Dapsone
M. Lindsay Grayson, Sara E. Cosgrove, Suzanne M. Crowe, M. Lindsay Grayson, William Hope, James S. McCarthy, John Mills, Johan W. Mouton, David L. Paterson in Kucers’ The Use of Antibiotics, 2017
Leprosy is predominately spread via aerosol from the respiratory secretions of patients with the multibacillary or lepromatous form of the disease. The incubation period varies considerably, from as little as a few months to more than 30 years, with the mean incubation period for paucibacillary disease being estimated to be 4 years and the mean incubation period for multibacillary disease estimated at 10 years. Subclinical infection is likely to be common in places where the disease has not been controlled. Up to 5% of people in villages in India and Indonesia where there are untreated cases of multibacillary disease have detectable M. leprae DNA on nasal swabs (Hatta et al., 1995; Ramaprasad et al., 1997). The majority of those who develop subclinical infection do not develop the disease. It is thought that approximately 5% of those who have subclinical infection develop the early clinical form of the disease called indeterminate leprosy. This manifests as a single skin lesion that usually spontaneously resolves after a period of time. About 25% of those who have had indeterminate leprosy go on to develop the progressive form of the disease.
Tissue Responses to Infection and Injury
Jeremy R. Jass in Understanding Pathology, 2020
We usually take the body’s defences against infection or injury for granted, not realising that potential pathogens are being repelled successfully on a continuous basis and before they have a chance to provoke a noticeable response. Some micro-organisms, particularly viruses, may initiate an immune response that is not accompanied by symptoms of any kind. This is termed a subclinical infection. It is also common, again mainly with certain types of virus, for infection to lie latent within the body, reawakening in response to a stimulus or to immune suppression. Viruses achieve this dormant state by integrating their own DNA with that of the host. Some bacteria, notably Mycobacterium tuberculosis, may also lie dormant for years. This chapter will be confined to a general overview of the major types of clinically apparent tissue response evoked by infective or injurious agents.
Herpes Simplex Virus Vaccines and the Viral Strategies Used to Evade Host Immunity
Marie Studahl, Paola Cinque, Tomas Bergström in Herpes Simplex Viruses, 2017
Ideally, an HSV vaccine should prevent both clinical and subclinical infection. Clinical infection is measured by lesion formation, while subclinical infection is detected by asymptomatic viral shedding or more commonly, by seropositivity in subjects who never knowingly had herpes lesions. The concept of preventing subclinical infection is referred to as sterile immunity. Can an HSV vaccine induce sterile immunity? The markers of sterile immunity include no lesion formation at the initial site of infection, no establishment of viral latency, and no asymptomatic virus shedding on mucosal or skin surfaces. These are high standards for a vaccine to achieve. An alternate outcome that may be more readily achieved is preventing symptoms, but not infection. However, the immunocompromised host is likely to remain at risk for serious recurrent infections in vaccinated populations unless sterile immunity is achieved. Below we discuss current strategies and progress on developing effective HSV vaccines.
The burden of pertussis in older adults: what is the role of vaccination? A systematic literature review
Published in Expert Review of Vaccines, 2019
Walid Kandeil, Petar Atanasov, Diana Avramioti, Josephine Fu, Nadia Demarteau, Xiao Li
However, several studies also attributed underreporting to the perceived mild nature of the disease in healthy older adults [31]. A study from The Netherlands conducted in 2006–2007 showed that only 17% and 36% of adults aged 50–64 and 65–79 years respectively, with serological evidence of recent pertussis infection, reported coughing [31]. Even though pertussis is often perceived as a mild disease, it is highly infectious and can therefore be easily transmitted to more vulnerable populations, such as neonates and the aforementioned patients with chronic diseases. Of note, serological cut-offs indicative of infection cannot clearly differentiate between clinical and subclinical infection. While only the former contributes to the true burden of disease, the latter remains important, since asymptomatic infected individuals represent a source of transmission, which can partly account for the observed increased in pertussis incidence over the last decades [90]. Moreover, in adults and in particular in the elderly, the distinction between asymptomatic infections and mild symptomatic ones may be difficult to make, especially in the presence of chronic respiratory diseases. A number of cases considered subclinical might not be in fact truly asymptomatic, and thus contributing to underreporting of pertussis.
Tetraventricular hydrocephalus with aqueductal flow void: an overlooked entity having consistent improvement following endoscopic third ventriculostomy
Published in British Journal of Neurosurgery, 2023
Sushanta K. Sahoo, Sivashanmugam Dhandapani, Chirag K. Ahuja
Within normal range of temperature and pressure, the density of CSF remains constant. Viscosity of CSF largely depends on protein, glucose and cell count. In cases of meningitis, high protein and cell count of CSF may be responsible for increased viscosity.12 In the absence of any pathological condition, the biochemical profile as well as the viscosity of CSF will not alter. In these cases, the velocity of flow largely depends up on the volume of CSF flowing per unit time. In this series, all patient showed CSF flow voids on MR images suggestive of turbulent CSF pattern. Radiologically nine patients had grade 4 and two had grade 3 CSF flow voids. There was no history of CSF infection in the past. Careful evaluation of radiology showed membranous out pouching below the fourth ventricular outlet in two pediatric patients (Figure 3(A)). Relative obstruction at the foramina of Magendie and Luschka can occur secondary to higher CSF flow. We believe that if the CSF outflow through the normal fourth ventricular outlet is unable to keep up with the hyperdynamic circulation, the proximal ventricular system may dilate. However, the possibility of subclinical infection in the past cannot be ruled out in these patients. Disparity between the rate of intraventricular CSF flow and fourth ventricular outlet area probably gives rise to a type of relative fourth ventricular outflow resistance in these cases resulting in TetHCP. We therefore consider the hyperdynamic CSF circulation/CSF flow void is not just an epiphenomenon.
Biofilm-related disease
Published in Expert Review of Anti-infective Therapy, 2018
Jose Luis Del Pozo
Biofilm microorganims growing in the environment of this foreign body reaction are now known to lead to degradation of the biomaterials with subsequent clinical device failure [12]. Depending on the balance of the interactions between the host, implant, microorganisms and their byproducts, different clinical presentations can be observed, which may occasionally shift from one to the other. Implant malfunction can display mild clinical signs/symptoms, such as light pain and/or slight soft tissue contracture or even functional impairment, with negative infection/inflammatory markers. Diagnosis of subclinical infection often requires prolonged cultures, specific microbiological laboratory procedures (sonication) and eventually genomic investigations for detection of biofilm pathogens [12,54].
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