What is vector transmission

Unsurprisingly models from the literature range greatly; from deterministic to stochastic, endemic including birth and death rates or epidemic an outbreak of limited duration , incorporating spatial spread, spatial heterogeneity, latency periods, age structure, acquisition and loss of immunity, multiple strains and many others. Even when only considering just one specific disease the variations in the disease within different populations may lead to changes in not just the parameterisation, but also of how one may wish to take the modelling approach.

This work considers the effects of using "host-only" transmission models such as the quasi-equilibrium assumption upon disease dynamics and also the effect of omitting the latency period upon epidemic predictions. Human African trypanosomiasis HAT , more colloquially known as sleeping sickness, is a deadly disease which is endemic across much of sub-Saharan Africa. Whilst the prevalence of HAT is not as high as that of other vector-borne diseases such as malaria or dengue there were just over reported cases of HAT but million estimated malaria cases in , the lack of chemical prophylaxis, the extremely unpleasant and often deadly treatment and the shortage of substantial scientic research has now placed HAT on the WHO's list of neglected tropical diseases.

The vector for HAT is the tsetse; its need to blood feed to prevent starvation and a unique vector-parasite interaction causing a "teneral susceptibility phenomenon" mean that HAT modelling is distinctly different to other vector-borne diseases such as malaria. Bluetongue is a viral disease BTV of ruminants transmitted by various Culicoides genus biting midge species.

Symptoms for livestock diseased with BTV included discomfort, high fever and cyanosis of the tongue, which gives the disease its name.

Amongst sheep BTV disease has a high associated mortality. Until the late s the European range of BTV was entirely associated with the range of the midge vector C. At the end of the '90s and into the early s there has been a previously unprecedented expansion of BTV into areas of Europe which are part of the range of other midge species such as those of the C.

Obsoletus complex and closely related midge species. The stabilizing effect of intraspecific genetic variation on population dynamics in novel and ancestral habitats. Alto, B. Age-dependent bloodfeeding of Aedes aegypti and Aedes albopictus on artificial and living hosts. Control Assoc. Google Scholar. Amarasekare, P. The intrinsic growth rate as a predictor of population viability under climate warming.

A framework for elucidating the temperature dependence of fitness. Anderson, R. Population biology of infectious diseases: part I. Nature , — The population dynamics of microparasites and their invertebrate hosts. B , — Approximation of the basic reproduction number R0 for vector-borne diseases with a periodic vector population.

On the biological interpretation of a definition for the parameter R0 in periodic population models. The epidemic threshold of vector-borne diseases with seasonality.

Growth rate and basic reproduction number for population models with a simple periodic factor. Bayarri, M. Using statistical and computer models to quantify volcanic hazards. Technometrics 51, — Bayoh, M. Effect of temperature on the development of the aquatic stages of Anopheles gambiae sensu stricto Diptera: Culicidae.

Beck-Johnson, L. The Effect of temperature on Anopheles mosquito population dynamics and the potential for malaria transmission. PLoS One 8:e Bellan, S. The importance of age dependent mortality and the extrinsic incubation period in models of mosquito-borne disease transmission and control.

PLoS One 5:e Blanchard, J. Potential consequences of climate change for primary production and fish production in large marine ecosystems. Bohbot, J. Functional development of the octenol response in Aedes aegypti. Bolnick, D. Why intraspecific trait variation matters in community ecology.

Trends Ecol. Bomblies, A. Hydrology of malaria: model development and application to a Sahelian village. Water Resour. Brady, O. Vectorial capacity and vector control: reconsidering sensitivity to parameters for malaria elimination.

Brand, S. The interaction between vector life history and short vector life in vector-borne disease control. PLoS Comput. Brown, J. Toward a metabolic theory of ecology. Ecology 85, — Caminade, C. Caraco, T. Stage-structured infection transmission and a spatial epidemic: a model for Lyme disease. Cator, L. Alterations in mosquito behaviour by malaria parasites: potential impact on force of infection.

CDC Lyme Disease : Data and Statistics. Charnov, E. London: Oxford University Press. Christensen, B. Melanization immune responses in mosquito vectors. Trends Parasitol. Ciota, A. The effect of temperature on life history traits of Culex mosquitoes. Clark, J. Models for Ecological Data: An Introduction. Clements, A. The analysis of mortality and survival rates in wild populations of mosquitoes. Coletta-Filho, H. Temporal progression of Candidatus Liberibacter asiaticus infection in citrus and acquisition efficiency by Diaphorina citri.

Phytopathology , — Coulson, T. Integral projections models, their construction and use in posing hypotheses in ecology. Oikos , — Crowder, D. Species interactions affect the spread of vector-borne plant pathogens independent of transmission mode. Ecology e Impact of small variations in temperature and humidity on the reproductive activity and survival of Aedes aegypti Diptera. De Xue, R. Age and body size effects on blood meal size and multiple blood feeding by Aedes aegypti Diptera: Culicidae.

Delatte, H. Influence of temperature on immature development, survival, longevity, fecundity, and gonotrophic cycles of Aedes albopictus , vector of chikungunya and dengue in the Indian Ocean. Dell, A. Systematic variation in the temperature dependence of physiological and ecological traits.

Temperature dependence of trophic interactions are driven by asymmetry of species responses and foraging strategy. Den Otter, C. Effect of age, sex and hunger on the antennal olfactory sensitivity of tsetse flies.

Depinay, J. A simulation model of African Anopheles ecology and population dynamics for the analysis of malaria transmission. Des Roches, S. The ecological importance of intraspecific variation. Incorporating plant functional diversity effects in ecosystem service assessments.

Dick, O. The history of dengue outbreaks in the Americas. Dohm, D. Donnelly, B. A systematic, realist review of zooprophylaxis for malaria control. Downs, C. Scaling of host competence. Eckhoff, P. A malaria transmission-directed model of mosquito life cycle and ecology.

Eigenbrode, S. Insect-borne plant pathogens and their vectors: ecology, evolution, and complex interactions. El Moustaid, F. Modeling temperature effects on population density of the dengue mosquito Aedes aegypti. Insects Enquist, B. Woodward, A. DeLong, and S. Faria, N. Zika virus in the Americas: early epidemiological and genetic findings. Science , — Focks, D. Dynamic life table model for Aedes aegypti Diptera: Culicidae : analysis of the literature and model development. Dynamic life table model for Aedes aegypti Diptera: Culicidae : simulation results and validation.

Getz, W. Making ecological models adequate. Gibert, J. Gilbert, B. A bioenergetic framework for the temperature dependence of trophic interactions. Gillooly, J. Effects of size and temperature on developmental time.

Nature , 70— Hancock, P. Predicting Wolbachia invasion dynamics in Aedes aegypti populations using models of density-dependent demographic traits. BMC Biol. Harrington, L. Age-dependent survival of the dengue vector Aedes aegypti Diptera: Culicidae demonstrated by simultaneous release-recapture of different age cohorts.

Heesterbeek, J. Threshold quantities for infectious diseases in periodic environments. Hillyer, J. Age-associated mortality in immune challenged mosquitoes Aedes aegypti correlates with a decrease in haemocyte numbers. Hooten, M. A guide to Bayesian model selection for ecologists. Hoshi, T. Uranotaenia novobscura ryukyuana Diptera: Culicidae population dynamics are denso-dependent and autonomous from weather fluctuations.

Imura, D. Genetic variation can promote system persistence in an experimental host-parasitoid system. Jeger, M.

Epidemiology of insect-transmitted plant viruses: modelling disease dynamics and control interventions. Johansson, M.

An open challenge to advance probabilistic forecasting for dengue epidemics. Johnson, J. Model selection in ecology and evolution. Johnson, L. Chen, B. Moulin, and J. Bayesain inference for bioenergetic models. Ecology 94, — Understanding uncertainty in temperature effects on vector-borne disease: a Bayesian approach. Ecology 96, — Phenomenological forecasting of disease incidence using heteroskedastic Gaussian processes: a dengue case study.

Kamiya, T. Temperature-dependent variation in the extrinsic incubation period elevates the risk of vector-borne disease emergence. Epidemics Keesing, F. Clearly there are risks and unknowns involved in conducting an open-environment experiment of an as-yet poorly understood technology. But allowing the Zika virus to spread unchecked is also risky. Does the threat of a Zika epidemic justify the ecological risk of genetically engineering mosquitos?

Are current methods of mosquito control sufficiently ineffective or harmful that we need to try untested alternatives? These are the questions being put to public health officials now. Individuals suspected or known to have been exposed to certain contagious pathogens may be quarantined , or isolated to prevent transmission of the disease to others.

Hospitals and other health-care facilities generally set up special wards to isolate patients with particularly hazardous diseases such as tuberculosis or Ebola Figure 6. Depending on the setting, these wards may be equipped with special air-handling methods, and personnel may implement special protocols to limit the risk of transmission, such as personal protective equipment or the use of chemical disinfectant sprays upon entry and exit of medical personnel.

The duration of the quarantine depends on factors such as the incubation period of the disease and the evidence suggestive of an infection. The patient may be released if signs and symptoms fail to materialize when expected or if preventive treatment can be administered in order to limit the risk of transmission. If the infection is confirmed, the patient may be compelled to remain in isolation until the disease is no longer considered contagious.

In the United States, public health authorities may only quarantine patients for certain diseases, such as cholera , diphtheria , infectious tuberculosis , and strains of influenza capable of causing a pandemic. Individuals entering the United States or moving between states may be quarantined by the CDC if they are suspected of having been exposed to one of these diseases.

Although the CDC routinely monitors entry points to the United States for crew or passengers displaying illness, quarantine is rarely implemented. Figure 6. Hospitals, retirement homes, and prisons attract the attention of epidemiologists because these settings are associated with increased incidence of certain diseases.

Higher rates of transmission may be caused by characteristics of the environment itself, characteristics of the population, or both. Consequently, special efforts must be taken to limit the risks of infection in these settings. Infections acquired in health-care facilities, including hospitals, are called nosocomial infections or healthcare-associated infections HAI.

HAIs are often connected with surgery or other invasive procedures that provide the pathogen with access to the portal of infection. For an infection to be classified as an HAI, the patient must have been admitted to the health-care facility for a reason other than the infection. In these settings, patients suffering from primary disease are often afflicted with compromised immunity and are more susceptible to secondary infection and opportunistic pathogens.

Health-care facilities seek to limit nosocomial infections through training and hygiene protocols such as those described in Control of Microbial Growth. A mosquito bites a person who subsequently develops a fever and abdominal rash.

What type of transmission would this be? What type of transmission of infectious agents would this be? A blanket from a child with chickenpox is likely to be contaminated with the virus that causes chickenpox Varicella-zoster virus.

What is the blanket called? A patient in the hospital with a urinary catheter develops a bladder infection. Many people find that they become ill with a cold after traveling by airplane. The air circulation systems of commercial aircraft use HEPA filters that should remove any infectious agents that pass through them.

What are the possible reasons for increased incidence of colds after flights? Skip to main content. Disease and Epidemiology. Search for:. Modes of Disease Transmission Learning Objectives Describe the different types of disease reservoirs Compare contact, vector, and vehicle modes of transmission Identify important disease vectors Explain the prevalence of nosocomial infections.

Think about It List some nonliving reservoirs for pathogens. Explain the difference between a passive carrier and an active carrier. Black fly. Kissing bug. Mite chigger. Sand fly. Tsetse fly. Think about It Describe how diseases can be transmitted through the air. Explain the difference between a mechanical vector and a biological vector. Key Concepts and Summary Reservoirs of human disease can include the human and animal populations, soil, water, and inanimate objects or materials.

Contact transmission can be direct or indirect through physical contact with either an infected host direct or contact with a fomite that an infected host has made contact with previously indirect.

Vector transmission occurs when a living organism carries an infectious agent on its body mechanical or as an infection host itself biological , to a new host. Lack of adequate personal protective equipment for healthcare workers and limited capacity for testing have been significant issues as countries deal with the outbreak.

Hospitals are increasingly being recognized as potential points of transmission for the virus, particularly as more patients acquire COVID and require hospitalization.