Transcript Adventurous Anopheles and Mysterious Malaria

Tales of the Unexpected
Odyssean and Non-MosquitoTransmitted Forms of Malaria
Dr John Frean
NICD/NHLS
South Africa
Historical Background
• ‘Paludisme aéroporté’: coined in 1970s
• 13 cases in Europe related to international
airports, via imported infected mosquitoes
• translated correctly as ‘airborne malaria’
• mutated into ‘paludisme d’aérodrome’ =
‘airport malaria’
By extension:
• container malaria
• baggage/luggage
malaria
• suitcase malaria
• minibus malaria
• port malaria
• taxi rank malaria
Next…?
• Spaceship
or space station malaria
• Submarine/submersible malaria
Classification of Malaria by
Mode of Transmission
• Mosquito-transmitted, locally acquired
= ‘autochthonous’
– indigenous: natural to area
– introduced: acquired in non-malarious
area from imported cases via local
mosquitoes
– Odyssean: acquired in non-malarious area
via imported mosquito
• airport
• baggage
• container etc
Classification (cont’d)
• Non-mosquito-transmitted
– induced: transfusion, needle malaria
– congenital: transplacentally acquired
Odyssean Malaria
‘Malaria acquired through the bite of an
imported Anopheles species mosquito in
people whose geographic history firmly
excludes exposure to the vector in malaria
endemic areas.’
M. Isaäcson & J. Frean, Lancet (2001) 357:235
• In practice, Odyssean malaria is a diagnosis
of exclusion
• The chance of positive identification of the
actual vector is remote
• Non-mosquito-borne forms of malaria (e.g.
transfusion, needle malaria) have to be
excluded
‘Odyssean’?
‘Odysseus…
who wandered
far and wide
[after the
Trojan war] and
saw the towns of
many men…’
Homer, Odyssey, 800 BC; 1:1
A
Mosquito
Odyssey
by
Anna
Nopheles
- Plasmodium Press -
If she:
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Escapes disinsection in aircraft cabin
Survives cold in aircraft hold or wheel bays
Avoids fatal compression in luggage
Survives wind and cold at destination
Avoids predation by birds, spiders, etc
Successfully catches a connecting car, bus,
taxi, train (optional)
• Avoids being squashed long enough to
feed...
She may transmit malaria……...
• Sometimes to more than one person
Or another pathogen:
‘Airport dengue’ has been described in Hawaii
In-flight viability:
Cages with mosquitoes were attached to nonpressurised inner wheel bays of 747B for up
to 9 hours
Cruising altitude:
~ 10 000 meters
External temperature: -47 ºC to -54 ºC
Results
• Mosquito survival: 80%
• Wheel bay temperature: 8 - 28 ºC
(Russell, RC. Bull.WHO 1987; 65:659-662)
When the Graf Zeppelin docked
in the USA in 1928, 10 species
of insects were found on plants
carried on board
Mosquitoes in Aircraft
Airport
Aircraft
Mosquitoes
Gatwick
67
Present in 12
New Orleans
210
81
Miami
1183
100
Honolulu
89
32
Trinidad
592
967 arthropods
The Case of the Commuter
Mosquito - I
• 35-year-old English woman flew Ethiopian
Airways, London-Rome
• 12 days later: febrile illness; initially treated
as enteritis
• After a week: respiratory and CNS disease
developed
• Flew home; falciparum malaria diagnosed
The Case of the Commuter
Mosquito - II
• Another passenger on same London-Rome
flight developed falciparum malaria
• Aircraft had originated in Abbas Ababa,
where mosquito presumably boarded
• Mosquito was probably disturbed and
continued meal on the second passenger
Disinsection of Aircraft
• Main objective: minimise importation of
vectors into non-endemic areas
• 3 methods:
– blocks-away
– preflight and top-of-descent
– residual insecticiding
‘Runway malaria’
• passengers bitten en route between nonendemic areas
• by infected mosquitoes flying into aircraft
• during brief stopovers in malaria endemic
areas
• a variation of imported malaria,
NOT ‘Airport malaria’
Incidence of Odyssean malaria
• Uncommon
• Italy 1986-1996: of 5012 malaria cases,
only 17 cases had no travel history
• 9 cases (0.18%) were airport or container
malaria
• Others were transfusion- or needle-related
Occupations of 21 cases of
Airport Malaria
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Customs officers
Cargo/baggage handlers
Mechanics
Soldiers
Saxophonist
Barman
Housewife
Other
6
2
2
2
1
1
1
6
Typical Features of OM
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Long delay before admission:
Long delay before diagnosis:
High gametocytaemia rate:
High rate of complications:
High case fatality rate:
2 - 30 days
4 - 42 days
37%
71%
17%
(Isaäcson M. Bull.WHO 1989; 67;737-743)
Mysterious Malaria in Gauteng
OM & IM in Gauteng (L. Blumberg)
• 25 OM, 2 IM cases recognised 1996-2001
• most common clinical diagnoses:
– influenza
– viral hepatitis
– septicaemia
• severe malaria in 14/27 (59%)
• mortality rate 6/27 (22%)
Waterkloof, Pretoria
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Couple living 2 km from Air Force base
Both had fever, headache
Wife was confused, very ill
Initially diagnosed as flu
Physician eventually looked for malaria
OM & IM in Gauteng
• Main indication for smear examination:
thrombocytopenia
• all had P. falciparum: <1% - 60%
• Take-home message: malaria should be
actively looked for in febrile patients in
whom there is no obvious cause of fever
Laboratory Aspects
• commonly used automated haematological
analysers do not detect malaria parasites
• microscopic smear examination not routine
• new laser depolarisation autoanalysers can
detect malaria pigment
• 72% sensitivity, 96% specificity overall
• less sensitive in whites (43%) than blacks
(90%) [Mendelow et al, Br J Haem]
Non-Mosquito-Transmitted
Malaria
• Induced: transfusion, needle malaria
• Congenital malaria
Infecting parasites are not sporozoites:
therefore, pre-patent period and relapses
are absent
Pre-erythrocytic cycle
Erythrocytic cycle
Induced Malaria
• Therapeutic: for neurosyphilis (1922)
• Transfusion: whole blood or components
– leukocytes
– platelets
– plasma
• Parasites can survive 2 years in
cryopreserved blood
Induced Malaria: other vehicles
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Multi-use heparin vials
Renal transplantation
Re-used intravascular catheters
Contaminated gloves
Needle-Induced Malaria
• At risk:
– intravenous drug abusers
– health care workers
– laboratory staff
• diagnosis
• research, especially in vitro malaria culture
• Like OM, diagnosis and treatment often
delayed…...
The Case of the English Patient
• A young English woman visited southern
Africa
• then travelled to Italy; 3 weeks later
developed fever and diarrhoea
• treated with IV fluid and antibiotics
• after 3 days, returned to England where
30% falciparum parasitaemia diagnosed
The English Patient, cont’d……
• The Italian doctor pricked his finger while
putting up her drip
• he became ill and died a month later
• falciparum malaria diagnosed at necropsy
• no prior history of exposure
‘Malaria should be actively sought
in febrile patients in whom there is
no obvious cause of fever, even if
the history is not suggestive.’