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Imported Malaria in Children
Abstract & Commentary
By Philip R. Fischer, MD, DTM&H
Dr. Fischer is Professor of Pediatrics, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, MN.
Dr. Fischer reports no financial relationships relevant to this field of study.
Synopsis: A new study of imported malaria in children returning to industrialized countries demonstrates that risk is highest in children who traveled overseas to visit friends and relatives, especially in Africa. More than 80% of affected children had not used chemoprophylaxis.
Source: Stager K, Legros F, Krause G, et al. Imported malaria in children in industrialized countries, 1992-2002. Emerg Infect Dis 2009;15:185-191.
Approximately 10% of international travelers are children (classified as those 18 years of age or younger in this study). As we note that more children are traveling, the number of malaria cases in travelers also is increasing.
Imported childhood malaria occurring during the decade 1992-2002 in Australia, Japan, the United States, and eight European countries was reviewed in an effort to better understand epidemiological trends that could impact upon potential preventive measures. In the 11 study countries, there were 17,009 cases of imported malaria, including only cases of those individuals who became symptomatic in a non-endemic country after traveling. More than 75% of the reported cases occurred in France, the United Kingdom, and the United States. Eighteen percent of cases were in adolescents aged 15-17 years. Seventy percent of cases were caused by P. falciparum. The case-fatality rate was less than 0.4%. Fewer than 18% of travelers who acquired malaria had taken any chemoprophylaxis. A majority of cases presented following travel in Africa. Based upon approximated numbers of children known to travel from different countries, case rates were calculated for various parts of Africa. (See Table 1.) Childhood malaria was associated particularly with travel to visit relatives; this was evidenced by the high rates of malaria in French travelers to the Comoro Islands and the lower rates in French tourists visiting Kenya.
Despite the presumed availability of personal protective measures and chemoprophylaxis, thousands of pediatric travelers are infected with malaria each year. While the risk varies by destination, this large series suggests that malaria is most common in travelers who neglect to use chemoprophylaxis while visiting relatives in Africa. Indeed, the vast majority of children with malaria in at least one hospital in France are from families of African origin.1 Presumably, these children are not gaining access to pre-travel consultation and care.
Children get malaria when they do not take advantage of pre-travel education and intervention. Only rarely, however, do children make their own health decisions. Parents must be informed about risks faced by traveling children, and pre-travel care should be accessible to them.
Imported malaria also is a major problem for adults. A study published this month suggests that blacks with malaria in England have an eight-fold lower risk of severe malaria than do Asians and whites, and that having a previous history of malaria is associated with a three-fold lower risk of severe disease.2 For adults, at least, previous exposures to malaria probably are providing some protective immunity. In that English study, less than one-third (23 of 75) of the patients with severe malaria had taken chemoprophylaxis, and only eight had taken it as prescribed. Sadly, six of those eight had been taking ineffective antimalarial preventive therapy.2
Immunity plays at least a temporary role in protecting against pediatric malaria as well. In Italy, children who acquired malaria while traveling to malaria-endemic countries to visit relatives had higher levels of parasitemia and lower platelet counts than did recent immigrant children with malaria.3
During pre-travel consultations, appropriate malaria protection should be provided, especially to children. Relevant aspects of pediatric pre-travel consultations recently have been reviewed.4 Community-based campaigns might be effective in reaching travelers who might not otherwise receive pre-travel care who are going to visit relatives.5