Travel related infection: Malaria

Question 1

Why are travellers vulnerable to infection?

Answer 1

Temptation to take risks away from home regarding food, water, animals, unprotected sex

Different epidemiology of some diseases - HIV, TB, polio, diphtheria

Incomplete understanding of health hazards

Stress of travel can have an effect on immune system

Refugees: deprivation, malnutrition, disease, injury

Question 2

Which infections are common worldwide? (4)

Answer 2

Influenza

Community acquired pneumonia

Meningococcal disease

STI’s

Question 3

Climate or environment related health problems (6)

Answer 3

Sunburn

Heat exhaustion and heatstroke

Fungal infections - warm/moist environments

Bacterial skin infections

Cold injury - extremes of latitude

Altitude sickness

Question 4

What are the 3 main ways public health measures can control infection

Answer 4

Sanitation - travellers’ diarrhoea, Hep A or E, typhoid etc

Immunisation - polio, diphtheria etc

Education - STI’s, HIV

Question 5

Name some arthropod-borne infections

Answer 5

Malaria

Dengue fever

Rickettsial infections like tick typhus

Question 6

Important Tropical Diseases (7)

Answer 6

Malaria
Typhoid
Dengue Fever
Schistosomiasis
Rickettsiosis
Viral haemorrhagic fevers
Zika fever

Question 7

What acts as the vector in malaria transmission?

Answer 7

The female Anopheles mosquito

Question 8

Describe the malaria life cycle

Answer 8

As the mosquito takes its blood meal from the human it injects sporozoites (premature forms of the parasite) into them.

These migrate to the liver and invade the liver cells. They mature here into merozoites which eventually rupture into the circulation and enter RBC’s.

The infected RBC’s that contain the parasite replicate and rupture and invade other RBC’s.

Some of the parasites develop into the male and female form (gametocytes). When the next mosquito comes along and takes a blood meal (>7days) the mosquito takes up some of the RBC’s containing the gametocytes. The M + F gametocytes fuse in the hind gut of this mosquito to form a zygote. The zygote develops there to produce sporozoite – these are then injected during the next blood meal

Question 9

At what point of the life cycle does a person become infected with Malaria how can this be detected?

Answer 9

When the merozoites rupture into the circulation and into the RBC’s.

At this point the patient becomes infected and a malaria diagnosis can be made from blood film.

Question 10

What is the incubation period of Malaria?

Answer 10

at least 7 days

May be 1-4 weeks or it could lie dormant for years

Question 11

What is the most dangerous/severe species of malaria?

Answer 11

Plasmodium falciparum

Question 12

How many species of malaria are there?

Answer 12

5

Question 13

Non-specific symptoms of Malaria (6)

Answer 13

Fever, sweats, rigors
Malaise 
Aching bones
Abdo pain/vomiting
Headache
Myalgia

Question 14

What are some complications of Malaria? (5)

Answer 14

Cerebral malaria (encephalopathy)

Algid malaria - gram -ve sepsis

Blackwater fever - severe intravascular haemolysis - acute renal failure

Pulmonary oedema

Jaundice

Severe anaemia due to haemolysis

Question 15

3 diagnostic tests for malaria

Answer 15

Thick and thin blood films - 3 samples done over 3 consecutive days due to life cycle

Quantitative buffy coat - uses centrifugation + UV microscopy

Rapid antigen tests - detecting evidence of malaria parasites (antigens) in your blood

Question 16

A severe or complicated case of malaria needs one or more of the following symptoms

Answer 16

Impaired consciousness or seizures

Hypoglycaemia

Parasite count ≥2%

Haemoglobin ≤ 8mg/dL

Spontaneous bleeding / Disseminated intravascular coagulation (DIC - small blood clots develop throughout the bloodstream)

Haemoglobinuria due to intravascular haemolysis

Pulmonary oedema or ARDS

Shock

Severe haemolytic anaemia

Question 17

Treatment for uncomplicated malaria caused by P. Falciparum species

Answer 17

Riamet (artemether-lumefantrine) - 3 day course

Question 18

What are some side effects of the drug Quinine

Answer 18

Tinnitus
Nausea
Deafness

Question 19

Treatment options for complicated or severe P. falciparum malaria

Answer 19

IV artesunate - most effective

Patients should be admitted for treatment and monitoring because they can deteriorate quickly. When patient is stable & able to swallow, switch to oral treatments

Question 20

Treatment of the 4 less serious, ‘benign’ species of malaria

Answer 20

chloroquine - 3 day course = most common

Riamet - 3 day course is sometimes used

need to add primaquine if they have p. ovale or p. vivax to inactivate liver forms

Question 21

Why do people with malaria have high fever spikes every 48 hours?

Answer 21

When the merozoites are in the RBCs they reproduce over 48 hours, after which the RBC’s rupture, releasing loads more merozoites into the blood. This causes a haemolytic anaemia (RBC’s are destroyed faster than they can be made)
This causes the fever every 48 hours

Question 22

Signs of malaria (3)

Answer 22

pallor due to anaemia

hepatosplenomegaly

mild jaundice - as bilirubin is released during rupture of RBC’s

Question 23

What type of infection is typhoid?

Answer 23

Salmonella infection