Tropical Medicine

Question 1

What is the bacteria behind diptheria?

Answer 1

Corynebacterium diphtheriae

Question 2

What is the pathophysiology of diptheria?

Answer 2

Produces exo-toxin, produced by a β-prophage
Exotoxin inhibits protein synthesis by catalyzing ADP-ribosylation of elongation factor EF-2

Question 3

What are the clinical features of diptheria?

Answer 3

Diptheria membrane on tonsils caused by necrotic mucosal cells.(Pseudomembrane)
Bulky cervical lymphadenopathy
Neuritis
Heart block

Question 4

What are viral haemorrhage fevers?

Answer 4

Dengue fever
Ebola
Lassa fever
Yellow fever

Question 5

What are the features of dengue fever?

Answer 5

Fever
Headache - retrobulbar headache
Myalgia, bone pain and arthralgia (‘break-bone fever’)
Pleuritic pain
Facial flushing (dengue)
Maculopapular rash
Haemorrhagic manifestations e.g. - positive tourniquet test, petechiae, purpura/ecchymosis, epistaxis

Red flags:
- abdominal pain
- hepatomegaly

persistent vomiting
clinical fluid accumulation (ascites, pleural effusion)

Question 6

What causes dengue fever?

Answer 6

Dengue virus is a RNA virus of the genus Flavivirus
Transmitted by the Aedes aegypti mosquito
incubation period of 7 days

Question 7

What are severe haematological features of dengue fever?

Answer 7

Disseminated intravascular coagulation (DIC) resulting in:
thrombocytopenia
spontaneous bleeding
around 20-30% of these patients go on to develop dengue shock syndrome (DSS)

Question 8

How should dengue fever be investigated and managed ?

Answer 8

serology
nucleic acid amplification tests for viral RNA
NS1 antigen test

Typically:
1. lymphopaenia
2. Thrombocytopenia
3. Raised aminotransferases

Question 9

What is leprosy?

Answer 9

Granulomatous disease primarily affecting the peripheral nerves and skin. It is caused by Mycobacterium leprae.

Question 10

What are the features of leprosy?

Answer 10

Patches of hypopigmented skin typically affecting the buttocks, face, and extensor surfaces of limbs
sensory loss

Question 11

What are the types of leprosy, and their course?

Answer 11

Low degree of cell mediated immunity → lepromatous leprosy (‘multibacillary’)
- Extensive skin involvement
- Symmetrical nerve involvement

High degree of cell mediated immunity → tuberculoid leprosy (‘paucibacillary’)
- Limited skin disease
- Asymmetric nerve involvement → hypesthesia
hair loss

Question 12

What is the treatment of leprosy?

Answer 12

Triple therapy: rifampicin, dapsone and clofazimine for 12 months

Question 13

What is shistosomiasis What are the two forms of schistosomiasis?

Answer 13

Schistosomiasis Haematobium
Schistosomiasis Mansoni
Schistosomiasis japonicum

Question 14

What are the features of an active schistosomiasis infection?

Answer 14

Swimmers’ itch
Acute schistosomiasis syndrome (Katayama fever)
- fever
- urticaria/angioedema
- arthralgia/myalgia
- cough
- diarrhoea
- eosinophilia

Question 15

What is the life cycle of schistosomiasis haematobium?

Answer 15

Deposit egg clusters (pseudopapillomas) in the bladder, causing inflammation. The calcification seen on x-ray is actually calcification of the egg clusters, not the bladder itself.

pseudopapillomas in the bladder, they can cause an obstructive uropathy and kidney damage.

Question 16

What are schistosomiasis haematobium at risk of long term?

Answer 16

Squamous cell carcinoma of the bladder

Question 17

How is schistosomiasis haematobium treated?

Answer 17

Single oral dose of praziquantel

Question 18

What is the life cycle of schistosomiasis mansion / japoncium?

Answer 18

Worms mature in liver - hepatosplenomegally/ splenomegaly due to portal system obstruction
Then inhabit the distal colon

Question 19

What is the life cycle of schistosomiasis mansion / japoncium?

Answer 19

Worms mature in liver - hepatosplenomegally/ splenomegaly due to portal system obstruction
Then inhabit the distal colon

Question 20

What are schistosomiasis mansion / japoncium at risk of long term?

Answer 20

Liver cirrhosis
Variceal disease
Cor Pulmonale

Question 21

What bacteria causes botulism?

Answer 21

Clostridium botulinum

Question 22

How does botulinum toxin work?

Answer 22

It is a neurotoxin: irreversibly blocks the release of acetylcholine

Question 23

How can a patient get botulism?

Answer 23

Eating contaminated food

Question 24

What are the features of clostridium botulism?

Answer 24

Patient usually fully conscious with no sensory Disturbance
Flaccid paralysis
Diplopia
Ataxia
Bulbar palsy

Question 25

How is botulism treated?

Answer 25

Botulism antitoxin

Question 26

What is meloidosis / whitmore's disease?

Answer 26

Infection caused by the gram-negative bacterium Burkholderia pseudomallei Found in trophic and subtropic regions Endemic in soil and fresh surface water Sign: Incubation period: 1-21 days ( mean around 9 days)

Question 27

What is the treatment of meloidosis / whoitmore's disease?

Answer 27

Initial intensive therapy: IV ceftazidime, imipenem, or meropenem for 10–14 days Followed by eradication therapy: oral TMP/SMX (plus doxycycline) for 3–6 months Adjunct therapy: abscess drainage.

Question 28

How do you differentiate between zika, chickengunya and dengue?

Answer 28

Zika is prevalent in South America. Chikengunya debilitating joint pain - abrupt onset fevers

Question 29

How is Zika virus spread?

Answer 29

Mosquito

Question 30

Complications of Zika virus?

Answer 30

Guillain barre Microcephally

Question 31

What is leishmaniasis? How is it spread?

Answer 31

An intracellular Protozoa. It is spread by bites from sandflies

Question 32

What are the types of leishmaniasis and where are they acquired?

Answer 32

Cutaneous leishmaniasis: Leishmania tropica or Leishmania mexicana - South and Central America Mucocutaneous leishmaniasis caused by Leishmania braziliensis - India and Africa Visceral leishmaniasis (kala-azar) mostly caused by Leishmania donovani occurs in the Mediterranean, Asia, South America, Africa

Question 33

What are the features of visceral leishmaniasis?

Answer 33

Fever, sweats, rigors Massive splenomegaly. hepatomegaly Poor appetite (increased appetite and weight loss), weight loss Grey skin - 'kala-azar' means black sickness Pancytopaenia secondary to hypersplenism the gold standard for diagnosis is bone marrow or splenic aspirate

Question 34

How is diphtheria treated?

Answer 34

Management intramuscular penicillin diphtheria antitoxin

Question 35

How is diphtheria grown / investigated?

Answer 35

Culture of throat swab: uses tellurite agar or Loeffler's media

Question 36

What is the commonest and most severe type of malaria?

Answer 36

Falciparum malaria

Question 37

What are the features of severe malaria?

Answer 37

Schizonts on a blood film Parasitaemia > 2% Hypoglycaemia Acidosis Temperature > 39 °C Severe anaemia complications as below

Question 38

What are the complications of malaria?

Answer 38

Cerebral malaria: seizures, coma Acute renal failure: blackwater fever, secondary to Intravascular haemolysis, mechanism unknown Acute respiratory distress syndrome (ARDS) Hypoglycaemia Disseminated intravascular coagulation (DIC)

Question 39

What is the treatment of severe malaria?

Answer 39

Intravenous artesunate

Question 40

When is plasma exchange indicated in malaria?

Answer 40

Parasite count > 10%

Question 41

what are the features of yellow fever?

Answer 41

flu-like illness → brief remission→ followed by jaundice and haematemesis. high fever, rigors, nausea & vomiting. Bradycardia may develop

Question 42

features of cholera?

Answer 42

profuse 'rice water' diarrhoea dehydration hypoglycaemia

Question 43

What type of bacteria is vibrio cholera?

Answer 43

Gram negative bacteria

Question 44

Treatment of cholera?

Answer 44

Management oral rehydration therapy antibiotics: doxycycline, ciprofloxacin

Question 45

How is typhoid transmitter?

Answer 45

Faecal oral route

Question 46

What are the features of typhoid?

Answer 46

initially systemic upset as above relative bradycardia abdominal pain, distension constipation: although Salmonella is a recognised cause of diarrhoea, constipation is more common in typhoid rose spots: present on the trunk in 40% of patients, and are more common in paratyphoid

Question 47

What causes typhoid? What causes paratyphoid?

Answer 47

Salmonella typhi and Salmonella paratyphi (types A, B & C)

Question 48

What are the complications of typhoid?

Answer 48

osteomyelitis (especially in sickle cell disease where Salmonella is one of the most common pathogens) GI bleed/perforation meningitis cholecystitis chronic carriage (1%, more likely if adult females)

Question 49

What are the features of katamya fever?

Answer 49

fever urticaria/angioedema - red itchy bumpy rash on ankles / feet arthralgia/myalgia cough diarrhoea eosinophilia

Question 50

What are the features of rabies?

Answer 50

prodrome: headache, fever, agitation hydrophobia: water-provoking muscle spasms hypersalivation Negri bodies: cytoplasmic inclusion bodies found in infected neurons

Question 51

What cytoplasmic inclusions do you see in rabies?

Answer 51

Negri bodies

Question 52

What type of virus is rabies?

Answer 52

RNA rhabdovirus (specifically a lyssavirus) and has a bullet-shaped capsid Travels up the neurone in a retrograde fashion

Question 53

What is the main feature of tetanus?

Answer 53

Opisthontonus - that picture.. you know the one

Question 54

In non-falciparum malaria, what additional treatment is needed to prevent relapses?

Answer 54

Primaquine