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Key Concepts in Infectious Disease Epidemiology
Published in Leonhard Held, Niel Hens, Philip O’Neill, Jacco Wallinga, Handbook of Infectious Disease Data Analysis, 2019
Closely related to the incubation period is the latent period which measures the time from infection to when an infected individual becomes infectious (and can thus transmit the infection to others). Often, the beginning of these time periods are determined by the time of exposure to an infectious agent since this time may be hard to distinguish from the occurrence of infection. Similarly, the end of the latent period often coincides approximately with the onset of symptoms so that the latent and incubation periods may be very similar. Incubation periods differ substantially for many common viral infections, ranging from a few days for influenza to around a week for dengue infection, 1 to 2 months for mononucleosis, and a decade or more for HIV. The length of the latent period is crucial in determining the risk of the spread of an infection, and infected individuals may not be ascertained during this time period (whereas interventions to limit infectiousness are available once symptoms are apparent).
Assessment of Medical Factors
Published in Abhaya Indrayan, Research Methods for Medical Graduates, 2019
A further implication of univariate and multifactorial terms is in risk assessment. Lung cancer can occur from smoking, exposure to radiation, asbestos dust, and other such toxicities. Any one of these factors can cause cancer. Also, one risk factor such as smoking can cause many diseases (lung cancer, asthma, coronary disease, etc.). An assessment of medical factors in research should give due consideration to such distinctions. In the case of noninfectious diseases, the latent period from exposure to onset can be long and the presence of other factors during this period can complicate the assessment.
An Introduction To Epidemiologic Methods
Published in Michele Kiely, Reproductive and Perinatal Epidemiology, 2019
Carol J. R. Hogue, George L. Rubin, Kenneth F. Schulz
A second advantage of case-control study design occurs in the study of disease with a long latent period. The latent period is the period of time elapsing between exposure to a particular factor and development of health problems from such exposure. Some conditions, particularly cancer, may take 20 years to develop after sufficient exposure. A cohort study design would require assembling an exposed and nonexposed group and following both groups for a minimum of 20 years to determine those subjects who develop the outcomes related to the exposure. A case-control approach would allow estimation of the relationship between exposure and outcome in a much shorter time. Thus, in the study of rare diseases or diseases with long latent intervals the case-control approach allows more rapid determination of the answer to a research question in a simpler and cheaper way than the cohort approach.
Uveitis and hypereosinophilia associated with dupilumab in an atopic dermatitis patient
Published in Journal of Dermatological Treatment, 2023
Shiyu Zhang, Lu Lu, Jindi Feng, Zhonghui Hu, Hongbin Song, Lu Yang, Yuehua Liu, Di Chen, Tao Wang
There were 5 cases of dupilumab-associated noninfectious uveitis reported in English literature, as summarized in Table 1. The ophthalmic symptoms in previous reports included redness, pain, impairment of visual acuity, and photophobia. These cases had pan uveitis (2 cases), anterior and intermediate uveitis, chorioretinitis, and posterior uveitis, respectively, which had more severe ocular inflammation and higher ophthalmic risks than our case. Ayasse et al. reported a 50-year-old AD patient who developed pan uveitis in both eyes uveitis after >1 year on dupilumab (4), which was relieved after stopping dupilumab and recurred within 1 month of restarting the drug. Padidam et al. reported 4 AD patients with uveitis in both eyes during dupilumab treatment (5). All 4 patients had a period of time longer than 6 months (>1 year, 2 years, 18 months, and 7 months, respectively) between dupilumab initiation and uveitis onset. In contrast, our case developed iridocyclitis (a form of uveitis) in one eye and in a shorter time after starting dupilumab. It might be supposed that lower severity might be associated with a shorter latent period, but this assumption needs further verification in larger-scaled studies.
Effectiveness of facemasks for opening a university campus in Mississippi, United States – a modelling study
Published in Journal of American College Health, 2022
C. Raina MacIntyre, Valentina Costantino, Linkan Bian, Cindy Bethel
Given the data are for informing the reopening of campus for the fall semester, we used current disease notification data from July 2020 with a hypothetical campus opening date of July 8th, 2020. The model is simulated for four months starting on July 8th 2020, and we started the epidemic with 6 infected people entering the MSU campus. This was estimated as a proportion of the total daily new notifications in the State two days later (July 10th) of 708, corresponding to the campus population representing 0.83% of the population of the whole state. The cases were distributed in the “latent, not infectious yet” compartment. The rest of the MSU population was considered susceptible. We considered the average latent period to last 5.2 days,10 of which the last two days before symptoms onset are considered infectious.9
Radiological Latency in Pineal Germinoma: A Case Report and Literature Review
Published in Neuro-Ophthalmology, 2022
Ivan Chi Hin Siu, Noel Ching Yan Chan, Xian Lun Zhu, Ryan Pak to Yuen, Zhexi He, Danny Tat Ming Chan
An interesting phenomenon seen in patients with intracranial GCTs is a latent period whereby radiological lesions are not evident upon symptoms onset. The “radiological latent” period has previously been well reported in patients with suprasellar GCTs,6–9 yet relatively infrequently with pineal region GCTs.10,11 This latent period and disease course pose diagnostic challenges and may lead to a delay in treatment, which carries negative impact on patient survival. We report a case of a 23-year-old male patient who presented with classic dorsal midbrain syndrome and yet had normal neuroimaging. When magnetic resonance imaging (MRI) was repeated at 30 months after symptom onset it revealed a pineal tumour, confirmed to be germinoma by stereotactic biopsy. The objective of this report is to arouse awareness of radiological latency in patients with pineal GCTs, and to explore the optimal time frame for MRI surveillance in this group of patients with suspected pineal GCT and yet negative MRI of the brain and brainstem at presentation.