Publications by authors named "Constantianus J M Koenraadt"

Biological control of ticks using entomopathogenic fungi (EPF) is a highly desired alternative to chemical acaricides for the control of tick-borne pathogens. For Metarhizium anisopliae isolate ICIPE 7, one of these EPFs, efficacy against multiple tick species has been demonstrated in laboratory and field settings. However, we currently have little quantitative understanding of how EPFs can impact transmission.

View Article and Find Full Text PDF
Article Synopsis
  • - Hard ticks use a protein-rich saliva to attach securely to their hosts, forming a solid cement cone, but the process behind this transformation is not yet understood.
  • - This study investigates a glycine-rich protein (GRP) in tick saliva, revealing that it can undergo liquid-liquid phase separation to form sticky biomolecular condensates in salty conditions.
  • - The research identifies key interactions in GRP that drive this phase separation and suggests that understanding these mechanisms could lead to new tick control methods and innovative biomedical applications like tissue sealants.
View Article and Find Full Text PDF
Article Synopsis
  • - The study investigates the role of Asaia bacteria as potential symbionts for Aedes aegypti mosquitoes, focusing on their effects on larval development and symbiotic relationships.
  • - Experiments involved comparing mosquito larvae with both intact and aseptic microbiomes to determine the impact of three Asaia species, revealing that while Asaia can alter the gut microbiome, it is a transient presence that mainly affects the abundance of other bacteria.
  • - Findings indicated that Asaia bacteria have limited benefits for Aedes aegypti, showing species-specific positive effects on larval development primarily through interaction with other gut bacteria, rather than through direct mutualistic benefits.
View Article and Find Full Text PDF

In temperate regions, female Culex pipiens biotype pipiens mosquitoes undergo diapause in winter. Diapausing biotype pipiens mosquitoes are potentially important winter reservoirs for mosquito-borne viruses, such as West Nile virus (WNV), Usutu virus (USUV), and Sindbis virus (SINV). Mosquitoes in diapause have not taken a bloodmeal prior to winter.

View Article and Find Full Text PDF

Usutu virus (USUV) is an emerging flavivirus that is maintained in an enzootic cycle with mosquitoes as vectors and birds as amplifying hosts. In Europe, the virus has caused mass mortality of wild birds, mainly among Common Blackbird (Turdus merula) populations. While mosquitoes are the primary vectors for USUV, Common Blackbirds and other avian species are exposed to other arthropod ectoparasites, such as ticks.

View Article and Find Full Text PDF
Article Synopsis
  • - The Asian bush mosquito Aedes japonicus has invaded the Netherlands and is a potential vector for West Nile virus (WNV), prompting a study to assess its role in potential virus transmission and outbreak risks.
  • - Researchers collected mosquitoes in 2021 and investigated their host-seeking behavior, finding that Ae. japonicus is most active during the day, with notable peaks in the morning and evening, and showed a higher population in August compared to other months.
  • - The study's vector competence tests revealed that Aedes japonicus has a higher infection and transmission rate for a local WNV strain than the traditional vector Culex pipiens, highlighting its potential impact on human health.
View Article and Find Full Text PDF

Tick-borne encephalitis virus (TBEV) is an emerging pathogen in the Netherlands. Multiple divergent viral strains are circulating and the focal distribution of TBEV remains poorly understood. This may, however, be explained by differences in the susceptibility of tick populations for specific viruses and viral strains, and by viral strains having higher infection success in their local tick population.

View Article and Find Full Text PDF
Article Synopsis
  • Culex pipiens is a type of mosquito that carries diseases like Usutu virus and West Nile virus. There are two main types of this mosquito that behave differently but look alike.
  • In a study, scientists collected these mosquitoes from city parks and residential areas to see where they get their blood meals from.
  • They found that the feeding habits of the mosquitoes were the same in both habitats, and while they saw different types of birds in parks versus residential areas, the number of birds was about the same in both places.
View Article and Find Full Text PDF
Article Synopsis
  • Rift Valley fever virus (RVFV) is a mosquito-borne disease affecting both humans and animals, with its transmission dependent on interactions between the vector (mosquito), host (lamb), and pathogen (virus).
  • In an experiment, lambs were exposed to either low or high numbers of infectious mosquitoes, revealing that high exposure led to 100% infection rates while low exposure had a lower success rate but still showed that a single infected bite can cause disease.
  • A mathematical model was developed using transmission efficiency data, indicating that RVFV outbreaks require high numbers of mosquitoes and optimal host conditions, emphasizing the need for further research on RVFV spread in populations.
View Article and Find Full Text PDF

The distribution of tick-borne encephalitis virus (TBEV) is expanding to Western European countries, including the Netherlands, but the contribution of different rodent species to the transmission of TBEV is poorly understood. We investigated whether two species of wild rodents native to the Netherlands, the wood mouse Apodemus sylvaticus and the yellow-necked mouse Apodemus flavicollis, differ in their relative susceptibility to experimental infection with TBEV. Wild-caught individuals were inoculated subcutaneously with the classical European subtype of TBEV (Neudoerfl) or with TBEV-NL, a genetically divergent TBEV strain from the Netherlands.

View Article and Find Full Text PDF

Background: Ixodes ricinus ticks are infected with a large diversity of vertically and horizontally transmitted symbionts. While horizontally transmitted symbionts rely on a vertebrate host for their transmission, vertically transmitted symbionts rely more on the survival of their invertebrate host for transmission. We therefore hypothesized horizontally transmitted symbionts to be associated with increased tick activity to increase host contact rate and vertically transmitted symbionts to be associated with higher tick weight and lipid fraction to promote tick survival.

View Article and Find Full Text PDF

Ticks and the microbes they transmit have emerged in sub-Saharan Africa as a major threat to veterinary and public health. Although progress has been made in detecting and identifying tick-borne pathogens (TBPs) across vast agroecologies of Kenya, comprehensive information on tick species infesting cattle and their associated pathogens in coastal Kenya needs to be updated and expanded. Ticks infesting extensively grazed zebu cattle in 14 villages were sampled and identified based on morphology and molecular methods and tested for the presence of bacterial and protozoan TBPs using PCR with high-resolution melting analysis and gene sequencing.

View Article and Find Full Text PDF

The Asian bush mosquito is rapidly invading North America and Europe. Due to its potential to transmit multiple pathogenic arthropod-borne (arbo)viruses including Zika virus, West Nile virus, and chikungunya virus, it is important to understand the biology of this vector mosquito in more detail. In addition to arboviruses, mosquitoes can also carry insect-specific viruses that are receiving increasing attention due to their potential effects on host physiology and arbovirus transmission.

View Article and Find Full Text PDF

The incidence and risk of mosquito-borne disease outbreaks in Northwestern Europe has increased over the last few decades. Understanding the underlying environmental drivers of mosquito population dynamics helps to adequately assess mosquito-borne disease risk. While previous studies have focussed primarily on the effects of climatic conditions (i.

View Article and Find Full Text PDF

Due to changes in climate, numerous mosquito species are continuously extending their geographical distributions, posing potential new public health threats as arbovirus infections emerge in these new areas. During probing and feeding on the vertebrate host, a mosquito can inject both arbovirus and saliva into the skin of the host. The presence of mosquito saliva in the host skin during arbovirus transmission contributes to high viral titers in the skin, enhanced viremia, and rapid dissemination of the virus to target organs.

View Article and Find Full Text PDF

Usutu virus (USUV) is a mosquito-borne flavivirus of African origin. Over the past decades, USUV has spread through Europe causing mass die-offs among multiple bird species. The natural transmission cycle of USUV involves .

View Article and Find Full Text PDF

Female mosquitoes require blood from their host for egg development. However, the relationship between the composition of host blood and mosquito reproduction, and whether and how this is linked to host selection, remain unclear. A better understanding of these issues is beneficial for mass-rearing of mosquitoes for vector control.

View Article and Find Full Text PDF
Article Synopsis
  • Tick-borne encephalitis virus (TBEV) is spreading in Western Europe, posing a risk of severe neurological diseases, highlighting the need for improved surveillance methods that are ethical and sustainable.* -
  • Traditional monitoring approaches, which involve killing small rodents to test for the virus, can be both ethically problematic and ineffective, as TBEV can still be transmitted despite undetectable levels in blood or organs.* -
  • This study found that non-destructive sampling of ear tissue from rodents shows promise for detecting TBEV-RNA, with 4.3% of tested individuals testing positive, suggesting it could replace more invasive sampling methods in future monitoring efforts.*
View Article and Find Full Text PDF

Background: Evidence suggests a vicious cycle between rice cultivation and malaria control in Rwanda. Rice fields offer an attractive breeding ground for malaria vectors, which increases the disease burden in rice farming communities, and, consequently, reduces productivity in the rice sector. Community-based larval source management in rice fields is propagated as a sustainable solution to break this cycle.

View Article and Find Full Text PDF

Aedes aegypti and A. albopictus mosquitoes are the main vectors for dengue virus (DENV) and other arboviruses, including Zika virus (ZIKV). Understanding the factors that affect transmission of arboviruses from mosquitoes to humans is a priority because it could inform public health and targeted interventions.

View Article and Find Full Text PDF
Article Synopsis
  • Genomic analyses in temperate Europe show that mosquito-borne viruses can persist over winter, but the mechanisms behind this survival are still unclear.
  • This study investigated whether diapausing mosquitoes in the Netherlands could harbor West Nile virus (WNV), Usutu virus (USUV), and Sindbis virus (SINV) during winter outbreaks.
  • Despite collecting 4200 mosquitoes and conducting extensive virus screening, no evidence of virus persistence was found, suggesting the need for further research on other potential ways these viruses survive winter.
View Article and Find Full Text PDF

Larval source management (LSM) could reduce malaria transmission when executed alongside core vector control strategies. Involving communities in LSM could increase intervention coverage, reduce operational costs, and promote sustainability via community buy-in. We assessed the effectiveness of community-led LSM to reduce anopheline larval densities in 26 villages along the perimeter of Majete Wildlife Reserve in southern Malawi.

View Article and Find Full Text PDF
Article Synopsis
  • Bunyaviruses often produce incomplete virus particles that lack genome segments, which could hinder their ability to infect and spread.
  • Using the Rift Valley fever virus, the study finds that two types of these incomplete particles can complement each other when co-infected in both mammalian and insect cells.
  • The research suggests that these incomplete particles can actually enhance virus spread within hosts and between hosts, similar to how multipartite viruses operate.
View Article and Find Full Text PDF

Mosquito species belonging to the genus Aedes have attracted the interest of scientists and public health officers because of their capacity to transmit viruses that affect humans. Some of these species were brought outside their native range by means of trade and tourism and then colonised new regions thanks to a unique combination of eco-physiological traits. Considering mosquito physiological and behavioural traits to understand and predict their population dynamics is thus a crucial step in developing strategies to mitigate the local densities of invasive Aedes populations.

View Article and Find Full Text PDF

Collecting blood-fed mosquitoes to monitor pathogen presence or to gather information on the host blood meal is often challenging. Fermenting molasses can be used to produce carbon dioxide to attract host-seeking mosquitoes, however, earlier work indicated that it may also attract blood-fed mosquitoes in the field. In the current study, these field results were validated in an experimental setting using a large cage setup with Anopheles coluzzii (Diptera, Culicidae).

View Article and Find Full Text PDF