Tropical Medicine 2

Question 1

41. Dengue fever

a. is spread by the vector Aedes aegypti
b. has an incubation period of 2-3 weeks
c. is caused by a flavivirus
d. characteristically causes severe myalgia
e. is more likely to cause haemorrhage in patients previously infected by a Dengue virus

Answer 1

True a. is spread by the vector Aedes aegypti
False b. has an incubation period of 2-3 weeks
True c. is caused by a flavivirus
True d. characteristically causes severe myalgia
True e. is more likely to cause haemorrhage in patients previously infected by a Dengue virus

Malaria, then dengue, as most common causes of fever in returning traveller

Incubation period 4 days.

Fever has biphasic “saddleback” picture

Question 2

42. Spastic paraparesis is a recognised complication of infection with

a. Streptococcus pyogenes
b. Polio virus
c. Mycobacterium tuberculosis
d. Taenia saginata
e. Plasmodium vivax

Answer 2

True a. Streptococcus pyogenes
False b. Polio virus
True c. Mycobacterium tuberculosis
False d. Taenia saginata
False e. Plasmodium vivax

Poliomyelitis is an anterior horn cell disease and characteristically causes flaccid paralysis, often of a single limb.

Tuberculosis of the spine (Pott’s disease) is an important cause of spastic paraparesis. Infection usually starts in the intervertebral region involving the discs and extending subdurally to involve the meninges. Paraparesis may result from vertebral collapse or tuberculous arteritis of the spinal arterioles.

Other infective causes of spastic paraparesis: schistosomiasis, cysticercosis and HTLV-1.

Question 3

43. Giardiasis

a. can be diagnosed by duodenal biopsy
b. leaves the small bowel morphologically normal
c. has an incubation period of less than 48 hours
d. causes abdominal distension
e. usually responds to treatment with metronidazole

Answer 3

True a. can be diagnosed by duodenal biopsy
False b. leaves the small bowel morphologically normal
False c. has an incubation period of less than 48 hours
True d. causes abdominal distension
True e. usually responds to treatment with metronidazole

Diagnosis is usually made by finding Giardia lamblia cysts in the stool. Other useful diagnostic techniques include: duodenal biopsy, microscopy of duodenal aspirate and enzyme immunoassay for Giardia antigens in the stool

Question 4

44. The following are correctly paired:

a. Schistosoma haematobium: Biomphalaria ssp
b. Onchocerca volvulus: Culex quinquefasciatus
c. Loa loa: Chrysops dimidiata
d. Borrelia duttoni (relapsing fever): soft tick (Ornithodorus moubata
e. Rickettsia tsutsugamushi: tromboculid mite

Answer 4

False a. Schistosoma haematobium: Biomphalaria ssp
False b. Onchocerca volvulus: Culex quinquefasciatus
True c. Loa loa: Chrysops dimidiata
True d. Borrelia duttoni (relapsing fever): soft tick (Ornithodorus moubata
True e. Rickettsia tsutsugamushi: tromboculid mite

Question 5

45. Enteric fever

a. Bone marrow culture increases diagnostic yield in those previously given antibiotics.
b. is zoonotic
c. is associated with poor sanitation
d. the incubation period is usually 4-6 weeks
e. rose spots occur in typhoid but not paratyphoid fever

Answer 5

True a. Bone marrow culture increases diagnostic yield in those previously given antibiotics.
True b. is zoonotic
False c. is associated with poor sanitation
False d. the incubation period is usually 4-6 weeks
False e. rose spots occur in typhoid but not paratyphoid fever

Rose spots appear on the abdomen and chest in the second week. They are pale red macules 2-4mm in diameter. They may occur in both typhoid and paratyphoid fevers.

Question 6

46. Brucellosis

a. is caused by a Gram positive bacillus
b. causes spondylitis
c. is treated with tetracycline
d. is a recognised cause if chronic depression
e. is contracted from unpasteurised milk

Answer 6

False a. is caused by a Gram positive bacillus
True b. causes spondylitis
True c. is treated with tetracycline
True d. is a recognised cause if chronic depression
True e. is contracted from unpasteurised milk

Question 7

What are late complications of brucella infeciton?

Answer 7

spondylitis
orchitis
arthritis
endocarditis
depression
menigo-encephalitis

Question 8

How to diagnose brucella infection?

Answer 8

blood culture
bone marrow biopsy
brucella antibody test

Question 9

what is treatment of brucella?

Answer 9

Doxycycline plus aminoglycoside 4 weeks

then

Doxycycline plus rifampicin for 8 weeks

Question 10

47. A 35 year old woman presented shocked with a one week history of sore throat and fever. Her blood pressure was 80 mmHg systolic, temperature 39.5C and pulse 130. She was mildly jaundiced and had a macular erythematous rash that blanched on pressure. She was oliguric and had biochemical evidence of renal failure. Her creatine kinase was twice the upper limit of normal. The differential diagnosis includes:

a. myocardial infarction
b. meningococcal septicaemia
c. leptospirosis
d. toxic shock syndrome
e. Rocky Mountain spotted fever

Answer 10

False a. myocardial infarction
True b. meningococcal septicaemia
True c. leptospirosis
True d. toxic shock syndrome
True e. Rocky Mountain spotted fever

Question 11

what symptoms point towards toxic shock syndrome?

Answer 11

The diagnosis of toxic shock syndrome requires five of the following:

1. High fever
2. Hypotension
3. Diffuse macular erythematous rash
4. Multi-system involvement
5. Desquamation (10-14 days after shock)
6. As far as possible, exclusion of other possible diagnoses. Blood cultures are usually negative but may be positive for Staph. aureus.

Question 12

48. traveller’s diarrhoea

a. the single most common causative organism is entero-invasive E. coli
b. has an incubation period of at least 48 hours
c. may be due to Aeromonas ssp.
d. may be due to Cryptosporidium
e. should be treated with antibiotics

Answer 12

False a. the single most common causative organism is entero-invasive E. coli
False b. has an incubation period of at least 48 hours
True c. may be due to Aeromonas ssp.
True d. may be due to Cryptosporidium
True e. should be treated with antibiotics

entero-toxigenic E.coli is most common cause

Question 13

49 The following are recognised features of infective endocarditis

a. erythema marginatum
b. Roth spots
c. proteinuria
d. Osler’s nodes
e. splenomegaly

Answer 13

False a. erythema marginatum
True b. Roth spots
True c. proteinuria
True d. Osler's nodes
True e. splenomegaly

Question 14

50. The following are characteristic features of acute schistosomiasis

a. fever
b. eosinophilia
c. convulsions
d. myocarditis
e. incubation period of 4-6 weeks

Answer 14

True a. fever
True b. eosinophilia
False c. convulsions
False d. myocarditis
True e. incubation period of 4-6 weeks

Acute schistosomiasis is sometimes called Katayama fever. It occurs most often in S.japonicum infections but also S.mansoni and occasionally S.haematobium. Usually it occurs only in previously naive subjects visiting endemic areas and exposed to large numbers of cercariae. It is thought to be an immune complex mediated phenomenon.

Question 15

51. Hepatocellular carcinoma

a. is more common in men than women
b. is radiosensitive
c. is associated with intake of aflotoxin
d. usually presents with weight loss, right hypochondrial pain and hepatomegaly
e. progress of the disease can be monitored by serial measurement of the tumour marker inhibin

Answer 15

True a. is more common in men than women
False b. is radiosensitive
True c. is associated with intake of aflotoxin
True d. usually presents with weight loss, right hypochondrial pain and hepatomegaly
False e. progress of the disease can be monitored by serial measurement of the tumour marker inhibin - AFP is used instead

Question 16

52. The following are recognised associations

a. Hanta virus: haemorrhagic fever with renal syndrome
b. E.coli 0157/H7: haemolytic uraemic syndrome
c. Plasmodium vivax: tropical splenomegaly syndrome
d. HTLV-1: AIDS
e. Chlamydia trachomatis: Fitzhugh Curtis syndrome

Answer 16

True a. Hanta virus: haemorrhagic fever with renal syndrome
True b. E.coli 0157/H7: haemolytic uraemic syndrome
False c. Plasmodium vivax: tropical splenomegaly syndrome
False d. HTLV-1: AIDS
True e. Chlamydia trachomatis: Fitzhugh Curtis syndrome

Fitzhugh Curtis syndrome is chlamydial perihepatitis.

Question 17

53. Effective malaria control interventions include:

a. mass use of Fansidar chemoprophylaxis
b. use of pyrethroid impregnated mosquito nets
c. vaccination with SPf66
d. larviciding
e. eradication of mosquito breeding sites

Answer 17

False a. mass use of Fansidar chemoprophylaxis
True b. use of pyrethroid impregnated mosquito nets
False c. vaccination with SPf66
True d. larviciding
True e. eradication of mosquito breeding sites

Question 18

54. In lepromatous leprosy

a. neuropathy occurs before skin lesions
b. skin lesions are typically anaesthetic
c. skin lesions are typically symmetrical
d. the lepromin test is positive
e. leonine facies occurs

Answer 18

False a. neuropathy occurs before skin lesions
False b. skin lesions are typically anaesthetic
True c. skin lesions are typically symmetrical
False d. the lepromin test is positive
True e. leonine facies occurs

Skin lesions are present before neuropathy develops. The initial skin lesions are small hypopigmented macules which are not anaesthetic. They are multiple and symmetrical. Later papules, nodules and diffuse dermal thickening may occur. In untreated cases the patient may develop the characteristic leonine facies.

Affected nasal cartilage may collapse causing a saddle-nose deformity.

Neuropathy. Peripheral nerve trunks (especially median, ulnar, sural, common peroneal) may be thickened and palsied.

Eyes. The eyes may be affected by iritis or may be traumatised because of seventh nerve palsy or corneal sensitivity.

Question 19

55. The following occur in Chagas’ disease (American trypanosomiasis)

a. lymphadenopathy
b. meningoencephalitis
c. Calabar swelling
d. mega-oesophagus
e. saddle-nose deformity

Answer 19

True a. lymphadenopathy
True b. meningoencephalitis
False c. Calabar swelling
True d. mega-oesophagus
False e. saddle-nose deformity

The acute phase may be asymptomatic. There may be a chagoma at the portal of entry. Hepatoslenomegaly and lymphadenopathy may occur in the acute phase. Some deaths occur as a result of cardiac failure and meningoencephalitis. Trypanosomes may be seen on a blood smear. Blood culture and xenodiagnosis increase diagnostic yield. If the diagnosis is made in this stage, treatment with nifurtimox or benzonidazole may reduce parasite numbers and the incidence of late complications.

The intermediate phase is asymptomatic but there is laboratory evidence of infection.

The chronic phase may occur decades after initial infection. Mega-oesophagus and dilated cardiomyopathy are typical.

Calabar swellings occur in loiasis

Question 20

What diseases are associated with saddle nose deformity?

Answer 20

congenital syphilis
lepromatous leprosy
relapsing polychondritis

Question 21

56. Chloroquine

a. is contraindicated in pregnancy
b. is schizonticidal for P.ovale
c. is the treatment of choice for non-falciparum malaria
d. causes cinchonism
e. inhibits plasmodial haemin polymerase

Answer 21

False a. is contraindicated in pregnancy
True b. is schizonticidal for P.ovale
True c. is the treatment of choice for non-falciparum malaria
False d. causes cinchonism
True e. inhibits plasmodial haemin polymerase

Chloroquine can be used for chemoprophylaxis and for treatment. It can be safely taken by pregnant and lactating women. Chloroquine resistance has been reported in P.vivax in India and parts of South East Asia but it is not widespread and chloroquine remains the treatment of choice for non falciparum malaria. Chloroquine is a 4-aminoquinoline, not a cinchona alkaloid. (Quinine can cause cinchonism - tinnitus, deafness, dizziness, nausea, tremor.)
Haemin is a toxic metabolite of haemoglobin digestion by the parasite. It is detoxified by haemin polymerase to form malarial pigment.
Side effects of chloroquine include dizziness, diplopia and pruritus.

Question 22

57. Blindness is a recognised complication of:

a. leprosy
b. onchocerciasis
c. vitamin A deficiency
d. cysticercosis
e. toxoplasmosis

Answer 22

All true

The leading causes of blindness in the developing world are:
cataracts
trachoma
vitamin A deficiency

In the developed world senile macular degeneration and diabetes are the major causes of sight loss.

Question 23

58. The following may present with fever and diarrhoea

a. malaria
b. Entamoeba coli
c. dengue
d. Campylobacter enteritis
e. brucellosis

Answer 23

True a. malaria
False b. Entamoeba coli
True c. dengue
True d. Campylobacter enteritis
True e. brucellosis

Entamoeba coli is non-pathogenic to man.

Question 24

Which “non-gastrointestinal” infections, can present with fever and diarrhoea?

Answer 24

malaria
dengue
scrub typhus
leptospirosis
brucellosis

Question 25

59. Chicken pox

a. has an incubation period of 3-5 days
b. rash is preceded by Koplic’s spots in the mouth
c. fever settles when the rash appears
d. should be treated by topical acyclovir
e. may follow from close contact with a case of shingles

Answer 25

False a. has an incubation period of 3-5 days
False b. rash is preceded by Koplic’s spots in the mouth
False c. fever settles when the rash appears
False d. should be treated by topical acyclovir
True e. may follow from close contact with a case of shingles

The incubation period is 11-20 days, usually 2 weeks.
Koplic’s spots precede the maculopapular eruption of measles.

The fever generally lasts about a week and settles as the last crop of spots appears.

The use of acyclovir in uncomplicated chicken pox is controversial. Systemic acyclovir should be used in complicated chicken pox, particularly in adults.

Recognised complications of chicken pox include impetigo, pneumonitis, encephalitis and thrombocytopaenia.

Non-immunes can acquire chicken pox from people with either chicken pox or shingles. Shingles occurs when immunity is lowered in a person who has suffered from chicken pox in the past.

Question 26

60. Hepatitis A

a. the virus has double stranded DNA
b. the incubation period is 2-6 weeks
c. the illness is milder in young people
d. is maximally infectious at the peak of jaundice
e. can be prevented by active immunisation

Answer 26

False a. the virus has double stranded DNA
True b. the incubation period is 2-6 weeks
True c. the illness is milder in young people
False d. is maximally infectious at the peak of jaundice
True e. can be prevented by active immunisation

Hepatitis A is a single stranded RNA virus.

In children the illness may be very mild. Clinical jaundice might not occur.

The infectious period is from 2 weeks before the onset of jaundice until 1 week after. The most infectious time is just before onset of jaundice.

Hepatitis A is usually acquired by consumption of faecally contaminated food or water.

Other gastrointestinal pathogens may be acquired from the same source. Many patients recall having had diarrhoea a few weeks before their jaundice and upto 15% have other pathogens isolated from the stool.

Question 27

61 Typical features of tropical splenomegaly syndrome are:

a. very low or absent malarial antibody titres
b. increased serum IgM
c. lymphocytic infiltration of hepatic sinusoids
d. Plasmodium falciparum parasitaemia
e. favourable response to prolonged anti-malarial drug therapy

Answer 27

Typical features of tropical splenomegaly syndrome are:
False a. very low or absent malarial antibody titres
True b. increased serum IgM
True c. lymphocytic infiltration of hepatic sinusoids
False d. Plasmodium falciparum parasitaemia
True e. favourable response to prolonged anti-malarial drug therapy

It is characterised by massive splenomegaly and its geographic distribution mirrors that of malaria. Malarial antibodies are present in high titres but there is no parasitaemia. The basis of treatment is prolonged antimalarial chemoprophylaxis.

Question 28

62. Visceral leishmaniasis is typically caused by

a. L.donovani
b. L.tropica
c. L.chagasi
d. L.major
e. L.infantum

Answer 28

True a. L.donovani
False b. L.tropica
True c. L.chagasi
False d. L.major
True e. L.infantum

L.donovani, L.infantum, and L.chagasi may all cause visceral leishmaniasis but there geographical distribution differs. L.donovani is found in India and sub-Saharan Africa, L.infantum in the Mediterranean and L.chagasi in South and Central America.

L.tropica usually causes cutaneous leishmaniasis but the cause of a small but well documented outbreak of “viscerotropic” leishmaniasis in veterans of Operation Dessert Storm.

L.major causes cutaneous leishmaniasis.

Question 29

63. Concerning HIV infection in pregnancy:

a. pregnancy approximately doubles the rate of progression to AIDS
b. the rate of vertical transmission of HIV is greater than 50%
c. perinatal administration of zidovudine to the mother reduces vertical transmission
d. breast feeding increases vertical transmission.
e. transmission of HIV to the neonate is confirmed if the neonate is HIV antibody positive

Answer 29

False a. pregnancy approximately doubles the rate of progression to AIDS
False b. the rate of vertical transmission of HIV is greater than 50%
True c. perinatal administration of zidovudine to the mother reduces vertical transmission
True d. breast feeding increases vertical transmission.
False e. transmission of HIV to the neonate is confirmed if the neonate is HIV antibody positive

The rate of vertical transmission is about 15-35%. In Europe it is nearer 15% and in Africa nearer 30%.
Zidovudine appears to reduce vertical transmission by 2/3.
Nearly all babies born to HIV antibody positive mothers will get antibody to HIV via transplacental transfer. Only 15-35% of these will also be infected by the virus itself. It follows that detection of HIV antibody in neonates does not necessarily indicate HIV infection. HIV infection can be diagnosed by detection of HIV p24 antigen or detection of HIV antibody at age 18 months.
The rate of vertical transmission is increased by breast feeding and vaginal delivery. It is also increased if the mother has advanced disease.

Question 30

64. Buruli ulcers are characteristically:

a. painful
b. undermined
c. caused by Fusobacterium
d. secondarily infected
e. responsive to penicillin

Answer 30

False a. painful
True b. undermined
False c. caused by Fusobacterium
False d. secondarily infected
False e. responsive to penicillin

The causative organism is Mycobacterium ulcerans.
Treatment is with topical antiseptics and clofazimine or rifampicin.
The mode of spread is unknown.

Question 31

65. Concerning plague:

a. it is caused by Bacillus pestis
b. the main vector is the rat
c. the pneumonic form is more common than the bubonic form
d. fraction I antigen in the bacterial capsular envelope confers anti-phagocytic activity
e. direct person to person spread may occur (i.e. without a vector)

Answer 31

False a. it is caused by Bacillus pestis
False b. the main vector is the rat
False c. the pneumonic form is more common than the bubonic form
True d. fraction I antigen in the bacterial capsular envelope confers anti-phagocytic activity
True e. direct person to person spread may occur (i.e. without a vector)

Plague is caused by Yersinia pestis. The main animal reservoir is the rat but the vector is the rat flea, Xenopsylla cheopis.

Bubonic plague is the more common form. The other forms are pneumonic, septicaemic, and meningeal.

Virulence of Y.pestis depends on V and W antigens whose genes are plasmid mediated. The bacterial cell wall contains a potent lipopolysaccharide endotoxin which may cause Gram negative shock. Exotoxins are also produced.

Cases of plague should be isolated because person to person spread may occur.

Question 32

66. Rabies vaccination

a. should be given annually to dogs in endemic areas
b. may usefully be given many months after exposure
c. Post-exposure vaccination is unnecessary if pre-exposure vaccination has been given
d. Specific rabies immunoglobulin for human use may be prepared from horse serum
e. is unnecessary after cat bites

Answer 32

True a. should be given annually to dogs in endemic areas
True b. may usefully be given many months after exposure
False c. Post-exposure vaccination is unnecessary if pre-exposure vaccination has been given
True d. Specific rabies immunoglobulin for human use may be prepared from horse serum
False e. is unnecessary after cat bite

Pasive immunisation with immunoglobulin derived from horse serum may result in serum sickness. Immunoglobulin derived from human serum also has this problem but to a lesser extent

Question 33

67. In a cholera epidemic

a. cases have copious watery diarrhoea
b. intravenous rehydration therapy has no place
c. the most important public health intervention is the provision of clean water and good sanitation
d. mass chemoprophylaxis with oral tetracycline should be arranged urgently
e. mass vaccination should be undertaken

Answer 33

True a. cases have copious watery diarrhoea
False b. intravenous rehydration therapy has no place
True c. the most important public health intervention is the provision of clean water and good sanitation
False d. mass chemoprophylaxis with oral tetracycline should be arranged urgently
False e. mass vaccination should be undertaken

Antibiotics reduce the duration of diarrhoea from a mean of 1.8 days to a mean of 0.8 days. Stool volume, intravenous fluid requirements and length of hospital stay are reduced by antibiotics. Tetracyclines, chloramphenicol, cotrimoxazole, doxycycline, ampicillin, ciprofloxacin and furazaladone have been used successfully. Treatment of household contacts with 200mg of doxycycline (single dose) is recommended but mass chemoprophylaxis is not

Question 34

68. Epstein-Barr virus is associated with

a. hairy cell leukaemia
b. leiomyosarcoma in young people with AIDS
c. nasopharyngeal carcinoma
d. teratogenesis
e. oral hairy leukoplakia

Answer 34

False a. hairy cell leukaemia
True b. leiomyosarcoma in young people with AIDS
True c. nasopharyngeal carcinoma
False d. teratogenesis
True e. oral hairy leukoplakia

glandular fever
chronic fatigue syndrome
oral hairy leukoplakia (in HIV infected patients)
nasopharyngeal carcinoma
leiomyosarcomas in young people with AIDS
Burkitt’s lymphoma

Question 35

69. Concerning Hydatid disease:

a. Surgical removal of cysts should not be attempted
b. It is caused by dog tapeworm
c. It is usually accompanied by eosinophilia
d. It is treated with albendazole
e. It is best diagnosed by microscopy of fluid obtained from ultrasound guided aspiration of the suspected cyst

Answer 35

False a. Surgical removal of cysts should not be attempted
True b. It is caused by dog tapeworm
False c. It is usually accompanied by eosinophilia
True d. It is treated with albendazole
False e. It is best diagnosed by microscopy of fluid obtained from ultrasound guided aspiration of the suspected cyst

The adult tapeworm’s definitive host is the dog

Question 36

70. Vitamin A (retinol)

a. is found in green leafy vegetables
b. high dose supplementation in pregnancy is teratogenic
c. supplementation reduces mortality from measles
d. supplementation reduces mortality from diarrhoeal disease
e. supplementation reduces mortality from respiratory disease

Answer 36

False a. is found in green leafy vegetables
True b. high dose supplementation in pregnancy is teratogenic
True c. supplementation reduces mortality from measles
True d. supplementation reduces mortality from diarrhoeal disease
False e. supplementation reduces mortality from respiratory disease

Retinol is not found in vegetables. Beta-carotene is found in dark green leafy vegetables, mangoes, papayas, yellow corn, carrot etc. Beta-carotene is a pro-vitamin, converted to vitamin A by enzymes in the gut mucosa

Supplementation is advised in communities where children are malnourished or have borderline nutrition. Many clinicians also advocate supplements of vitamin A (200 000 iu daily per os for 2 days, and repeated after 1 week), at time of diagnosis of measles. Measles causes reduced uptake and increased metabolic requirements. Furthermore, the virus itself may cause eye lesions. Xerophthalmia is rare outside the context of protein energy malnutrition.