Karan, L. S. | Search bioRxiv

bioRxiv2019

Lassa Virus in the Host Rodent Mastomys Natalensis within Urban Areas of N’zerekore, Guinea

Lassa virus is the causative agent of a dangerous zoonotic disease distributed in West Africa. A primary reservoir host of Lassa virus is Mastomys natalensis. These mice associate closely with humans and are commonly found in villages. Consequently, previous studies of Lassa virus have focused on rural areas. The prevalence of the virus in large cities has not been studied.\n\nWe conducted a study in NZerekore city, which has a population of approximately 300,000 residents. Small mammals were captured during a pilot study in May, and the main study was performed in August 2018. Based on the pilot study, we designed and implemented a stratified random sample to investigate the prevalence of Lassa virus among M. natalensis in NZerekore. The total sampling efforts consisted of 45 and 985 trapping nights in May and August, respectively. Samples of rodent tissues were screened for Lassa virus by RT-PCR.\n\nIn May, we trapped 20 rodents, including 19 M. natalensis. Viral RNA was detected in 18 M. natalensis. In August, 149 small mammals were captured, including 43 M. natalensis. The prevalence of Lassa virus among M. natalensis in NZerekore was 23.3% (CI 95%: 11.8-38.6%). Sequencing showed that the isolates belonged to lineage IV. We detected four Lassa virus hotspots located in different parts of the city. The largest Lassa virus hotspot was found in the neighborhood of the central market, which suggests that the virus was originally introduced into the city through the market.

epidemiology↗

bioRxiv2018

The first reliable autochthonous case of ticks-borne encephalitis infection and detection of tick-borne encephalitis virus in Ixodes ricinus ticks and their hosts in an urban park of Moscow, Russia

Here, we report the first confirmed autochthonous tick-borne encephalitis case diagnosed in Moscow in 2016 and describe the detection of Tick-borne encephalitis virus (TBEV) in ticks and small mammals in a Moscow park.\n\nThe paper includes data from two patients who were bitten by TBEV-infected ticks within the Moscow city limits; one of these cases led to the development of the meningeal form of TBE. Both TBEV-infected ticks attacked patients in the same area. We collected ticks and trapped small mammals in this area in 2017. All samples were screened for the presence of pathogens causing tick-borne diseases by PCR. The TBEV-positive ticks and small mammals tissue samples were subjected to virus isolation. The sequencing of the complete polyprotein gene of the positive samples was performed.\n\nA total of 227 questing ticks were collected. TBEV was detected in five specimens of Ixodes ricinus. We trapped 44 small mammals, mainly bank voles (Myodes glareolus) and pygmy field mice (Apodemus uralensis). Two samples of brain tissue from bank voles yielded a positive signal in RT-PCR for TBEV. We obtained six virus isolates from the ticks and brain tissue of a bank vole. Complete genome sequencing showed that the obtained isolates belong to the European subtype and have low diversity with sequence identities as high as 99.9%. GPS tracking showed that the maximum distance between the exact locations where the TBEV-positive ticks were collected was 185 m. We assume that the forest park was free of TBEV and that the virus was recently introduced.

epidemiology↗