Phylodynamics unveils invading and diffusing patterns of dengue virus serotype-1 in Guangdong, China from 1990 to 2019 under a global genotyping framework.

BACKGROUND: The strong invasiveness and rapid expansion of dengue virus (DENV) pose a great challenge to global public health. However, dengue epidemic patterns and mechanisms at a genetic scale, particularly in term of cross-border transmissions, remain poorly understood. Importation is considered as the primary driver of dengue outbreaks in China, and since 1990 a frequent occurrence of large outbreaks has been triggered by the imported cases and subsequently spread to the western and northern parts of China. Therefore, this study aims to systematically reveal the invasion and diffusion patterns of DENV-1 in Guangdong, China from 1990 to 2019. METHODS: These analyses were performed on 179 newly assembled genomes from indigenous dengue cases in Guangdong, China and 5152 E gene complete sequences recorded in Chinese mainland. The genetic population structure and epidemic patterns of DENV-1 circulating in Chinese mainland were characterized by phylogenetics, phylogeography, phylodynamics based on DENV-1 E-gene-based globally unified genotyping framework. RESULTS: Multiple serotypes of DENV were co-circulating in Chinese mainland, particularly in Guangdong and Yunnan provinces. A total of 189 transmission clusters in 38 clades belonging to 22 subgenotypes of genotype I, IV and V of DENV-1 were identified, with 7 Clades of Concern (COCs) responsible for the large outbreaks since 1990. The epidemic periodicity was inferred from the data to be approximately 3 years. Dengue transmission events mainly occurred from Great Mekong Subregion-China (GMS-China), Southeast Asia (SEA), South Asia Subcontinent (SASC), and Oceania (OCE) to coastal and land border cities respectively in southeastern and southwestern China. Specially, Guangzhou was found to be the most dominant receipting hub, where DENV-1 diffused to other cities within the province and even other parts of the country. Genome phylogeny combined with epidemiological investigation demonstrated a clear local consecutive transmission process of a 5C1 transmission cluster (5C1-CN4) of DENV-1 in Guangzhou from 2013 to 2015, while the two provinces of Guangdong and Yunnan played key roles in ongoing transition of dengue epidemic patterns. In contextualizing within Invasion Biology theories, we have proposed a derived three-stage model encompassing the stages of invasion, colonization, and dissemination, which is supposed to enhance our understanding of dengue spreading patterns. CONCLUSIONS: This study demonstrates the invasion and diffusion process of DENV-1 in Chinese mainland within a global genotyping framework, characterizing the genetic diversities of viral populations, multiple sources of importation, and periodic dynamics of the epidemic. These findings highlight the potential ongoing transition trends from epidemic to endemic status offering a valuable insight into early warning, prevention and control of rapid spreading of dengue both in China and worldwide.

A Cross-Sectional Survey on the Malaria Control and Prevention Knowledge, Attitudes, and Practices of Caregivers of Children Under-5 in the Western Area of Sierra Leone.

(1) Background: Children under 5 years of age are the most vulnerable to malaria infection, and they suffer serious complications. Sierra Leone is one of the countries with the highest malaria burden in the world. This study aimed to assess the knowledge, attitudes, and practices (KAPs) toward malaria control and prevention among caregivers of children under 5 in the Western Area of Sierra Leone. (2) Methods: A cross-sectional survey was conducted among caregivers of children under-5 visiting the out-patient department of six selected hospitals/community health centers. Data were collected via questionnaire interviews with 350 caregivers. (3) Results: A total of 97.1% of the respondents were women and the majority of them were young mothers; 46.3% of respondents were unemployed; and 27.1% received no education. Only 1.4% accessed malaria related information from the internet/social media. This KAPs survey indicated that a misconception of the cause, transmission, and clinical symptoms of malaria; unawareness of its lethality and its severity; and inappropriate prevention and treatment behaviors, such as self-medicating, were still in existence among some caregivers. However, a positive correlation in knowledge−attitudes (rs = 0.13, p < 0.05) and in attitudes−practices (rs = 0.45, p < 0.001) was revealed. The caregivers, being mothers and having at least a secondary education, demonstrated positive attitudes and practices. Meanwhile, more urban caregivers (79.8%) followed a complete malaria treatment course of artemisinin-based combination therapies than the rural (63.3%), but in view of insecticide treated net use, more rural caregivers presented positive attitudes (85.3%) and practices (70.1%) than the urban (69.9%, 52.0%). (4) Conclusions: For better protection of children under-5 against lethal malaria, it is essential to provide better guidance at the community level for their caregivers, especially young mothers, in order to reduce some misconceptions and inappropriate behaviors. An increase in education and employment opportunities for women, establishment of an accessible community-based malaria counselling service, and construction of an effective communication channel are also needed.