Malaria, other vectorborne and parasitic diseases

Malaria factsheet (WPRO)

April 2012

Key facts

  • Malaria is a life-threatening disease caused by parasites that are transmitted to people through the bites of infected mosquitoes.
  • In the WHO Western Pacific Region, 10 out of 37 countries and areas are endemic for malaria. They are Cambodia, China, Lao PDR, Malaysia, Papua New Guinea, Philippines, Republic of Korea, Solomon Islands, Vanuatu and Viet Nam.
  • In 2010 there were 262,192 confirmed malaria cases reported in the Region with an estimated 899 malaria deaths.
  • Malaria is transmitted by female Anopheles mosquitoes. There are over 15 species of Anopheles in the Region capable of malaria transmission; each has its own breeding preferences and biting habits.
  • Malaria is preventable and curable.
  • Over the past decade, many countries in the Region have been very successful in reducing the burden of malaria. From 2000 to 2010, the number of confirmed malaria cases was reduced by 37% while malaria deaths declined by 62%. However, many cases and deaths still go unrecorded.
  • Artemisinin resistant falciparum malaria remains one of the biggest challenges to malaria control in the Region. While containment efforts on the Cambodia-Thailand border have been successful, new foci of resistance are being discovered in other areas, necessitating a regional containment strategy.
  • The importance of vivax malaria is increasing throughout the Region. More than half of malaria endemic countries do not provide radical cure to vivax patients out of concern of adverse effects that can occur in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency, which is widely prevalent in the Region.
  • Knowlesi malaria is a monkey malaria that can also infect humans and can be fatal. Populations living or working close to forested areas where macaque monkeys and suitable vector mosquitoes are present are at most risk. There is no evidence of human-to-human transmission of knowlesi malaria.

Regional milestones

  • The Regional Action Plan for Malaria Control and Elimination in the Western Pacific (2010–2015) was developed in close association with Member States and calls for consolidating and building on achievements made in malaria control and progressively eliminating malaria where possible.
  • The Regional Malaria Programme Managers' meeting, held in August 2011, was satisfied with progress towards achieving the objectives of the Regional Action Plan. The meeting urged further commitment towards malaria control and elimination. This report was shared with the 2011 Regional Committee.
  • In the Region, nine out of ten malaria-endemic countries are embarking on malaria elimination and implementing elimination strategies. These nine countries have incorporated elimination objectives into their national malaria strategic plans.
  • A regional consultative meeting on public health significance of knowlesi malaria was convened by WHO. Recommendations were made and are being implemented.

Malaria vector control

  • The use of insecticidal bed nets is the mainstay of malaria prevention in all malaria endemic areas and has been shown to reduce malaria mortality and morbidity. In the Region, all countries receiving support from the Global Fund are switching from insecticide-treated nets, which need periodic retreatment, to long-lasting insecticidal nets.
  • Indoor residual spraying (IRS) is a first-line intervention for containing malaria epidemics and is effective in reducing malaria prevalence and incidence in areas of high transmission. It is also a malaria elimination tool. Seven out of ten malaria endemic countries are currently using IRS to supplement insecticide treated mosquito nets as a vector control intervention.
  • Insecticide resistance can substantially impact on vector control efficacy. To combat this threat and support countries, a web-based Asia Pacific Insecticide Resistance Monitoring Network was established in 2011 to track efficacy of insecticides and monitor spread of resistance in vectors of both malaria and dengue.

Artemisinin and artemisinin resistance

  • Artemisinin, also known as Qing-haosu, is a traditional Chinese herbal drug used for more than 1500 years primarily to treat fevers. Artemisinin and its derivatives are the most rapidly effective antimalarial drugs known and are active against malaria parasite strains that are resistant to other common antimalarials.
  • However when treated with an artemisinin-based monotherapy, patients may discontinue treatment prematurely following the rapid disappearance of malaria symptoms and this can lead to the development of resistance. This has been observed in areas of Southeast Asia. More comprehensive information is available in the Global Plan for Artemisinin Resistance Containment (GPARC).
  • Artemisinin resistant falciparum malaria remains an important challenge both to malaria control and elimination efforts in the Region. WHO recommends that artemisinin drugs should always be used in specific combinations.
  • Intensified therapeutic efficacy monitoring has identified other areas with artemisinin resistant falciparum malaria including in southern Vietnam and in Thailand/Myanmar border areas. A joint assessment of artemisinin resistance status and response capacity by Member States and partners has been conducted and a regional strategy – Greater Mekong Subregion Plan for Artemisinin Resistance Containment developed.

Counterfeit anti-malarial drugs

  • Evidence from surveys has shown that counterfeit anti-malarial medicines are widespread in the Greater Mekong Sub-region. The packaging of some, especially of fake artesunate, is increasingly sophisticated, making it hard to differentiate the fakes from the real drugs.
  • WPRO has produced an advocacy video on fake drugs that targets decision-makers and the general public. It has been widely distributed and shown on global and local TV stations. It is available in Lao, Khmer, Vietnamese and Chinese languages.
  • In cooperation with partners, including INTERPOL, WHO is supporting countries to detect and stop the production and distribution of fake antimalarial medicines.
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