Molecular and Entomological Characterization of 2023 Dengue Outbreak in Dhading District, Central Nepal

In 2023, Nepal faced its second largest dengue outbreak ever, following a record-breaking number of dengue cases in 2022, characterized by the expansion of infections into areas of higher altitudes. However, the characteristics of the 2023 circulating dengue virus (DENV) and the vector density remain poorly understood. Therefore, we performed DENV serotyping, clinical and laboratory assessment, and entomological analysis of the 2023 outbreak in central Nepal. A total of 396 fever cases in Dhading hospital suspected of being DENV positive were enrolled, and blood samples were collected and tested by different techniques including PCR. Of these, 278 (70.2%) had confirmed DENV infection. Multiple serotypes (DENV-1, -2, and -3) were detected. DENV-2 (97.5%) re-emerged after six years in Dhading while DENV-3 was identified for the first time. Dengue inpatients had significantly higher frequency of anorexia, myalgia, rash, diarrhea, nausea, vomiting, abdominal pain, and thrombocytopenia (p < 0.05). In this area, Aedes mosquitoes largely predominated (90.7%) with the majority being A. aegypti (60.7%). We also found high levels of Aedes index (20.0%) and container index (16.7%). We confirmed multiple DENV serotype circulation with serotype re-emergence and new serotype introduction, and high vector density in 2023. These findings call for the urgent initiation and scaling up of DENV molecular surveillance in human and mosquito populations for dengue control and prevention in Nepal.

[Topographical radiological anatomy of the extra-hepatic biliary system seen in lateral view. Tone and projecting movements of the hepatic/bile ducts (author's transl)]

This study is based essentially on lateral views of 244 examinations of the biliary tract by non-operative trans-hepato-cholecystographic radiomanometry and on some lateral views of cholecystograms. Despite the classical conception (Lutkens) of gall bladders invariably oblique, it showed that some are vertical, horizontal or even descending. Contrary to this classical conception which describes the infundibulum and cystic ducts as being oblique from the front backwards in the same direction as the long axis of an oblique gall bladder, these lateral views showed that, whilst the infundibulum may continue in the same direction as the long axis of the gall bladder, the same does not apply to the neck and cystic duct. They run from behind forwards and almost always in the direction of feet to head of the subject. Very rarely the neck is directed from head to foot. In addition, and once again contrary to Lukens description, the common bile duct is not the most posterior of the parts of the biliary tree. It is the infundibulocervical region which is the most inclined, regardless of the type of gall bladder. These lateral views also made it possible to demonstrate the pathognomic appearances of hypotonic and hypertonix hepatic/bile ducts and the antero-posterior projecting movements of the main bile duct.