Malaria (Plasmodium Infection)
Malaria is
a disease caused by a plasmodium parasite, transmitted by the bite of
infected mosquitoes. Malaria is also called plasmodium infection and it is
preventable and curable.
Malaria in Human is
caused by four distinct species of malaria parasite-
1. Plasmodium vivax
2. Plasmodium falciparum
3. Plasmodium malariae
4. Plasmodium ovale
Malaria is a disease caused by Plasmodium parasites that are transmitted to people
through the bites of infected female Anopheles mosquitoes.
Plasmodium vivax and Plasmodium falciparum
has the widest geographic distribution throughout the world.
1. Urban malaria – Anopheles stephensi is a
primary mosquito vector of malaria in urban India.
2. Rural malaria- Anopheles culicifacies is widely distributed transmission in
india.
3. Tribal malaria- General vector involved in transmission is Plasmodium falciparum.
Note - Don’t confuse with Filariasis disease. Filariasis is a parasitic disease caused by filarial worms, spread by infected mosquitoes.
Epidemiological Triad
Agent – Malaria is caused by four distinct
species;
1. Plasmodium vivax
2. Plasmodium falciparum
3. Plasmodium malariae
4. Plasmodium ovale
In india 70% of cases
occur due to plasmodium vivax.
Host - Malaria affect all ages and affect both
sexes. Children under age of 5 years are the most vulnerable group
affected by malaria.
Pregnant women are risk
Humans are their only
relevant reservoir for malaria
Environment- Rainfall, wind, temperature; optimal temperature in the insect vector required for the development of parasites is 20°C to 30°C,
Humidity, Irrigation channels, Garden pools, Stagnant water in coolers
Mode of Transmission
Malaria is caused
by protozoan parasites Plasmodium. The parasites are spread to human through
the bites of infected female Anopheles mosquitoes, called "malaria vectors’.
The parasites are spread
to human through the bites of infected female Anopheles mosquitoes. Transmission occurs from
infected person to healthy person by vector transmission (Anopheles mosquito).
1. Mosquito
to Man
2. Man
to Mosquito to Man
Malaria is transmitted by blood, so it can also be transmitted
through-
1. Direct transmission
a. Blood transfusion
b. Organ transplant
C. Needlestick injury
D. Sharing of needles of
infected drug addicts
2. Congenital - Infected mother to new born
Exposure
to malaria during pregnancy may result in fatal.
Malaria can be transmitted from a infected
mother to her unborn infant before or during delivery (congenital malaria).
If parasites are transmitted
pass the placenta that could be result in
congenital malaria. Plasmodium falciparum
was the only main parasite species that present in the
umbilical cord blood.
Incubation period
The incubation period of
-
1. Plasmodium vivax –
8-17 days
2. Plasmodium falciparum
– 9-14 days
3. Plasmodium malariae –
18-40 days
4. Plasmodium ovale –
16-18 days
Pathophysiology of
1. Human gets bite from
an infected Mosquito
2. Parasite start
reproducing in the liver and some parasites remaining dormant for years before
becoming activated
3. In the bloodstream
further reproduction occurs within red blood cell (erythrocytes)
4. Parasite reproduction
result in further red blood cell infection
5. Cycle of red blood
cell infection and destruction
6. Occurs fever and
chills
The
life cycle of Plasmodium species divided into two distinct phases-
1.
The asexual cycle in humans and
2.
The sexual cycle in mosquitoes
1. Female mosquito
anopleles bite an infected person and gametocytes are ingested.
2. Inside the mosquito
body, sexual cycle occurs led to the development of parasite from gametocyte to
sporozoite stage in 10-20 days under favourable condition.
3. When this infected
mosquito bites a person, injects sporozoits.
4. Asexual cycle in
humans Sporozoites turn into
merozoites
5. Man is the reservior
of agent of malaria
Man - Intermediate host
Mosquito - Definitive host
Sporozoites are
infective form, it present in the salivary of female anopheles mosquito
After bite of infected
mosquito sporozoites are introduced into blood circulation.
Clinical Manifestation
Malaria is an acute
febrile illness. In individuals, symptoms usually appear 10–15 days after the
infective mosquito bite.
1. Fever with
chills, rigors
2. Headache
3. Vomiting
4. Nausea
5. Tachycardia
6. Tachypnea
7. Sweating
Children with severe
malaria frequently develop one or more of the symptoms-
1. Severe anaemia
(Caused by haemolysis)
2. Respiratory distress
3. Hepatosplenomegaly
4. Cerebral
malaria - Most severe neurological complication due to
infection with Plasmodium falciparum malaria.
5. Congenital malaria
Attack of Malaria Stages
Paroxysmal attack of
Malarial found in Three Stages, with clinical manifestations are -
1. Cold Stage
2. Hot Stage
3. Sweating Stage
1. Cold Stage
Headache, nausea,
chills, fever rise rapidly, vomiting, tachycardia,
2. Hot Stage
Feel burning hot, Skin
hot and dry, Tachypnea
3. Sweating Stage
Temperature decreases
with Sweating, Skin cool and moist
Complications of Malaria
1. Cerebral malaria -
coma, altered mental status, or multiple fits (seizures) or coma (convulsion)
2. Liver failure and
jaundice – yellowing of skin and whites of eyes
3. Shock – a sudden drop
in blood pressure
4. Pulmonary oedema – a
build-up of fluid in the lungs
5. Acute respiratory
distress syndrome - associated with severe P. falciparum malaria
Malaria in Pregnancy
If infected malaria
while pregnant, get an increased risk of developing serious complications, such
as-
1. Premature birth –
birth before 37 weeks of pregnancy
2. Low birth weight
3. Restricted growth of
the baby in the womb
4. Stillbirth -
when a baby is born dead after 24 completed weeks of pregnancy
5. Miscarriage
Laboratory Diagnosis
1. Malaria Blood Smear -
checked for malaria parasite. Two types of blood films are prepared-
a. Thin film
b. Thick film
2. Serology test
3.
Polymerase chain reaction (PCR)
4.
Malaria drug resistance test
5. The peripheral smear
6. Bone marrow smear
7. CBC complete blood count test; including red blood cells (RBCs), white blood cells
(WBCs), and platelets (PLTs),
TC (total count; measures the number of white blood cells)
DC (blood differential test; detect
abnormal or immature cells)
Treatment - Antimalarial Drugs
Antimalarial
drugs can also be used to prevent malaria disease.
The treatment of a
suspected and clinical case of malaria according to drug policy for malaria
under National- malarial programme is presumptive treatment
and radical treatment.
Presumptive therapy - only given to febrile
patients. Presumptive treatment of all suspected malaria.
Radical treatment - Extensive or complete therapy
individuals with confirmed either Plasmodium vivax or Plasmodium ovale.
To
elimination of dormant liver stage parasites (hypnozoites) found in Plasmodium
vivax and Plasmodium ovale.
Prevention and Control
1. Early diagnosis and Treatment
2. Chemoprophylaxis - Take recommended
antimalarial drugs to prevent acute malaria attacks. For travelers, malaria can be prevented through
chemoprophylaxis, which suppresses the blood stage of malaria infections and
preventing malaria disease.
3. Mass drug
administration - Administration of
antimalarial treatment to every person living in a defined geographical area.
4. Mosquito control
measures – Malarial Vector control is the main way to prevent and
reduce malaria transmission with effective malaria vector control.
a. Anti-larval measure
b. Anti-adult measures
5. Protection against
mosquito
6. Reduction of mosquito
breeding
7. Anti-malarial
programme
Vaccines Against Malaria
Malaria vaccine is
a vaccine, used to prevent malaria.
Only approved vaccine is RTS,S/AS01
(Mosquirix) – It acts against Plasmodium falciparum. It defend against the first stages when
the Plasmodium falciparum malaria parasite enters the human host's bloodstream
through a mosquito bite and infects liver cells.
Antimalarial Drug Resistance
Antimalarial drug resistance is the ability of
a strain of parasite to survive and/or to multiply despite the
administration and absorption of medicine is given in doses equal to or higher
than those usually recommended.
Resistance of malaria parasites
arises from various factors-
1. Overuse of
antimalarial drugs for prophylaxis
2. Inadequate or incomplete
therapeutic treatments of active infections
3. Resulted from a high level
of parasite adaptability at the genetic and metabolic levels.
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