Travel Related illness

Question 1

HIV Opportunistic Infections

Answer 1

candidiasis—oropharyngeal and oesophageal cryptococcal meningitis and pulmonary cryptococcosis gastrointestinal protozoal infections—Cryptosporidium cytomegalovirus (CMV) hepatitis B virus (HBV) hepatitis C virus (HCV) herpes simplex virus—genital and oral Mycobacterium avium complex (MAC) tuberculosis Pneumocystis jirovecii pneumonia (PJP) Toxoplasma gondii encephalitis syphilis varicella-zoster virus - shingels

Question 2

Fever Returned Traveller - < 7 - 10 days

Answer 2

< 7-10 days

• Dengue fever, 5-8 days
• Meningococcal disease, variable
• Japanese B encephalitis, 4-14 days
• Yellow fever, 3-6 days
• Zika virus
• Rickettsial diseases
• viral haemorrhagic fevers, Ebola, 2-7 days

Question 3

Fever Returned Traveller - 7-30 days

Answer 3

7-30 days

• Hepatitis A, 15-45 days
• leptospirosis
• malaria, 2-8 weeks for Falciparum
• amoebic dysentery, 7-21 days
• enteric (typhoid) fever, 7-14 days
• giardiasis, 2 weeks
• Rickettsial disease
• Lassa fever, 7-18 days

Question 4

Fever Returned Traveller - 1 - 6 months

Answer 4

1-6 months

• acute schistosomiasis, 4-8 weeks
• Strongyloides, weeks to years
• filariasis, weeks to years
• viral hepatitis, weeks to months

Question 5

Travel History - important items

Answer 5

Travel history

• usually volunteered, but not always
• 90% present within 6 months of travel

-beware of late presentations, 6-12 months after return

Travel details

•all countries and areas visited

-especially West Africa (Ebola), Middle east (MERS) at present

• arrival and departure dates from each destination
• onset of symptoms in relation to arrival abroad
• duration of stay
• mode of travel e.g. cruise ship
• travel or stay in rural areas

Preventative actions

• immunisations
• antimalarial prophylaxis

-prior, during and following return for 2 weeks

• nets, repellents, screens
• water and food precautions
• STD prophylaxis, when relevant

Other features

• known mosquito or other bites for malaria and haemorrhagic fevers
• known outbreaks or epidemics during stay
• purpose of trip and occupation abroad
• contact with animals
• brucellosis
• rabies (especially Monkeys)
• antelopes
• Q fever

•swimming

• leptospirosis
• schistosomiasis
• medical treatment received whilst overseas
• injections or blood transfusions overseas
• sexual contact
• drug use
• new tattoos or piercings

Question 6

Physical Findings in Tropical Diseases

Answer 6

Physical Finding / Likely Infection or Disease

Rash

• Dengue fever, typhus, syphilis, gonorrhea, Ebola fever, brucellosis, Chikungunya, HIV seroconversion

Jaundice / Hepatitis

• malaria, yellow fever, leptospirosis, relapsing fever

Lymphadenopathy

• Rickettsial infections, brucellosis, HIV, Lassa fever, leishmaniasis, Epstein-Barr virus, cytomegalovirus, toxoplasmosis, trypanosomiasis

Hepatomegaly

• Amebiasis, malaria, typhoid, hepatitis, leptospirosis

Splenomegaly

• Malaria, relapsing fever, trypanosomiasis, typhoid, brucellosis, kala-azar, typhus, dengue fever, schistosomiasis

Eschar

• Typhus, borreliosis, Crimean-Congo hemorrhagic fever, anthrax

Hemorrhage

• Lassa, Marburg, or Ebola viruses; Crimean-Congo hemorrhagic fever; meningococcemia, epidemic louse-borne typhus

Question 7

Specific Exposures / Related Disease

Answer 7

Contact/Exposure; Possible Infections

Untreated water, unpasteurized dairy products

• Salmonellosis, shigellosis, hepatitis, amebiasis, brucellosis, listeriosis, TB

Raw or undercooked shellfish

• Clonorchiasis, paragonimiasis, Vibrio, hepatitis A

Raw or undercooked animal flesh

• Trichinosis (e.g., pig, horse, bear), Salmonella, enterohemorrhagic Escherichia coli

Raw vegetables, water plants (e.g., watercress)

• Fascioliasis

Animal contact (and animal products)

• Rabies, Q fever, tularemia, brucellosis, echinococcosis, anthrax, plague, Nipah virus, toxoplasmosis, herpes B encephalitis

Rodent contact

• Hantavirus, viral hemorrhagic fevers, murine (endemic) typhus, Lassa fever, plague, leptospirosis

Arthropod vectors

 Mosquitoes

• Malaria, dengue fever, Chikungunya, filariasis, yellow fever, and other arboviral infections

 Ticks or mites

• Rickettsioses, tularemia, scrub typhus, Crimean-Congo hemorrhagic fever, African tick bite fever

 Reduviid (kissing) bugs

• American trypanosomiasis (Chagas’ disease)

 Tsetse flies

• African trypanosomiasis (African sleeping sickness)

 Fleas

• Typhus, plague

 Sandflies

• Leishmaniasis, sandfly fever

Freshwater exposure

• Schistosomiasis, leptospirosis

Barefoot exposure

• Strongyloidiasis, cutaneous larva migrans, hookworm

Sexual contacts

• Human immunodeficiency virus, hepatitis B, syphilis, gonorrhea, chlamydia, herpes simplex

Infected persons contact

• Viral hemorrhagic fever, enteric fever, meningococcal infection, TB

Question 8

Regional Exposures / Possible Diseases

Answer 8

Africa:

• malaria, human immunodeficiency virus, TB, hookworm, tapeworm, roundworm, brucellosis, yellow fever (and other hemorrhagic fevers such as Lassa fever or Ebola), relapsing fever, schistosomiasis, tick typhus, filariasis, strongyloidiasis

Central and South America:

• malaria, relapsing fever, dengue fever, filariasis, TB, schistosomiasis, Chagas’ disease, typhus

Mexico and the Caribbean

• dengue fever, hookworm, malaria, cysticercosis, amebiasis

Australia, New Zealand

• dengue fever, Q fever, Murray Valley encephalitis, Japanese encephalitis

Middle East

• hookworm, malaria, anthrax, brucellosis

Europe

• giardiasis, Lyme disease, tickborne encephalitis, babesiosis

China and East Asia

• dengue fever, hookworm, malaria, strongyloidiasis, hemorrhagic fever, Japanese encephalitis

Question 9

Potentially life-threatening exotic illnesses

Answer 9

•Falciparum malaria

• malaria the most common diagnosis
• especially for travellers from West Africa
• enteric (typhoid) fever
• bacterial sepsis, including Meningococcus
• Rickettsial infections
• haemorrhagic fevers
• Hepatitis A, B, C, other
• Dengue fever, leptospirosis, schistosomiasis
• HIV infection
• amoebiasis, cholera, brucellosis
• MERS
• Ebola

Question 10

Investigations

Answer 10

Haematology

FBE

• haemolysis
• anaemia - malaria / typhoid fever
• neutropenia + lymphocytosis - typhoid fever
• eosinophilia
• common in parasitic infestation
• eosinophil count > 15% of total WBC or > 500 associated with a high probability of a travel-related illness

•thrombocytopenia

• malaria
• dengue
• leptospirosis
• Ebola

Thick and thin blood films

• a negative smear does not exclude malaria
• chemotherapy may suppress parasitaemia
• RBC with > 1 parasite suggests P falciparum

Clotting studies

• PT prolonged in hepatitis
• DIC in severe malaria

Biochemistry

Renal function tests

• dehydration
• malaria - acute kidney injury

Glucose

•low in malaria

LFT’S

• hepatitis
• tuberculosis
• amoebic liver abscess
• Weil’s disease

Serology

• Hepatitis serology
• HIV serology

Urine

•haemoglobinuria with malaria

Cultures

Blood cultures

• Typhoid - 80% positive in first week
• Brucellosis - positive in 50 - 80%
• usually positive in 14 days
• may take 6 weeks to become positive

Stools

• ova and parasites
• bacterial culture
• leukocytes
• large blood and polymorphs suggest Shigella

Urine M/C/S

•Typhoid - positive in 30%

Sputum M/C/S

Radiology

CXR

• TB
• typhoid fever - pneumonia
• malaria - pulmonary oedema

Other

• +/ - Ultrasound abdomen
• CT scan etc

Question 11

Malaria Species

Answer 11

protozoan disease, Plasmodium species, transmitted by bite of female Anopheles mosquito

•Plasmodium falciparum

• dominant in SE Asia, PNG, Indonesia
• accounts for most deaths
• approximately 60% of cases in returned travellers

•Plasmodium vivax

• most prevalent on worldwide basis
• especially Latin America
• rare in sub-Saharan Africa
• approximately 20% of cases in returned travellers

•Plasmodium ovale

•Plasmodium malariae

•Plasmodium knowlesi

• found in SE Asia
• most common cause of malaria in Malaysia
• infects Macques
• may cause severe disease in humans

Question 12

Malaria Life Cycle

Answer 12

Life cycle

• sporozoites injected into blood stream
• migrate to liver
• hepatocytes invaded, asexual reproduction occurs (pre-erythrocytic stage)
• hepatocyte ruptures, merozoites released into circulation
• erythrocytes invaded (erythrocytic stage)
• clinical manifestations first appear in erythrocytic stage

Question 13

Malaria Geogrpahy

Answer 13

High risk areas

• Solomon Islands
• SE Asia
• Africa
• Indian subcontinent
• South America

Endemic areas of chloroquine resistance

• East Africa
• Thailand, Vietnam, Philippines
• Papua New Guinea
• visitors to these areas are at particular risk

Question 14

Malaria - Timing of Infection

Answer 14

Timing

• incubation period 8 days to several weeks
• within 2 months
• > 90% of Falciparum evident
• only 50% of Vivax evident
• mean time to relapse in returned travellers infected with Vivax or Ovale is 9 months
• may take longer to become symptomatic if partial prophylaxis taken
• Bactrim, tetracyclines and fluoroquinolones have some antimalarial activity
• commonly used by travellers and may modify malaria symptoms and make diagnosis more difficult

Question 15

Malaria History

Answer 15

History

• malaise, weakness
• headache
• high grade fevers, rigors
• chest pain, cough
• abdominal pain, nausea
• arthralgia
• fever abates after several hours
• profusely sweaty and exhausted

Cycle of chills, fever and sweating

• related to life cycle of parasite
• not reliable or accurate in determining species
• P ovale and P vivax 2nd daily (tertian)
• P malariae 3rd daily (quartern)
• P falciparum often lacks periodicity
• benign malarias cannot reliably be distinguished clinically from Falciparum

Question 16

Malaria Investigations

Answer 16

Full blood examination

•normochromic, normocytic anaemia

-usually mild/moderate

•findings suggestive of haemolysis

-elevated LDH, bilirubin

•mild leukopenia

• present in 50%
• elevation of neutrophils in only 3%

• thrombocytopenia

• usually moderate (50-200)
• present in 80% with Vivax, 65% with Falciparum

•raised ESR

Blood gases

• lactic acidosis common
• may be due to capillary dysfunction
• may me contributed to by fluid loss, haemolysis

Rapid antigen test

• can be performed in minutes
• initial data suggests > 90% sensitive and specific
• vivax-specific rapid detection tests are
• 95% sensitive
• 99% specific

Thick film

• examination for the presence of intra-erythrocytic parasites
• allows more specimen to be examined
• more sensitive than thin film
• takes a minimum of 6 to 8 hours to be prepared
• uses Giemsa stain
• need experienced observer
• may have false negatives so does not exclude malaria

-repeat two to four times a day for 3 days

Thin film

•purpose

• identification of the Plasmodium spp in malaria
• determining the percentage of affected red blood cells
• can also make the diagnosis of babesiosis
• higher specificity
• parasite counts help assess response to treatment
• species diagnosis essential

-P falciparum may be resistant to many drugs

•parasites may deteriorate over the course of a few hours if sample is submitted in heparinised blood tubes

-if submitted in non-heparinised tube, must be prepared and read quickly

PCR

•mostly used to confirm and to identify the species of malaria on positive blood smears

Anti-circumsporozite protein

• produced in clinical and subclinical infection
• identified using ELISA technique
• only 60% sensitive
• > 95% specific

Parasite LDH antigen assay

• rapidly performed
• sensitivity and specificity of approximately 90%
• dipstick tests currently only detect Falciparum

Others

• bone marrow smear may be justified
• false positive VDRL
• hypoglycaemia common
• therapeutic trial if in doubt

Question 17

Malaria Complications

Answer 17

Complications

•may occur rapidly in untreated malaria, especially P falciparum

Hyperparasitaemia

•density of asexual forms in smear usually correlates with mortality

-10% RBCs has > 50% mortality

Cerebral malaria

• spectrum of neurological disturbance
• drowsy, coma, seizure
• movement disorder
• diffuse encephalopathy
• 20-50% mortality if untreated

Acute kidney injury

• occurs in 10%
• acute tubular necrosis

Black water fever

• massive haemolysis and haemoglobinuria
• may be severe and life threatening
• may be triggered by sulphones in G-6-PD deficiency
• results in acute kidney injury

Acute pulmonary oedema

• pathogenesis unknown
• associated with acute tubular necrosis
• invariable in fatal cases
• resembles ARDS

Severe anaemia

• 30% have Hct < 20%
• requires transfusion
• especially children and pregnant women

Hypoglycaemia

•always consider in the patient who deteriorates late

Spontaneous bleeding

• gums, skin, GIT, venepuncture site
• thrombocytopenia
• defibrination
• occasionally DIC

Secondary infection

• septicemia
• pneumonia
• often over looked

Chronic malaria

•Vivax, Ovale

Question 18

Malaria Management

Answer 18

Supportive

•cases of Falciparum malaria should be admitted to hospital

• cycling occurs every 48 hours so deterioration after starting treatment may still occur
• initial increase in parasite numbers occurs in 25% of cases
• ABC
• rehydration and fluid replacement
• cooling
• treat hypoglycaemia, renal failure, anaemia, APO, seizures etc
• exchange transfusion may be of use in very severe cases
• treatment is based on known geographical patterns of resistance

Severe malaria

•defined as altered consciousness, jaundice, oliguria, severe anaemia, severe hypoglycaemia

• parasites in > 5% of RBCs
• parasite count > 100,000/mm3
• vomiting and acidosis
• treat immediately
• assume chloroquine resistant P falciparum

Artesunate

• artemisinin group of drugs extracted from wormwood plant in China
• used effectively against malaria since 16th century
• artesunate one of many semi-synthetic derivatives
• highly active against all species of Plasmodium inhumans
• may be used in combination with standard anti-malarials
• superior to IV quinine, 37% reduction in mortality
• recommended by WHO for uncomplicated malaria
• recommended in Vietnam, Thailand, PNG and Cambodia
• not yet licensed for use in Australia

-hospital pharmacies can import for category A patients under special access scheme

• use instead of IV quinine, if immediately available
• dose
• 2.4 mg/kg IV on admission
• repeat at 12 and 24 hours
• once daily until oral therapy possible
• change to artemether and lumefantrine when oral treatment possible

Quinine

• use if IV artesunate not immediately available
• dose
• quinine dihydrochloride 20 mg/kg IV over 4 hours as loading dose or
• quinine dihydrochloride 7 mg/kg IV over 30 minutes and follow with 10 mg/kg over 4 hours
• 10 mg/kg 8 hourly maintenance dose
• quinidine is an effective substitute, has greater antimalarial activity and is readily available
• change to combined oral treatment when clinically improved

Potentially complicated malaria

• parasite count > 2%
• jaundice
• pregnancy

Uncomplicated Falciparum malaria

Artemisinin derivatives

• artemether and lumefantrine 20 + 120 mg
• now recommended as first choice
• taken orally with fatty food at 0, 8, 24, 36, 48 and 60 hours
• initial treatment in hospital recommended

or

Quinine and doxycyline regime

• quinine sulphate 600 mg orally, 8 hourly, 7 days, and
• doxycycline 100 mg orally, 12 hourly, 7 days or
• clindamycin 300 mg orally, 8 hourly for 7 days

or

Atovaquone and proguanil

• 250 + 100 mg adult formulation
• four tablets orally with fatty food for three days
• contraindicated if had been already used for prophylaxis

or

Mefloquine

• 750 mg orally initially
• 500 mg orally 6-8 hours later
• don’t use if nausea or vomiting prominent

Other malarias

• i.e, Vivax, Malariae and Ovale
• resistance usually not an issue
• have been reports of chloroquine resistant Vivax from PNG, Indonesia, SEA
• chloroquine
• 650 mg orally stat
• 300 mg 6 hours later
• 310 mg on days 2 and 3, and

•primaquine

• exclude G6PD deficiency prior to treatment
• 30 mg daily for 2 weeks
• reduce dose if nauseated
• increase dose for Vivax from SE Asia or Pacific Islands

Question 19

Malaria Prophylaxis

Answer 19

Prophylaxis

• malaria a big problem for pregnant women and post-splenectomy patients
• recommended that these patient groups do NOT go to malarious areas
• prophylaxis for children may be problematic

Anti-mosquito measures

• personal insect repellent
• avoid dusk to dawn exposure
• avoid mosquito prone areas
• light coloured clothing
• long sleeves and trousers
• avoid perfumes and after shave
• mosquito nets

Chemoprophylaxis

• multi-drug resistant Falciparum complicate prophylaxis recommendations
• wide variations in recommendations
• many drugs (e.g. quinine) are antipyretics and may mask the symptoms and signs of malaria
• not 100% effective
• recommendations change frequently due to resistant parasites
• consult local travel medicine gurus

Chloroquine sensitive area

• chloroquine 310 mg orally, weekly
• take for 1 weeks prior to travel and 4 weeks following return

Chloroquine resistant areas

• atovaquone + proguanil 1 tablet orally with fatty food
• start 1-2 days prior to entering area, continue for 7 days afterwards
• adult and paediatric tablets available

or

• mefloquine 250 mg orally, weekly
• take 1 week prior to travel and for 4 weeks following return
• contraindicated in patients with epilepsy, cardiac conduction defects

or

• doxycycline 100 mg orally, daily
• start 2 days prior to leaving, continue 4 weeks after return

Mefloquine resistant areas

• doxycycline as above, or
• proguanil and chloroquine

Question 20

Classic dengue

Answer 20

Classic dengue

• occurs primarily in non-immune, non-indigenous adults and children
• relatively benign course
• short incubation period

History and examination

Fever

• abrupt onset
• usually 39.5-41.4° C
• frontal or retro-orbital headache
• conjunctival erythema
• lasts 1-7 days then settles for 1-2 days
• fever settles
• profuse sweating may occur
• recurs with second rash but not as high

First rash

• during first 1-2 days of fever
• diffuse skin flushing of the face, neck, and chest
• evolves into a maculopapular or rubelliform rash of the whole body, usually on day 3 or 4 of the fever
• may be petechial

Second rash

• occurs in 80%
• appears within 1-2 days of fever normalising
• usually first appears on dorsum of hands / feet
• spreads from extremities to trunk with facial sparing
• morbiliform
• maculopapular
• sparing palms and soles
• lasts 1-5 days
• occasionally desquamates

Bone / muscle pain

• occurs after the onset of fever
• usually worse in neck, back, legs
• absent in DHF / DSS
• increases in severity

Other symptoms

• cutaneous hyperaesthesia
• altered taste
• anorexia / nausea
• URTI symptoms are usually absent

Question 21

Dengue haemorrhagic fever (DHF)

Answer 21

Dengue haemorrhagic fever (DHF)

• occurs in a small proportion of cases
• predominantly a disease of children < 10 years of age
• usually occurs during a second dengue infection in people with preexisting acquired immunity

-therefore rare in travellers

•abrupt onset

History and examination

•muscle / joint pain and lymphadenopathy does not occur

Minor stage

• 2-4 days duration
• pharyngitis
• cough bronchopneumonia
• nausea, vomiting
• abdominal pain, may be severe
• hepatomegaly
• bleeding due to increased vascular permeability and DIC

Dengue shock syndrome (DSS)

Shock

• develops as well as features of DHF
• occurs in 20-30% of DHF cases
• occurs 2 - 6 days after onset
• sudden collapse or rapid deterioration common

Examination

• fever
• hypotension
• relative bradycardia
• narrowed pulse pressure
• delayed capillary refill the first sign of intravascular volume depletion
• hypotension a late sign in children
• circumoral cyanosis
• hepatomegaly occasionally
• positive tourniquet test
• petechiae / purpura / features of abnormal bleeding

Complications

• uncommon
• CNS damage from prolonged shock or intracranial haemorrhage
• myocarditis
• encephalopathy
• liver failure

Question 22

Dengue Fever - Investigations

Answer 22

Investigations

•usually a clinical diagnosis

Serology

• viral PCR in the first five days of illness
• serological tests usually more useful after the fifth day of illness

-viral IgM and IgG ELISA monoclonal antibody or haemagglutination

•viral culture also possible

Haematology

FBE

• features of haemoconcentration, haematocrit increased 10-20%
• thrombocytopenia, usually < 100,000
• leukopenia
• 2,000- 4,000 common by 2nd day of fever
• persists during the febrile phase

•WCC elevated in 1/3

DIC screen

•panel, as indicated

Biochemistry

Electrolytes

• acidosis
• urea increased

LFTs

• elevated transaminases
• hypoproteinaemia

Radiology

CXR

• bronchopneumonia
• pleural effusion

CT head

• if altered mental state
• intracranial bleeding
• cerebral oedema

Others

Urinalysis

•moderate proteinuria and casts may be found

Faecal occult blood

• early sign of coagulopathy
• should be performed on all suspected cases

Question 23

Typhoid (Enteric Fever) - hx and exam

Answer 23

Pathology

• enteric fever may be caused by Typhi and Paratyphi
• also known as typhoid and paratyphoid fever
• food or water borne infection
• colonises small intestine
• penetrates mucosal wall, invades mesenteric nodes and spleen
• bacteraemia occurs
• infection localises to small intestine
• not endemic in Australia, most cases in tropical / underdeveloped countries
• may present in returned travellers

Assessment

History

• incubation period 5-14 days
• insidious onset
• low grade fever, headache, anorexia
• dry cough, sore throat
• myalgias, arthralgias
• abdominal pain
• initial constipation followed by diarrhoea

Examination

• high fever 38 - 40C
• step wise fever rising daily

-peaks at 7-10 days

•relative bradycardia

• heart rate lower than expected considering the extent of the fever
• not typhoid specific
• common with many intracellular organisms - malaria, legionellosis, babesiosis
• clouded consciousness, rigors, meningism
• at 7 - 10 days very ill
• toxic facies
• dehydration
• prostration
• exhaustion
• splenomegaly +/- hepatomegaly
• doughy slightly tender abdomen

Rose spots

• 2-4 mm blanching macules
• slightly raised, irregular and pink
• transient
• usually found on anterior chest wall and abdomen
• arise in clusters of 5-15
• persist for 3-4 days

Question 24

Typhoid (Enteric Fever) - investigations and Management

Answer 24

Investigation

FBE

• normal or low WCC
• normocytic normochromic anaemia common

Cultures

•blood cultures

• 80% positive in first week
• 30% positive in second week

•stool culture

• rarely positive in first week
• 30-60% positive in second week

•bone marrow culture, sensitivity up to 90%

Widal test

• measures antibodies against flagella and somatic antigens of Salmonella species
• inexpensive, commonly used in developing countries
• sensitivity 30-90%
• lacks specificity as many non-typhoid Salmonella share same antigens

Others

•ELISA test developed for anti-lipopolysaccharide and anti-flagellin antibodies

• reported sensitivity 94%
• specificity 95%

•PCR technology also developing

• sensitivity 100%
• specificity 93%

Complications

• occur in 30% of untreated cases
• account for 75% of deaths
• may involve any system
• GIT haemorrhage or perforation
• cholecystitis, hepatitis
• pneumonia, bronchitis, empyema
• myocarditis, pericarditis
• bacteraemic metastatic sepsis e.g. abscess in bone, genitourinary tract, meninges
• neurological disturbance
• polyneuritis
• meningitis
• psychosis
• cerebellar ataxia

Differential diagnosis

• many illnesses as non-specific initial presentation
• malaria
• brucellosis
• occult abscess
• endocarditis

Management

Supportive

• management of ABC
• fluid and electrolyte management
• enteric precautions

Definitive

• ciprofloxacin 500mg orally twice daily for 7-10 days
• IV ciprofloxacin if oral treatment not tolerated
• alternative antibiotics
• ceftriaxone 3g IV daily till sensitivities known
• change to amoxycillin, cotrimoxazole or chloramphenicol

•Indian and Vietnamese strains increasingly resistant to ciprofloxacin

Prevention

•vaccine only 60-70% effective

Question 25

Schistosomiasis (Bilharziasis)

Answer 25

Schistosomiasis (Bilharziasis)

Parasitology

• affects > 300 million people world wide
• causative agent is Schistosoma haematobium
• distributed from Africa to India

Lifecycle

• larvae directly penetrate the skin from infected water
• then migrate to the portal venous system and develop into adult worms
• they then migrate to the mesenteric or haemorrhoidal venules and produce eggs
• eggs migrate through the tissues and exit via the bowel or urine
• urinary bladder involved when schistosomiasis schistosomules migrate to the small venules of the bladder

Clinical

• haematuria
• diagnosis by detection of eggs in the urine or stool

Management

•extra doses may be needed

Schistosoma haematobium or mansoni

•praziquantel 20 mg/kg orally for 2 doses, 4 hours apart

Schistosoma japonicum and mekongi

•praziquantel 20 mg/kg orally for 3 doses, 4 hours apart

Question 26

Rabies natural history

Answer 26

Background

• acute viral disease of the CNS that affects all mammals
• caused by Lyssa virus

Epidemiology

• not endemic in Australia
• very common in dogs in Bali / Indonesia so may affect travellers
• bat Lyssa virus is known to infect fruit bats in Australia and has similar features
• transmitted by infected secretions (most commonly saliva)
• most common mode of contact is the bite of an infected animal
• dogs responsible for 99% of cases in humans
• insect eating bats have high prevalence of disease in some countries
• proximal bites have more rapid onset and worse prognosis
• virus spreads up peripheral nerves to the CNS, probably through peripheral nerve axoplasm

Assessment

History and examination

•history of exposure

• animal type
• country
• highest risk areas are Asia, Middle east and most of Africa (apart from the southern most countries)
• bite location
• features of illness in the responsible animal
• ability to observe the animal
• nearly all infected dogs will die within 2 weeks
• presence of bleeding following the exposure

•average incubation period 30 - 60 days

• range of 4 days - many years
• 5% of cases may take more than 1 year to manifest

•almost invariably fatal once clinical features of encephalomyelitis occur

Earlier signs

•bite site symptoms in 40-80%

• paraesthesia or itching
• neuropathic pain from region of the bite
• intense pruritus progressing to involve the limb or side of the face

•myoedema

• a sustained contraction of the muscle elicited by being struck by a tendon hammer
• resolves within seconds

Later signs

• depression / agitation
• muscular spasms especially of laryngeal and pharyngeal muscles
• myoclonus
• tremor
• salivation
• spinal paralysis
• may occur without other features
• may be ascending, like Guillain Barre
• fever usually present
• hydrophobia (inability to drink) is characteristic
• encephalopathy

Investigation

• usually a clinical diagnosis
• confirmed by nuchal skin biopsy

-viral antigens or RNA detected at the base of hair follicles containing peripheral nerves

•saliva, CSF and brain tissue may also be tested

Question 27

Rabies Management

Answer 27

Management

Supportive

•general supportive care

-especially sedation

• isolation
• saliva is infective
• ICU admission
• treatment very rarely successful once disease apparent clinically
• mortality rate essentially 100%

Prevention

• mainstay of medical treatment
• tourists from overseas often present to EDs

-may have had contact with rabies

•require immunisation and immunoglobulin

-require special permission to use in Australia

•due to the prolonged incubation period, immunisation and immunoglobulin administration following exposure is close to 100% effective at preventing clinical disease

Wound management

• wash and irrigate a rabies prone wound with soap and water
• apply ethanol, aqueous solution of iodine or 0.1% quaternary ammonium compounds
• do not suture the wound

Rabies vaccine

• indicated for minor scratches or abrasions as well as wounds that produced bleeding
• inactive virus
• dose of 0.1 mL given IM in deltoid
• antibodies detected within 7 days
• peak levels reached at 30 days, then start to decline
• multiple doses needed to maintain immunity
• used for post-exposure immunisation or pre-exposure immunisation in those at risk
• course of 4 vaccine doses on days 0,3,7,14 post exposure, if unimmunised prior to exposure
• a fifth dose on day 28 may be used in immunocompromised patients
• patients immunised prior to exposure only require two IM booster doses on days 0 and 3 and no rabies immunoglobulin is required

Rabies immunoglobulin

• indicated only when wound has produced bleeding
• dose of 25 Units/kg
• 2-3 mL infiltrated subcutaneously around the bite site
• remainder (10-15 mL) given as deep IM injection into thigh
• immunoglobulin is a scarce resource and may occasionally be unavailable
• immunoglobulin and vaccine are obtained in Australia by contacting the Communicable Diseases Control Branch (CDCB) for authorisation (82267177, 24 hours a day) by the medical officer on call for CDCB
• following approval, CDCB contacts CSL to deliver vaccine/ immunoglobulin
• details required by the CDCB include: patient demographics, contact details, weight, details of the exposure, delivery details and follow up plans for further vaccine administration