Volume 07 · Issue 05 · 2018

The control of vector-borne diseases (VBD) is one of the greatest challenges on the global health agenda. Rapid and uncontrolled urbanization has heightened the interest in addressing these challenges through an integrated vector management (IVM) approach. The aim was to identify components related to impacts, economic evaluation, and sustainability that might contribute to this integrated approach to VBD prevention.

We conducted a scoping review of available literature (2000-2016) using PubMed, Web of Science, Cochrane, CINAHL, Econlit, LILACS, Global Health Database, Scopus, and Embase, as well as Tropical Diseases Bulletin, WHOLIS, WHO Pesticide Evaluation Scheme, and Google Scholar. MeSH terms and free-text terms were used. A data extraction form was used, including TIDieR and ASTAIRE. MMAT and CHEERS were used to evaluate quality. Of the 42 documents reviewed, 30 were focused on dengue, eight on malaria, and two on leishmaniasis. More than a half of the studies were conducted in the Americas. Half used a quantitative descriptive approach (n = 21), followed by cluster randomized controlled trials (n = 11). Regarding impacts, outcomes were: a) use of measures for vector control; b) vector control; c) health measures; and d) social measures. IVM reduced breeding sites, the entomology index, and parasite rates. Results were heterogeneous, with variable magnitudes, but in all cases were favourable to the intervention. Evidence of IVM impacts on health outcomes was very limited but showed reduced incidence. Social outcomes were improved abilities and capacities, empowerment, and community knowledge. Regarding economic evaluation, only four studies performed an economic analysis, and intervention benefits outweighed costs. Cost-effectiveness was dependent on illness incidence. The results provided key elements to analyze sustainability in terms of three dimensions (social, economic, and environmental), emphasizing the implementation of a community-focused eco-bio-social approach.

IVM has an impact on reducing vector breeding sites and the entomology index, but evidence of impacts on health outcomes is limited. Social outcomes are improved abilities and capacities, empowerment, and community knowledge. Economic evaluations are scarce, and cost-effectiveness is dependent on illness incidence. Community capacity building is the main component of sustainability, together with collaboration, institutionalization, and routinization of activities. Findings indicate a great heterogeneity in the interventions and highlight the need for characterizing interventions rigorously to facilitate transferability.

Since the 1990s, evidence has accumulated of an increased prevalence of epilepsy in onchocerciasis-endemic areas in Africa as compared to onchocerciasis-free areas. Although the causal relationship between onchocerciasis and epilepsy has yet to be proven, there is likely an association. Here we discuss the need for disease burden estimates of onchocerciasis-associated epilepsy (OAE), provide them, detail how such estimates should be refined, and discuss the socioeconomic impact of OAE, including a cost-estimate for anti-epileptic drugs.

Providing OAE burden estimates may aid prevention of epilepsy in onchocerciasis- endemic areas by inciting and informing collaboration between onchocerciasis control programmes and mental health services. Epilepsy not only massively impacts the health of those affected, but it also carries a high socioeconomic burden for the households and communities involved. We used previously published geospatial estimates of onchocerciasis in Africa and a separately published logistic regression model quantifying the association between onchocerciasis and epilepsy to estimate the number of OAE cases. We then applied disability weights for epilepsy to quantify the burden in terms of years of life lived with disability (YLD) and estimate the cost of treatment. We estimate that in 2015 roughly 117 000 people were affected by OAE across onchocerciasis-endemic areas previously under the African Programme for Onchocerciases control (APOC) mandate where OAE has ever been reported or suspected, and another 264 000 persons in onchocerciasis-endemic areas where OAE has never been investigated before. The total number of YLDs due to OAE was 39 300 and 88 700 in these areas respectively, based on a weighted mean disability weight of 0.336. The burden of OAE is approximately 13% of the total YLDs attributable to onchocerciasis and 10% of total YLDs attributable to epilepsy. We estimated that by 2015 the total costs of treatment with anti-epileptic drug for OAE cases would have been a minimum of 12.4 million US$.

These estimates suggest a considerable health, social and economic burden of OAE in Africa. The treatment and care for people with epilepsy, especially in hyperendemic onchocerciasis areas with high epilepsy prevalence thus requires more financial and human resources.

In 2015, following a call for proposals from the Special Programme for Research and Training in Tropical Diseases (TDR), six scoping reviews on the prevention and control of vector-borne diseases in urban areas were conducted. Those reviews provided a clear picture of the available knowledge and highlighted knowledge gaps, as well as needs and opportunities for future research. Based on the research findings of the scoping reviews, a concept mapping exercise was undertaken to produce a list of priority research needs to be addressed.

Members of the six research teams responsible for the "VEctor boRne DiseAses Scoping reviews" (VERDAS) consortium's scoping reviews met for 2 days with decision-makers from Colombia, Brazil, Peru, Pan-American Health Organization, and World Health Organization. A total of 11 researchers and seven decision-makers (from ministries of health, city and regional vector control departments, and vector control programs) completed the concept mapping, answering the question: "In view of the knowledge synthesis and your own expertise, what do we still need to know about vector-borne diseases and other infectious diseases of poverty in urban areas?" Participants rated each statement on two scales from 1 to 5, one relative to 'priority' and the other to 'policy relevance', and grouped statements into clusters based on their own individual criteria and expertise.

The final map consisted of 12 clusters. Participants considered those entitled "Equity", "Technology", and "Surveillance" to have the highest priority. The cluster considered the most important concerns equity issues, confirming that these issues are rarely addressed in research on vector-borne diseases. On the other hand, the "Population mobility" and "Collaboration" clusters were considered to be the lowest priority but remained identified by participants as research priorities. The average policy relevance scores for each of the 12 clusters were roughly the same as the priority scores for all clusters. Some issues were not addressed during the brain-storming. This is the case for governance and for access and quality of care.

Based on this work, and adopting a participatory approach, the concept mapping exercise conducted collaboratively with researchers from these teams and high-level decision-makers identified research themes for which studies should be carried out as a priority.

Arboviral disease transmitted by Aedes albopictus such as dengue fever is an important threat to human health. Pyrethroid resistance raises a great challenge for mosquito control. A systematic assessment of Ae. albopictus resistance status in China is urgently needed, and the study of correlation between pyrethroid resistance and knockdown resistance (kdr) mutations would provide information to guide the control of the Ae. albopictus vector.

Five field populations of Ae. albopictus were collected from Jinan (JN), Hangzhou (HZ), Baoshan (BS), Yangpu (YP) and Haikou (HK), China in 2017. Insecticide-impregnated papers were prepared with four pyrethroid chemicals, deltamethrin, permethrin, beta-cypermethrin and lambda-cyhalothrin. The susceptibility of Ae. albopictus to pyrethroids was tested by the WHO tube assay. Kdr mutations were identified by PCR and sequencing. Moreover, the correlation analysis between kdr alleles and pyrethroid resistance was performed.

All five populations of Ae. albopictus showed resistance to four pyrethroid insecticides. One kdr mutant allele at codon 1532 and three at 1534 were detected with frequency of 5.33% (I1532T), 44.20% (F1534S), 1.83% (F1534 L) and 0.87% (F1534C), respectively. Both 1532 and 1534 mutation mosquitoes were found in the BS and YP populations. Allele I1532T was negatively correlated with deltamethrin resistance phenotype (OR<1), while F1534S mutation was positively correlated with deltamethrin and permethrin resistance (OR>1).

The five field populations of Ae. albopictus adults were all resistant to deltamethrin, permethrin, beta-cypermethrin and lambda-cyhalothrin. Mutant F1534S was clearly associated with pyrethroid resistance phenotype in Ae. albopictus and this could be developed as a molecular marker to monitor the pyrethroid resistance problem in China.

Angiostrongyliasis is a food-borne parasitic zoonosis. Human infection is caused by infection with the third-stage larvae of Angiostrongylus cantonensis. The life cycle of A. cantonensis involves rodents as definitive hosts and molluscs as intermediate hosts. This study aims to investigate on the infection status and characteristics of spatial distribution of these hosts, which are key components in the strategy for the prevention and control of angiostrongyliasis.

Three villages from Nanao Island, Guangdong Province, China, were chosen as study area by stratified random sampling. The density and natural infection of Pomacea canaliculata and various rat species were surveyed every three months from December 2015 to September 2016, with spatial correlations of the positive P. canaliculata and the infection rates analysed by ArcGIS, scan statistics, ordinary least squares (OLS) and geographically weighted regression (GWR) models.

A total of 2192 P. canaliculata specimens were collected from the field, of which 1190 were randomly chosen to be examined for third-stage larvae of A. cantonensis. Seventy-two Angiostrongylus-infected snails were found, which represents a larval infection rate of 6.1% (72/1190). In total, 110 rats including 85 Rattus norvegicus, 10 R. flavipectus, one R. losea and 14 Suncus murinus were captured, and 32 individuals were positive (for adult worms), representing an infection rate of 29.1% of the definitive hosts (32/110). Worms were only found in R. norvegicus and R. flavipectus, representing a prevalence of 36.5% (31/85) and 10% (1/10), respectively in these species, but none in R. losea and S. murinus, despite testing as many as 32 of the latter species. Statistically, spatial correlation and spatial clusters in the spatial distribution of positive P. canaliculata and positive rats existed. Most of the spatial variability of the host infection rates came from spatial autocorrelation. Nine spatial clusters with respect to positive P. canaliculata were identified, but only two correlated to infection rates. The results show that corrected Akaike information criterion, R², R² adjusted and σ² in the GWR model were superior to those in the OLS model.

P. canaliculata and rats were widely distributed in Nanao Island and positive infection has also been found in the hosts, demonstrating that there was a risk of angiostrongyliasis in this region of China. The distribution of positive P. canaliculata and rats exhibited spatial correlation, and the GWR model had advantage over the OLS model in the spatial analysis of hosts of A. cantonensis.

More than half of the world's population currently lives in urban settlements that grow both in size and number. By 2050, approximately 70% of the global population will be living in urban conglomerations, mainly in low- and middle-income countries. Mobility, poverty, different layers of inequalities as well as climate variability and change are some of the social and environmental factors that influence the exposure of human populations in urban settings to vector-borne diseases, which pose eminent public health threats. Accurate, consistent, and evidence-based interventions for prevention and control of vector-borne and other infectious diseases of poverty in urban settings are needed to implement innovative and cost-effective public policy and to promote inclusive and equitable urban health services.

While there is growing awareness of vector-borne diseases epidemiology at the urban level, there is still a paucity of research and action being undertaken in this area, hindering evidence-based public health policy decisions and practice and strategies for active community engagement. This paper describes the collaboration and partnership of the Special Programme for Research and Training in Tropical Diseases (TDR) hosted by the World Health Organization (WHO) and the "VEctor boRne DiseAses Scoping reviews" (VERDAS) Research Consortium as they joined efforts in response to filling this gap in knowledge and evidence by supporting the development of a series of scoping reviews that highlight priority research gaps and policy implications to address vector-borne and other infectious diseases at the urban level.

The set of scoping reviews proposed in this special issue presents a critical analysis of the state-of-the-art of research on urban health interventions for the prevention and control of vector-borne and other infectious diseases of poverty. The authors of the 6 reviews highlighted severe gaps in knowledge and identified organizational and theoretical limitations that need to be urgently tackled to improve cities preparedness and vector control response. The more pressing need at present is to ensure that more implementation research on vector-borne diseases in urban settings is conducted, addressing policy and practice implications and calling for more political commitment and social mobilization through adequate citizen engagement strategies.

African swine fever (ASF), caused by African swine fever virus, is a hemorrhagic and often fatal disease of domestic pigs and wild boar, which is notifiable to the World Organization for Animal Health. On August 3, 2018, China reported the first outbreak of ASF in Shenyang, a northeastern city of China. As of October 8, a total of 33 ASF outbreaks were reported in eight provinces in China, the biggest pork producer and consumer in the world.

This commentary summarizes the current situation of ASF in China, measures that China has taken to control the disease, lessons learnt from other countries, challenges and recommendations on ASF control in China, and possible international collaborations on ASF.

ASF is an unprecedented disaster and challenge to the Chinese swine industry. It will be a formidable and protracted campaign to control ASF in China, which requires joint participation and coordination of stakeholders and agencies at different levels.

A high prevalence of epilepsy has been observed in onchocerciasis endemic areas in the Democratic Republic of Congo (DRC). With this study we aimed to investigate whether Onchocerca volvulus infection is a risk factor for developing epilepsy in onchocerciasis endemic regions in the DRC.

Between October and December 2015, a multi-centre case control study was performed in onchocerciasis endemic health zones (HZ) in the DRC: one study site was situated in Tshopo Province in the HZ of Wanierukula (village of Salambongo) where there had been 13 annual community distributions of treatment with ivermectin (CDTI), a second was situated in Ituri Province in the HZ of Logo (village of Draju) where ivermectin had never been distributed and in the HZ of Rethy (village of Rassia) where there had been THREE CDTI annual campaigns before the study. Individuals with unprovoked convulsive epilepsy of unknown etiology were enrolled as cases (n = 175). Randomly selected healthy members of families without epilepsy cases from the same village and age-groups and were recruited as controls (n = 170).

Onchocerciasis associated symptoms (e.g., itching and abnormal skin) were more often present in cases compared to controls (respectively, OR = 2.63, 95% CI: 1.63-4.23, P < 0.0001 and OR = 3.23, 95% CI: 1.48-7.09, P = 0.0034). A higher number of cases was found to present with microfilariae in skin snips and with O. volvulus IgG4 antibodies in the blood compared to controls. Moreover, the microfilariae load in skin snips was 3-10 times higher in cases than controls.

This case control study confirms that O. volvulus is a risk factor for developing epilepsy in onchocerciasis endemic regions in the DRC.

Street children are forced to spend a lot of time away from their homes and some of them do not have homes at all, due to economic and family problems, which makes them exposed to many health problems, such as the hepatitis C virus (HCV) infection. Iran, like many other countries in the world, experiences the burden of street children, however, the rate of HCV among street children is virtually unknown. This study aimed to determine the prevalence of HCV among street children in Iran.

This systematic review and meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The study protocol of this review was registered in PROSPERO under identification term CRD42018082336. A comprehensive literature search was conducted to identify published studies reporting on the prevalence of HCV among street children in Iran. Several international scholarly databases, including Web of Science, PubMed^®/MEDLINE^®, Embase, Scopus^®, Google Scholar and Directory of Open Access Journals, as well as Iranian databases such as Maglran and Barakathns were searched. Studies published between 1988 and December 2017 with any of the following keywords were selected: (street OR homeless OR labour) AND (children OR child OR infant) AND (hepatitis C OR hepatitis C virus OR HCV OR viral hepatitis OR hepatitis OR hepacivirus) AND Iran. Moreover, a grey literature search was performed in order to obtain other potentially relevant studies. The search was carried out without any language restrictions. Four studies, surveying a total of 1691 street children, conducted between 2006 and 2017 were found to be eligible for inclusion in the review and therefore analysed. Three studies were conducted in Tehran and one in Isfahan. The prevalence of HCV among street children in Iran was found to be high, at 2.4% (95% CI: 1.8-3.3).

Since the prevalence of HCV among street children in Iran is quite high, health decision- and policy-makers should pay more attention to street children and widen support channels, both social and economic. Further studies should be conducted among street children in different cities of Iran to add to the knowledge base of HCV among street children in the country. The health system should provide facilities for street children to be screened to quickly diagnose illnesses and prevent them from developing complications.

This paper presents the overall approach undertaken by the "VEctor boRne DiseAses Scoping reviews" (VERDAS) consortium in response to a call issued by the Vectors, Environment and Society unit of the Special Programme for Research and Training in Tropical Diseases hosted by the World Health Organization. The aim of the project was to undertake a broad knowledge synthesis and identify knowledge gaps regarding the control and prevention of vector-borne diseases in urban settings.

The consortium consists of 14 researchers, 13 research assistants, and one research coordinator from seven different institutions in Canada, Colombia, Brazil, France, Spain, and Burkina Faso. A six-step protocol was developed for the scoping reviews undertaken by the consortium, based on the framework developed by Arksey and O'Malley and improved by Levac et al. In the first step, six topics were identified through an international eDelphi consultation. In the next four steps, the scoping reviews were conducted. The sixth step was the VERDAS workshop held in Colombia in March 2017.

In this article, we discuss several methodological issues encountered and share our reflections on this work. We believe this protocol provides a strong example of an exhaustive and rigorous process for performing broad knowledge synthesis for any given topic and should be considered for future research initiatives and donor agendas in multiple fields to highlight research needs scientifically.