INFECTIOUS DISEASE

1. MALARIA

2. MALARIA - INTRODUCTION
Malaria is a vector born disease caused by a single celled protozoan
parasite called plasmodium ,transmitted by female mosquitoes.
Malaria is one of the major public health problems of the country
It is one of the world’s biggest killers. It infects upto 250 million
people and kills nearly 800,000 people per year.

3. HISTORY
Malaria is an ancient disease and was first appeared in
6000BC.
Missionaries in peru in early 1600s discovered that powdered
bark of chinchona tree could be successfully used to treat
malaria.
In 1880, Louis alphonse laveran discovered that malaria was
caused by plasmodium while studying the blood samples from
soldiers with fevers.he was awarded nobel prize in 1907.
In 1898, Ronald ross had not only only worked on the
lifecycle of plasmodium but also proved that female anopheles
mosquito transmitted the malarial parasites. He was awarded
nobel prize in the year 1902.

4. EPIDEMOLOGY
Malaria was successfully eliminated from countries with temperate climates
during mid-20th century using public health measures.
However it is still found throughout the tropics and subtropics of the Africa ,
Asia and South America.
Malaria is a world wide infection that affects 500 million and kills more than 1
million people every year.
People who are at high risk:-
Children – because they have not developed natural immunity to that disease.
Another high risk group is pregnant women because of the natural changes
during pregnancy which make infection more likely. Malaria in pregnancy laed
to premature babies ,low birth weight and low healthy babies.
People who are at reduced risk:-
People with sickle cell anaemia and people who are suceptible to developing
systematic lupus erythematosis.

6. CAUSATIVE ORGANISM AND TYPES OF MALARIA
Malaria in man is caused by 4 distinct species of malarial parasites –plasmodium vivax, P.falciparum,
P.malariae, and P. ovale.
Sl.no Types of malaria Causative agent effect
1 Tertian,benign tertian/vivax malaria P. vivax Common type, here the fever recurs every 3rd
day
2 Quartan malaria P.malariae Feverish fits every 4th day
3 Mild tertian malaria P.ovale Found in west Africa.fever recurs every 3rd day.
4 Malignant tertian or quotidian malaria P.falciparum It has highest death rate.here the blood cell
parasitized and tend to clump and block small
blood vessels and damage essential organs .tis
type is said to be more dangerous type

8. MODE OF TRANSMISSION:-
1) VECTOR TRANSMISSION:-
malaria is transmitted by the bite of certain species of infected female anopheles mosquito. A
single infected vector during her life time may infect several persons. The mosquito is not
infective unless its sporozoites present in its salivary glands.
2) DIRECT TRANSMISSION :-
Malaria may be induced accidentally by transfusion of blood or plasma.the parasites keep their
infectivity atleast for 14 days in the blood bttle stored at -4 C.
3) CONGENITAL MALARIA:-
Infection of newborn from infected mother.

9. SIGNS AND SYMPTOMS
Fever
Headache
Chills and rigors
Myalgia,arthralgia
Anorexia ,nausea and vomiting
The malaria is known to mimic the signs and symptoms of many
common infectious diseases, the other causes should also be suspected
and investigated in presence of the following manifestations.
Running nose , cough, diarrhoea , burning micturition /lower
abdominal pain , skin rash /infections ,painful swelling in joints , ear
discharge , lymphadenopathy.

10. CONDITIONS SEEN IN SEVERE MALARIA
Coma (cerebral malaria)
Metabolic acidosis
Severe anaemia
Hypoglycemia
Acute renal failure
Acute pulmonary edema

11. INCUBATION PERIOD:-
The period of incubation is usually not
less than 10 days.
The duration of incubation varies with the
species of parasites.
With some strains of P.vivax the
incubation period may be delayed for long
as 9 months.this may also occurs in people
who have been taking antimalarial drugs.

12. PATHOGENESIS:-
The lifecycle of plasmodium involves two hosts, the man and the mosquito.
The modes of development in these two hosts are different.
The mode of reproduction
Man is a intermediate host
Mosquito is a definitive host.
In man - asexual
in mosquito - sexual

13. LIFE CYCLE IN MAN:- SCHIZOGONY
Two phases
Preerythrocytic
cycle
/exoerythrocytic
cycle in liver cells
Endo erythrocytic
cycle inside RBC’s

14. Infected female mosquito bites
1000’s of slender
,sickle shaped
sporozites are
injected
enter capillary vessel
and into circulation
Circulate for
30 minutes
Enter the reticuloendothelial
cells of liver
Develop into
cryptozoites
Then feed on liver
cells and develop
into big size
(crypto schizont)
Undergo
Schizogony
and the
resulting
cells are
called as
crypto-
merozoites
Rupture the
liver cells
Enter RBC’s
and fresh liver
cells
This cycle is
considered to be the
period of incubation
During this period
7-17 days parasites
are not seen in the
blood stream
Pre- erythrocytic cycle

15. Erythrocytic cycle
Cryptomerozite enters
the RBC feed on it and
gets a amoeboid shape
Growing stage is
called as
tropozoite
Develops a vacuole and
increases in size so the
nucleus pushed on to
one side and this is
called as signet ring
stage
Vacuoles
disappears
and
ameobula
occupies
entire
schizont
In schizont
nucleus breaks
into 6-24 bits and
is surrounded by
cytoplasm and
this stage is called
as merozoite
Merozoites
rupture the
RBC and
released
with
heamozoin
This causes
malarial fever
The released
merozoites
attack another
RBC and start
new life
cycle.this is
called as
autoinfection
.
After schizogony ,some merozoites
which invade RBC’s instead of
developing into tropozoites and schizonts
develop into gametocytes.the
gametocytes are of two types micro and
macro.their further development takes
place on their entry into stomach of
female anopheles mosquito.

16. LIFE CYCLE IN MOSQUITO-SPOROGONY
When female anopheles mosquito bites an infected
person it sucks blood along with all stages of
parasite .
But in gut only mature gametocytes survive.
Gametocytes develop into gametes and the process
is called as gametogony.

17. Gametogony,syngamy and sporogony
Micro and macrogamete
come into union and
nuclear fusion takes
placeand resultant formed
is the zygote.the kind of
union is called syngamy.
The zygote assumes elongated and move it is called ookinete, pierces stomach wall and lies under the outer layer of
stomach wall , it forms a cyst wall . the stationary zygote with cyst wall is oocyst . this oocyst divides , inside this large
number of cell divides develop into minute, slender sporozoites. this wriggle forward and enter salivary gland of
mosquito, when this infected mosquito bites healthy person it injects sporozoites . this kind of transmission is called as
inoculation.

19. LABORATORY DIAGNOSIS OF MALARIA:-
Laboratory diagnosis of malaria requires the identification of the parasite or its antigens/
products in the patient’s blood.
The requirements of a diagnostic test are specificity, sensitivity, ease of performance and a
reasonable cost.
Current available techniques can be separated in three categories:
Immunological techniques
Molecular techniques
Microscopy

20. THIN AND THICK BLOOD SMEAR:-
Thick and thin blood smear study is the gold standard method for malaria diagnosis. The procedure follows these steps:
collection of peripheral blood, staining of smear with Giemsa stain and examination of red blood cells for malaria parasites
under the microscope.
Thick smear. It is not fixed in methanol; this allows the red blood cells to be hemolyzed, and leukocytes and any malaria
parasites present will be the only detectable elements. However, the hemolysis may lead to distorted plasmodial
morphology making plasmodium species differentiation difficult. Therefore, thick smears are mainly used to detect
infection and to estimate parasitemia.
Thin smear. It is fixed in methanol. Thin smears allow the examiner to identify malaria species, quantify parasitemia, and
recognize parasite forms like schizonts and gametocytes.
MICROSCOPICAL TECHNIQUES

21. Advantages:
It is an inexpensive method
It gives the examiner the opportunity to quantify parasites and differentiate malaria species
Disadvantages:
The diagnostic accuracy depends on quality of blood smear and equipment, abilities of the microscopist,
parasite density and the time spent on reading the smear. All these may result in therapeutic delays.
Not suitable for large- scale epidemiological studies .
False positive. Defective blood film preparation may lead to artifacts that can be incorrectly regarded as
malaria parasites. Sometimes, platelets also confound diagnosis.
False negative. It is associated with low parasite density or low number of fields examined by the
microscopist.

23. QUANTATIVE BUFFY COAT TEST (QBC TEST)
This method involves centrifuged and compressed red blood cell layer stained with acridine
orange and then examinated under an ultra-violet light source. The whole procedure takes place in
a glass hematocrit tube which is precoated internally with acridine orange stain and potassium
oxalate; it is filled with 55-65 μl of blood. The tube is centrifuged and so the components separate
according to their densities forming bands.
Fluorescing parasites are then observed, with a UV microscope, at the red blood cell/white blood
cell interface .
Advantages and disadvantages:-
QBC test is easier and faster than classic peripheral blood smear microscopy but the equipment
required is expensive and species identification and accurate enumeration are impossible.

25. IMMUNOLOGICAL TECHNIQUES
Rapid
diagnostic
tests

26. ANTIBODY BASED TECHNIQUE
INDIRECT FLUORESCENT ANTIBODY TEST:-
The antigen consists of infected blood bound to a 12-spot microscope slide.
A drop of diluted washed infected red blood cells is placed on each spot and allowed to dry. It
is then incubated with the serial dilutions of the test serum, followed by a solution of anti-
human immunoglobulin labeled with fluorescein isothiocyanine which contains Evans blue
as a counterstain. When the slides are dried, they are examined by fluorescence microscopy.
Antibody in the test serum reacts with antigen of parasites.
The disadvantages of this method are the requirement of a fluorescence microscope and the
need for high technichal skills.

27. ENZYME LINKED IMMUNE SORBENT ASSAY
This method uses a soluble malarial antigen coated on the walls of a microtitre plate .
If the test is positive, the antibody binds the antigen resulting in a visible colour change.
When the test is negative, in the absence of antibody, there is no change of colour of the
substrate.

28. ANTIGEN BASED TECHNIQUE
RAPID DIAGNOSTIC TEST:-
 RDT is a device that can detect malaria antigen in a small amount of blood (5μl) by immunochromatographic
assay (colour change in an absorbing nitrocellulose strip) with monoclonal antibodies directed against the parasite
antigen.
 PfHRP2 test strips have 2 lines, one for the control and the other for the PfHRP2 antigen.
 The PfHRP2/PMA test strips and the pLDH (parasite LDH) test strips have 3 lines, 1 for control, and the other
2 for P. falciparum and non-falciparum antigens.
 Change of color on the control line is necessary for the test to be validated. With color change only on the
control line and not in the other lines, the test is regarded as negative.
 In PfHRP2 test, color change on both the lines is interpreted as a positive test for P. falciparum malaria
 With the PfHRP2/PMA and the pLDH tests, color change on the control line and the pan specific line indicates
non-fa1ciparum infection and color change on all the 3 lines indicates the presence of P. falciparum infection

29. Advantages:
Doesn’t require electricity so it can be done on the field distant from microscopy provision
Simple to perform and to interpret with a result given in 15- 30 minutes
Ability for outbreak investigation and screening febrile returnees from endemic areas
Disadvantages:
Low sensitivity in detecting asymptomatic patients particularly in low parasitemias
Cross reactions to autoantibodies (such as rheumatoid factor in case of HRP2 test)

31. MOLECULAR TECHNIQUES:-
POLYMERASE CHAIN REACTION (PCR)
Using PCR amplification, it is possible to detect all 4 species of malaria parasites with a reportedly 10-
fold greater sensitivity than microscopy
Advantages:
High sensitivity and specificity
Detection of mixed species infections and drug- resistant strains
Automation, high speed turnover
Quantitative determination of parasite and species differentiation ability
Disadvantages:
Too sensitive for clinical use
Unsuitable for field conditions
Expensive
Technically demanding

32. CONTROL OF MALARIA:-
Treatment of
infected patient
Prevention of
infection
Control of vector

33. Treatment of infected patient
1.Treatment of uncomplicated malaria:-
Treatment algorithm for malaria:-

34. 2) chemoprophylaxis:-
The chemoprophylaxsis mostly advised for travellers when planning to travel and stay in malaria
endemic zones.
Doxycycline (short term prophylaxis) – 100 mg daily in adults and 1.5mg/kg body weight for children
more than 8 years old. the drug should be started before two days of travel and continued for 4 weeks
after leaving the malarious area.
Mefloquine ( long term prophylaxis) – 5mg/kg of body weight ( upto 250 mg) weekly and should be
administered two weeks before , during, and 4 weeks after leaving that area.
Doxycycline
Mefloquine
Contraindicated in
pregnancy,lactation
Contraindicated in the case
of
convulsions,neuropsychatri
ac problems and cardiac
conditions.

35. PREVENTION AND CONTROL OF INFECTION :-
Use of protective measures such as mosquito nets,anti –mosquito creams, and coils .
It is perfectly clear that if the vector is completely exterminated the infection cannot be transmitted
from one person to another .it is the most effective method of controlling malaria.achieved by using
insecticides and by draining swamps.it destroys the breeding places of mosquito.
Adult mosquito can be controlled by sparying DDT,Malathion or other insecticides in houses.
Fumigating with pyrethrum cresol or other compounds like naphtha.
Sterlisation of male mosquitoes.
Young mosquitoes and larvae can be controlled by introducing larvivorous fishes in the
pond,canals, tanks etc.

37. THANK YOU