The average annual number of organized trips from Finland abroad during 1999 to 2007 was around 940,000 (Figure 2). There was a sudden drop in the numbers during 2001 to 2003, down to 880,000 trips per year. A concomitant drop was seen in the number of malaria cases. During 1997 to 2008 the total number of overnight leisure trips abroad nearly doubled, from 1.7 million in 1998 to 3.3 million in 2008. The increasing trend
observed with overnight leisure trips was also seen in travel to malaria-endemic countries, including high-risk areas (Figure 3). Antimalarial drug sales decreased nearly 50%, from 49,000 units in 1997 to 25,000 in 2005, but since 2005 a new increase was observed, and in 2007 the number of units sold was roughly 61,000. The same trend was observed Selleckchem Tofacitinib Selleck PD-1 inhibitor for sales expressed in daily treatment doses (DDD) for different antimalarials
(Figure 4). Antimalarial drug sales were highest during the first (35%) and last quarters (18%) of the years and followed the same seasonal pattern as traveling (Figure 5). Malaria cases occurred year-round with an increasing trend toward the end of the year (data not shown). This nationwide population-based study showed that even though traveling to malaria-endemic areas increased during the 14-year period, no corresponding increase in malaria cases occurred. Moreover, during the same period, the overall antimalarial drug sales decreased, while a slight increase was 2-hydroxyphytanoyl-CoA lyase observed with the last available data. The increase in travels to endemic areas with no concomitant increase in drug sales suggests that travel advice was not reaching all groups of travelers. It appears that this concerns especially immigrants visiting friends and relatives (VFR) in their former home country and travelers on self-organized trips, because a significant proportion of travelers with malaria in Finland were observed in these groups. During the study period, nearly 500 malaria cases (average annual incidence 0.7/100,000 population) were
reported in Finland. All cases were imported; no autochthonous cases have been found in Finland since the 1950s.11 Malaria is a notifiable disease in most of the European countries, but underreporting exists; in some European countries, underreporting of imported malaria cases is estimated to be as high as 60%,12 whereas the estimate for Finland is around 20%.13 We believe, however, that in reality, there is no significant underreporting in Finland. The reference laboratory collects additional information from clinicians, and these two databases have been compared annually; the same individual cases have been identified in both (H. Siikamäki, unpublished results). Data from annual surveys showed a linear increase in the total number of leisure trips abroad since 1997.