Table 1.

Possible routes of Plasmodium falciparum transmission for the two case-patients described, the Netherlands

Possible cause	Arguments in favor	Arguments against	Interpretation
Travel to malaria-endemic countries	Schistosoma infection for case-patient 1	No history of recent travel to malaria-endemic countries	Possible for case-patient 1
Acquired in The Netherlands	2 case-patients notified within a short period, without travel history to a malaria-endemic country, and living nearby each other (10 km)	Presence of gametocytes for case-patient 2; low vector capacity; travel history/incubation time are not suggestive	Unlikely
Local transmission in southern Europe	Suggestive history/incubation time; friends sharing household and had complaints of malaria; reported presence of mosquitoes; insect bites present in case-patient 2	No known efficient vector present, but presence of vector cannot be ruled out without research at location of stay; rarely described and no other cases reported in 2012	Not ruled out, not clearly demonstrated
Airport malaria	Reported airport visit for case-patient 2	No airport/seaport visit for case-patient 1	Possible for case-patient 2
Luggage malaria	Both case-patients stayed with others returning from malaria-endemic countries; insects/insect bites observed	–	Possible for both case-patients
Blood transfusion/intravenous drug use	–	No history of blood transfusion or intravenous drug use	Unlikely
Late recrudescence	Both case-patients had had malaria in the past; both have lived in malaria-endemic countries (possible semi-immune status)	Very uncommon; rarely described for P. falciparum	Unlikely