Imported malaria is falling in Netherlands and Europe

Abstract

Since the authors used a linear regression for analysis of linear trend over a much longer period of 20 years, this newly evolving trend of falling incidence rates since 2001 may have been lost.

The increase in falciparum malaria in the UK reported by Smith et al 1 does not correspond with our own observations on imported malaria in the Netherlands during recent years. We examined all consecutive malaria cases in the Harbour Hospital and Institute for Tropical Diseases in Rotterdam between 1 January 1999 and 1 January 2008. The number of falciparum cases fell from 40 patients in 2001 to 20 in 2007. Imported malaria with non-falciparum species also declined in this observational period. In the Netherlands as a whole, official malaria notifications fell from 569 cases in 2000 to 210 cases in 2007. 2 3 Further, the World Health Organization's data on imported malaria in most European countries show that reported falciparum malaria cases have declined over the past years. 4

As in the UK, travellers to Ghana and Nigeria account for about half of all imported falciparum cases in the Netherlands, suggesting considerable overlap in countries of acquisition of malaria. 3 From table 1 in the paper, 1 it seems that during the past five years of the study period, numbers of falciparum malaria cases have fallen compared with 1996-2001. This is supported by the number of imported falciparum malaria cases in 2007, as reported by WHO for the UK, 4 which has not been so low since 1994. Since the authors used a linear regression for analysis of linear trend over a much longer period of 20 years, this newly evolving trend of falling incidence rates since 2001 may have been lost.

Decreased incidence rates of imported malaria in the Netherlands and most European countries may indicate that travellers to malaria endemic regions are better prepared against the transmission of Plasmodium species by mosquito bites, either by adhering more strictly to personal protective measures-such as insect repellents-or a more compliant intake of newer and more convenient chemoprophylactic drugs (for example, atovaquone-proguanil).

Footnote

Competing interests: None declared.

References

1 Smith AD, Bradley DJ, Smith V, Blaze M, Behrens RH, Chiodini PL, et al. Imported malaria and high risk groups: observational study using UK surveillance data 1987-2006. BMJ 2008; 337: a120. (3 July.)

2 Van der Eerden LJM, Bosman A, Visser LG. Afname van importmalaria, een overzicht van 2002 [in Dutch]. Infectieziekten Bull 2003; 14: 419-23.

3 Rahamat-Langendoen JC, van Vliet JA, van Lier EA. Government report on infectious diseases in the Netherlands 2007 [in Dutch]. Bilthoven: RIVM, 2008. www.rivm.nl/cib/binaries/StaatvanInfectieziekten2007_tcm92-53097.pdf

4 World Health Organization Regional Office for Europe. Centralized information system for infectious diseases (CISID). http://data.euro.who.int/cisid