EQUINE | Equine Disease Quarterly
with a history of respiratory disease.
Equine infectious anemia was reported from Canada
(single cases on two premises), Germany (one case),
Greece (one case), and the USA (18 cases involving
six states; 12 cases were in Texas).
RSA reported that equine piroplasmosis was widely
present in the country with multiple cases of the
disease confirmed in five provinces.
Germany confirmed Taylorella equigenitalis, the
causal agent of contagious equine metritis in eight
stallions and one mare, all of the Icelandic breed.
Seven premises were involved.
Single cases of equine coital exanthema caused by
equine herpesvirus 3 were recorded by Switzerland
and the USA.
Cases of salmonellosis were reported from Ireland
(one case) and the USA (12 cases, the majority
associated with strains of salmonella belonging to
serogroup B). The USA confirmed three cases of equine
neorickettsiosis (Potomac horse fever), and Germany
one case of rotaviral diarrhea in a foal.
A single case of rabies was confirmed in Nebraska,
USA.
The USA recorded 10 cases of Eastern equine
encephalomyelitis, all in Florida.
Single cases of West Nile encephalitis were reported
from Brazil and RSA.
RSA also recorded 16 cases of encephalitis due to
Middleburg virus infection and two cases due to Shuni
virus infection.
Equine encephalosis was reported from RSA. Thirty-
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three cases were diagnosed in five provinces; these
included seven in the Western Cape Province.
Rhodococcus equi infection is endemic in the USA; 14
cases were confirmed during the period under review.
Germany reported a case of anaplasmosis and
Switzerland four cases of ehrlichiosis.
Asian Longhorned Tick (Haemaphysalis
longicornis): Challenges from an Invasive
Ixodid Tick
Asian longhorned ticks (ALT) have small, reddish-brown
bodies with no distinctive markings to facilitate quick
recognition. In addition, unfed adults are smaller (3 to
4 mm long) than the familiar commonly encountered
hard ticks. The initial confirmed identification of ALT
in the USA was based on specimens collected from
a heavily-infested sheep in New Jersey in 2017. This
was thought to be the first detection of a new tick
species in the USA in 50 years. However, subsequent
investigation revealed that specimens removed from
a dog in New Jersey in 2013, which were initially
identified as the native rabbit tick Haemaphysalis
leporispalustris, were also ALT. Consequently, the
species has been present for several years and has
spread. As of August 2018, this invasive tick has been
found in at least one location in Arkansas, Connecticut,
Maryland, New Jersey, New York, North Carolina,
Pennsylvania, Virginia, and West Virginia (Figure 1).
Reported hosts have included cattle, a dog, a horse,
an opossum, and white-tailed deer.
Native to China, Korea, and Japan, the ALT became
established in Australia and New Zealand, where
it feeds on a variety of wild and domestic animals
and humans. This species does best in moist, warm
environments. However, it can withstand temperatures
from its developmental threshold of ~12ºC to a lethal
high temperature of 40ºC. Adults and particularly
• Equine Health Update •