Tropical Medicine Flashcards
What group of microorganisms?
African trypanosomiasis
(sleeping sickness), American trypanosomiasis
(Chagas disease), amoebiasis, babesiosis,
coccidiosis and microsporodiosis,
cryptosporidiosis, giardiasis, leishmaniasis—
cutaneous and visceral (kala-azar), malaria,
toxoplasmosis, trichomonas
Protozoan
What group of microorganisms?
Cysticercosis ( Taenia
solium, T. saginata ), echinococcus (hydatid
disease
Cestodes (tapeworms
What group of microorganisms?
Schistomiasis (bilharziasis),
clonorchiasis, paragonimiasis
Trematodes (flukes):
What group of microorganisms?
Ascariasis, enterobiasis
(pinworm), Dracunculus medinensis (Guinea
worm), filariasis, hookworm, larva migrans
(cutaneous and visceral), strongyloidiasis,
trichinosis ( Trichinella spiralis ), trichuriasis
(whipworm)
HIV
seroconversion infection.Nematodes (roundworms):
Problems in the returned tropical traveller:
Most will present within 2 weeks except ____
HIV
seroconversion infection.
Problems in the returned tropical traveller:
Common infections encountered are
dengue
fever, giardiasis, hepatitis A and B, gonorrhoea
or Chlamydia trachomatis, malaria and helminthic
infestations.
Problems in the returned tropical traveller:
An important non-infection problem requiring
vigilance is _________ and ______________
deep venous thrombosis (DVT) and
thromboembolism.
returned tropical traveller:
What to do in patients with mild diarrhea:
Stool microscopy and culture
• Look for and treat associated helminthic
infestation (e.g. roundworms, hookworms
Etiology of Moderate or prolonged (>3 weeks)
diarrhoea
Usually due to Giardia lamblia, Entamoeba histolytica,
Campylobacter jejuni, Salmonella, Yersinia enterocolitica
or Cryptosporidium
Consider exotic causes such as _______, ______, ______ in unusual
chronic post-travel ‘gastroenteritis
schistosomiasis,
strongyloidiasis and ciguatera
What type of rash:
dengue, HIV, typhus, syphilis, arbovirus infections, leptospirosis, Q fever
• Maculopapular:
What type of rash:
________ viral haemorrhagic fevers,
leptospirosis, dengue
_______: typhoid
_________typhus (tick and scrub), anthrax
_________ African trypanosomiasis, syphilis
- Petechiae:
- Rose spots
- Eschar:
- Chancre:
An Australian study of fever in returned
travellers 3 revealed the most common diagnosis
was
_____ (27%) followed by________ (24%), _______(14%), ________ (8%) and bacterial pneumonia (6%).
malaria
respiratory tract infection
gastroenteritis
dengue fever
The common serious causes of fever are
malaria, typhoid,
hepatitis (especially A and B), dengue fever and
amoebiasis
Most deaths from malaria have occurred after
at least ________ days of symptoms that may be
mild. Death can occur within 24 hours
3 or 4
Be vigilant for ________—can present with a
toxic megacolon, especially if antimotility drugs
are given
amoebiasis
If well but febrile, first-line screening tests:
— full blood examination and ESR
— thick and thin films
Malaria
• Incubation period: P. falciparum _____ days; others
12–40 days
• Most present within 2 months of return
• Can present up to ______
7–14
2 or more years
What needs to be ruled out in patients with malaria?
G6PD deficiency?
How to treat?
P. vivax, P. ovale, P. malariae
(Riamet)
4 tablets with food at 0, 8, 24, 36, 48, 60 hours
(i.e. 24 tablets) in 60 hours
+
primaquine dose by weight to achieve a total dose
of 6 mg/kg. For most people this equals 30 mg (o)
daily for 14–21 days
How to treat?
P. falciparum uncomplicated
Riamet (as above) or quinine sulphate 600 mg (o) 8 hourly, 7 days \+ doxycycline 100 mg (o) 12 hourly, 7 days or clindamycin 300 mg (o) tds, 7 days (children, pregnancy)
How to treat
complicated (severe):
artesunate 2.4 mg/kg IV statim, 12 hours, 24 hours,
then once daily until oral therapy (Riamet) is possible
or
quinine dihydrochloride 20 mg/kg up to 1.4 g IV
(over 4 hours) then after 4-hour gap 7 mg/kg IV 8
hourly until improved (ECG/cardiac monitoring)
then
quinine (o) 7 days
• Insidious onset
• Headache prominent
• Dry cough
• Fever gradually increases in ‘stepladder’ manner
over 4 days or so
• Abdominal pain and constipation (early)
• Diarrhoea (pea soup) and rash—rose spots (late)
• ± splenomegaly
Typhoid fever
How to diagnose Typhoid fever?
- On suspicion—blood and stool culture
* Serology not very helpful
How to Tx Typhoid fever
• Azithromycin l g (o) for 7 days
or
• Ciprofloxacin 500 mg (o) bd for 7–10 days
What is the dx?
• Subclinical
• Mild, uncomplicated episode of diarrhoea
• Fulminant lethal form with severe water and
electrolyte depletion, intense thirst, oliguria,
weakness, sunken eyes and eventually collapse
Cholera
fever + vomiting + abrupt onset
‘rice water’diarrhoea
cholera
Mx of cholera
Treatment
• In hospital with strict barrier nursing
• IV fluid and electrolytes
• Doxycycline
VIRAL HAEMORRHAGIC FEVERS
These include:
yellow fever, Lassa fever etc., dengue
fever and chikungunya
In yellow fever,
Milder cases may present with flu-like symptoms and
relative bradycardia, what sign?
Faget’s sign
Signs and symptoms of yellow fever
abrupt fever then prostration, jaundice and abnormal
bleeding from the gums and possibly haematemesis
These rare but deadly tropical diseases usually
commence with a flu-like illness, gastrointestinal
symptoms with thrombocytopenia, anaemia and,
if severe, findings consistent with disseminated
intravascular coagulation leading to bleeding and
possibly shock and frank haemorrhage
Lassa fever, Ebola virus, Marburg
virus, Hanta virus
Also known as ‘breakbone’ fever, it is widespread in
the south-east Pacific and endemic in Queensland. A
returned traveller with myalgia and fever <39 ° C is
more likely to have dengue than malaria.
Dengue fever
vector of DFS
Mosquito-borne ( Aedes aegyptii ) viral infection
DX:
Abrupt onset fever, malaise, headache, nausea,
pain behind eyes, severe backache, prostration
DFS
DFS, what type of rash?
_____________ →
trunk (hand pressure for 30 seconds causes
blanching
Maculopapular rubelliform rash on limbs
Kind of erythema in DFS
Generalised erythema with ‘islands of sparing’
Diagnosis of DFS
• Dengue-specific IgM serology—best on day 5
• PCR
• FBE: leukopenia; thrombocytopenia in
haemorrhagic form
This is an alpha-viral mosquito-borne infection with
a similar clinical picture to dengue fever; it can cause
haemorrhagic fever. It is encountered in tropical
South-East Asia, Indian Ocean islands and parts of
Africa.
Chikungunya
Dx of Chikungunya
Positive serology
presents with fever, nausea and
vomiting then progressing to stupor, coma and
convulsions.
Encephalitis
Encephalitis:
Mosquito-borne cases include
Japanese
B encephalitis and West Nile fever
the Gram-negative bacillus Burkholderia pseudomallei,
a soil saprophyte that infects humans mainly
by penetrating through skin wounds, especially
abrasions.
Melioidosis
Where is Melioidosis obtained?
It is mostly acquired while wading in rice
paddie
Presentation of Melioidosis
It may manifest as a focal infection
or as septicaemia with abscesses in the lung, kidney,
skin, liver or spleen.
It is called the ‘Vietnamese time
bomb’ because it can present years after the initial
infection, as seen in Vietnamese war veterans
Melioidosis
Fever, headache, cough, pleuritic pain and
generalised myalgia
Melioidosis
Dx of Melioidosis
Blood culture, swabs from focal lesions,
haemagglutination test
Tx of Melioidosis
Treatment (adults) 8 • Ceftazidime 2 g IV, 6 hourly or • Meropenem 1 g IV, 6 hourly or • Imipenem 1 g IV, 6 hourly • All for at least 14 days, followed by oral cotrimoxazole ± doxycycline bd + folic acid for 3 months
Prevention of Melioidosis
Traumatised people with open wounds (especially
diabetics) in endemic areas (tropical South-East
Asia) should be carefully nursed
Plague (Black Death), which is caused by the Gramnegative bacterium _______ , is endemic in parts of Asia, Africa and the Americas
Yersinia pestis
2 forms of plague
bubonic plague and pneumonic plague
painful suppurating inguinal or axillary lymphadenitis (buboes)
bubonic plague
flu-like symptoms
with haemoptysis, septicaemia and a fatal
haemorrhagic illness ( ± buboes
pneumonic plague
Plague:
There is a rapid onset of high fever and prostration
with black patches of skin due to _______
subcutaneous
haemorrhage.
Dx of plague
• Serology and smear/culture of buboes
†x of plague
• Streptomycin and doxycycline
________ is a rhabdovirus acquired by bites from an
infected mammal, for example a dog, cat, monkey,
fox or bat.
Rabies
What kind of rabies sx: malaise, headache,
abnormal behaviour including agitation and fever
Prodromal symptoms
Type of rabies
‘dumb rabies’ and ‘furious rabies
excessive
salivation and excruciating spasms of the pharyngeal
muscles on drinking water (in particular).
‘furious rabies’,
Tx of rabies
Post-bite prophylaxis (endemic area)
Wash the wound immediately then clean it. Administer
rabies vaccine (if unimmunised) and rabies immune
immunoglobulin ASAP (within 48 hours).
This is a type of food poisoning caused by eating
tropical fish, especially large coral trout and large
cod, caught in tropical waters (
Ciguatera
How does ciguatera kill?
The problem is caused by a
type of poison that concentrates in the fish after
they feed on certain micro-organisms around reefs.
Ciguatera poisoning presents within hours as a
bout of ______
‘gastroenteritis
Neuro Sx of Ciguatera
muscle aching and weakness,
paraesthesia and burning sensations of the skin,
particularly of the fingers and lips
Hansen’s disease (Gerhard Hansen, 1869) is caused
by the acid-fast bacillus_________
Mycobacterium leprae
Leprosy:
It is
a disorder of tropical and warm temperate regions,
especially
South-East Asia.
Transmission of leprosy
It is considered to be
transmitted by nasal secretions with an incubation
period of 2–6 years
WHO Guidelines for Leprosy
Diagnosis is one or more of:
• Skin lesions—usually anaesthetic;
________or reddish maculopapules or
______ lesions
• Thickened peripheral nerves with loss of sensation,
e.g___, ______, ________, ______); also
peripheral neuropathy or motor nerve impairment
hypopigmented
annular
. ulnar (elbow), median (wrist), common
peroneal (knee) and greater auricular (neck
Cont..
WHO Guidelines for Leprosy
Diagnosis is one or more of:
• Demonstration of ______ in a skin smear
or on biopsy
• It can be localised ______ or _______
(lepromatous
acid-fast bacilli
(tuberculoid)
generalised
Leprosy diagnosis:
Diagnosis is by ____, _____
cultivation of the organisms or by PCR tests
biopsy, the lepromin test,
WHO Tx options for Leprosy
multiple
drug therapy, e.g. rifampicin, clofazimine
and dapsone, but therapy is constantly being
evaluated
Scrub typhus is found in South-East Asia, northern
Australia and the western Pacific. It is caused by
________, which is transmitted by
mites
Rickettsia tsutsugamushi
SSX of scrub typhus:
• Abrupt onset febrile illness with headache and
myalgia
• A________ at the site of the bite with regional
and generalised lymphadenopathy
• Short-lived______
• Can develop severe complications (e.g.
________
black eschar
macular rash
pneumonitis, encephalitis
Treatment of scrub typhus:
• Doxycycline 100 mg bd for 7–10 days
Queensland tick typhus, which is caused by
_______is directly related to a tick bite.
The symptoms are almost identical to scrub typhus,
although less severe, and the treatment is identical
Rickettsia australis,
2 stages of African trypanosomiasis
Stage 1 (haemolymphatic) Stage 1 (haemolymphatic)
Other name of African trypanosomiasis
(sleeping
sickness)
What stage of (sleeping sickness)
- Incubation period about 3 weeks
- Fever, headache and a skin chancre or nodule
- Lymphadenopathy, hepatosplenomegaly
Stage 1 (haemolymphatic)
What stage of (sleeping sickness)
- weeks or months later
- cerebral symptoms including hypersomnolence
Stage 2 (meningoencephalitic)
Dx of African trypanosomiasis (sleeping
sickness:
Demonstrating _______ in peripheral
blood smear or chancre aspirate
trypomastigotes
Dx of African trypanosomiasis (sleeping
sickness:
- Suramin IV
* Infectious disease consultation essential
Prevention African trypanosomiasis
• Avoid bites of the_____.
If visiting areas of
East, Central and West Africa, especially the
safari game parks, travellers should use insect
repellent and wear protective light-coloured
clothing, including long sleeves and trousers.
tsetse fly
This is transmitted by bites of sand flies and by blood
transfusions and IV drug use.
Visceral leishmaniasis (kala-azar)
Visceral leishmaniasis (kala-azar)
The _________ is targeted and
presenting features include fever, wasting,
hepatosplenomegaly and lymphadenopathy
haemopoietic system
Visceral leishmaniasis (kala-azar)
• Among other signs is __________
hence the Hindu name kala-azar (‘black fever’)
• Most cases are
hyperpigmentation of the skin,
subclinical
This may be encountered in travellers and servicemen
and servicewomen returning from the Middle East,
especially the Persian Gulf, and also travellers
returning from Central and South America
Cutaneous leishmaniasis
Cutaneous leishmaniasis
The protozoa is transmitted by a ______ and has an
average incubation period of 9 weeks.
sandfly
Cutaneous leishmaniasis
The key clinical finding is an _____
erythematous papule
Dx of Cutaneous leishmaniasis
Performing a punch biopsy and culturing tissue
in a special medium
How to Tx extensive lesions of Cutaneous leishmaniasis
Treatment for extensive lesions is with highdosage
ketoconazole for 1 month
How to Tx extensive lesions of Cutaneous leishmaniasis
Smaller lesions should be treated topically
with 15% paromomycin and 12% methyl
benzethonium chloride ointment applied bd for
10 days
First clinical sign of Schisto
The first clinical sign is a local skin reaction at
the site of penetration of the parasite (it then
invades liver, bowel and bladder). This site is
known as ‘swimmer’s itch
Dx of Schisto:
• Serology
• Detecting eggs in the stools, the urine or in a
rectal biopsy
Tx of Schisto
• Praziquantel (may need retreatment
_____can be diagnosed
in a sick traveller returning from an endemic area
with severe diarrhoea characterised by blood and
mucus.
Amoebiasis ( Entamoeba histolytica )
Cx of Schisto
Complications include fulminating colitis,
amoebomas (a mass of fibrotic granulation tissue) in
the bowel and liver abscess
Acute amoebic dysentery
is treated with oral____ or ______
tinidazole or metronidazole.
What is the dx?
Clinical features • High swinging fever • Profound malaise and anorexia • Tender hepatomegaly • Effusion or consolidation of base of right chest
Amoebic liver abscess
T or F Amoebic liver abscess
There is often no history of dysentery, and
jaundice is unusual
T
Dx of Amoebic liver abscess
• Serological tests for amoeba and by imaging
CT scan
Treatment of Amoebic Liver Abscess:
• Metronidazole and by percutaneous CT-guided
aspiration
• Often asymptomatic
• Symptoms include abdominal cramps, bloating,
flatulence and bubbly, foul-smelling diarrhoea,
which may be watery, explosive and profuse.
Giardiasis
Dx of Giardia:
Three specimens of faeces for analysis (cysts and trophozoites): ELISA/PCR
Tx of Giardia
Scrupulous hygiene: metronidazole or tinidazole
______ which refers to the infestation of body
tissues by the larvae (maggots) of flies, often presents
as itchy ‘boils’.
Myiasis,
Primary myiasis invariably occurs in
travellers to tropical areas such as Africa _________
and Central and South America ______, whereby the
fly can introduce the larvae into the skin, or it can be
due to secondary invasion of pre-existing wounds
(Tumbu fly)
bot fly
Tx of cutaneous myasis:
simplest
treatment is lateral pressure and tweezer extraction
or place paraffin jelly (Vaseline) or thick ointment
over the lesion to induce emergence by restricting
oxygen, then apply a topical antibiotic.
Pinworm
Also known as _____ this is a ubiquitous
parasite infesting mainly children of all social classes
‘threadworm’,
Clinical features of pinworm:
Pruritus ani (in about 30% of cases) • Diarrhoea (occasionally)
Pinworm meds:
Medication
• Any one of pyrantel, albendazole or
mebendazole—as single dose orally
pyrantel 10 mg/kg up to 750 mg or mebendazine 100 mg (child <10 kg: 50 mg) or albendazole 400 mg (child <10 kg: 200 mg)
How soon to repeat tx in pinworm
2-3 weeks
By finding eggs in the faeces. The worm is very
sensitive to any of the three agents used for
pinworm. May give positive faecal occult blood
test.
Human roundworm
Tx of human roundworm
A first-line option is pyrantel 20 mg/kg up to
750 mg orally, as a single dose—to be repeated
after 7 days if a heavy infestation
These used to be common in Indigenous communities,
possibly causing failure to thrive, anaemia, abdominal
pain and diarrhoea and rectal prolapse with heavy
chronic infestation. The worms are about 1–2 cm long
Whipworm
Tx of whipworm
• Single large doses of mebendazole or albendazole
These are found in humid tropical regions but are
now uncommon in northern Australia. About 1–1.5
cm long, the parasites are acquired by walking
barefoot (or wearing thongs or sandals) on earth
contaminated by faeces
Hookworm
First sign of hookworm
The first sign is local irritation or ‘creeping eruption’
at the point of entry, known as ‘ground itch’, which
is often unnoticed
Cx of hookworm
They can cause iron/protein
deficiency anaemia in chronic infestation
Hookworm
infection is the commonest cause of ________ in the world
iron deficiency
anaemia
Dx of hookworm
finding
eggs on microscopy of faeces
Tx of hookworm
• A single dose of mebendazole 100 mg bd for 3
days or 400 mg single dose pyrantel
These are tiny parasites (2 mm or so) and have
a worldwide distribution. Infestation can cause
symptoms such as recurrent abdominal pain and
swelling and diarrhoea, skin and respiratory symptoms,
with blood eosinophilia
Human threadworm
(Strongyloides
Strongyloides
The problem is
aggravated by ______ therapy and may present
with a severe infection, such as septicaemia
corticosteroid
Strongyloides Tx
• Ivermectin 200 mcg/kg (o) two doses 2 weeks
apart (not in children < 5 years) or albendazole
200 mg bd for 3 days
___________should be suspected in any pruritic,
erythematous lesion with a serpiginous eruption
on the skin, especially the hands, legs and feet of a
person from a subtropical or tropical area
Cutaneous larva migrans (creeping eruption)
Dx of CLM
Clinical (characteristic appearance), eosinophilia
biopsy usually not indicated
Tx of CLM
Ivermectin (single dose) or Albendazole
Antihistamines for pruritus
T or F
CLM is self-limitinf
T
This nematode infection has two main forms which
are spread by mosquitoes and biting black flies
respectively
Filariasis
________ causes acute
adenolymphangitis and chronic lymphoedema
with obstruction of lymph flow.
The latter
can manifest as a____, ______, _________ especially of the extremities,
genitals and breasts.
Diagnosis is by_____ and _____
Lymphatic filariasis
hydrocele, scrotal oedema
or elephantiasis
blood film
and serology
__________starts as a
nodule at the bite site followed by chronic skin
disease and eye lesions such as uveitis and
optic atrophy
Onchocerciasis (river blindness)
It is the second leading cause of
blindness worldwide.
Onchocerciasis (river blindness)
Onchocerciasis (river blindness)
Dx and Tx
Diagnosis is by PCR testing,
treatment by ivermectin
Hydatid disease is acquired by ingesting eggs of the
dog parasite __________ which is found in
sheep farming areas here and in several countries in
Asia.
Echinococcus granulosus,
Sx of echinococcus:
There may be no symptoms although the patient may
complain of abdominal discomfort or cystic lesions on the
skin and other sites.
Rupture of a cyst (usually hepatic)
can cause severe ______ with possible death
anaphylaxis
Tx of echinococcus
Treatment
• Usually surgical removal of a cyst and
albendazole
This is the longest nematode. It is transmitted by tiny
crustaceans in water
Dracunculus medinensis (Guinea worm)
