theileriosis east coast fever
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THEILERIOSISEAST COAST FEVER
By Julie Murchie and Victoria Paesani
EAST COAST FEVER Phylum Apicomplexa
Caused by a tick-borne obligate intracellular parasite, Theileria parva, in sub- Saharan Africa, infecting ungulates
Major constraint to livestock production & food security in many developing countries Causes high morbidity & mortality, killing 1 million cattle every year
Prevents introduction of very productive but disease-susceptible breeds of cattle
Expensive to control Places a huge economic burden on poor smallholder farmers Costs nearly $170 million yearly Some African counties use the cattle as forms of currency
T. parva has ability to induce cancer in host cell in a way that is reversible Studies have provided clear links to cancer biology in humans Studying this parasite has given researchers clues for the right direction
Vaccines have the power to eradicate the disease
Not hazardous to human health
Brown Ear Tick
GEOGRAPHIC RANGEThreat mostly in eastern, central, & southern Africa
T. PARVA PRIMARY HOSTS
Cattle * Waterbuc
k
Indian Water Buffalo*
African Buffalo
*develop symptomatic infections
T. PARVA LIFECYCLE
4) Lymphocyte lymphoblast (enlarged lymphocyte) and…
3) Sporozoite enters lymphocyte (WBC) schizont
6) 10-15 days post-infection, schizont merozoite (invades erythrocyte (RBC))
1) Sporozoites produced in tick salivary glands
2) Sporozoites transfer to ungulate if tick is attached for 48-72 hrs
5) …divides with schizont inside 2 infected daughter cells
7) In RBC, merozoite piroplasm (infect ticks)
8) RBCs ingested by nymphs during feeding
Incubation PeriodExperimentally Infected: 8-12 daysNaturally Infected: up to 3 weeks
9) Once in gut, undergoes sexual reproduction motile stage, moves to tick’s salivary gland
* 5-8 days post-infection: found in lymph nodes* Schizonts increase 10-fold every 3 days
CLINICAL SIGNSFirst Signsappear 7-25 days after tick attaches Parotid gland swells
Ear is preferred feeding site Fever Anorexia & decrease in overall conditionLater Signs Lacrimation, corneal opacity Nasal discharge, terminal dyspnea Interlobular emphysema & sever pulmonary edema Before death, temperature falls & dyspnea intensifies Some develop neurologic disease “turning sickness”
Due to affected cells blocking circulation in capillaries within the CNS Death (18-30 days after infestation by ticks) The few survivors become lifelong immune carriers. Majority of these
cases, asymptomatic carriers can be recognized with little or no effect ontheir productivity. Minority develop chronic disease problems that result in stunted growth in calves and lack of productivity in adult cattle.
TREATMENT, PREVENTION, & CONTROL Vaccination
Infect animal with the sporozoite form of the parasite while at the same time treating the cattle with an antibiotic drug to lessen the severity of the infection
Pasture Management
Herd-Selection of Resistant Animals
Tick Control & Eradication
CASE STUDY
Induction of Acquired Immunity in Pastoral Zebu Cattle Against East
Coast Fever After Natural Infection by Early Diagnosis and Early Treatment
Matovelo et al. 2003
OBJECTIVES 1. Examine efficiency of
chemotherapy of natural ECF cases to look at protective immunity against ECF in cattle.
2. Design a regimen farmers can use to help minimize cattle loss due to ECF. This is done by establishing early disease diagnosis and early treatment.
METHODS AND MATERIALS Two villages in the Morogoro Rural
District Two seasons (April and November) Ear tagged 280 calves
METHODS AND MATERIALS Farmers were trained to monitor the animals
for clinical symptoms of ECF. Qualifying clinical symptoms: enlargement
of superficial lymph nodes, increase inbody temperature, dullness, and respiratory distress.
Animals diagnosed with ECFwere treated with buparvaquone.
Severity of the disease at the time of treatment was categorized based on the criteria set for ECF clinical reactions with some modifications.
CATEGORIES OF CLINICAL STATUS OF ECF
CASES BEFORE TREATMENTIndicator Variable Clinical status
Rectal Temperatur
e
Lymph node
status
Respiratory
performance
Demeanor
Mild Above 39.5 ºC
Swollen parotid
lymph-node
Normal Normal
Moderate Above 39.5 ºC
Swollen parotid and Prescapular
node
Slight labored
breathing Nasal
discharges
Normal
Severe Above 39.5 ºC
Swelling off all superficial lymph nodes
Respiratory distress
Reluctant to move/
recumbence
METHODS AND MATERIALS Treatment responses were categorized
as prompt/rapid, slow, or died.
Examined serum antibodies to T. parva, with samples at the beginning and end of study, using ELISA.
Studied blood and lymph node smears for T. Parva parasites.
RESULTS 100 animals were diagnosed with ECF
Most prominent clinical signs were fever and lymph node enlargements.
81% of animals were positive for ECF on
at least one screening method.
During follow-up, only 5 individuals were diagnosed with ECF a second time.
Diagnostic Means
Cases Tested
Missing Clinical Responses
Total Cases
Mild Moderate
Severe
Clinical signs of ECF
100 0 100(100%)
4 66 30
Lymph node smears
99 1 67(67.68%)
3 42 22
Blood Smears
98 2 41(41.84%)
1 27 13
No test detected
__ __ 19(19%) 1 13 5
DISCUSSION Majority of cattle that were treated
recovered. (98% recovery rate)
Shows that early diagnosis and early treatment is a reliable means to diagnose cattle with ECF on a basis of clinical signs in endemic areas.
Reliable early signs of infection are fever and swollen lymph nodes.
DISCUSSION CONT. Use of chemotherapy with the early
detection and early treatment approach reduced mortality and helped cattle develop immunity.
In terms of immunization, the early detection and early treatment approach is a reasonable alternative to the infection and treatment.
CONCLUSION East Coast Fever is caused by Theileria parva Hosts
Intermediate= cattle Definitive= ticks
Incubation time is anywhere from 8 days to 3 weeks.
Very expensive High morbidity & mortality rates No harm to human health
SOURCES Matovelo, Gwakisa, Gwamaka, Chilongola, Silayo, Mtenga, Maselle, and Kambarage. "Induction of
Acquired Immunity in Pastoral Zebu Cattle Against East Coast Fever After Natural Infection by Early Diagnosis and Early Treatment." The Journal of Applied Research In Veterinary Medicine. 2003. Web. 23 Mar. 2011. <http://www.jarvm.com/articles/Vol1Iss2/Matovelo.htm>.
Azeem Photos. 2010. A blue water is looking well with animal Waterbucks. <http://azeem-photos.blogspot.com/2010/09/blue-water-is-looking-well-with-animal.html>. Accessed 22 March 2011.
Department for International Development Animal Health Programme, University of Edinburgh. 2005. R8042 – Integrated control of East Coast fever in cattle of small-holder farmers. <http://www.dfid-ahp.org.uk/index.php?section=4&subsection=48>. Accessed 21 March 2011.
Food and Agriculture Organization of the United Nations. 1983. Eradication – an alternative to tick and tick-borne disease control. <http://www.fao.org/docrep/004/x6538e/X6538E00.htm#TOC>. Accessed 22 March 2011.
International Laboratory for Research on Animal Diseases. 1991. ILRAD 1990: Annual Report of the International Laboratory for Research on Animal Diseases. Nairobi: International Laboratory for Research on Animal Diseases.
Malcolm J. G., et al. 2005. Genome Sequence of Theileria parva, a Bovine Pathogen That Transforms Lymphocytes. Science 309:134-136.
Melhorn, H. Genus Ripicephalus Brown ear tick. Heinrich-Heine-Dusseldorf University. <http://www.butox-info.com/ectoparasites/ripicephalus.asp>. Accessed 22 March 2011.
Morzaria, S.P. Identification of Theileria species and characterization of Theileria parva stocks. International Laboratory for Research on Animal Diseases. <www.fao.org/Wairdocs/ILRI/x5549E/x5549e0t.htm>. Accessed 23 March 2011.
Science and Development Network. 2005. Genetic codes of cattle-killing parasites cracked – SciDev.Net. <http://www.scidev.net/en/news/genetic-codes-of-cattlekilling-parasites-cracked.html>. Accessed 22 March 2011.
Smith, M.C. Special Problems of Meat Goats (VET-595). Ambulatory and Production Medicine, New York State College of Veterinary Medicine, Cornell University. <http://www.vin.com/proceedings/Proceedings.plx?CID=WSAVA2002&Category=&PID=5736&O=Generic>. Accessed 22 March 2011.
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