AFRICAN HORSE SICK­NESS (AHS)

EQUUS - - Eq Casereport -

Def­i­ni­tion: Highly fatal, in­sect­borne vi­ral dis­ease en­demic to sub-Sa­ha­ran coun­tries.

Causes: AHS is caused by in­fec­tion with one of nine strains (serotypes) of a virus in the Reoviri­dae fam­ily. Two in­sect vec­tors, both of which are bit­ing midges, are known to carry the virus: Culi­coides im­i­cola and Culi­coides boliti­nos. The dis­ease is trans­mit­ted be­tween horses, mules, don­keys and ze­bras through the bites of these in­sects, peak­ing dur­ing warm months of the year when in­sects are most ac­tive. Ze­bras are thought to be reser­voir hosts, mean­ing they har­bor the virus for long pe­ri­ods of time with­out be­com­ing sig­nif­i­cantly ill.

Signs: There are three types of AHS: A car­diac form, which leads to swelling in the de­pres­sions just above the eyes, along with the head, neck, throat and shoul­der, in ad­di­tion to a fever be­tween 102 and 106 de­grees Fahren­heit; a res­pi­ra­tory form, char­ac­ter­ized by dif­fi­culty breath­ing, coughing, a frothy dis­charge from the nos­trils and a fever of 104 to 106 de­grees Fahren­heit; and a “mixed” form with char­ac­ter­is­tics of both. The mor­tal­ity rate is be­tween 50 and 90 per­cent de­pend­ing on the form of the dis­ease and sever­ity of the case; horses typ­i­cally die within a week of on­set of ill­ness.

Di­ag­no­sis: The only con­clu­sive test for AHS re­quires de­tect­ing the virus in a blood sam­ple, which can take sev­eral days. Due to the fast-mov­ing na­ture of the dis­ease, most di­ag­noses are made on clin­i­cal signs alone, tak­ing into ac­count en­vi­ron­men­tal fac­tors such as in­sect ac­tiv­ity and weather pat­terns.

Treat­ment: In­tra­venous flu­ids and other sup­port­ive care. Non­s­teroidal anti-in­flam­ma­tory med­i­ca­tions and cor­ti­cos­teroids are used to ad­dress the fever and other clin­i­cal signs. An­tibi­otics may be ad­min­is­tered to pre­vent sec­ondary bac­te­rial in­fec­tions, par­tic­u­larly in res­pi­ra­tory cases. Horses may also be given in­tra­venous flu­ids.

BIT­ING MIDGE ( CULI­COIDES IM­I­COLA)

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