Epidemiology of canine echinococcosis in northwest Libya, northwest Kenya (Turkana) and mid-Wales

Buishi, IE

Abstract

Echinococcus granulosus is a cestode species responsible for human cystic
echinococcosis (CE). The domestic dog is the primary definitive host for the
transmission of E.granulosus infection to domestic livestock intermediate hosts and to
humans. In order to determine the prevalence and risk factors for canine echinococcosis,
epidemiological studies were conducted in known endemic localities in three different
countries i.e. Libya, Kenya and Wales. Stray dogs were subject to direct examination of
the small intestine at necropsy. Owned dogs (total n=1659) were screened for
E.granulosus infection using a genus specific coproantigen ELISA test that was re-
standardised against 75 dog necropsy results, and exhibited 100% sensitivity and 98%
specificity. Analysis of risk factors for canine echinococcosis associated with
Echinococcus coproantigen positive results was evaluated based on dog-owner
questionnaires. In Libya, the overall infection of E.granulosus in autopsied dogs was
25.8%, and an overall coproantigen prevalence of 21.6% was obtained for owned dogs
(n= 334). Risk factors (p<0.05) for a coproantigen positive owned dog in Libya were,
dog age (< 5 years), non-restraint of dogs, dogs fed on offal, sheepdog class, owners
that did not de-worm their dogs, and dogs owned by farmers who admitted to frequent
slaughter of livestock. Dog sex was not a significant risk factor for a positive
coproantigen ELISA in dogs from all study areas. Worm burdens in necropsied dogs in
Libya ranged from 29 to 2900 (mean 1064) and were positively correlated to
coproantigen ELISA OD values (r= 0.76), but negatively associated with dog age (r= -
0.64). Canine echinococcosis in Libya measured by locality varied, with Alkhums
(Leptis-Magna) district having the highest coproantigen prevalence at 38.7% (p=0.001),
followed by Azahwia district with 19.2%. Tripoli district had the lowest copro-
prevalence where 17.5% of dogs were copro-positive. In Tripoli an abattoir survey for
livestock CE was also undertaken and is reported. In northern Kenya, post-mortem
examination of the small intestines of 17 dogs from Turkana, revealed 29.4% harboured
E.granulosus infection, with a mean worm burden of 1570 adults. Overall 26% (42/161)
of Turkana dogs were copro-positive, with the highest copro-prevalence identified in
dogs from Lokichoggio division. Younger dogs (< 5 years), free-roaming dogs, dogs
fed on offal, and dogs of owners that practiced home slaughter of livestock and that had
no knowledge about echinococcosis, appeared to have a significantly higher risk of
being coproantigen positive (p<0.05). In mid-Wales a list of 321 sheep farms were
selected at random, from which 1164 farm-dogs were screened using rectal faecal
samples tested for Echinococcus coproantigens, and owners questioned using a
modified dog-owner questionnaire. Furthermore, the potential impact of the 2001 foot-
and-mouth disease (FMD) epidemic, on the prevalence of E.granulosus in farm dogs
was assessed. An overall coproantigen positive rate of 8.0% was recorded on 22% of
farms surveyed, which compared to a rate of 3.4% obtained in the same region in 1993.
There was no significant difference in copro-positive prevalence between FMD affected
properties and those that were unaffected. Significant risk factors for a positive farm
dog in Wales were associated with allowing dogs to roam free, and infrequent de-
worming (>4month intervals) of dogs. The data are discussed in relation to a previous
pilot hydatid control program in that area of Wales (1983-89) and the potential for
increase in transmission to humans. Identification of risk factors associated with canine
echinococcosis appear to be similar in all three communities studied and help to
demonstrate practices that may be amenable to change as part of hydatid control
programmes.

Citation

Buishi, I. Epidemiology of canine echinococcosis in northwest Libya, northwest Kenya (Turkana) and mid-Wales. (Thesis). Salford : University of Salford

• Thesis Type: Thesis
• Deposit Date: Oct 3, 2012
• Award Date: Jan 1, 2004