Tales of the UnexpectedTales of the UnexpectedOdyssean and Non-Mosquito-Transmitted Forms of MalariaOdyssean and Non-Mosquito-Transmitted 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’

• container malaria

• baggage/luggage malaria

• suitcase malaria

• minibus malaria

• port malaria

• taxi rank malaria

By extension:

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

‘Odysseus… who wandered far and wide [after the Trojan war] and saw the towns of many men…’

Homer, Odyssey, 800 BC; 1:1

‘Odyssean’?

A Mosquito Odyssey

A Mosquito Odyssey

by

Anna Nopheles

- Plasmodium Press -- Plasmodium Press -

• 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...

If she:

She may transmit malaria……...

• Sometimes to more than one person

Or another pathogen:

‘Airport dengue’ has been described in Hawaii

Cages with mosquitoes were attached to non-

pressurised inner wheel bays of 747B for up

to 9 hours

Cruising altitude: ~ 10 000 meters

External temperature: -47 ºC to -54 ºC

In-flight viability:

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 non-endemic 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

• Customs officers 6

• Cargo/baggage handlers 2

• Mechanics 2

• Soldiers 2

• Saxophonist 1

• Barman 1

• Housewife 1

• Other 6

Typical Features of OM

• Long delay before admission: 2 - 30 days

• Long delay before diagnosis: 4 - 42 days

• High gametocytaemia rate: 37%

• High rate of complications: 71%

• High case fatality rate: 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

• 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

• 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.’

‘Malaria should be actively sought in febrile patients in whom there is no obvious cause of fever, even if the history is not suggestive.’