Epidemiology of hydatid disease in Sardinia: a study of fertility of cysts in sheep

Hydatidosis, caused by Echinococcus granulosus, is a cyclozoonotic disease of economic significance in Sardinia. The life-cycle involves stray and sheep dogs as definitive hosts and sheep, pigs, goats and cattle as intermediate hosts. The most important intermediate host is sheep, due to home slaughtering with ready access of the viscera to dogs. This survey was undertaken in 1987 to ascertain the epidemiological significance of sheep in maintaining the life-cycle. A total of 700 (91.3%) of 767 sheep harboured hydatid cysts. The frequency distribution of the number of hydatid cysts was over-dispersed. Of 497 infected sheep, 7.6% had fertile cysts, 75.7% sterile cysts and 16.7% fertile + sterile cysts.     

Prevalence of hydatid in buffaloes in India and report of a severe liver infection

Of 3200 buffaloes examined at Bareilly abattoir 915 (28.6%) were positive for hydatidosis. The hydatid infected organs were lungs (60%), liver (32%), spleen (4%), kidneys (2%), heart (0.9%) and brain (0.1%). The number of hydatid cysts encountered in lungs of an individual buffalo was 1-9 and 1-7 in liver. One buffalo liver showed severe hepatomegaly, cirrhosis and had an exceptionally high number of hydatid cysts. Infectivity studies in pups showed 16-29 per cent worm establishment with the presence of shelled eggs within the uterus of the parasite on day 45 post-infection.     

Biochemical profiles of hydatid cyst fluids of Echinococcus granulosus of human and animal origin in Libya.

A comparative study on the biochemical parameters in hydatid cyst fluids of sheep, goats, camels, cattle and human cystic forms of Echinococcus granulosus has been made in Libya. Quantitative variations in the levels of sodium, potassium, calcium, cholesterol, glucose, urea, creatinine and gamma glutamyl transpeptidase (gamma GT) were found in the cystic fluids of different host origins although these differences were statistically insignificant compared with the hydatid fluids of sheep. However, the concentration of triglycerides and proteins were significantly elevated in the cyst fluids of sheep compared with the other fluids studied. Similarities in the biochemical composition of different hydatid cyst fluids suggest the existence of sheep strains of E. granulosus in human and other domestic animal intermediate hosts in Libya.     

Molecular Characterization of Echinococcus granulosus Sensu Lato from Farm Animals in Egypt

Little is known on the diversity and public health significance of Echinococcus species in livestock in Egypt. In this study, 37 individual hydatid cysts were collected from dromedary camels (n=28), sheep (n=7) and buffalos (n=2). DNA was extracted from protoscoleces/germinal layer of individual cysts and amplified by PCR targeting nuclear (actin II) and mitochondrial (COX1 and NAD1) genes. Direct sequencing of amplicons indicated the presence of Echinococcus canadenesis (G6 genotype) in 26 of 28 camel cysts, 3 of 7 sheep cysts and the 2 buffalo derived cysts. In contrast, Echinococcus granulosus sensu stricto (G1 genotype) was detected in one cyst from a camel and 4 of 7 cysts from sheep, whereas Echinococcus ortleppi (G5 genotype) was detected in one cyst from a camel. This is the first identification of E. ortleppi in Egypt.     

Molecular characterization of Echinococcus isolates indicates goats as reservoir for Echinococcus canadensis G6 genotype in Neuquén, Patagonia Argentina

Human cystic echinococcosis is a highly endemic zoonotic disease in the province of Neuquén, Patagonia Argentina, although a hydatid control programme has been carried out since 1970. Human infection due to Echinococcus canadensis (G6 genotype) is frequent in Neuquén. However, the reservoir for this species remains undetermined in a region where camels are absent. We investigated the fertility, viability and molecular epidemiology of hydatid cysts obtained from local goats, pigs and sheep in order to identify the possible reservoirs of E. canadensis (G6). We also analyzed isolates from infected dogs. A total of 67 isolates were identified by the DNA sequencing of the mitochondrial cytochrome c oxidase subunit 1 gene. Cysts from sheep (n = 16), goats (n = 23) and pigs (n = 18) and adult worms from 10 infected dogs were analyzed. The fertility of the hydatid cysts was 78.6%; 90.4% and 94.4% for sheep, goats and pigs, respectively. We detected E. canadensis (G6) in 21 of 23 goat samples and in 1 dog isolate, E. canadensis (G7) in all the pig isolates, E. granulosus sensu stricto (G3) in 1 sheep and the G1 genotype in 15 sheep, 2 goats and 9 dog samples. The G1 haplotypes included the common sheep strain sequence and 2 microvariants of this sequence. E. granulosus sensu stricto (G3) is described for the first time in South America. We conclude that goats act as reservoir for E. canadensis (G6) in Neuquén, and that control strategies may have to be adapted to local molecular epidemiology to improve the control of parasite transmission.     

The prevalence, intensity and viability of hydatid cysts in slaughtered animals in the Ardabil province of Northwest Iran

In a cross-sectional study, a total of 5381 slaughtered animals, namely 928 cattle, 243 buffaloes, 3765 sheep and 445 goats were inspected macroscopically for hydatid cysts in northwest Iran, with prevalence values of 38.3%, 11.9%, 74.4% and 20%, respectively, being recorded. Prevalences were higher in females compared with males, but a significant difference (P < 0.001) was only found in sheep and cattle. Most cases which were condemned were seen in the lungs of sheep (13.4%) indicating that sheep are the most important intermediate hosts for Echinococcus granulosus in this area.     

Further studies on prevalence of hydatidosis in slaughtered animals from North Jordan

Examination of 471 sheep, 118 goats, 157 cattle and 56 camels slaughtered in abattoirs in North Jordan was carried out during March-May 1984. Drought conditions that prevailed during the preceding winter led to slaughtering old female sheep (greater than or equal to 4 years) due to scarcity of food, which allowed us to analyse the prevalence of hydatidosis in various age groups of sheep. An overall infection rate of 27.8, 1.7, 5.8 and 10.7 percent was found in sheep, goats, cattle and camels, respectively. The infection rate was as low as 1.5 percent in male and 1.9 percent in female sheep under 2 years of age. However, the rate of hydatid infection increased with age and reached as high as 63.7 percent in ewes 4 years of age and older. The percentage of animals with fertile cysts was also highest in sheep (68.7 percent of infected animals) and increased with age reaching 100 percent in ewes which were 10 years of age or older. Analysis of all cysts recovered from the livers and lungs of infected ewes from various age groups revealed a sharp increase in the mean total number of cysts in age groups over 8 years of age. The fertility rate of the cysts in the liver was significantly greater in ewes 6 years old or more (64.8--78.6 percent) than in younger age groups (8.7-46.2 percent). In the lung, the fertility rate increased progressively with age reaching as high as 97.9 percent in ewes 10 years old or more. These findings of high infection and fertility rates of hydatid disease in sheep, particularly of older age groups, prompt plans for further epidemiological studies and control programmes.     

Growth and genotypes of Echinococcus granulosus found in cattle imported from Australia and fattened in Japan

At the abattoir on study in Miyazaki, Japan, 9537 imported cattle from Australia in average were slaughtered annually in the last 5 years (2006 to 2010) and hydatid cysts were constantly detected in about 1.8% of the cattle. In order to assess the risk of Echinococcus granulosus delivered to Japan by imported cattle, 250 cysts found in 103 cattle at the abattoir were examined for their biological characteristics and genotypes. The cattle slaughtered were imported from Australia at an age of 10-12 months old and fattened for 17-18 months in Japan. The cysts showed their size ranging from 4 to 108 mm and were mainly found in the lung. Mature protoscoleces were detected in the three largest cysts, all were of the G1 genotype. Most of the other cysts contained clear cyst fluid and had thin laminated layer with no protoscoleces. The finding implies a potential risk of E. granulosus being established in Japan, thus strict and proper meat inspection and consequent offal condemnation are requisite at abattoirs that deal with imported cattle. Genotyping based on partial fragments of mitochondrial cox1, rrnS and nad1 genes were performed on the 66 cysts, showing that most of the cysts were G1 genotype (common sheep strain). However, two and four cysts were considered as G2 (Tasmanian sheep strain) and G3 (buffalo strain) genotypes, respectively. Since it has been widely recognized that G1 is the only genotype distributing in mainland Australia and that G2 genotype has been eradicated from Tasmania, the finding of those genotypes from Australian cattle indicated that certain genotypes other than G1 genotype are distributing in mainland Australia.     

Hydatidosis in camels (Camelus dromedarius) and their potential role in the epidemiology of Echinococcus granulosus in Iran

Hydatid cysts were recovered from 35.2% (233/661) of camels (Camelus dromedarius) slaughtered in five different regions of Iran. The degree of prevalence between males (34.4%) and females (36.6%) was not statistically significant. The highest rate of infection (59.3%) was found in the Isfahan region (in the central part of Iran) while the lowest (25.7%) was found in Kerman province. The organ distribution of cysts was 49.4% in lungs alone, 30.0% in both liver and lungs, 14.6% in liver only and 6.0% in other organs. Therefore, the lungs were the predominant sites of the hydatid cyst. The range in the number of cysts was 1-48 in infected animals. The majority of the camels had 1-5 cysts, with 21.9%, 11.6% and 5.6% of infected camels having 6-10, 11-20 and 21 or more cysts respectively. There was a direct relationship between the rate and intensity of infection and host age. The fertility rate of lung cysts (69.7%) was higher than that of liver cysts (58.7%) and other organs (50.0%) whilst the viability rate of protoscoleces of liver fertile cysts (80.3%) was significantly higher than that of lung cysts (55.8%) and other organs (57.1%). The role of camels in the epidemiology of Echinococcus granulosus in Iran is discussed.     

Echinococcus granulosus: DNA extraction from germinal layers allows strain determination in fertile and nonfertile hydatid cysts

A method for the isolation of Echinococcus granulosus DNA from germinal layers of hydatid cysts is described. The method includes a hexadecyltrimethylammonium bromide/chloroform extraction and an adsorption to diatomaceous earth suspension. DNA suitable for polymerase chain reaction was obtained and used for parasite strain determination by mitochondrial cytochrome c oxidase I gene sequencing. Fertile and nonfertile cyst isolates from sheep, cattle, pigs, and humans were characterized. Hitherto, no direct parasite strain characterization has been made on nonfertile hydatid cysts, whereas here we report that nonfertile hydatid cysts were produced by sheep strain (G1 genotype) in sheep, cattle, and humans and by pig strain (G7 genotype) in pigs.     

Identification of Sarcocystis hominis-like (Protozoa: Sarcocystidae) cyst in water buffalo (Bubalus bubalis) based on 18S rRNA gene sequences

DNA templates were extracted from isolates of Sarcocystis hominis-like cysts collected from cattle and water buffalo, as well as from Sarcocystis fusiformis cysts and Sarcocystis suihominis cysts. The 18S rRNA genes were amplified using DNA from a single cyst as the templates. Approximately 1,367-1,440 bp sequences were obtained. The sequence difference in isolates of Sarcocystis hominis-like cysts from water buffaloes, and isolates of S. hominis cysts from cattle were very low, only about 0.1%, much lower than the lowest value (1.7%) among different species. Combined with their morphological structure, these sequence data indicate that the 4 isolates from cattle and water buffalo might be the same species, i.e., S. hominis, suggesting that both cattle and water buffalo may serve as the intermediate hosts for this parasite. Apparently, this is the first report using a single cyst to do such work and is a useful way to distinguish the Sarcocystis cyst in an intermediate host that may be simultaneously infected by several different Sarcocystis species.     

The prevalence and fertility of hydatid cysts in buffaloes from Iran

Cystic echinococcosis caused by Echinococcus granulosus is considered to be an important parasitic infection in livestock. In the present study, which aimed to determine the epidemiology of hydatidosis in buffalo in Iran, slaughterhouses of West Azerbaijan (Urmia), East Azerbaijan (Tabriz), Ardabil (Ardabil), Gilan (Rasht and Hashtpar) and Khuzestan (Ahvaz) were inspected. Age, sex and infected organs were recorded separately, and the observed cysts were examined for fertility and viability. Our results showed that 344 (9%) of 3832 inspected buffaloes were infected with hydatid cysts. The maximum and minimum infection rates occurred in Khuzestan (9.9%) and Ardabil (8%) provinces, respectively. There was no significant difference in the rate of infection in all provinces. Of 344 infected buffaloes, the rate of fertility was 7.3% and the rate of viability in fertile cysts was 78.75%. Hydatid cysts were more prevalent in female compared with male buffaloes (P < 0.05). There was a positive correlation between the age and number of infected hosts in all provinces except East Azerbaijan. The prevalence of infection in lungs was significantly higher than that in the livers of buffaloes in the provinces studied (P < 0.001). In conclusion, the fertility of hydatid cysts in buffaloes was low, as previously demonstrated in cattle, and this animal may play a minor role in the epidemiology of hydatidosis in Iran.     

Two Different Macaviruses,ovine herpesvirus-2 and caprine herpesvirus-2, Behave Differently in Water Buffaloes than in Cattle or in Their Respective Reservoir Species

The ongoing global spread of “exotic” farm animals, such as water buffaloes, which carry their native sets of viruses, may bear unknown risks for the animals, into whose ecological niches the former are introduced and vice versa. Here, we report on the occurrence of malignant catarrhal fever (MCF) on Swiss farms, where “exotic” water buffaloes were kept together with “native” animals, i.e. cattle, sheep, and goats. In the first farm with 56 water buffaloes, eight cases of MCF due to ovine herpesvirus-2 (OvHV-2) were noted, whereas additional ten water buffaloes were subclinically infected with either OvHV-2 or caprine herpesvirus-2 (CpHV-2). On the second farm, 13 water buffaloes were infected with CpHV-2 and two of those succumbed to MCF. In neither farm, any of the two viruses were detected in cattle, but the Macaviruses were present at high prevalence among their original host species, sheep and goats, respectively. On the third farm, sheep were kept well separated from water buffaloes and OvHV-2 was not transmitted to the buffaloes, despite of high prevalence of the virus among the sheep. Macavirus DNA was frequently detected in the nasal secretions of virus-positive animals and in one instance OvHV-2 was transmitted vertically to an unborn water buffalo calf. Thus, water buffaloes seem to be more susceptible than cattle to infection with either Macavirus; however, MCF did not develop as frequently. Therefore, water buffaloes seem to represent an interesting intermediate-type host for Macaviruses. Consequently, water buffaloes in their native, tropic environments may be vulnerable and endangered to viruses that originate from seemingly healthy, imported sheep and goats.     

Epidemiological and histomorphic studies in sheep infected with hydatid cyst in Taif area

Hydatidosis is a zoonotic disease caused by Echinococcus granulosus larvae, which affects sheep worldwide, especially in rural communities. This study aims to determine the prevalence and structure of hydatid cyst in sheep. A total number of 1,198 sheep in different age groups G1 (<1 year), G2 (1–2 years) and G3 (>2 years) were slaughtered at Taif abattoirs, then examined for the presence of hydatid cysts in lung, liver, and mesentery. Prevalence of hydatid cyst infection in imported sheep (13.0%) was higher than of local sheep (10.2%). Particularly, as per gender, prevalence of imported females (71.9%) was higher than those of local females (28.1%), while that of imported males (66.3%) was higher than those of local males (33.7%). Large sizes of hydatid cysts and fertility recorded in G3 were higher in both local and imported sheep than those of G1 and G2. Morphometric analysis of pathological lesions in liver of all infected sheep showed a significant increase compared to non-infected healthy sheep (have no lesions) (P < 0.001). In addition, for all infected sheep, histochemical investigation with Masson’s trichrome stain showed collagen fibers inside the hydatid cyst capsules and in pericystic region. The collagen fibers content and the cellular laminated membranes took the green color, while immunohistochemical evaluation detected a positive reaction for CD3.     

An abattoir-based study on the prevalence of hydatidosis in livestock in Mashhad, Iran

A 6-year (2004-2010) retrospective study was carried out to determine the prevalence of hydatidosis in livestock slaughtered in Mashhad abattoir, Mashhad, in north-eastern Iran and the capital of Khorasan province. Between 20 March 2004 and 19 March 2010, 5,131,485 animals (411,163 cattle; 4,547,618 sheep; 172,704 goats) were slaughtered in the study area and 388,399 (7.5%) livers and 1,139,529 (22.2%) lungs were discarded. Hydatidosis was responsible for 4% and 6.5% of total livers and lungs inspected, respectively. Of the cattle livers and lungs inspected over the survey period, 5.5% and 7.9% were condemned, respectively, because they held hydatid cysts. The corresponding values for livers and lungs of sheep (2%, 4%) and of goats (4.5%, 7.8%), respectively, were also condemned due to hydatidosis. Data showed a prominent seasonal pattern for hydatidosis. Liver condemnations due to hydatidosis were higher in winter and autumn for cattle and sheep, respectively, whereas lung condemnations were higher in summer for sheep and cattle. In goats, liver and lung condemnations were higher in winter. This could be attributed to various factors, such as sources of slaughtered animals, changes in management practice and ecological factors. The present survey provides baseline data for the future monitoring of this potentially important parasitic disease in the region.     

In vitro culture of the strobilar stage of Echinococcus granulosus from protoscoleces of human, camel, cattle, sheep and goat origin from Kenya and buffalo origin from India

Protoscoleces from human, camel, cattle, sheep, goat (all from Kenya) and buffalo (from India) hydatid cysts were cultured under identical conditions in vitro using the diphasic culture system of Smyth (1979b). Organisms from all sources grew and segmented in culture. Genital anlagen developed in all cultured worms but further genital differentiation occurred only in cultures of cattle (testes) and camel (testes and genital pore) material. The possible significance of these results is discussed in relation to the general epidemiology of hydatid disease and the potential infectivity of the different strains to man.     

Genetic variants of ribosomal DNA and mitochondrial DNA between swamp and river buffaloes

To clarify the genetic relationship between Swamp and River buffaloes, the restriction fragment length polymorphisms (RFLPs) of nuclear genomic ribosomal DNA (rDNA) and cytoplasmic mitochondrial DNA (mtDNA) were analysed. Blood or liver samples from 73 Swamp and three River buffaloes were collected in East and South-east Asian countries. DNA samples from cattle, goats and sheep were used for comparisons. The analysis of rDNA allowed water buffaloes, cattle, goats and sheep to be characterized by four distinct repeat-types. However, swamp and river buffaloes showed the same repeat-type. Divergence of water buffalo and cattle is considered to have occurred approximately four to six million years ago. The RFLPs for mtDNA divided water buffaloes into three haplotypes, swamp-1, swamp-2 and river types. Swamp-1 accounted for 91% of all swamp buffaloes while swamp-2 was observed only in water buffaloes from Thailand (9%). All river buffaloes were of the same haplotype. No differences were observed between swamp and river buffaloes at the rDNA level. In contrast, a few distinct differences between them were found at the mtDNA level. Therefore, mtDNA polymorphisms provide an adequate means for classifying water buffaloes into either swamp or river buffaloes.     

Conservation within artiodactyls of an AATA interrupt in the IGF-I microsatellite for 19-35 million years

Occurrence of an AATA interrupt in the IGF-I microsatellite was investigated in a number of Artiodactyl species, namely pigs, camels, deer, cattle, goats, and sheep. Comparison of DNA sequences in the 5' flank of the microsatellite in these species revealed that the interrupt within the microsatellite is conserved in deer, cattle, sheep, and goats but is absent from camels and pigs. The interrupt was introduced into the Artiodactyl phylogeny after the divergence of the Camelidae but before the divergence of the Cervidae, and thus its time of origin can be estimated to be 19-35 MYA. In contrast to the repeat units which are hypermutable, the interrupt has been conserved for a very long time and may even have suppressed microsatellite variation by inhibiting replication slippage. A 12-bp deletion in the 5' flank of the microsatellite in camels corresponds to a consensus reversed repeat in deer, cattle, sheep, and goats with unknown functional significance. Apart from this deletion, the 5' flank of the microsatellite is highly conserved in Artiodactyl species.     

Infection Status of Hydatid Cysts in Humans and Sheep in Uzbekistan

Uzbekistan is endemic of cystic echinococcosis (CE). In order to estimate endemicity of CE, we collected data from emergency surgery due to CE in 2002-2010 and also investigated the prevalence of hydatid cysts in the liver and lungs of sheep at an abattoir in Uzbekistan from July 2009 to June 2010. In 14 emergency hospitals, 8,014 patients received surgical removal or drainage of CE during 2002-2010, and 2,966 patients were found in 2010. A total of 22,959 sheep were grossly examined of their liver and lungs, and 479 (2.1%) and 340 (1.5%) of them were positive for the cyst in the liver and lungs, respectively. Echinococcus granulosus is actively transmitted both to humans and sheep, and CE is a zoonotic disease of public health priority in Uzbekistan.     

Morphological characteristics of Echinococcus granulosus derived from buffalo in Iran

Cystic echinococcosis is a significant parasitic disease in Iran, where a variety of animals act as intermediate hosts. In this study, 25 isolates of Echinococcus granulosus obtained from water buffalo from various parts of Iran were characterized on the basis of the morphology of the metacestode and the adult worm. The characteristics of protoscoleces from the different studied areas were nearly similar. They showed 2 rows of alternating large and small hooks and their shapes were smooth in outline. In contrast to the protoscoleces, the adult rostellar hooks showed a rough outline. The results showed that the total length, the blade lengths of the large and small hooks and the number of hooks are almost similar to those isolated from sheep but significantly different from those isolated from camels. The growth rates of adult E. granulosus (total worm length, segmentation and maturation) of buffalo origin, at 35 and 41 days post-infection of dogs, were nearly comparable to the common sheep strain. The form of the strobila and the morphology of the reproductive system were also similar to those of sheep origin. This suggests that the common sheep strain (G1) of E. granulosus may also use buffaloes as its intermediate host.