group a1(a)2

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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