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The Asia-Pacific International Center of Excellence in Malaria Research (ICEMR) was funded in 2016 to conduct a coordinated set of field and in-depth biological studies in Cambodia and Papua New Guinea (PNG), in sites that span the range of transmission intensities currently found in the Asia-Pacific regions. The overall objective is to gain an understanding of key parasite, human host, and vector factors involved in maintaining transmission in the face of intensified control and elimination programs, and to develop novel approaches to identify and target residual transmission foci. In this article, we will describe how the ICEMR program was designed to address key knowledge gaps and priority areas for the malaria control programs in each country. In PNG, partners have worked together on two consecutive ICEMR grants (2009–2016 and 2017–2024) and we present a case study of the partnership and engagement approach that has led to stronger coordination of research activities and integration with program, informing country-level strategic planning and prioritization of control activities. In both settings, the ICEMR program has generated insights into transmission foci, risk factors for ongoing transmission, highlighting the hidden burden of vivax malaria, and the need for additional complementary vector control tools. Finally, we will summarize the emerging research questions and priority areas—namely surveillance, vivax malaria, new vector control tools, and community/health systems-oriented approaches—where further tool development and implementation research have been identified as being needed to guide policy.

Plasmodium falciparum resistance to artemisinin-based combination therapy (ACT) is a global threat to malaria control and elimination efforts. Mutations in the P. falciparum kelch13 gene (Pfk13) that are associated with delayed parasite clearance have emerged on the Thai-Cambodian border since 2008. There is growing evidence of widespread Pfk13 mutations throughout South-East Asia and they have independently emerged in other endemic regions. In Papua New Guinea (PNG), Pfk13 “C580Y” mutant parasites with reduced in vitro sensitivity to artemisinin have been isolated in Wewak, a port town in East Sepik Province. However, the extent of any local spread of these mutant parasites in other parts of PNG is unknown. We investigated the prevalence of Pfk13 mutations in multiple malaria-endemic regions of PNG. P. falciparum isolates (n = 1152) collected between 2016 and 2018 and assessed for Pfk13 variation by sequencing. Of 663 high quality Pfk13 sequences a total of five variants were identified. They included C580Y, a mutation at a previously documented polymorphic locus: N499K, and three previously undescribed mutations: R471C, K586E and Y635C. All variants were found in single isolates, indicating that these Pfk13 mutations were rare in the areas surveyed. Notably, C580Y was absent from Maprik district, which neighbours Wewak where C580Y mutant parasites were previously identified. The single C580Y isolate was found in the port town of Lae, Morobe Province, a potential entry site for the importation of drug resistant parasites into PNG. Although sample size in this location was small (n = 5), our identification of a C580Y mutant in this second location is concerning, highlighting the urgent need for further surveillance in Lae. Other Pfk13 mutants were rare in PNG between 2016 and 2018. Continued surveillance for molecular markers of drug resistance is critically important to inform malaria control in PNG.

Papua New Guinea (PNG) has the highest malaria transmission outside of Africa. Long-lasting insecticidal nets (LLINs) are believed to have helped to reduce average malaria prevalence in PNG from 16% in 2008 to 1% in 2014. Since 2015 malaria in PNG has resurged significantly. Here, we present observations documenting decreased bioefficacy of unused LLINs with manufacturing dates between 2013 and 2019 collected from villages and LLIN distributors in PNG. Specifically, we show that of n = 167 tested LLINs manufactured after 2013, only 17% are fulfilling the required World Health Organisation bioefficacy standards of ≥ 80% 24 h mortality or ≥ 95% 60 min knockdown in bioassays with pyrethroid susceptible Anopheles farauti mosquitoes. In contrast, all (100%, n = 25) LLINs with manufacturing dates prior to 2013 are meeting these bioefficacy standards. These results suggest that decreased bioefficacy of LLINs is contributing to the malaria resurgence in PNG and increased scrutiny of LLIN quality is warranted., Malaria prevalence in Papua New Guinea has risen in recent years after almost a decade of decline. In this study, the authors demonstrate that long-lasting insecticidal nets used in the country that were manufactured since 2013 have significantly reduced bioefficacy.

Malaria surveillance and response-systems are essential for identifying the areas most affected by malaria and for targeting interventions and optimising resources. This study aimed to assess whether the visualisation of routinely collected health facility data linked to village of residence provides evidence for targeting control interventions in four sentinel health facilities in Papua New Guinea. A video format was used to visualise the dynamics in case incidence over time and space alongside photographs illustrating the context of the data collection in the study sites. Incidence changes overtime were illustrated in animated maps. Despite limitations, this approach appeared useful in sites with very few remaining cases or with increasingly marked heterogeneity. Villages that could benefit from targeted interventions or investigations were identified.

Background In 2009, the Papua New Guinea (PNG) Department of Health adopted artemether–lumefantrine (AL) and dihydroartemisinin–piperaquine (DHA-PPQ) as the first- and second-line treatments for uncomplicated malaria, respectively. This study was conducted to assess the efficacy of both drugs following adoption of the new policy. Methods Between June 2012 and September 2014, a therapeutic efficacy study was conducted in East Sepik and Milne Bay Provinces of PNG in accordance with the standard World Health Organization (WHO) protocol for surveillance of anti-malarial drug efficacy. Patients ≥ 6 months of age with microscopy confirmed Plasmodium falciparum or Plasmodium vivax mono-infections were enrolled, treated with AL or DHA-PPQ, and followed up for 42 days. Study endpoints were adequate clinical and parasitological response (ACPR) on days 28 and 42. The in vitro efficacy of anti-malarials and the prevalence of selected molecular markers of resistance were also determined. Results A total of 274 P. falciparum and 70 P. vivax cases were enrolled. The day-42 PCR-corrected ACPR for P. falciparum was 98.1% (104/106) for AL and 100% (135/135) for DHA-PPQ. The day-42 PCR-corrected ACPR for P. vivax was 79.0% (15/19) for AL and 92.3% (36/39) for DHA-PPQ. Day 3 parasite clearance of P. falciparum was 99.2% with AL and 100% with DHA-PPQ. In vitro testing of 96 samples revealed low susceptibility to chloroquine (34% of samples above IC50 threshold) but not to lumefantrine (0%). Molecular markers assessed in a sub-set of the study population indicated high rates of chloroquine resistance in P. falciparum (pfcrt SVMNT: 94.2%, n = 104) and in P. vivax (pvmdr1 Y976F: 64.8%, n = 54). Conclusions AL and DHA-PPQ were efficacious as first- and second-line treatments for uncomplicated malaria in PNG. Continued in vivo efficacy monitoring is warranted considering the threat of resistance to artemisinin and partner drugs in the region and scale-up of artemisinin-based combination therapy in PNG. Electronic supplementary material The online version of this article (10.1186/s12936-018-2494-z) contains supplementary material, which is available to authorized users.

Background The objective of the study was to describe an m-health initiative to strengthen malaria surveillance in a 184-health facility, multi-province, project aimed at strengthening the National Health Information System (NHIS) in a country with fragmented malaria surveillance, striving towards enhanced control, pre-elimination. Methods A remote-loading mobile application and secure online platform for health professionals was created to interface with the new system (eNHIS). A case-based malaria testing register was developed and integrated geo-coded households, villages and health facilities. A malaria programme management dashboard was created, with village-level malaria mapping tools, and statistical algorithms to identify malaria outbreaks. Results Since its inception in 2015, 160,750 malaria testing records, including village of residence, have been reported to the eNHIS. These case-based, geo-coded malaria data are 100% complete, with a median data entry delay of 9 days from the date of testing. The system maps malaria to the village level in near real-time as well as the availability of treatment and diagnostics to health facility level. Data aggregation, analysis, outbreak detection, and reporting are automated. Conclusions The study demonstrates that using mobile technologies and GIS in the capture and reporting of NHIS data in Papua New Guinea provides timely, high quality, geo-coded, case-based malaria data required for malaria elimination. The health systems strengthening approach of integrating malaria information management into the eNHIS optimizes sustainability and provides enormous flexibility to cater for future malaria programme needs.

Malaria is endemic across lowland Papua New Guinea (PNG) and case management has been based on symptomatic diagnosis and presumptive treatment of fever cases with an antimalarial. This study aimed to investigate the prevalence of malaria infection among fever cases presenting to 5 purposely selected sentinel health facilities in order to estimate the proportion of patients requiring antimalarial drugs. A total of 1807 fever patients were screened. Overall, 45% of fever patients had a positive malaria blood slide; 35% were infected with Plasmodium falciparum, 9% with P. vivax and 2% with P. malariae. Slide positivity was highest in Dreikikir (75%) and lowest in Wipim (2%). Among patients aged 1-4 years, 22% had moderate to severe anaemia (Hb8 g/dI) and 21% of children 2-9 years of age showed signs of splenomegaly (Hackett score 1-5). Comorbidity differed significantly between study sites and was not closely correlated with malaria infection. Clinical diagnosis by health facility staff was malaria for 67% of all fever cases, including 89% of slide-positive and 48% of slide-negative patients. 70% of rapid diagnostic test-negative cases were treated with an antimalarial. It is estimated that due to the lack of parasitological diagnosis the selected health facilities reported an excess of 18% (Dreikikir) to 98% (Wipim) malaria patients on average each month. In consideration of the significant differences in malaria-attributable fevers between study sites, the implementation of parasitological diagnosis in health facilities and administration of antimalarials only to test-positive patients has the potential to significantly improve the management of fever cases and reporting of malaria. A better tailoring to different settings may increase the effectiveness of malaria control interventions.

The Global Fund to Fight AIDS, Tuberculosis and Malaria is the major funaer Of the National Malaria Control Program in Papua New Guinea (PNG). One of the requirements of a Global Fund grant is the regular and accurate reporting of program outcomes and impact. Under-performance as well as failure to report can result in reduction or discontinuation of program funding. While national information systems should be in a position to provide accurate and comprehensive information for program evaluation, systems in developing countries are often insufficient. This paper describes the five-year plan for the evaluation of the Global Fund Round 8 malaria grant to PNG (2009-2014) developed by the Papua New Guinea Institute of Medical Research (PNGIMR). It builds on a complementary set of studies including national surveys and sentinel site surveillance for the assessment of program outcomes and impact. The PNGIMR evaluation plan is an integral part of the Global Fund grant. The evaluation program assesses intervention coverage (at individual, household and health facility levels), antimalarial drug efficacy, indicators of malaria transmission and morbidity (prevalence, incidence), and all-cause mortality. Operational research studies generate complementary information for improving the control program. Through the evaluation, PNGIMR provides scientific expertise to the PNG National Malaria Control Program and contributes to building local capacity in monitoring and evaluation. While a better integration of evaluation activities into routine systems would be desirable, it is unlikely that sufficient capacity for data analysis and reporting could be established at the National Department of Health (NDoH) within a short period of time. Long-term approaches should aim at strengthening the national health information system and building sufficient capacity at NDoH for routine analysis and reporting, while more complex scientific tasks can be supported by the PNGIMR as the de facto research arm of NDoH.

BACKGROUND: Papua New Guinea exhibits a complex malaria epidemiology due to diversity in malaria parasites, mosquito vectors, human hosts, and their natural environment. Heterogeneities in transmission and burden of malaria at various scales are likely to affect the success of malaria control interventions, and vice-versa. This manuscript assesses changes in malaria prevalence, incidence and transmission in sentinel sites following the first national distribution of long-lasting insecticidal nets (LLINs). METHODS: Before and after the distribution of LLINs, data collection in six purposively selected sentinel sites included clinical surveillance in the local health facility, household surveys and entomological surveys. Not all activities were carried out in all sites. Mosquitoes were collected by human landing catches. Diagnosis of malaria infection in humans was done by rapid diagnostic test, light microscopy and PCR for species confirmation. RESULTS: Following the roll-out of LLINs, the average monthly malaria incidence rate dropped from 13/1,000 population to 2/1,000 (incidence rate ratio = 0.12; 95 % CI: 0.09-0.17; P < 0.001). The average population prevalence of malaria decreased from 15.7 % pre-LLIN to 4.8 % post-LLIN (adjusted odds ratio = 0.26; 95 % CI: 0.20-0.33; P < 0.001). In general, reductions in incidence and prevalence were more pronounced in infections with P. falciparum than with P. vivax. Additional morbidity indicators (anaemia, splenomegaly, self-reported fever) showed a decreasing trend in most sites. Mean Anopheles man biting rates decreased from 83 bites/person/night pre-LLIN to 31 post-LLIN (P = 0.008). Anopheles species composition differed between sites but everywhere diversity was lower post-LLIN. In two sites, post-LLIN P. vivax infections in anophelines had decreased but P. falciparum infections had increased despite the opposite observation in humans. CONCLUSIONS: LLIN distribution had distinct effects on P. falciparum and P. vivax. Higher resilience of P. vivax may be attributed to relapses from hypnozoites and other biological characteristics favouring the transmission of P. vivax. The effect on vector species composition varied by location which is likely to impact on the effectiveness of LLINs. In-depth and longer-term epidemiological and entomological investigations are required to understand when and where residual transmission occurs and whether observed changes are sustained.

Objectives: To assess the population prevalence of malaria in villages across Papua New Guinea (PNG) following the first roll-out of free long-lasting insecticidal nets (LLIN). Methods: Between October 2008 and August 2009, a household survey was conducted in 49 random villages in districts covered by the LLIN distribution campaign. The survey extended to 19 villages in sentinel sites that had not yet been covered by the campaign. In each village, 30 households were randomly sampled, household heads were interviewed and capillary blood samples were collected from all consenting household members for microscopic diagnosis of malaria. Results: Malaria prevalence ranged from 0% to 49.7% with a weighted average of 12.1% (95% CI 9.5, 15.3) in the national sample. More people were infected with Plasmodium falciparum (7.0%; 95% CI 5.4, 9.1) than with P. vivax (3.8%; 95% CI 2.4, 5.7) or P. malariae (0.3%; 95% CI 0.1, 0.6). Parasitaemia was strongly age-dependent with a P. falciparum peak at age 5-9 years and a P. vivax peak at age 1-4 years, yet with differences between geographical regions. Individual LLIN use and high community coverage were associated with reduced odds of infection (OR = 0.64 and 0.07, respectively; both P < 0.001). Splenomegaly in children and anaemia were common morbidities attributable to malaria. Conclusions: Malaria prevalence across PNG is again at levels comparable to the 1970s. The strong association of LLIN use with reduced parasitaemia supports efforts to achieve and maintain high country-wide coverage. P. vivax infections will require special targeted approaches across PNG.

To investigate changes in malaria prevalence in Papua New Guinea after the distribution of long-lasting Insecticide-treated nets, starting in 2004, and the introduction of artemisinin-based combination therapy in 2011.Two malaria surveys were conducted in 2010-2011 and 2013-2014. They included 77 and 92 randomly selected villages, respectively. In each village, all members of 30 randomly selected households gave blood samples and were assessed for malaria infection by light microscopy. In addition, data were obtained from a malaria survey performed in 2008-2009.The prevalence of malaria below 1600 m in altitude decreased from 11.1% (95% confidence interval, CI: 8.5-14.3) in 2008-2009 to 5.1% (95% CI 3.6-7.4) in 2010-2011 and 0.9% (95% CI 0.6-1.5) in 2013-2014. Prevalence decreased with altitude.Large-scale insecticide-treated net distribution was associated with an unprecedented decline in malaria prevalence throughout Papua New Guinea, including epidemic-prone highland areas. The decline was accompanied by broader health benefits, such as decreased morbidity. Better clinical management of nonmalarial fever and research into residual malaria transmission are required.Étudier les changements observés à l'égard de la prévalence du paludisme en Papouasie-Nouvelle-Guinée suite à la distribution, depuis 2004, de moustiquaires imprégnées d'insecticides de longue durée et à l'introduction, depuis 2011, d'une combinaison thérapeutique à base d’artémisinine.Deux enquêtes portant sur le paludisme ont été menées en 2010-2011 et 2013-2014. Elles incluaient respectivement 77 et 92 villages, sélectionnés d'une manière aléatoire. Dans chacun de ces villages, tous les membres de 30 foyers sélectionnés aléatoirement ont donné des échantillons sanguins et été soumis à un test de dépistage de l'infection palustre par microscopie optique. Des données ont par ailleurs été tirées d'une enquête sur le paludisme réalisée en 2008-2009.La prévalence du paludisme à moins de 1600 m d'altitude est passée de 11,1% (intervalle de confiance, IC, à 95%: 8,5–14,3) en 2008–2009 à 5,1% (IC à 95%: 3,6–7,4) en 2010–2011 et 0,9% (IC à 95%: 0,6–1,5) en 2013–2014. La prévalence diminuait avec l'altitude. Plasmodium falciparum n'était pas systématiquement plus courant que P. vivax, mais l'était dans l'ensemble et, dans un premier temps, la prévalence de l'infection à P. vivax a diminué plus lentement que la prévalence de l'infection à P. falciparum. Les infections palustres ont été regroupées par foyers. Contrairement à ce qu'indiquaient les résultats obtenus en 2008-2009, aucune corrélation significative entre l'utilisation d'une moustiquaire et la prévalence n'a été constatée dans le cadre des deux dernières enquêtes. Les prévalences de la fièvre et de la splénomégalie ont également diminué, mais leur corrélation avec l'infection palustre est devenue plus forte.La distribution à grande échelle de moustiquaires imprégnées d'insecticides a été associée à un déclin sans précédent de la prévalence du paludisme dans l'ensemble de la Papouasie-Nouvelle-Guinée, et notamment dans les régions montagneuses sujettes aux épidémies. Ce déclin s'est accompagné d'autres bienfaits sur la santé, et notamment d'une diminution de la morbidité. Il est nécessaire d'améliorer la prise en charge clinique de la fièvre non palustre ainsi que les recherches sur la transmission résiduelle du paludisme.Investigar los cambios en la prevalencia de la malaria en Papua Nueva Guinea tras la distribución de mosquiteros tratados con insecticida de larga duración, a partir de 2004, y la introducción de terapias combinadas basadas en la artemisinina en 2011.Se llevaron a cabo dos encuestas sobre la malaria en 2010–2011 y 2013–2014. Incluían 77 y 92 aldeas seleccionadas al azar, respectivamente. En cada aldea, todos los miembros de 30 hogares seleccionados al azar dieron muestras de sangre y se evaluaron de infección de malaria con microscopio óptico. Además, se obtuvieron datos de la encuesta sobre la malaria realizada en 2008–2009.La prevalencia de la malaria por debajo de 1600 m de altitud descendió del 11.1% (intervalo de confidencia (IC) del 95%: 8.5–14.3) en 2008–2009 al 5.1% (95% IC 3.6–7.4) en 2010–2011 y 0.9% (95% IC 0.6–1.5) en 2013–2014. La prevalencia descendía con la altitud.La distribución de mosquiteros tratados con insecticida a gran escala se asoció con un descenso sin precedentes en la prevalencia de la malaria en toda Papua Nueva Guinea, incluidas las áreas altas con propensión a causar epidemias. El descenso estuvo acompañado de beneficios saludables más amplios, como el descenso de la morbilidad. Se requieren una mejor gestión clínica de la fiebre no relacionada con la malaria y la investigación de la transmisión residual de la malaria.التحقيق في تغيرات انتشار الملاريا في بابوا غينيا الجديدة بعد توزيع الناموسيات المُعالَجة بالمبيد الحشري ذات المفعول الممتد، بدءًا من عام 2004، وطرح العلاج المجمّع المرتكز على مادة الأرتيميسينين في عام 2011.أُجريت دراستان استقصائيتان للملاريا في عامي 2010-2011 و2013-2014. وشملتا 77 و92 قرية تم اختيارها عشوائيًا على التوالي. في كل قرية، قدم جميع أفراد الثلاثين أسرة التي تم اختيارها عشوائيًا عينات من الدم وتم تقييمها بواسطة الفحص المجهري لمعرفة ما إذا كان هناك إصابة بالملاريا. وبالإضافة إلى ذلك، تم الحصول على البيانات من مسح الملاريا الذي تم إجراؤه في الفترة ما بين عامي 2008-2009.انخفض معدل انتشار الملاريا في المناطق التي لا يزيد ارتفاعها عن 1600 متر من‏11.1 % (بنطاق ثقة يبلغ 95‏%: 8.5–14.3) في الفترة ما بين عاميّ 2008–2009 إلى ‏5.1‏% (بنطاق ثقة ‏95‏%: 3.6–7.4) في الفترة ما بين عاميّ 2010–2011، و0.9‏% (بنطاق ثقة 95‏%: 0.6–1.5) في الفترة ما بين عامي 2013–2014، بما يعني انخفاض انتشار المرض مع زيادة الارتفاع. كانت "المتصورة المنجلية" (الملاريا الخبيثة) أكثر شيوعًا من "المتصورة النشيطة" بشكل إجمالي ولكن ليس في كل الأماكن، كما انخفض معدل انتشار الإصابة "بالمتصورة النشيطة" بمعدل أبطأ من الإصابة "بالمتصورة المنجلية". وتم تجميع إصابات الملاريا في الأسر. وفي مقابل النتائج التي تم التوصل إليها في الفترة ما بين عامي 2008-2009، لم يتم العثور على ارتباط كبير بين استخدام الناموسية ومعدل الانتشار في الدراستين الأخيرتين. كما انخفض انتشار الحمى وتضخم الطحال ولكن أصبح ارتباطهما بعدوى الملاريا أقوى.ارتبط توزيع الناموسية المُعالَجة بالمبيد الحشري على نطاق واسع بحدوث انخفاض غير مسبوق في انتشار الملاريا في جميع أنحاء بابوا غينيا الجديدة، بما في ذلك المناطق المرتفعة المعرضة للأوبئة. ورافق هذا الانخفاض فوائد صحية أكثر، مثل انخفاض معدلات الاعتلال. ويلزم توفير إدارة سريرية أفضل للحمى غير الملارية وإجراء الأبحاث حول انتقال الملاريا المتبقية.旨在调查自 2004 年开始分发长效驱虫蚊帐并于 2011 年开始引入青蒿素联合疗法后，新几内亚（旧称巴布亚）疟疾患病率的变化。.在 2010 年至 2011 年和 2013 年至 2014 期间分别进行过两次疟疾调查。这两次调查分别包括了 77 个和 92 个随机选择的村庄。 在每个村庄，30 个随机选择的家庭的所有成员均提供了血液样本，并通过光学显微镜评估疟疾感染情况。 另外，数据还来自于 2008 年至 2009 年进行的疟疾调查。.自 2008 年至 2009 年期间，海拔 1600 米以下的疟疾患病率从 2008 年至 2009 年的 11.1％（95％ 置信区间，CI: 8.5–14.3）降到 2010 年至 2011 年的 5.1%（95% 置信区间，CI：3.6–7.4）并在 2013 年至 2014 年降到 0.9%（95% 置信区间，CI：0.6–1.5)。患病率随着海拔高度下降而降低。 总体而言大规模驱虫蚊帐的普及与新几内亚（旧称巴布亚）疟疾患病率前所未有的下降之间有相关性，包括流行病高发的高海拔地带。 这种下降伴随着范围更广的健康益处，如发病率下降。 需要对非疟疾发烧进行更有效的临床管理和研究，以降低尚有残留的疟疾传播。.Изучить изменения в распространенности малярии в Папуа — Новой Гвинее после внедрения сеток, обработанных инсектицидами длительного действия, с 2004 года и после введения в 2011 году комбинированной терапии на основе артемизинина.В 2010–2011 гг. и 2013–2014 гг. были проведены два обследования на инфицирование малярией. Они включали соответственно 77 и 92 случайно выбранных поселка. В каждом поселке все представители 30 случайно отобранных домохозяйств сдали образцы крови, которые прошли исследование с использованием световой микроскопии на предмет заражения малярией. Кроме того, были получены результаты обследования на малярию, проведенного в 2008–2009 гг.Распространенность малярии на высоте ниже 1600 м над уровнем моря снизилась с 11,1% (95%-й доверительный интервал, ДИ: 8,5–14,3) в 2008–2009 гг. до 5,1% (95%-й ДИ: 3,6–7,4) в 2010–2011 гг. и до 0,9% (95%-й ДИ: 0,6–1,5) в 2013–2014 гг. Распространенность инфекции снижалась по мере роста высоты над уровнем моря. ВозбудительШирокомасштабное распространение использования сеток, обработанных инсектицидами длительного действия, было связано с беспрецедентным снижением распространенности малярии во всей Папуа — Новой Гвинее, включая районы, подверженные эпидемии. Снижение распространенности инфекции сопровождалось более широкими преимуществами для здоровья, такими как снижение заболеваемости. Требуется введение более качественных клинических протоколов ведения и лечения лихорадки, не связанной с малярией, а также проведение исследования оставшихся очагов распространения малярии.

Background Papua New Guinea (PNG) is a highly malaria endemic country in the South-West Pacific with a population of approximately 6.6 million (2009). In 2004, the country intensified its malaria control activities with support from the Global Fund. With the aim of achieving 80% ownership and usage, a country-wide campaign distributed two million free long-lasting insecticide-treated nets (LLINs). Methods In order to evaluate outcomes of the campaign against programme targets, a country-wide household survey based on stratified multi-stage random sampling was carried out in 17 of the 20 provinces after the campaign in 2008/09. In addition, a before-after assessment was carried out in six purposively selected sentinel sites. A structured questionnaire was administered to the heads of sampled households to elicit net ownership and usage information. Results After the campaign, 64.6% of households owned a LLIN, 80.1% any type of mosquito net. Overall usage by household members amounted to 32.5% for LLINs and 44.3% for nets in general. Amongst children under five years, 39.5% used a LLIN and 51.8% any type of net, whereas 41.3% of pregnant women used a LLIN and 56.1% any net. Accessibility of villages was the key determinant of net ownership, while usage was mainly determined by ownership. Most (99.5%) of the household members who did not sleep under a net did not have access to a (unused) net in their household. In the sentinel sites, LLIN ownership increased from 9.4% to 88.7%, ownership of any net from 52.7% to 94.1%. Usage of LLINs increased from 5.5% to 55.1%, usage of any net from 37.3% to 66.7%. Among children under five years, usage of LLINs and of nets in general increased from 8.2% to 67.0% and from 44.6% to 76.1%, respectively (all p ≤ 0.001). Conclusions While a single round of free distribution of LLINs significantly increased net ownership, an insufficient number of nets coupled with a heterogeneous distribution led to overall low usage rates. Programme targets were missed mainly as a result of the distribution mechanism itself and operational constraints in this very challenging setting.