Coastal fever
The Coast fever or East Coast fever is a by the single-celled parasite Theileria parva caused disease of the domestic cow , which in tropical Africa occurs and ticks of the species Rhipicephalus appendiculatus is transmitted.
Pathogen
Theileria parva is a unicellular parasite that belongs to the suborder Piroplasmorina and is therefore related, among other things, to Babesia . The generic name Theileria honors the Swiss-South African veterinarian Arnold Theiler , who researched the life cycle of the parasite. The sporozoites live in the tick's salivary glands and are released into the blood when it bites.
There are three known subspecies of T. parva : T. p. parva and T. p. lawrencei are very virulent , T. p. bovis a little less. The subspecies parva and bovis are mostly transmitted from cattle to cattle, the subspecies Lawrencei uses the African buffalo as a reservoir host .
Life cycle
The sporozoites that get into the blood with the tick saliva attack the lymphocytes and develop into schizonts within 5 to 10 days . These stimulate the lymphocytes to divide , and the schizont also divides with each cell division. The infected cell population then multiplies strongly and is distributed throughout the lymphatic system . Later, some of the schizonts develop into merozoites , which switch from lymphocytes to red blood cells . Some divisions of the parasite occur again within the red blood cells, but the blood cell itself no longer divides. These infected cells are ingested when a tick bites and in turn develop into sporozoites in the tick, which attack the salivary glands, from where they can spread to another cattle with the next bite.
Symptoms
Due to the uncontrolled multiplication of lymphocytes, infected cattle develop a clinical picture that macroscopically resembles a lymphosarcoma . The lymph nodes swell greatly, and parasitized lymphocytes can infiltrate other organs. At the same time, affected cattle suffer from a high fever of over 42 ° C. Death usually occurs 18 to 24 days after infection, mostly from pulmonary edema and sometimes massive internal bleeding. After surviving an infection, surviving animals are immune to the causative subspecies , but not to the other subspecies.
treatment
Treatment against Theileria spp. occurs through parvaquon and the substance buparvaquon derived from it . This treatment can usually cure the early stages of the disease; in advanced cases, however, the prognosis is reserved even after treatment with parvaquones.
prevention
A vaccination against Theileria parva is currently not available. In practice, deliberate infection with the parasite is used in combination with the simultaneous administration of oxytetracycline . Although this substance shows only inadequate action against the parasite in the case of a clinically apparent infection, it suppresses its life cycle when administered early.
Alternatively, immunization against coastal fever can also be achieved by deliberate infection with parvaquones after seven to nine days. However, this method is less common in practice because it requires the cattle to be caught twice.
Cattle should be immunized three to four weeks before moving to an enzootic area. Prevention by combating ticks is also possible, but is hardly practiced because of the high expenditure.
swell
literature
- East Coast Fever . In: The Merck Veterinary Manual , 9th edition, Whitehouse Station, NJ, USA, 2005, ISBN 0-911910-50-6 , pp. 30 ff
Web links
- East Coast Fever: A Review ( August 27, 2010 memento on the Internet Archive ) on the University of Georgia website
- Necropsy of a cattle who died of coastal fever
Individual evidence
- ↑ H. Unsuren, A. Kurtdede, K. Goksu: Effectiveness of parvaquone in cattle infected with Theileria annulata. In: Tropical animal health and production Volume 20, Number 4, November 1988, pp. 256-258, ISSN 0049-4747 . PMID 3238773 .