Experimental transmission of Echinococcus granulosus of "camel-dog" origin to goats, sheep, cattle and donkeys

The infectivity of a camel strain of Echinococcus granulosus experimentally raised in dogs for domesticated food and burden animals was investigated. Of the animal species that were inoculated orally with gravid segments, hydatid cysts developed poorly in goats and sheep, less well in cattle and not at all in donkeys by six month post-inoculation. Cysts were most frequently found in the lungs, although other organs such as liver and spleen also contained cysts. Histological examination of affected organs in these animals revealed the cysts surrounded by a granulomatous cellular reaction. Protoscolices and brood capsules were lacking at the time of examination. Thus it appears that although hydatid cysts could develop in some of these animal species within six months, the cysts were immature.

[Hydatidosis: new concepts in an old disease (First part) (author's transl)]

In the first part of this review several aspects of the classical echinococcosis due to E. granulosus are commented on (geographical distribution, morphological, epidemiological, taxonomic and pathogenetic characteristics). The real incidence of this disease in Spain is unknown due to the absence of global epidemiological data, especially by the lack of sero-epidemiological surveys. Epidemiological measures necessary to establish a control program for this zoonosis are recommended. In relation to the pathogenesis of the parasitosis, the authors mention some clinicopathologic characteristics which are conditioned to the anatomy and function of the organs where hydatids are located.

Food-borne parasitic infections--old stories and new facts

A review is presented of food-borne parasitic infections. Parasitic infections with public health hazards both from conventional slaughter animals and from seafood (fish and shellfish) are discussed. The former category includes cysticercosis, echinococcosis, and trichinosis, the latter category covers various trematode, cestode, nematode, and possibly also protozoan infections. Examples of trematode infections are heterophyidiasis, transmitted to man by marine fish, and Paragonimus spp parasites, transmitted by crustaceans. Cestode infections include diphyllobothriasis transmitted by both fresh water fish and fish from brackish waters. Special attention is drawn to the condition known as sparganosis. Of the nematode infections, the eosinophilic granulomatous enteritis due to the genera Anisakis, Phocanema, and Contracaecum, transmitted to man by either marine fish or crustaceans, is mentioned. Two other nematode infections. Angiostrongylus cantonensis and Capillaria philippinensis, can also be transmitted to man by marine fish. Free living amoebae (a.o. Naegleria) may be transmitted to man via shellfish as vehicles. Apart from a possible direct effect of these parasites, chemical alterations in seafood resulting from the presence of parasites may also be deleterious to the consumer. Special attention is drawn to a newly developed serological detection method, the enzyme-linked immunosorbent assay, which makes detection of infection possible not only at the slaughterhouse but also at the farm or in large herds. Strategies to control parasitic infections both in conventional slaughter animals and in seafood are discussed.

Serial passages of larval Echinococcus granulosus from equine origin in mice. I. Infection with protoscolices

Starting with protoscolices from Echinococcus granulosus cysts of equine origin it was possible to isolate and maintain several "strains" of the parasite in mice through successive transfers of protoscolices. The most advanced strain is now in its 7th generation. Several criteria to evaluate the results are presented and discussed. It is concluded that serial echinococcosis of E. granulosus through passages with protoscolices is a practical method to maintain different strains for fundamental and applied comparative studies.

The Styx Field Trial: effect of treatment of the definitive host for tapeworms on larval forms in the intermediate host

A 13-year assessment has been made of the effectiveness of a monthly drug treatment programme for the control of tapeworms in dogs in order to prevent hydatidosis (Echinococcus granulosus) and cysticercosis (Taenia hydatigena and T. ovis) in sheep. The age-specific prevalence of T. hydatigena in lambs was used as the principal indicator. The trial was carried out in the Styx Valley of the Maniototo Plain in the South Island of New Zealand.Over an 8-year period dogs were treated monthly with bunamidine hydrochloride at about 25 mg/kg with little effect on the prevalence of T. hydatigena in lambs. The addition of niclosamide at 50 mg/kg for 1 year also had little effect. Eggs appeared to survive from one season to the next. Those shed prior to the lamb-rearing season gave rise to endemic-type patterns; whereas patent infections occurring during this period rapidly gave rise to an epidemic-type pattern or a "cysticercosis storm". In this 9-year period there were 16 "cysticercosis storms" and all susceptible lambs were infected. These storms did not necessarily give rise to a similar prevalence on neighbouring farms, but may have contributed to the overall infective pattern. A similar situation occurred in the first year that nitroscanate at 100 mg/kg was introduced. During this 10-year period, arecoline surveillance of the dog population was undertaken in the remainder of the county and many dogs were found to harbour tapeworms. Both resident and introduced dogs may have contributed to the infective patterns in the Styx Valley.Treatment with nitroscanate was continued monthly in the Styx Valley and niclosamide was used in the remainder of the County for a further 3 years. There was a marked reduction in the age-specific prevalence and lambs on many farms were free from T. hydatigena at slaughter. However, one "breakdown" occurred and this was almost certainly autochthonous.Comparisons with an earlier period when arecoline surveillance was used in the Styx Valley, indicate that the present evidence favours a drug-orientated treatment programme of the definitive host for the control of cysticercosis. However, "breakdowns" caused by either autochthonous or itinerant sources have profound effects, since they involve all susceptible age-cohorts including those that have never been infected and those that have lost the immunity induced by an earlier infection.

The anti-echinococcosis campaign in Cyprus

A national anti-echinococcosis campaign was started in 1971, in which education of the public, the control of dogs and the control of slaughter were emphasised. The campaign has already achieved almost total elimination of infection in food animals born subsequent to its initiation. Stray dogs are rare and all others are registered and examined three or four times a year. Infection in dogs has decreased by over 80 per cent (from 6-8 in 1972 to 1-1 in 1976). Legislation governing abattoir functioning and dog control is in force. Violation of legislation is penalised, although the level of awareness of the problem by the public, who co-operate willingly, does not often warrant this.

An evolving pattern of human hydatid disease transmission in the United States

Echinococcus granulosus infection was being acquired in the contiguous United States by Virginia sharecroppers and small-holders by the turn of the century. The last recorded human infection from that general area was diagnosed in 1947. By 1920 human infections were also being acquired in the lower Mississippi valley. Apparently, infection in both of these areas was maintained chiefly in swine. By 1940 a third transmission area definitely existed in the Central Valley of California, with its reservoir intermediate host sheep. Seemingly, infection has been disseminated from these California foci into Utah and more recently into northern New Mexico and Arizona. Human populations now at unusual risk in the western United States are transhumant sheep ranchers, including Basque-Americans in California, Mormons in central Utah, and Navajo and Zuni Indians in New Mexico and Arizona. Conditions highly favorable to E. granulosus transmission, intensification and spread now exist throughout relatively large areas of the American West.

Hydatid disease in New Zealand: an epidemiological study of transmission among Maoris

An epidemiological study was designed to determine the factors placing the Maori people of New Zealand at an unusually high risk of infection with Echinococcus granulosus. Using stepwise multiple regression techniques, it was shown that the most important determinant of the incidence rate of human hydatid disease was the proportion of Maoris in the local population. It was found that the Maori system of land tenure, based on the Maori land laws led to the formation of many small fragmented properties under multiple ownership, decreasing the incentive of individual Maori farmers to improve their farming methods. In addition, long-standing behavioral patterns, such as an easy familiarity with working dogs and the feeding of dogs on raw offal, were practices that changed slowly, thus contributing to the maintenance of high E. granulosus prevalence in dogs owned by Maoris. Those cultural and behavioral factors, together with poor dog control, exposed all members of the rural Maori community to an increased risk of infection with E. granulosus, with the result that the incidence rate of hydatid disease for all age-groups and for both sexes was strikingly higher in Maoris than in non-Maoris.

Epidemiologic investigation of echinococcosis in American Indians living in Arizona and New Mexico

Ten cases of echinococcosis diagnosed in American Indians in Arizona and New Mexico between 1972 and 1975 were investigated as part of a regional epidemiologic study. Patients were visited at home to discover factors associated with local parasite transmission, to detect possible additional cases among family members, and to perform diagnostic tests on dogs. Six patients were Navajo, 2 Zuni, and 2 Santo Domingo Indians. An additional case in a Navajo man was detected by serologic testing of patients' family members; this was the 20th case diagnosed in the region since 1965. Dogs owned by three of the Navajo patients were infected with Echinococcus granulosus. Arecoline-purge testing of 110 dogs in the Zuni pueblo demonstrated echinococcosis in a single stray dog. The findings at slaughter of Navajo-owned sheep indicate that the infection is enzootic in this intermediate host. The epidemiologic findings suggest that humans were infected from dogs which contracted their infections from two sources. The first was sheep raised locally in rural areas of the Navajo Reservation where the infection is enzootic in the dog-sheep cycle; transmission was apparently facilitated by the widespread practice of home butchering. A second source of human infection was dogs which became infected by eating viscera of sheep of off-reservation origin; these sheep were purchased and butchered by individual families in urban areas of the Navajo Reservation and in the Zuni and Santo Domingo pueblos.

Echinococcosis in cattle and goats

In the 500 cattles examined, 90 (18%) had hydatid cysts in one or more organs whereas only 12(2.4%) goats, out of 500 had the disease. This is considered to be due to shorter period of longevity and age of slaughter of goats compared to catte. Since dog is an important definitive host responsible for the spread of echinococcosis, a survey on the incidence of hydatid cyst in dogs is necessary from public health point of view.

The role of native domestic animals in the dissemination of Echinococcus infection among dogs in the state of Kuwait

Infection with hydatid cysts of domestic animals slaughtered by private individuals and at the Government Central Slaughterhouse is recorded. Both fertile and non-fertile cysts were seen in the infected animals. The home slaughtered sheep seems to play an important role in the dissemination of the parasite and the life cycle of Echinococcus granulosus in the State of Kuwait is assumed to be sheep--dog--sheep.

The role of the Tasmanian devil in the epizootiology of ovine cysticercosis and echinococcosis

Tasmanian devils were fed infective cystic material of Taenia ovis, T. hydatigena and Echinococcus granulosus and later killed and examined for adult tapeworms. No infections with T. ovis were found after feeding 23 cysts to 8 devils. T. hydatigena were recovered from 5 to 41 devils and 10 worms established after feeding 417 cysticerci. No E. granulosus were recovered from any of 3 devils. Specimens of T. hydatigena appeared to develop as well in devils as in dogs. From these and previous results devils could be successful hosts to T. hydatigena and T. ovis. A survey of 320 devils failed to detect any natural infections with any of these 3 species.

Sylvatic echinococcosis in Argentina. II. Susceptibility of wild carnivores to Echinococcus granulosus (Batsch, 1786) and host-induced morphological variation

Domestic dogs and cats, 3 fox species, Dusicyon culpaeus (Molina,1782), D, griseus (Gray, 1837) and D. gymnocercus (Thomas, 1914), Geoffroy's cats, Felis geoffroyi (D'Orbigny and Gervais, 1843), and grisons, Galictus cuja (Molina, 1782) were fed larvae of Echinococcus granulosus (Batsch, 1786) from domestic sheep in Argentina. Dogs and the 3 species of foxes became infected. The susceptibility of D. culpaeus compared favorably to that of dogs. Most D. griseus and D. gymnocercus were less susceptible than dogs but gravid strobilae were recovered from some animals of both species. Eggs from strobilae in dogs and Dusicyon spp. were infective to CF1 mice. The mean strobilar length and the diameters of the rostellar pad and suckers of worms in foxes were significantly reduced when compared with previously reported data for strobilae from dogs. The potential significance of Dusicyon spp. as reservoir hosts of E. granulosus in Argentina is discussed as is the confusion surrounding the taxonomic identification of cestode infections previously reported from these wild carnivores. It is suggested that Echinococcus spp. reported from Argentine foxes are E. granulosus and that foxes become infected by killing and scavenging on sheep in localities where E. granulosus is endemic.