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GROUP A1(a)
TOPIC 5
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The case
A 23 year old woman recently returned from a 3
week holiday in Cambodia presents with
sudden onset of fever, intense headache and
abdominal pain. She has no respiratory
symptoms.
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Differential Diagnosis
Dengue Fever
Chikungunya
Malaria
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Dengue Fever Dengue is a mosquito-borne infection that causes a severe flu-like illness,
and sometimes a potentially lethal complication called dengue
haemorrhagic fever.
Global incidence of dengue has grown dramatically in recent decades.
About two fifths of the world's population are now at risk.
Dengue is found in tropical and sub-tropical climates worldwide, mostly in
urban and semi-urban areas.
Dengue haemorrhagic fever is a leading cause of serious illness and death
among children in some Asian countries.
There is no specific treatment for dengue, but appropriate medical care
frequently saves the lives of patients with the more serious dengue
haemorrhagic fever.
The only way to prevent dengue virus transmission is to combat the
disease-carrying mosquitoes.
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Chikungunya Chikungunya is a viral disease that is spread by mosquitoes. It causes fever
and severe joint pain. Other symptoms include muscle pain, headache,
nausea, fatigue and rash.
The disease shares some clinical signs with dengue, and can be
misdiagnosed in areas where dengue is common.
There is no cure for the disease. Treatment is focused on relieving thesymptoms.
The proximity of mosquito breeding sites to human habitation is a
significant risk factor for chikungunya.
The disease occurs in Africa, Asia and the Indian subcontinent. In recent
decades mosquito vectors of chikungunya have spread to Europe and theAmericas.
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Diagnosis: Malaria
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There are four types of humanmalaria:
Plasmodium falciparumPlasmodium vivax Plasmodium malariaePlasmodium ovale
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Aetiology and Pathogenesis
Malaria is caused by a parasite called
Plasmodium, which is transmitted via the bites
of infected mosquitoes.
In the human body, the parasites multiply in
the liver, and then infect red blood cells
- WHO
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epidemiology
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* estimated that about 300-500 million clinicalcases of malaria occur each year.
* ~ 2.5 million die from malaria each year
* usually a 'rainy season disease'; coinciding withincreased mosquito abundance.
*endemic in some 90 countries in Africa, Asia, Oceaniaand South America.
*majority in children under 5 years old; pregnant
women are also especially vulnerable.
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Signs & symptoms
CHILLS & RIGORS FEVER. schizont rupture and release of
merozoites.
HEADACHE MYALGIA
MALAISE
ABDOMINAL PAIN
SPLENOMEGALY
ANAEMIA
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SEVERE MALARIACerebral malaria
Renal ( haemoglobinuria -->black water fever),oliguria
Blood (Severe anaemia, DIC, spontaneous bleeding)
Respiration (pulmonary edema, ARDS)
Metabolic (hypoglycaemia, metabolic acidosis)
Gastrointestinal (diarrhoea, jaundice, splenicrupture)
Other (hyperpyrexia, shock)
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Factors that Determine The
Occurrence of Malaria
Climate
AnophelesMosquitoes
Humans
Parasites
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DIAGNOSIS
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LIGHT MICROSCOPY (detection of
Giemsa-stained blood smears by light
microscope)
1. thin smears identification of species
stage of circulating parasite
measurement of parasite density
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P. Falciparum thin delicate rings that may be
postioned against the inner surface of the red
cell membrane.Banana shaped gametocyte.
Ring-form trophozoites of
P. falciparum in a thin blood
smear.
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P. Vivax and P. Ovale have thicker rings, ameboid trophozoites and
schizonts and spherical shaped gametocytes.
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Band form trophozoite of P.
Malariae.
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2. thick smears
Parasite density especially at low levels of
parasitemia
parasites in each thick smear field are counted until 200 white cells
have been observed (assuming an average white blood cell count of
8000/microL)
The total white blood cell is divided by 200 (for example, 8000 divided
by 200 equals 40)
the result is multiplied by the number of parasites, which indicates the
number of parasites per microliter of blood (for example 10 parasitesmultiplied by 40 equals 400 parasites per microL)
The percent parasitemia is 400 divided by 8000 times 100, or 5
percent
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Dye-labeled antibody, specific for target antigen, is present on the lower end of
nitrocellulose strip or in a plastic well provided with the strip. Antibody, also
specific for the target antigen, is bound to the strip in a thin (test) line, and eithe
antibody specific for the labeled antibody, or antigen, is bound at the control line
Rapid Diagnostic Tests
Mode of action of common malaria
RDT format
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Blood and buffer, which have been placed on strip or in the well, are mixed
with labeled antibody and are drawn up strip across the lines of bound
antibody
If antigen is present, some labeled antibody will be trapped on the test line.
Excess-labeled antibody is trapped on the control line.
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target the histidine-rich protein 2 of P. falciparum, a pan-malarial
plasmodium aldolase, and the parasite specific lactate
dehydrogenase
Histidine-rich protein 2 of P. falciparum (PfHRP2)
water soluble protein that is produced by the asexual stages and
gametocytes of P. falciparum
expressed on the red cell membrane surface
remain in the blood for at least 28 days after the initiation of
antimalarial therapy
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Plasmodium aldolase
enzyme of the parasite glycolytic pathway expressed by the
blood stages of P. falciparum as well as the non-falciparummalaria parasites
Monoclonal antibodies against Plasmodium aldolase are pan-
specific in their reaction and have been used in a combined
'P.f/P.v' immunochromatographic test that targets the panmalarial antigen (PMA) along with PfHRP2
Parasite lactate dehydrogenase (pLDH)
soluble glycolytic enzyme produced by the asexual and sexual
stages of the live parasites
present in and released from the parasite infected
erythrocytes
found in all 4 human malaria species and different isomers of
pLDH for each of the 4 species exist
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TREATMENT
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Treatment; 2 criteria to be considered«..
Types of species; P.Malariae, P.Vivax,
P.Ovale, P.Falciparum
Pregnancy
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Types of species;For all species (except chloroquine resistant
P.Falciparum); Chloroquine
Treatment of chloroquine resistant P.Falciparum;- In Yunnan >90% resistant & widespread in SE Asia
-drug;mefloquine & Artemisinin
Treatment of drug resistant P.Vivax (chloroquine);Atovaquone
Relapse prevention(P.Vivax & P.Ovale only);
primaquine
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In the case of pregnancy«.
Artemisinin & derivatives can be used in 2nd &3rd trimester
Not recommended for 1st trimester
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PREVENTION
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What to do???
Notifiable Infectious Disease
Inform Public Health
Global Public Health Burden Treat condition promptly
Advise on prevention
Chemoprophylaxis No vaccine
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AVOIDMOSQUITO BITES
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PREVENTIVE MEDICINE
Mefloquine
Some people would rather
taking medicine weekly
For long trip
Can be used in second or
third trimester
Not in mefloquine
resistance
Not in the psychiatricpatient & seizures
Not recommend in patient
with cardiac abnormalities
Not a good choice for lastminute travellers.
4 weeks after travelling.
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Atovaquone/Proguanil (Malarone)
Last Minute travelers.
Daily medicine
For a short trip
Well tolerated
Pediatric tablets are
available.
Pregnant women/Breast
feed
Contraindicated in renalimpairment.
Expensive
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LASTLY!!!!!!!
CREATE AWARENESS =D
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