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 Signs

appear 7-25 days after tick attaches

Parotid gland swells Ear is preferred feeding site

Fever

Anorexia & decrease in overall condition

Later 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>.

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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.

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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.

QUESTIONS?