Abstract
Canine ehrlichiosis is an infection of canids causing a clinical disease in domestic dogs and asymptomatic infections in wild canids. Currently, the disease assumes a cosmopolitan distribution. This chapter summarises published information on the disease from across Africa. Some studies were able to demonstrate experimental infections in these canids. Different diagnostic methods, cell culture, direct microscopy, serology, hematology, and molecular methods were employed in different studies for detection of ehrlichiosis. Treatment of the disease mainly involved use of oxytetracycline, doxycycline, imidocarb disproportionate, and levamisole. In severe cases, management has involved administration of supportive therapy such as blood transfusion. Generally, though available, the information on different aspects of the disease in the Africa is scant and fragmented. There is still a need to generate more information on the epidemiology, diagnosis, clinical aspects, and treatment of the disease.
TopBackground
Description of Canine Ehrlichiosis: Definition, Aetiology, and Epidemiology
Canine ehrlichiosis, also known as canine rickettsiosis, canine haemorrhagic fever, tracker dog disease, canine tick typhus, Nairobi bleeding disorder, and tropical canine pancytopenia, is an important tick-borne disease that is a member of the family Canidae, which is particularly found in dogs (Dubie et al., 2014). Canine ehrlichiosis was reported for the first time in Algeria in the year 1935 (Donatien & Lestoquard, 1937). Since then, the disease has distributed worldwide (Beall et al., 2012), and Africa suffers the highest burden. The geographical distribution of causative agents corresponds to distribution of their vector tick, Rhipicephalus sanguineus. Several species have been reported to cause ehrlichiosis in domestic dogs and wild canids: Ehrlichia canis, E. chaffeensis, E. ewingii, and E. ruminantium (Kelly, 2000; Ndip et al., 2010; Parola et al., 2003; Pretorius & Kelly, 1998). E. canis is responsible for most of the cases worldwide (Dhliwayo et al., 2019; Penzhorn et al., 2018). E. canis is transmitted transstadially and intrastadially by R. sanguineus (Bremer et al., 2005). The infective stages, elementary bodies, are transmitted to new hosts via tick bites. These infective stage bodies enter the host’s monocytes, or other types of leucocytes, by phagocytosis. They then replicate inside phagosomes by binary fission, forming clusters of tightly packaged elementary bodies termed “initial bodies” (Forbes et al., 2007), which develop further to form morulae. The rupture of affected host cells release elementary bodies, which then infect new cells (Kruss et al., 2003).
Key Terms in this Chapter
Lethargy: Is tiredness, weariness, fatigue, or lack of energy. It can be accompanied by depression, decreased motivation, or apathy.
Pancytopenia: A reduction in all blood lines (reduction in the number of red and white blood cells as well as platelets).
Binary Fission: Asexual reproduction by a separation of the body into two new bodies.
Phagosomes: Vesicles formed around a particle engulfed by a phagocyte via phagocytosis. Professional phagocytes include macrophages, neutrophils, and dendritic cells.
Myelosuppressive or Bone Marrow Suppression: A decrease in the ability of the bone marrow to produce blood cells, which may result in a lack of red blood cells, white blood cells, and platelets.
Tenesmus: A continual or recurrent inclination to evacuate the bowels, caused by disorder of the rectum or other illness.
Phagocytosis: A fundamental process of cells to capture and ingest foreign particles.