China
Africa
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Tick Typhus
Published in James H. S. Gear, CRC Handbook of Viral and Rickettsial Hemorrhagic Fevers, 2019
The prototypes of these infections are boutonneuse fever, occurring in the countries bordering on the Mediterranean, and South African tick-bite fever — the variety of tick typhus occurring in southern Africa. The pathogenesis and clinical manifestations of the disease will be noted.
Ticks
Published in Gail Miriam Moraru, Jerome Goddard, The Goddard Guide to Arthropods of Medical Importance, Seventh Edition, 2019
Gail Miriam Moraru, Jerome Goddard
African tick bite fever (ATBF), caused by the spotted fever group rickettsia, Rickettsia africae, is clinically similar to BF with the exception that there is usually an absence of rash in ATBF patients.49,50 ATBF also produces an eschar. The disease has been recognized in sub-Saharan Africa (especially South Africa) and the French West Indies and is transmitted by Amblyomma hebraeum and A. variegatum ticks.51,52 ATBF appears to be an emerging cause of influenza-like illness in travelers.53
Infections of the Blood
Published in Keith Struthers, Clinical Microbiology, 2017
This chapter is primarily concerned with the presence of bacteria in the blood. However, many other organisms enter the blood to cause disease. These include those transmitted by various arthropod vectors, such as mosquitoes of the genera Anopheles (malaria), Aedes (yellow fever virus, dengue fever virus), Culex (West Nile virus) and the tsetse fly, Glossina morsitans (African trypanosomiasis/sleeping sickness). Ticks of the genus Ixodes transmit Lyme disease (Borrelia burgdorferi), while rickettsial diseases are transmitted by Dermacentor (Rocky Mountain spotted fever) and Amblyomma (African tick-bite fever) ticks. Wucheria bancrofti, a tissue nematode, is distributed in parts of the tropics and subtropics. Adult worms reside in the lymphatics, and their microfilaria enter the blood to be taken up by blood-feeding female mosquitoes of the genera Aedes, Anophyles and Culex. Passing through the insect's midgut, they reach the thoracic muscles, and mature into larvae that infect the human when the mosquito next feeds.
Platelet toll-like receptors are crucial sensors of infectious danger moieties
Published in Platelets, 2018
Hind Hamzeh-Cognasse, Philippe Berthelot, Bernard Tardy, Bruno Pozzetto, Thomas Bourlet, Sandrine Laradi, Olivier Garraud, Fabrice Cognasse
In addition, it has been shown that a gram-positive bacterium involved in periodontitis, Porphyromonas gingivalis, is able to induce – via the TLR2 – the expression of the CD40L activation marker on platelets, leading to the release of sCD40L and RANTES and to an increased intracellular free calcium concentration (41). Assinger et al. demonstrated that TLR2 expression on platelets is required for the efficient phagocytosis of periodonto-pathogens since it promotes the binding of platelets to neutrophils upon exposure to these bacteria (42). Furthermore, TLR2 was shown to be specifically engaged by Rickettsia africae, the causative agent of African tick bite fever, inducing platelets to release sCD40L (43).