Health Organization
2018). The incidence rate was 72 in 2010 and it became 59 in 2017. In between, 2010 to 2017,
the malaria related deaths are declined to 435000 from 607000 cases in the world. According to
the estimation of death cases were reduced by 2017 in comparison with the death cases in 2010.
In cases of children, it is estimated that, 61% of death cases are child’s death. However, 93% of
all deaths are reported in the WHO African region in 2017 among the all deaths in the world.
Among the all the deaths in the world, almost 80% cases are from the WHO African region and
India. It was also reported that, among all the death cases in Africa region of WHO, almost 53%
was associated with Nigeria, Sierra Leone, Niger, Republic of the Congo, Burkina Faso, United
Republic of Tanzania and India. Among the total 80% malaria deaths in the world, Nigeria holds
the first position in this list by contributing almost 19% death cases related to malaria (World
Health Organization 2018).

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Disease
There are various complications that are induced by the P. falciparum infection in the
human body. One of the most complicated diseases that is induced by the P.falciparum infection,
is the cerebral malaria and it is also defined as coma (Storm and Craig 2014). This situation is
related with the altered mental status of the patients. In some cases it is also observed that
multiple seizures can also happen due to P.falciparum infection. Therefore, cerebral malaria is
the most dangerous situations that is associated with P.falciparum infection as most of the deaths
occur due to this condition. Seizures is another major complications associated with the malaria
infections. Almost 30% cases of renal failure is observed due to the P.falciparum infection.
Noncardiogenic pulmonary edema is mainly associated with pregnant woman who are infected
with the parasites and that causes almost 80 % of death cases. Another serious complication that
is associated with the P.falciparum parasite infection is the blackwater fever or Hemoglobinuria.
In this disease, dark urine, hemolysis, hemozoinuria, hemoglobinemia are observed as symptoms
of this disease (Lon et al. 2014). Moreover in young child and in woman it is often observed that,
profound hypoglycemia is associated with the falciparum infection (Herchline 2018). Therefore,
the signs and symptoms are not at all detectable in case of this disease. In some rare cases,
coagulopathy is also noted after having malaria infection.
Therapy
Therapy of Malaria includes the preventive measures and along with this the required
supplementation can also be given as a part of the treatment of the disease. For the prevention of
this falciparum infection, WHO strongly recommends to control the vectors as it is a vector
borne disease. In addition, chemoprevention that is prevention of infection by busing drugs is
also recommended strongly by the organization. In Sub-saharan Africa region it is ovbserved

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that, the use of intermittent preventive treatment in pregnancy (IPTp) along with
sulfadoxinepyrimethamine (SP) has reduced the malaria related anemia among the woman.
Therefore use of intermittent preventive treatment in infants (IPTi) with SP is also capable of
preventing clinical anemia among the children. It is observed that application of Seasonal
malaria chemoprevention (SMC) with amodiaquine (AQ) plus SP (AQ+SP) has reduced the
cases of clinical malaria among the children who are in the age group of 3-59 months. As per
this report, WHO has recommended SMC for the children who live in areas of highly seasonal
malaria. In addition, mass drug administration is also recommended by WHO for all the age
groups. Therefore, use of mosquito nets are also highly recommended practice for the prevention
of this disease (World Health Organization 2018). As a part of the treatment, the diagnostic
testing such as RDT is recommended. After the test, antimalarial treatment can be started.
Artemisinin-based combination therapies (ACTs) is also used for the treatment of the
P.falciparum infections. In recent time, ACT is the most effective anti- malarial treatment and
the use of the ACT should be based on the severity of the disease. In case of treating a severe
malaria, artesunate should be used through intravenous or intramuscular injections and after that,
a complete 3 day course of ACT treatment should be continued (World Health Organization
2018).
Conclusion
Hence it can be concluded that the Malaria has become one of the most dangerous
diseases in the world. Most of the African countries like Nigeria, Madagascar, and Republic of
Congo has the highest number of prevalence rate and those countries also have the very high
death rate due to this disease in the whole world. Therefore, the Asian country India also has a
higher prevalence rate and death rate due to this disease. Moreover, there are other complications

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that are associated with the malaria parasite infections and that are also a serious area of concern.
WHO recommends various ways of treatment and prevention plan for this disease. Therefore it is
also evident that, by using those treatment measure and preventive measures, the number of
reported cases has also decreased.

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