Specific Infections in Children
Miriam Orcutt, Clare Shortall, Sarah Walpole, Aula Abbara, Sylvia Garry, Rita Issa, Alimuddin Zumla, Ibrahim Abubakar in Handbook of Refugee Health, 2021
In children, dengue is often a milder disease than in adults and may go unnoticed but is sometimes severe. Severity is increased after previous exposure to a different serotype and in the presence of genetic susceptibility. The self-limiting dengue fever consists predominantly of fever, rash, headache and muscle and joint pain, without any clinical warning signs. Dengue haemorrhagic fever is more serious and involves plasma leakage characterised by a rise in haematocrit (>20%) and thrombocytopaenia. Clinical signs include pleural effusions and ascites, and signs of bleeding ranging from a positive tourniquet test to active bleeding (e.g. from mucosae, the gastrointestinal tract and injection sites). Severe plasma leakage leads to dengue shock, multi-organ failure and potentially death.
Viral and Rickettsial Hemorrhagic Fevers: Laboratory Investigation of the Hemorrhagic State
James H. S. Gear in CRC Handbook of Viral and Rickettsial Hemorrhagic Fevers, 2019
The full blood count in the hemorrhagic patient almost always shows thrombocytopenia, which may be moderate or severe. The white cell count may be decreased, normal, or increased (frequently in that order chronologically during the course of the disease), the increase usually reflecting a neutrophilia. These variations are also related to the heterogeneity of the hemorrhagic fevers themselves. The hemoglobin concentration and red cell indices are usually unremarkable, although a mild-to-moderate anemia may develop. An elevation of the hematocrit or hemoglobin concentration due to hemoconcentration is characteristic in dengue hemorrhagic fever. Morphological examination of blood films discloses atypical lymphocytes and granulocytic changes, including toxic granulation and a left shift, in some cases resembling the Pelger-Huet anomaly.87,106 Platelets are scanty and may be larger than normal. None of these changes is of any great diagnostic value as they may be found in many of the conditions listed in Table 1. Qualitative abnormalities of red cells, including fragmentation and spherocytosis, may be markers of microangiopathic hemolysis and suggestive of DIC or thrombotic thrombocytopenic purpura (TTP).
Engineering and infectious disease
Sandy Cairncross, Richard Feachem in Environmental Health Engineering in the Tropics, 2018
The fourth and final route is for water-related diseases to be spread by insects which either breed in water or bite near water. Malaria, yellow fever, dengue and onchocerciasis (river blindness), for example, are transmitted by insects which breed in water, while West African sleeping sickness is transmitted by riverine tsetse flies (Glossina spp.) which bite near water. Environmental methods for control of dengue are a particular concern, because: dengue (and often-fatal dengue haemorrhagic fever) are becoming more and more common worldwide (Guzman and Harris 2015)no effective vaccine or drug treatment is available, so that vector control is the only viable control methodthe same mosquito species which transmits dengue also transmits other emerging viruses such as the zika virus.
Platelet interactions with viruses and parasites
Published in Platelets, 2015
Dengue hemorrhagic fever is unusual as it typically occurs in response to a secondary infection with the primary infection producing relatively minor flu-like symptoms. In fact, there are four serotypes of DENV and it is infection with a second serotype that leads to dengue hemorrhagic fever. This suggests that the presence of anti-DENV antibodies is necessary for DHF to occur and this process is known as antibody-dependent enhancement (ADE) [33, 34]. These antibodies have been shown to enhance virus uptake and replication through an interaction with Fc receptors [34–37]. However, just as antibody binding to bacteria can trigger platelet activation, it is likely that antibody binding to DENV will also activate platelets in an FcγRIIa-dependent manner. This platelet activation has been shown to lead to enhanced endothelial permeability [38]. Bone marrow infection occurs in animal models of Dengue [39] which could lead to thrombocytopenia due to impaired platelet production.
Original antigen sin and COVID-19: implications for seasonal vaccination
Published in Expert Opinion on Biological Therapy, 2022
Original antigenic sin may reveal an asymmetric pattern of protective antibody cross-reactivity determined by exposure to previously existing strains of a given pathogen, and this phenomenon appears to occur more frequently in response to viruses [25–27]. Early work on immune imprinting focused primarily on the response to influenza [28–30]. This was due to the presumed influenza anamnesis of the human population born before 1956 – the year when A(H1NI) influenza viruses came out of circulation [31]. However, the phenomenon original antigenic sin has also been observed in response to dengue, a viral infection transmitted to humans through the bite of infected mosquitoes [32]. Symptoms typically occur 3 to 14 days after infection and may include fever, joint pains, rash, nausea, vomiting, and headache [33]. In some cases, the condition progresses to dengue hemorrhagic fever, which results in bleeding and severe hypotension that may be lethal [34–36].
Biologics for dengue prevention: up-to-date
Published in Expert Opinion on Biological Therapy, 2023
Adam T Waickman, Krista Newell, Timothy P Endy, Stephen J Thomas
Dengue is a growing public health problem with the global disease burden growing annually. Infection may not manifest clinically or cause severe plasma leakage and/or hemorrhage and death. Numerous risk factors for severe disease have been proposed but the most convincing data points to sequential infections with different DENV types. Treatment is supportive as there are no licensed anti-DENV antivirals or immuno-therapeutics. A single dengue vaccine has been licensed and there are two others in advanced clinical development. Dengvaxia has been licensed in more than 20 countries, but use has been minimal as a result of safety signals in the youngest recipients and those who were dengue naïve at the time of vaccination. There are a number of antivirals being used therapeutically to treat severe dengue illness but none of them have established clinical efficacy to date. The world still requires a safe and efficacious tetravalent dengue vaccine capable of protecting seropositive and seronegative recipients across a broad age range and an effective antiviral to either prevent infection or treat severe dengue hemorrhagic fever.
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