Malaria 2018

Annual report on imported malaria 2018

In 2018, the Danish Departments of Clinical Microbiology (DCMs) and Statens Serum Institut (SSI) detected a total of 64 cases of malaria imported to Denmark, Table 1. The annual report is based partly on mandatory notifications submitted to the SSI, partly on supplementary data extraction from the Danish Microbiology Database (the MIBA). The DMCs notified 44 cases, but according to the MIBA, an additional 20 malaria cases were diagnosed in Denmark in 2018, but not notified to the SSI. In cases with missing information about country of infection, such information was obtained by contacting the hospitals.

Table 1. Number of malaria cases imported to Denmark, by place of infection and type of malaria, 2018.

Of the 64 malaria cases, the majority (85 cases, 91%) were acquired during travel in Africa, geographically equally distributed between countries located in Western, Eastern and Southern Africa, respectively. Only five cases were acquired in Asia, including four in Afghanistan, whereas a single case was acquired in either Thailand or Malaysia in Southeast Asia. A single malaria case was acquired in Papua New Guinea in Oceania, whereas no cases were observed from Central or South America in 2018.

The majority of cases, 49 (78%), were caused by Plasmodium falciparum infection. Additionally, 10 cases (16%) were seen of Plasmodium vivax, two cases of Plasmodium ovale, one case of Plasmodium malariae and a case of Plasmodium cynomolgi, a zoonotic species of malaria usually only seen in monkeys in Southeast Asia. One case could not be identified by species but was identified as Plasmodium by DNA analysis.

In 2018, all cases of P. falciparum were acquired in Africa. From Africa, additional five cases of P. vivax were seen, two cases of P. ovale and one case of P. malariae. The five cases of P. vivax were all seen in travellers from Eritrea/Ethiopia, as has been the case in recent years, but this trend was decreasing. From Asia, no cases were seen of P. falciparum, but four cases were seen of P. vivax from Afghanistan and one case of P. cynomolgi acquired in either Thailand or Malaysia. The case imported from Papua New Guinea was also caused by P. vivax.

The median age for the reported malaria cases was 37 years (range 4 to 73 years). Slightly more male than female travellers had become infected, 37 and 27 persons, respectively.

A majority of 42 (66%) of all imported malaria cases were seen in travellers of non-Danish origin, including five cases in children below 10 years of age.

In Denmark, one death due to malaria was recorded in 2018: A Danish man returning from West Africa. The specifics of the disease course currently remain unknown.

Figure 1 presents the development in the number of malaria cases imported to Denmark since 1998, by place of infection, whereas Figure 2 presents the development in the number of cases by type of malaria detected in Denmark since 1998. The curves illustrate a marked decrease in imported malaria in 2018, which may partly be explained by the decline in the cases of vivax malaria among refugees and migrants from Eritrea/Ethiopia, which increased considerably during the 2014-2016 period.

This report is also described in EPI-NEWS 27a/19.