Plasmodium knowlesi can cause severe malaria in adults; however, descriptions of clinical disease in children are lacking. We reviewed case records of children (age <15 years) with a malaria diagnosis at Kudat District Hospital, serving a largely deforested area of Sabah, Malaysia, during January–November 2009. Sixteen children with PCR-confirmed P. knowlesi monoinfection were compared with 14 children with P. falciparum monoinfection diagnosed by microscopy or PCR. Four children with knowlesi malaria had a hemoglobin level at admission of <10.0 g/dL (minimum lowest level 6.4 g/dL). Minimum level platelet counts were lower in knowlesi than in falciparum malaria (median 76,500/µL vs. 156,000/μL; p = 0.01). Most (81%) children with P. knowlesi malaria received chloroquine and primaquine; median parasite clearance time was 2 days (range 1–5 days). P. knowlesi is the most common cause of childhood malaria in Kudat. Although infection is generally uncomplicated, anemia is common and thrombocytopenia universal. Transmission dynamics in this region require additional investigation.

In South East Asia, dengue epidemics have increased in size and geographical distribution in recent years. We examined the spatiotemporal distribution and epidemiological characteristics of reported dengue cases in the predominantly rural state of Sabah, in Malaysian Borneo-an area where sylvatic and urban circulation of pathogens are known to intersect. Using a public health data set of routinely notified dengue cases in Sabah between 2010 and 2016, we described demographic and entomological risk factors, both before and after a 2014 change in the clinical case definition for the disease. Annual dengue incidence rates were spatially variable over the 7-year study period from 2010-2016 (state-wide mean annual incidence of 21 cases/100,000 people; range 5-42/100,000), but were highest in rural localities in the western districts of the state (Kuala Penyu, Nabawan, Tenom and Kota Marudu). Eastern districts exhibited lower overall dengue rates, although a high proportion of severe (haemorrhagic) dengue cases (44%) were focused in Sandakan and Tawau. Dengue incidence was highest for those aged between 10 and 29 years (24/100,000), and was slightly higher for males compared to females. Available vector surveillance data indicated that during large outbreaks in 2015 and 2016 the mosquito Aedes albopictus was more prevalent in both urban and rural households (House Index of 64%) than Ae. aegypti (15%). Demographic patterns remained unchanged both before and after the dengue case definition was changed; however, in the years following the change, reported case numbers increased substantially. Overall, these findings suggest that dengue outbreaks in Sabah are increasing in both urban and rural settings. Future studies to better understand the drivers of risk in specific age groups, genders and geographic locations, and to test the potential role of Ae. albopictus in transmission, may help target dengue prevention and control efforts.

3435 In South East Asia, dengue epidemics have increased in size and geographical distribution in 36 recent years. Most studies investigating dengue transmission and control have had an urban 37 focus, while less consideration is currently given to rural settings, or where urban and rural 38 areas overlap. We examined the spatiotemporal distribution and epidemiological 39 characteristics of reported dengue cases in the predominantly rural state of Sabah, in 40 Malaysian Borneo -an area where sylvatic and urban circulation of pathogens are known to 41 intersect. We found that annual dengue incidence rates were spatially variable over the 7-42 year study period from 2010-2016 (state-wide mean annual incidence of 21 cases/100,000 43 people; range 5-42/100,000), but were highest in rural localities in the western districts of 44 the state (Kuala Penyu, Nabawan, Tenom and Kota Marudu). The eastern districts exhibited 45 lower overall dengue rates; however, we noted a concentration of severe (haemorrhagic) 46 dengue cases (44%) in Sandakan and Tawau districts. Dengue incidence was slightly higher 47 for males than females, and was significantly higher for both genders aged between 10 and 48 29 years (24/100,000; p=0.029). The largest ever recorded outbreaks occurred during 2015-49 2016, with the vector Aedes albopictus found to be most prevalent in both urban and rural 50 households (House Index of 64%), compared with Ae. Aegypti (15%). These findings suggest 51 that dengue outbreaks in Sabah are driven by the sporadic expansion of dengue virus in both 52 urban and rural settings. This may require tailoring of preventative strategies to suit 53 different transmission ecologies across Sabah. Further studies to better understand the 54 drivers of dengue in Sabah may aid dengue control efforts in Malaysia, and more broadly in 55 South East Asia.3 56 Author summary 57 58 In order to combat the rising regional incidence of dengue in South East Asia, the drivers of 59 transmission must be better characterised across different environmental settings. We 60 conducted the first retrospective analysis of dengue epidemiology in the predominantly rural 61 state of Sabah, Malaysia, where both urban and sylvatic transmission cycles exist. Human 62 notification data over a 7-year period were reviewed and spatiotemporal and demographic 63 risk factors identified. We found: 64 1. Urban habitats and population density are not the only determinants mediating the 65 spread of epidemic dengue in Sabah. Case from both urban and rural localities 66 contributed equally to dengue outbreaks. 67 2. Human demographic risk factors included being aged between 10 and 29 years, and 68 being male. 69 3. High incidence areas for dengue do not predict the occurrence of severe dengue. Severe 70 dengue was largely localised to lower incidence districts in the east of the state. 71 4. The sole presence of Aedes albopictus in and around the majority of urban and rural 72 case households suggests that this vector may play a major role in facilitating outbr...