Malaria Outbreak in Riau Province, Sumatra

Malaria cases continue to be reported in the Rokan Hilir regency of the Province of Riau (central east Sumatra). The outbreak was declared an emergency in 2024, and the Health Ministry has struggled to bring it under control over the last 2 years.

More than 230 cases of malaria have been reported since the beginning of this year. Over 95% cases of malaria (2,875) in the province have been tagged to this region.  

Riau Province is home to the Tesso Nilo National Park.

Malaria in Indonesia - Understanding the broader context

Although the number of cases of malaria in Indonesia is the second highest (to Papua New Guinea) in the Western Pacific Region, it is generally accepted that the overall risk to travellers to major urban areas is low.  Malaria cases are concentrated in the remote Eastern Provinces of Papua and West Papua. These areas have limited coverage for health services aimed at prevention, diagnosis and treatment. 

According to the Global Malaria Report for 2025, Indonesia accounts for just over 25% malaria cases or just over 500,000 cases in the region.  Five provinces (East and West Java, Bali, Jakarta and Banten) report no local transmission.

It’s important to be aware that the Western Pacific Region accounts for less than 1% of global malaria.  To put this region into perspective, there are an estimated 282 million global cases of malaria annually with 94% occurring in Africa. 

Malaria is not a rare disease, and it requires special attention if travelling to an area of risk. 

Malaria as a notifiable disease in Australia

Malaria is a notifiable disease in Australia

Four hundred and thirty-seven cases have been reported in the 12 months up to February 2, 2026.  This is more than the 5 yearly averages prior to the pandemic. As a travel health physician is always helpful to know the number of cases identified in Australia but it is more important to see a breakdown of cases by country of travel.  

In a study of imported cases to Australia between 2012 and 2022, 1,433 of 3,024 (45%) were from Sub-Saharan Africa. These cases are mostly individuals visiting family and friends. Another 25% contracted their disease in Papua New Guinea and India. 

Indonesia was not identified as a high-risk location. (Indonesia was in WHO’s Southeast Asia region at the time of the study and only 6% cases were from this region)

This type of information is vital for the practice of good quality travel medicine, and we would hope the newly formed Australian CDC will be able to provide this data in the future. Currently, we rely on World Health Organisation statistics and data from the UK and CDC in the USA.

Malaria risk to travellers

Trips can be very different, even if the country is the same. These differences must be considered when advising on whether someone should take prophylaxis. Travel medicine practitioners will never say there is no risk of contracting malaria in a country which is endemic (eg Indonesia, Vietnam).

It is only possible to give an idea of risk level and leave it up to the traveller to decide whether they want to reduce their risk using prophylaxis or rely on mosquito-avoidance measures only.  For much of Indonesia we rely on mosquito avoidance measures. The latter also helps to reduce the risk of other mosquito-borne disease such as dengue fever which is often of much greater risk.

It is important to consider the following and discuss them with your health provider:

Travel itinerary

While a country may be listed as having endemic malaria it doesn’t mean that all the country has the same risk of exposure. Thailand and Vietnam are both listed as endemic for malaria but in recent years the number of reported cases has dramatically decreased, particularly in urban areas where the conditions are often not favourable for the mosquito which transmits malaria. The same applies to many countries with endemic malaria. Altitude and environmental temperatures also play a role, particularly in a place like South Africa. The malaria mosquito prefers temperatures between 20C and 30C and 

Season of travel

Malaria risk varies according to season of travel. While malaria transmission is consistent for much of the year throughout tropical Africa, it is certainly much less in the cooler months in southern Africa and increases with the wet in Sub-Saharan Africa.  Periodic chemoprophylaxis programs are often used to reduce morbidity and mortality in young children in high transmission months. Transmission is also much reduced in India during the cooler, drier months in northern India and Pakistan. The conditions become less favourable for breeding.  Nighttime temperatures have a major influence.

Accommodation

Malaria is mostly transmitted by a nighttime biting mosquito. The mosquito may be active both outside and inside. Activity may also vary during the night. Some species in Africa are most active in the second half of the night. Staying in well screened accommodation together with air conditioning substantially reduces your risk of exposure. Sleeping under an insecticide impregnated bed net and using knockdown sprays in living areas can also reduce risk.  

Length of stay

Expatriate workers and those visiting family and friends are much more likely to experience a bout of malaria than short term travellers. It is not only due to cumulative risk.  Many will start out on chemoprophylaxis but cease during their stay.  This can have serious consequences if they have not researched the local support services for their diagnostic capability or the quality of medication (fake medication should always be considered). The trans Africa traveller has a much greater risk of serious disease as they usually have limited knowledge of local services. Carrying Emergency Standby Treatment (EST) and having a good understanding of the signs and symptoms of malaria is very important.

Activities

It is important to consider what activities you might be doing on your trip.  In Asia, many activities are during the day. At night you are often in your accommodation or at a venue. 

In Africa, many activities take place early in the early morning or at sunset. During the middle of the day, you retire to your accommodation for rest. 

Malaria risk is a complex subject.  No database can cover the vagaries of international travel.