HEARTWATERAnother Potential Foreign Animal Disease

Prepared by : Debbra Marcel

Monoclonal Antibody Section,Veterinary Research Institute (VRI)

• a.k.a COWDRIOSIS, is non-zoonotic disease but oftenacute, fatal, infectious and tick-borne (Amblyomma ticks)rickettsial on ruminants.

• caused by bacteria Ehrlichia ruminantium (Dumler, 2001).

• widespread in most of Africa, also found on a fewCaribbean islands and threatening the American mainland.However, no case reported in Asia regions yet (OIE, 2010).

• can cause high mortality (up to 90%) in susceptible wildand domestic ruminants (cattle, sheep, goats, antelope andbuffalo) esp. young animals and non-native breeds

INTRODUCTION

Goats and sheep are more susceptible than cattle, and European breeds are generally more susceptible than

indigenous African breeds.

Amblyomma ticks

Goat Sheep Cattle

GEOGRAPHICAL DISTRIBUTION

According to OIE 2010, no case for this disease ever reported in Southest Asia (including Malaysia)

CLINICAL SIGNS• caused by an increased vascular permeability and consequent oedema and

hypovolaemia.

• symptoms include neurological signs such as tremors and head pressing,respiratory signs such as coughing and nasal discharge, and systemic signs such asfever and loss of appetite.

• high death rates in acute stage without many clinical manifestations while in thehigher recovery rate in peracute stage.

• physical examination may reveal petechiae of the mucous membranes, tachycardiaand muffled heart sounds.

EXTRA INFO:

• can also cause reproductive and gastrointestinal disease.

• recovered animals become carriers of infection

• certain wild animals can play a role as reservoir

fever and loss of appetitecoughing and nasal dischargeoedema and hypovolaemiaa

DIAGNOSIS(POST-MORTEM EXAMINATION)

• Light yellow transudate within the thorax, pericardium andabdomen.

• Pulmonary oedema and mucosal congestion are regularlyseen along with frothy fluid in the airways and cut surfaces ofthe lungs.

• Hydropericardium, hydrothorax and lung oedema arecommonly associated post-mortem signs.

Histopathological identification of Ehrlichia ruminantium:

by preparing the hippocampus under Giemsa staining or by

Histopathology (brain/kidney).

stained Ehrlichia ruminantium

DIAGNOSTIC TECHNIQUES(based on OIE Terrestrial Manual)

1. Identification of the agent (Isolation of Ehrlichia ruminantium )

a) using in-vitro culture

b) using in-vivo culture

2. Molecular methods (detection of Ehrlichia ruminantium )

a) using DNA probes

b) using PCR and nested PCR

c) using the reverse line blot technique

d) using real-time PCR

3. Serological tests

a) IFAT with infected endothelial cell tissue culture as

antigen (CIFA test)

b) MAP1-B enzyme-linked immunosorbent assay

c) MAP1 competitive enzyme-linked immunosorbent

assay

Bacterial Isolation

Fluorecense Test

ELISA

TREATMENT AND CONTROLTREATMENT

• During the early stages, animals may be treated withsulfonamides and tetracyclines.

• In advanced disease, prognosis is poor.

CONTROL• Tetracyclines can also be used prophylactically when animals

are introduced into an area endemic with cowdriosis.

• A live blood vaccine is available for protection of young stock,but animals may require treatment for the disease post-vaccination.

• Ectoparasiticides dips such as Rhipicephalus (Boophilus) andHyalomma species will contribute to control of vectors ofEhrlichia ruminantium.

REFERENCES1. Dumler JS, Barbet AF, Bekker CP, et al. (2001). "Reorganization of genera in the

families Rickettsiaceae and Anaplasmataceae in the order Rickettsiales: unificationof some species of Ehrlichia with Anaplasma, Cowdria with Ehrlichia and Ehrlichiawith Neorickettsia, descriptions of six new species combinations and designation ofEhrlichia equi and 'HGE agent' as subjective synonyms of Ehrlichia phagocytophila".Int. J. Syst. Evol. Microbiol. 51 (Pt 6): 2145–65. doi:10.1099/00207713-51-6-2145.PMID 11760958.

2. http://www.ebi.ac.uk/2can/genomes/bacteria/Ehrlichia_ruminantium.html

3. "Heartwater". Animal and Plant Health Inspection Service. U.S. Department ofAgriculture. Retrieved 2008-04-13.

4. C H A P T E R 2 . 1 . 6 . HEARTWATER. OIE Terrestrial Manual (2008).

5. CFSPH Technical Fact Sheets. Heartwater at http://www.cfsph.iastate.edu/DiseaseInfo/

6. Heartwater: Another Potential Foreign Animal Disease. http://www.vetmed.ucdavis.edu/vetext/INF-DA/INF-DA_HEARTWATER.HTML

7. USDA APHIS factsheet. Heartwater. http://www.aphis.usda.gov/lpa/pubs/fsheet_faq_notice/fs_ahheartw.html

Prepared by : Debbra Marcel

Monoclonal Antibody Section,Veterinary Research Institute (VRI)