Epidemiology of dengue reported in the World Health Organization's Western Pacific Region, 2013-2019.

The global burden of dengue, an emerging and re-emerging mosquito-borne disease, increased during the 20-year period ending in 2019, with approximately 70% of cases estimated to have been in Asia. This report describes the epidemiology of dengue in the World Health Organization's Western Pacific Region during 2013-2019 using regional surveillance data reported from indicator-based surveillance systems from countries and areas in the Region, supplemented by publicly available dengue outbreak situation reports. The total reported annual number of dengue cases in the Region increased from 430 023 in 2013 to 1 050 285 in 2019, surpassing 1 million cases for the first time in 2019. The reported case-fatality ratio ranged from 0.19% (724/376 972 in 2014 and 2030/1 050 285 in 2019) to 0.30% (1380/458 843 in 2016). The introduction or reintroduction of serotypes to specific areas caused several outbreaks and rare occurrences of local transmission in places where dengue was not previously reported. This report reinforces the increased importance of dengue surveillance systems in monitoring dengue across the Region.

Concurrent outbreaks of circulating vaccine-derived poliovirus types 1 and 2 affecting the Republic of the Philippines and Malaysia, 2019-2021.

Concurrent outbreaks of circulating vaccine-derived poliovirus serotypes 1 and 2 (cVDPV1, cVDPV2) were confirmed in the Republic of the Philippines in September 2019 and were subsequently confirmed in Malaysia by early 2020. There is continuous population subgroup movement in specific geographies between the two countries. Outbreak response efforts focused on sequential supplemental immunization activities with monovalent Sabin strain oral poliovirus vaccine type 2 (mOPV2) and bivalent oral poliovirus vaccines (bOPV, containing Sabin strain types 1 and 3) as well as activities to enhance poliovirus surveillance sensitivity to detect virus circulation. A total of six cVDPV1 cases, 13 cVDPV2 cases, and one immunodeficiency-associated vaccine-derived poliovirus type 2 case were detected, and there were 35 cVDPV1 and 31 cVDPV2 isolates from environmental surveillance sewage collection sites. No further cVDPV1 or cVDPV2 have been detected in either country since March 2020. Response efforts in both countries encountered challenges, particularly those caused by the global COVID-19 pandemic. Important lessons were identified and could be useful for other countries that experience outbreaks of concurrent cVDPV serotypes.

Street Food in Malaysia: What Are the Sodium Levels?

Street food is a major source of food in middle- and low-income countries as it is highly accessible and inexpensive. However, it is usually perceived as unhealthy due to the high levels of sodium, sugar, and fat content. However, there is little analytical data on the sodium levels in the street foods of Malaysia. This study started with a survey to determine the most frequently available street foods in every state in Malaysia, followed by food sampling and the analysis of sodium (reported mg/100 g sample). Street food in the snack category contained the highest amount of sodium (433 mg), followed by main meals (336.5 mg) and desserts (168 mg). Approximately 30% of the local street food in this study was deep-fried. Snacks from processed food (8%) contained high sodium content (500−815 mg). Fried noodles and noodle soup contained the highest amount of sodium (>2000 mg sodium) based on per serving. Most main dishes that use a variety of sauces contained high amounts of sodium. These findings were recorded in the Malaysian Food Composition Database. Moreover, this study could raise awareness and serve as baseline data for future interventions on the sodium content in the street foods of Malaysia.

Molecular surveillance of pfcrt, pfmdr1 and pfk13-propeller mutations in Plasmodium falciparum isolates imported from Africa to China.

BACKGROUND: The emergence and spread of multidrug resistance poses a significant risk to malaria control and eradication goals in the world. There has been no indigenous malaria cases reported in China since 2017, and China is approaching national malaria elimination. Therefore, anti-malarial drug resistance surveillance and tracking the emergence and spread of imported drug-resistant malaria cases will be necessary in a post-elimination phase in China. METHODS: Dried blood spots were obtained from Plasmodium falciparum-infected cases returned from Africa to China between 2012 and 2015, prior to anti-malarial drug treatment. Whole DNA were extracted and known polymorphisms relating to drug resistance of pfcrt, pfmdr1 gene, and the propeller domain of pfk13 were evaluated by nested PCR and sequencing. The haplotypes and prevalence of these three genes were evaluated separately. Chi-squared test and Fisher's exact test were used to evaluate differences among the different sub-regions of Africa. A P value < 0.05 was used to evaluate differences with statistical significance. The maps were created using ArcGIS. RESULTS: A total of 731 P. falciparum isolates were sequenced at the pfcrt locus. The wild type CVMNK was the most prevalent haplotype with prevalence of 62.8% and 29.8% of the isolates showed the triple mutant haplotype CVIET. A total of 434 P. falciparum isolates were successfully sequenced and pfmdr1 allelic variants were observed in only codons 86, 184 and 1246. Twelve haplotypes were identified and the prevalence of the wild type pfmdr1 NYD was 44.1%. The single mutant pfmdr1 in codons 86 and 184 was predominant but the haplotype NYY with single mutation in codon 1246 was not observed. The double mutant haplotype YFD was common in Africa. About 1,357 isolates were successfully sequenced of pfk13-propeller domain, the wild type was found in 1,308 samples (96.4%) whereby 49 samples (3.6%) had mutation in pfk13. Of 49 samples with pfk13 mutations, 22 non-synonymous and 4 synonymous polymorphic sites were confirmed. The A578S was the most common mutation in pfk13-propeller domain and three mutations associated with artemisinin resistance (M476I, R539T, P553L) were identified in three isolates. CONCLUSION: This study provides evidence that could give insight into potential issues with anti-malarial drug resistance to inform national drug policy in China in order to treat imported cases.

Use of a public-private partnership in malaria elimination efforts in Sri Lanka; a case study.

BACKGROUND: In special circumstances, establishing public private partnerships for malaria elimination may achieve targets faster than the state sector acting by itself. Following the end of the separatist war in Sri Lanka in 2009, the Anti Malaria Campaign (AMC) of Sri Lanka intensified malaria surveillance jointly with a private sector partner, Tropical and Environmental Diseases and Health Associates Private Limited (TEDHA) with a view to achieving malaria elimination targets by 2014. METHODS: This is a case study on how public private partnerships can be effectively utilized to achieve malaria elimination goals. TEDHA established 50 Malaria Diagnostic Laboratories and 17 entomology surveillance sentinel sites in consultation with the AMC in areas difficult to access by government officials (five districts in two provinces affected by war). RESULTS: TEDHA screened 994,448 individuals for malaria, of which 243,867 were screened at mobile malaria clinics as compared to 1,102,054 screened by the AMC. Nine malaria positives were diagnosed by TEDHA, while the AMC diagnosed 103 malaria cases in the same districts in parallel. Over 13,000 entomological activity days were completed. Relevant information was shared with AMC and the data recorded in the health information system. CONCLUSIONS: A successful public-private partnership model for malaria elimination was initiated at a time when the health system was in disarray in war ravaged areas of Sri Lanka. This ensured a high annual blood examination rate and screening of vulnerable people in receptive areas. These were important for certification of malaria-free status which Sri Lanka eventually received in 2016.

Effects of weather factors on dengue fever incidence and implications for interventions in Cambodia.

BACKGROUND: Dengue viruses and their mosquito vectors are sensitive to their environment. Temperature, rainfall and humidity have well-defined roles in the transmission cycle. Therefore changes in these conditions may contribute to increasing incidence. The aim of this study was to examine the relationship between weather factors and dengue incidence in three provinces in Cambodia, in order to strengthen the evidence basis of dengue control strategies in this high-burden country. METHODS: We developed negative binomial models using monthly average maximum, minimum, mean temperatures and monthly cumulative rainfall over the period from January 1998 to December 2012. We adopted piecewise linear functions to estimate the incidence rate ratio (IRR) between dengue incidence and weather factors for simplicity in interpreting the coefficients. We estimated the values of parameters below cut-points defined in terms of the results of sensitivity tests over a 0-3 month lagged period. RESULTS: Mean temperature was significantly associated with dengue incidence in all three provinces, but incidence did not correlate well with maximum temperature in Banteay Meanchey, nor with minimum temperature in Kampong Thom at a lag of three months in the negative binomial model. The monthly cumulative rainfall influence on the dengue incidence was significant in all three provinces, but not consistently over a 0-3 month lagged period. Rainfall significantly affected the dengue incidence at a lag of 0 to 3 months in Siem Reap, but it did not have an impact at a lag of 2 to 3 months in Banteay Meanchey, nor at a lag of 2 months in Kampong Thom. CONCLUSIONS: The association between dengue incidence and weather factors also apparently varies by locality, suggesting that a prospective dengue early warning system would likely be best implemented at a local or regional scale, rather than nation-wide in Cambodia. Such spatial down-scaling would also enable dengue control measures to be better targeted, timed and implemented.

The prevention and control of dengue after Typhoon Haiyan.

OBJECTIVE: Many of the areas in the Philippines affected by Typhoon Haiyan are endemic for dengue; therefore, dengue prevention was a priority in the initial post-disaster risk assessment. We describe the dengue prevention and response strategies applied after Haiyan. METHODS: The dengue response was implemented by a wide range of national and international stakeholders. Priorities included the rapid re-establishment of an effective surveillance system to quickly identify new dengue cases, monitor trends and determine the geographical distribution of cases. Dengue rapid diagnostic tests (RDTs) were distributed to sentinel health facilities, and comprehensive vector control activities and entomological surveys were implemented. Several training sessions for key stakeholders and awareness campaigns for communities were organized. RESULTS: There were RDT-positive dengue cases reported from urban and semi-urban areas where entomological surveys also confirmed a high density of Aedes aegypti mosquitoes. Although there was an increase in dengue cases in January 2014, the number of cases remained below the epidemic threshold throughout the remaining months of 2014. DISCUSSION: There was no large outbreak of dengue after Haiyan, possibly due to the targeted, multifaceted and rapid response for dengue after Haiyan. However, surveillance differed after Typhoon Haiyan, making comparisons with previous years difficult. Multiple players contributed to the response that was also facilitated by close communication and coordination within the Health Cluster.

Patient satisfaction and uptake of private-sector run malaria diagnosis clinics in a post-conflict district in Sri Lanka.

BACKGROUND: With the incidence of malaria in Sri Lanka declining, intensive parasitological surveillance has been identified as a key strategy to achieve elimination by end 2014. Tropical and Environmental Diseases and Health Associates Private Limited (TEDHA) in collaboration with the Anti-Malaria Campaign established 43 malaria diagnostic laboratories (MDL) in four post-conflict districts of the Northern and Eastern Provinces. This study assesses the patterns of referral of patients with fever for malaria diagnosis by health care providers (HCPs) in four government hospitals in one of the districts of the Northern Province, and patient satisfaction with the laboratory services offered. METHODS: In this prospective descriptive study, data was collected on the proportion of fever patients being referred by the HCP in hospitals for malaria screening, and the proportion thereof who underwent screening. An interviewer-administered questionnaire was also used to assess patient satisfaction among those attending MDL, which was graded on a scale of 0-4. RESULTS: Of patients presenting to the hospitals with fever, only 44.3% were referred for malaria screening; 81.7% of them underwent screening. Referral depended largely on the presence of a permanent staff HCP. Satisfaction levels were high, with 86.55% giving an overall rating of 4. Comfort within the laboratory was rated satisfactory in three of the four hospitals. CONCLUSIONS: This study demonstrates the success of a public-private partnership in the malaria control programme in Sri Lanka. Malaria is considered low on the differential diagnosis in patients with fever even in previously malaria-endemic areas, due to the declining incidence of malaria and the increase in other febrile illnesses in these areas during the recent past. Private sector run malaria diagnostic services provided free of charge within government hospitals are viable and effective, and had good patient satisfaction ratings. In a country on the brink of eliminating malaria, there should be further emphasis on ensuring that HCPs refer patients for malaria diagnosis, in order to prevent a resurgence of the disease.

The importance of accuracy in diagnosis of positive malaria cases in a country progressing towards malaria elimination.

BACKGROUND: With Sri Lanka aiming towards malaria elimination by 2015, the National Anti Malaria Campaign has stressed on the importance of identification of the species of Plasmodium either by examination of stained blood smears for malaria parasites or by Rapid Diagnostic Tests for malaria antigens before the initiation of treatment. This study aims at confirmation of the accuracy of clinical and/or microscopical malaria diagnosis using serology. MATERIALS AND METHODS: Study population comprised 51 individuals diagnosed with malaria either microscopically or clinically during the first half of 2011. ELISA for detection of the two significant blood antigens (AMA-1 and MSP1-19) was carried out in these individuals, 14-28 days after being diagnosed as being positive for malaria microscopically. RESULTS: ELISA confirmed the microscopic diagnosis in all 47 of the patients including two mixed infections which flagged positive for both parasite antigens. However, four individuals diagnosed clinically as being positive for P. vivax by Health Care Providers were negative for malaria antibodies by ELISA. CONCLUSIONS: With 175 cases of malaria reported in 2011, a formidable challenge exists to diagnose malaria positive blood smears due to the large number of negative blood smears being seen daily. After routine cross checking of positive slides, it is heartening to note that there were no false positives detected through serological assays amongst patients who were diagnosed as malaria positive by microscopy. Presumptive treatment of febrile patients with anti-malarials can lead to waste of resources and adversely impact the condition of the patient if the fever is not due to malaria.

Malaria control and elimination in Sri Lanka: documenting progress and success factors in a conflict setting.

BACKGROUND: Sri Lanka has a long history of malaria control, and over the past decade has had dramatic declines in cases amid a national conflict. A case study of Sri Lanka's malaria programme was conducted to characterize the programme and explain recent progress. METHODS: The case study employed qualitative and quantitative methods. Data were collected from published and grey literature, district-level and national records, and thirty-three key informant interviews. Expenditures in two districts for two years--2004 and 2009--were compiled. FINDINGS: Malaria incidence in Sri Lanka has declined by 99.9% since 1999. During this time, there were increases in the proportion of malaria infections due to Plasmodium vivax, and the proportion of infections occurring in adult males. Indoor residual spraying and distribution of long-lasting insecticide-treated nets have likely contributed to the low transmission. Entomological surveillance was maintained. A strong passive case detection system captures infections and active case detection was introduced. When comparing conflict and non-conflict districts, vector control and surveillance measures were maintained in conflict areas, often with higher coverage reported in conflict districts. One of two districts in the study reported a 48% decline in malaria programme expenditure per person at risk from 2004 to 2009. The other district had stable malaria spending. CONCLUSIONS/SIGNIFICANCE: Malaria is now at low levels in Sri Lanka--124 indigenous cases were found in 2011. The majority of infections occur in adult males and are due to P. vivax. Evidence-driven policy and an ability to adapt to new circumstances contributed to this decline. Malaria interventions were maintained in the conflict districts despite an ongoing war. Sri Lanka has set a goal of eliminating malaria by the end of 2014. Early identification and treatment of infections, especially imported ones, together with effective surveillance and response, will be critical to achieving this goal.

Usefulness of polymerase chain reaction to supplement field microscopy in a pre-selected population with a high probability of malaria infections.

This study determines the use of nested PCR as a diagnostic tool to supplement field microscopy in symptomatic individuals suspected of being positive for malaria, and it explores its role in active case detection to identify asymptomatic parasite carriers. In symptomatic individuals, compared with PCR, microscopy had a sensitivity of 86.6% (95% confidence interval [CI] = 77.8-92.4) and specificity of 100% (95% CI = 96.9-100). During active case detection, two asymptomatic persons were diagnosed as having vivax malaria by polymerase chain reaction (PCR) but not microscopy. Currently, PCR is being carried out in Sri Lanka only for population surveys to estimate the hidden reservoir of malaria. Based on the results of this study and because of cost considerations, pooled PCR will be used in the future to screen samples from clinically suspected foci to increase the proportion of malaria cases detected. This strategy will assist the success of the malaria elimination program in Sri Lanka.

Shrinking the malaria map: progress and prospects.

In the past 150 years, roughly half of the countries in the world eliminated malaria. Nowadays, there are 99 endemic countries-67 are controlling malaria and 32 are pursuing an elimination strategy. This four-part Series presents evidence about the technical, operational, and financial dimensions of malaria elimination. The first paper in this Series reviews definitions of elimination and the state that precedes it: controlled low-endemic malaria. Feasibility assessments are described as a crucial step for a country transitioning from controlled low-endemic malaria to elimination. Characteristics of the 32 malaria-eliminating countries are presented, and contrasted with countries that pursued elimination in the past. Challenges and risks of elimination are presented, including Plasmodium vivax, resistance in the parasite and mosquito populations, and potential resurgence if investment and vigilance decrease. The benefits of elimination are outlined, specifically elimination as a regional and global public good. Priorities for the next decade are described.

Operational strategies to achieve and maintain malaria elimination.

Present elimination strategies are based on recommendations derived during the Global Malaria Eradication Program of the 1960s. However, many countries considering elimination nowadays have high intrinsic transmission potential and, without the support of a regional campaign, have to deal with the constant threat of imported cases of the disease, emphasising the need to revisit the strategies on which contemporary elimination programmes are based. To eliminate malaria, programmes need to concentrate on identification and elimination of foci of infections through both passive and active methods of case detection. This approach needs appropriate treatment of both clinical cases and asymptomatic infections, combined with targeted vector control. Draining of infectious pools entirely will not be sufficient since they could be replenished by imported malaria. Elimination will thus additionally need identification and treatment of incoming infections before they lead to transmission, or, more realistically, embarking on regional initiatives to dry up importation at its source.

Geographic structure of Plasmodium vivax: microsatellite analysis of parasite populations from Sri Lanka, Myanmar, and Ethiopia.

Genetic diversity and population structure of Plasmodium vivax parasites can predict the origin and spread of novel variants within a population enabling population specific malaria control measures. We analyzed the genetic diversity and population structure of 425 P. vivax isolates from Sri Lanka, Myanmar, and Ethiopia using 12 trinucleotide and tetranucleotide microsatellite markers. All three parasite populations were highly polymorphic with 3-44 alleles per locus. Approximately 65% were multiple-clone infections. Mean genetic diversity (H(E)) was 0.7517 in Ethiopia, 0.8450 in Myanmar, and 0.8610 in Sri Lanka. Significant linkage disequilibrium was maintained. Population structure showed two clusters (Asian and African) according to geography and ancestry. Strong clustering of outbreak isolates from Sri Lanka and Ethiopia was observed. Predictive power of ancestry using two-thirds of the isolates as a model identified 78.2% of isolates accurately as being African or Asian. Microsatellite analysis is a useful tool for mapping short-term outbreaks of malaria and for predicting ancestry.

Absence of asymptomatic malaria infections in previously high endemic areas of Sri Lanka.

As the goal of malaria elimination from Sri Lanka is currently being pursued, this study was planned to determine the prevalence of asymptomatic malaria infections. Five health areas in Trincomalee and Kurunegala districts that reported high prevalence in the recent past were purposively selected. The smallest administrative units (GN divisions) having high malaria risk within each area were identified. From these divisions, 20% of the population was randomly selected for blood smear examination and in a 50% sub-sample polymerase chain reaction (PCR) assay was performed. A population of 3,730 from 13 GN divisions was sampled. Thick and thin Giemsa-stained blood smears were negative for malaria parasites. The PCR carried out in 50% of the study sample was also negative for malaria parasites. The findings illustrate the absence of asymptomatic carriers in previously high transmission areas and it appears that achieving malaria elimination in Sri Lanka by 2015 is feasible.