Chapter 1 – Introduction: Canadian recommendations for the prevention and treatment of malaria

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An Advisory Committee Statement (ACS) from the
Committee to Advise on Tropical Medicine and Travel (CATMAT)

Preamble

The Committee to Advise on Tropical Medicine and Travel (CATMAT) provides the Public Health Agency of Canada (PHAC) with ongoing and timely medical, scientific, and public health advice relating to tropical infectious disease and health risks associated with international travel. PHAC acknowledges that the advice and recommendations set out in this statement are based upon the best current available scientific knowledge and medical practices, and is disseminating this document for information purposes to both travellers and the medical community caring for travellers.

Persons administering or using drugs, vaccines, or other products should also be aware of the contents of the product monograph(s) or other similarly approved standards or instructions for use. Recommendations for use and other information set out herein may differ from that set out in the product monograph(s) or other similarly approved standards or instructions for use by the licensed manufacturer(s). Manufacturers have sought approval and provided evidence as to the safety and efficacy of their products only when used in accordance with the product monographs or other similarly approved standards or instructions for use.

Chapter 1 - Introduction

Malaria is a common and serious infection caused by five different species of the genus Plasmodium: falciparum, vivax, ovale, malariae and knowlesi. Malaria is transmitted by the bite of infected female anopheline mosquitoes. Rarely, transmission may occur through transfused blood^{Footnote 1}, by sharing needles or from mother to fetus^{Footnote 2}.

The disease is characterized by fever and flu-like symptoms such as myalgia, headache, abdominal pain and malaise. Rigours and chills often occur. The alternate-day or periodic fevers described above are, in fact, often not present.

The symptoms of malaria are nonspecific and definitive diagnosis is not possible without microscopy of a blood film or an antigen detection test (rapid diagnostic test).

Malaria-associated deaths are frequently the result of delays in the diagnosis and treatment of the infection^{Footnote 3}; ^{Footnote 4}. Infections caused by P. falciparum have the highest fatality rates but all the species have the potential to cause severe disease. The majority of deaths due to malaria are preventable.

Widespread resistance of P. falciparum to chloroquine has complicated the prevention and treatment of malaria. Drug-resistant strains of malaria are now common in much of the world.

According to the World Health Organization (WHO), about 3.3 billion people were at risk of malaria in 2010, resulting in an estimated 219 million cases, of which about 80% occurred in 17 countries and about 40% were in India, Nigeria and the Democratic Republic of Congo ^{Footnote 4}. In that same year, there were 660,000 malaria-associated deaths worldwide, of which about 80% occurred in 14 countries^{Footnote 4}. Figure 1 shows the trends in reported malaria incidence between 2000 and 2011.

The global health goals of the Millennium Development Goals (MDGs) include a target to halt the spread of malaria by 2015 and to begin to reverse its incidence^{Footnote 5}. A recent report on the MDGs indicates that between 2000 and 2009, malaria-associated deaths worldwide were reduced by about 20% through the use of critical interventions involving tools effective in preventing and treating the disease. The focus was on sub-Saharan Africa. Since 2000, 11 countries in Africa have reduced the number of confirmed malaria cases and deaths by 50%^{Footnote 5}.

The Canadian Notifiable Diseases Surveillance System (CNDSS), a passive surveillance system co-ordinated by the Public Health Agency of Canada (the Agency), is used to monitor more than 40 nationally notifiable infectious diseases. Notification by provinces and territories to the federal level is voluntary, and cases are based on predetermined surveillance definitions. From 2001 to 2011, 4,254 cases of malaria were diagnosed and reported to the CNDSS; between 2009 and 2011, 18.3% of 1,387 reported cases were among those aged 19 years or less (D Taylor, unpublished data, 2013).

From 2006 to 2010, there were 7,542 malaria cases reported to the Centers for Disease Control and Prevention in the United States (annual average: 1,508 cases; range: 1,298–1,691 cases). Children (< 18 years) represented 19% of these cases (1,418) and 360 (5%) were aged 4 years or less (K Cullen and P Arguin, unpublished data, 2012).

In 2009, 35% of Canadian travellers who went to a destination other than the United States visited a country with a risk of malaria, an increase of 131% from 2000^{Footnote 4}; ^{Footnote 6}. There were 94 cases of malaria diagnosed among returned Canadian travellers presenting to the five Canadian GeoSentinel Surveillance Network sites between September 2009 and September 2011; 60% of these cases were caused by P. falciparum^{Footnote 7}.

Figure 1 – Text equivalent

• Trends in malaria incidence
  • Not applicable or malaria-free
  • On track for 75% decrease in incidence 2000–2015
  • 50–75% decrease in projected incidence 2000–2015
  • <50 decrease in projected incidence 2000–2015
  • Increase in incidence 2000–2011
  • Insufficiently consistent data

Figure 1 footnote *

This map is intended as a visual aid only; see Appendix I for specific country recommendations. Reproduced with permission from: WHO, 2013^{Footnote 8}.

Return to figure 1 footnote * referrer

The Canadian Malaria Network (CMN), in collaboration with the Agency and Health Canada's Special Access Programme, maintains supplies of intravenous artesunate and intravenous quinine at major medical centres across the country to facilitate rapid access to effective treatment of severe malaria. See Appendix V for information on the CMN sites.

From August 2001 to August 2012, there were 195 cases diagnosed with severe or complicated malaria reported to the CMN. Of these 195 cases, 21.1% were aged 17 years and younger and 88.2% were assumed to have acquired malaria in Africa. Where the reason for travel was known, 25.1% were visiting friends and relatives, 17.9% were immigrants, 14% were business travellers and 8% were on vacation. Parenteral quinine was requested for 62.6%, artesunate for 36.4% and both for 1.0%. There were delays in malaria management; only 19.5% presented to medical care within 24 hours of onset of symptoms, and 43.8% waited more than three days before seeking medical care. Diagnosis was delayed more than 24 hours in 33.5% of the cases^{Footnote 9} (Personal communication, A McCarthy and J Geduld, 2012).

Almost all malaria-associated deaths among travellers are due to P. falciparum. The overall case- fatality rate of imported falciparum malaria varies from about 1% to 5% and increases to 20% for those with severe malaria, even when the disease is managed in intensive care units^{Footnote 9}; ^{Footnote 10}. Progression from asymptomatic infection to severe and complicated malaria can be extremely rapid, with death occurring within 36 to 48 hours. The most important factors that determine patient survival are early diagnosis and appropriate therapy.

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