Complex relationships between Aedes vectors, socio-economics and dengue transmission-Lessons learned from a case-control study in northeastern Thailand

• Published in: PLoS neglected tropical diseases 2020-10, Vol.14 (10), p.e0008703
• Main Authors: Fustec, Benedicte, Phanitchat, Thipruethai, Hoq, Mohammad Injamul, Aromseree, Sirinart, Pientong, Chamsai, Thaewnongiew, Kesorn, Ekalaksananan, Tipaya, Bangs, Michael J, Corbel, Vincent, Alexander, Neal, Overgaard, Hans J
• Format: Article
• Language: English
• Subjects: Abundance; Adolescent; Adult; Aedes; Aedes albopictus; aegypti diptera; Animals; Annan medicin och hälsovetenskap; antibody-response; antigen; Aquatic insects; Biology and Life Sciences; Bites; Case studies; Case-Control Studies; Child; Control; culicidae; Defence mechanisms; Dengue; Dengue - epidemiology; Dengue - transmission; Dengue - virology; Dengue fever; Disease prevention; Disease transmission; Distribution; DNA; Economics; endemic area; Entomology; Epidemiology; Evaluation; exposure; Family Characteristics; Female; Fever; Health aspects; Health risk assessment; Health risks; Health surveillance; Hospitals; Households; Houses; Human diseases; Human papillomavirus; Humans; Immune response; Immune system; Immunity; Immunology; indexes; Infections; Infectious Diseases; Insect bites; Life Sciences; Male; Medical research; Medicine; Medicine and Health Sciences; Medicine, Experimental; Monitoring; Mortality; Mosquito Vectors - virology; Mosquitoes; Nucleotide sequence; Other Medical Sciences; Parasitology; Patients; PCR; People and Places; Population; Proteins; Provinces; Public health; Residential areas; risk; Risk analysis; Risk Factors; Social classes; Socioeconomic aspects; Socioeconomics; Supervision; surveillance; Telemedicine; Thailand - epidemiology; Transmission; Tropical climate; Tropical diseases; Tropical Medicine; Vector-borne diseases; Vectors; Viral diseases; Virus-vector relationships; Viruses; Young Adult
• ISSN: 1935-2735; 1935-2727; 1935-2735
• DOI: 10.1371/journal.pntd.0008703

Dengue fever is an important public health concern in most tropical and subtropical countries, and its prevention and control rest on vector surveillance and control. However, many aspects of dengue epidemiology remain unclear; in particular, the relationship between Aedes vector abundance and dengue transmission risk. This study aims to identify entomological and immunological indices capable of discriminating between dengue case and control (non-case) houses, based on the assessment of candidate indices, as well as individual and household characteristics, as potential risk factors for acquiring dengue infection. This prospective, hospital-based, case-control study was conducted in northeastern Thailand between June 2016 and August 2019. Immature and adult stage Aedes were collected at the houses of case and control patients, recruited from district hospitals, and at patients' neighboring houses. Blood samples were tested by RDT and PCR to detect dengue cases, and were processed with the Nterm-34 kDa salivary peptide to measure the human immune response to Aedes bites. Socioeconomic status, and other individual and household characteristics were analyzed as potential risk factors for dengue. Study findings showed complex relationships between entomological indices and dengue risk. The presence of DENV-infected Aedes at the patient house was associated with 4.2-fold higher odds of dengue. On the other hand, Aedes presence (irrespective of infectious status) in the patient's house was negatively associated with dengue. In addition, the human immune response to Aedes bites, was higher in control than in case patients and Aedes adult abundance and immature indices were higher in control than in case houses at the household and the neighboring level. Multivariable analysis showed that children aged 10-14 years old and those aged 15-25 years old had respectively 4.5-fold and 2.9-fold higher odds of dengue infection than those older than 25 years. DENV infection in female Aedes at the house level was positively associated with dengue infection, while adult Aedes presence in the household was negatively associated. This study highlights the potential benefit of monitoring dengue viruses in Aedes vectors. Our findings suggest that monitoring the presence of DENV-infected Aedes mosquitoes could be a better indicator of dengue risk than the traditional immature entomological indices.