by Catryn Power
“quid est homo, esca vermium”
The tapeworm Echinococcus granulosus is the source of one of the more serious parasitic infections in humans. Hydatidosis, the disease caused by this tapeworm, is an infestation with parasitic cysts (called hydatid cysts) formed by the larval stage of this particular tapeworm. The type of evidence discussed here is the hydatid cyst.
Evidence of parasitisation from human archaeological remains is rare. This may simply be that the evidence is not always recognised or may not have survived in the soil. However, an experienced osteoarchaeologist would recognise the cream-to brown-coloured eggshell-thin fragments of the hydatid cyst, which look like disintegrating rock. The processes of cleaning skeletons may also result in the loss of this fragile diagnostic material. Consequently, it is essential to have the relevant expertise on site during the excavation of human remains. Otherwise, valuable information will be lost forever. One archaeological excavation where the osteological specialist (the author) was on site, at Caherquin, Co. Kerry, is discussed here.
A case of tapeworm infestation in medieval Kerry was seen in a female skeleton excavated at the site at Caherquin (Plate I). This woman, who died during pregnancy, could have died from causes unrelated to her childbearing condition, such as hydatidosis, which is evident in the form of a calcified cyst.
In total, three Irish cases of tapeworm infestation have been discovered by the author in archaeological contexts. Two of these, including that at Caherquin, date to the medieval period while the third may date to the 18th/19th century. All were found with human skeletal remains in graveyards in Munster. These individuals had probably become infected as children when handling domestic, probably farm, dogs. In modern times, where hydatidosis is endemic, the disease occurs most frequently among people who rear livestock with the use of dogs and where these dogs have access to raw offal, either through feeding practices or through occasional scavenging on the carcases of fallen livestock.
The Global Tapeworm, Echinococcosis, and Hydatid Disease
Tapeworms belong to a class of parasitic worm called Cestodes. These worms have an elongate, flat, segmented body. The life cycle is indirect, requiring one or more intermediate hosts. These worms lack an intestinal tract and absorb nutrients through their integument (Soulsby, 1978).
Hippocrates, who lived in the 5th and 4th centuries BC, described the hydatid cyst, which is caused by the tapeworm of the species Echinococcus. The word hydatid is derived from the Greek hydatis meaning watery vesicle. Later, Galen, a 2nd-century physiologist, philosopher and writer who is often considered the most important contributor to medicine following Hippocrates, also recorded this type of cyst.
The tapeworm E. granulosus is the most common and widespread species of Echinococcus. The definitive host is the dog or other canine. The adult tapeworm is about 5mm in length and matures in the intestine of the primary host carnivore. Infective eggs shed in the animal’s faeces are accidentally ingested by intermediate hosts such as grazing sheep, cattle and a variety of wild animals, but sheep are the most common intermediate hosts in most areas of the world. An infected dog or fox, for example, may have several thousand adult worms. Once ingested by the intermediate host, the eggs hatch in the intestine, producing larvae which penetrate into the intestinal bloodstream and from there are distributed to body organs, particularly the lungs and liver. In these locations the larvae develop into fluid-filled cysts called hydatid cysts. The indirect lifecycle is completed when dogs and other carnivores ingest the hydatid cysts when eating the infected flesh of the intermediate hosts, e.g. sheep, cattle, pigs.
Human beings become infected through close contact with dogs, lack of hygiene and accidental ingestion of food contaminated by dogs’ faeces, which results in humans acquiring the disease, particularly during childhood.
A hydatid cyst enlarges slowly and is generally well tolerated by an infected person, but after many years or decades, hydatid cysts can become big enough to cause a notable mass effect on the body.
Few regions in the world are completely free from E. granulosus. Hydatitosis, although primarily found in sheep-and cattle-rearing regions, can also occur among humans in regions of the world where hunting societies are prevalent. With domestication of animals over the centuries, hydatidosis has become a serious threat to humans. European colonisation led to the disease’s spread to the Americas and Australasia. In the mid 19th century, Iceland was another location, but education, dog control and sanitary slaughtering have eradicated the disease in these countries. Public health measures are the key to eradicating the disease. These include treatment of dogs to eliminate the parasite, prohibition on the feeding of animal offal to dogs and the observance of strict personal hygiene when in contact with dogs and dog faeces.
In Europe, hydatid disease in humans is caused by E. granulosus (dog/sheep cycle) and E. multioccularis (fox/small rodent cycle). For instance the dog/sheep cycle is prevalent in large areas of mid-Wales.
Between 1970 and 1974, 21 people in England and 11 in Wales died from hydatid infection (Beresford-Jones and Jacobs, 1984). During 1973-76, 2.7 per cent of sheep offal and 1.5 per cent of cattle offal was partially condemned on account of hydatidosis (ibid.) In mid-Wales, between 9 per cent and 29 per cent of farm dogs and foxhounds and 3.37 per cent of foxes were found to be infected with the tapeworm E. granulosus (Beresford-Jones and Jacobs, 1984).
Plate I. The archaeological excavation at Caherquin, where a female skeleton displayed tapeworm infestation (photograph, with permission from Laurence Dunne).
Evidence for E. granulosus tapeworm infestation in human remains on archaeological sites survives in the form of calcified hydatic cysts. Calcification indicates that a body part becomes hard or stiff as a result of the deposit of calcium salts. The wall of the cyst sometimes calcifies. The resulting calcareous capsule is roughly spherical in shape with an irregular surface.
The Mother at Catherquin, Co. Kerry
At the southern limits of Smerwick Harbour, on the north-western end of the Dingle Peninsula, lies an archaeological site in the townland of Caherquin. This site extends along the beach for over 200m and was continuously eroded by the tide, wind and holidaymakers. Eroded masonry and skeletal remains were frequently evident in the dunes.
Consequently, excavations were undertaken in advance of a series of conservation works proposed for the site by the National Monuments Service of the Department of the Environment, Heritage and Local Government, with the Department of Communications, Marine and Natural Resources. Excavation at Caherquin was carried out on behalf of the Department of the Environment, Heritage and Local Government (DoEHLG) by Dunne and Bartlett (2008). Previously Bennett (1996) indicated a 14th/15th-century date for activity on the site. Excavation in areas of marram grass rejuvenation was avoided.
As well as five drywall structures, 20 archaeological layers and deposits, a pot-boiler and 13 inhumation burials were recorded during this recent campaign (Plate I). The 13 burials included five adults and eight children, including three neonates. Five of the burials were fully exposed, while the remaining eight were only partially revealed and recorded in section. The supine burials had been interred in a formalised Christian manner in a general east-west orientation. The excavators dated the archaeological findings to the mid-15th to the early 17th century, based on dates obtained by Bennett (1996). One section of walling may, in fact, be An Teampeall Bán, a church with associated burial ground.
Six of the skeletons were interred with beach-derived cobbles at each side of the skull, used as “earmuff” stones to hold the skull in an upright position. On initial discovery, it was thought that a lintelled grave had been located. However, excavation revealed that the stone setting comprised a formalised grave marker with a quantity of rounded quartz pebbles scattered within.
Two of the burials were fully excavated and removed for specialist analysis (by the author) and dating, while the remainder were preserved in situ subsequent to full recording and examination. Of particular interest was an adult female burial, whose remains clearly showed that she had died while pregnant.
This woman, buried at Caherquin, could have died from causes unrelated to her childbearing condition, such as hydatidosis, which is evident in the form of a calcified cyst. The cyst was associated with the left ribs of this female and had probably involved the liver or the lung. Hydatidosis is very rare in pregnant women, and healthy babies are born to women who have hydatidosis.
Examination during excavation exposed a fragmented calcified hydatid cyst which was located at the internal surface of the left ribs of the skeleton, nearest the costal/rib joints (Plate II). The hydatid cyst is fragmented into 24 pieces; in its original state it was ovoid in shape and it may have been 4cm in diameter. The largest fragment is 4.5cm in length.
Plate II. The skeletal remains of the Caherquin female, exhibiting calcified fragments (dark brown fragments) adjacent to the left rib cage (photograph, with permission from Laurence Dunne).
Though it was found with the ribs, it was not possible to determine the exact position of the foetus (vital) and hence if labour was imminent. The cause of death cannot be ascertained positively. This mother could have died from an infection or coronary problem, among many possible factors likely to be fatal but not ascertainable from the remains. On the other hand, the hydatid cyst may have ruptured with consequent catastrophic consequences. Problems associated with pregnancy and hydatidosis include placental invasion by the tapeworm, premature labour and rupture of the uterus.
The symptoms of hydatid disease in this woman would probably have been indistinguishable from many other types of infections. Symptoms may have included abdominal pain, cramps, nausea, coughing and weight loss. The disease is potentially dangerous because the patient, in this case the Caherquin mother, would most likely have been unaware of its existence. Hydatid cysts are basically space- occupying lesions, like, for example, benign tumours, and the danger they pose is simply the result of the physical disruption they cause by virtue of their location and size. When they rupture, multiple secondary cysts result. Their pathological potential is purely the result of their physical presence.
In an infected person, the larvae of the Echinococcus tapeworm enter the intestinal blood stream and are thus dispersed to various organs, particularly the liver and lungs and more rarely the brain, bones and kidneys. In these locations the larvae slowly develop and grow into hydatid cysts. It can take 5-20 years, after the initial infestation, for the hydatid cysts to fully develop. Most patients have single org a n involvement, and most will have a solitary hydatid cyst. Humans are accidental intermediate dead-end hosts, i.e. infected humans do not release infective eggs.
Other Irish Archaeological Evidence
The example of an hydatid cyst from Caherquin brings to three the number of reported cysts from archaeological sites from Ireland; these also include another medieval female, from Cork (Power, 1997), as well as one 18th/19th-century male skeleton from Co. Tipperary (V.R. O’Sullivan, personal communication)
The Man from Moorabbey, Co. Tipperary
The Franciscan friary of Moorabbey was the subject of archaeological investigations in the early 1980s, directed by Ann Lynch, in advance of conservation works by the Office of Public Works (Lynch,1989/90). This friary is located about a mile to the east of the village of Galbally, near the border with Co. Limerick, and beside the picturesque Galtee Mountains. The friary was founded in the early part of the 13th century by Donough Cairbreach O’Brien, king of Thomond. The church and tower remain today. During excavations in 1985, widespread disturbance caused by post-Dissolution burials and modern drains was uncovered. Parts of the east and west claustral range walls were exposed. The remains of scaffolding posts erected during the construction of the 15th-century church were evident as stone-lined post-holes, some with the wooden post still in situ. Three burials, all facing west, were found in the south cloister walk. A bronze crucifix, found with one of the burials, may date to the 16th/17th centuries.
Moorabbey is probably the first archaeological site in Ireland where there is a reported case of human hydatid disease; it was found with Burial 6, located in the ruined chancel of the abbey, and was possibly dated to the 18th/19th century. The remains of a calcified cyst-like structure, originally 12cm in diameter, were found by the author in the upper part of the thorax on the right side of Burial 6, a mature adult. The surviving fragments contain many irregular fenestrations; the combined area of these openings amounts to 7 per cent of the total surface area of the cyst. The calcified wall varies in thickness between 0.4mm and 3.84mm.
The Case at Medieval Cove Street, Cork
The church of St Nicholas is on the site of an earlier church known as the church of St Sepulchre, which is associated with the Hiberno- Norse settlement in Cork. This church is located on the south bank of the south channel of the river Lee.
Archaeological excavations on Cove Street/Travers Street, which is about 40m north of the present St Nicholas’ Church, exposed a medieval graveyard associated with St Nicholas’ Church. The excavation uncovered disarticulated human bones, which may be the remains of disturbed burials. It is possible that further undisturbed burials lie below the present surface.
The second recorded Irish case of hydatidosis was found with a medieval female skeleton from a graveyard at Cove Street (Power, 1997). The fragments of the calcified cyst wall were present with the left ribs of this woman, who was aged about 45 years at the time of death. The largest fragment is 2.5cm long. It is 1mm thick, elliptical in shape, and the curvature suggests that the intact cyst was not more than 3cm in diameter.
The Evidence from Archaeological Excavations Outside of Ireland
There are comparatively few records of calcified hydatic cysts in the palaeopathological literature. One example was found in a medieval leper cemetery in Denmark (Weiss and Moller-Christensen, 1971). In this case, about a hundred calcified cysts were associated with the remains of a teenage female. All of the cysts had a trabeculated interior, and one was 2.5-3cm in diameter. One of the earliest in date (100AD) was recorded from Orton Longueville in England (Wells and Dallas, 1976). A cyst described as resembling a chicken’s egg, with a “shell” 1mm in thickness, came from the left side of the thoracic cavity of a female aged about 45 years.
In the New World, three hydatid cysts were evident in an adult female from a pre-European contact population in Kodiak Island, Alaska (Ortner and Putschar, 1985). It was 25mm in diameter and 0.8-3mm thick and hollow. Other New World evidence of E. granulosus, in the form of ova, was found in a Middle Woodland coprolite from Michigan (Wilke and Hall, 1975).
In all these Irish cases of calcified hydatid cysts, bone involvement was absent or inconclusive. All the cysts were elliptical or spherical, irregular in appearance, and had apertures in the calcified wall. The cyst from Cork City is similar in size (2.5cm in diameter) to the examples quoted from other European countries and from the New World. The cyst from Moorabbey is much larger, 12cm in diameter. With the exception of the Moorabbey subject who was male, the other cases involve females. The male and the Cove Street woman were aged in their forties.
It is not possible to determine if any of these cases died directly from hydatid disease, or perhaps from organ dysfunction following cyst enlargement.
In historic Ireland, infection was probably more common, if not considerably greater, than today due to closer contact with domesticated animals, as well as due to a lack of personal hygiene and generally poor sanitary conditions. Hydatidosis is considered exotic to Ireland today. One case was confirmed in a foreigner in 2007. Today it is accepted that we do not have this tapeworm in our dog/fox population. (Edmond O’Sullivan, Veterinary Department, Cork County Council, personnal communication.)
In the Irish examples, the animals may have been domesticated or living in the vicinity. The occurrence of this parasite in Ireland indicates close contact between dogs and humans and dogs/foxes having access to hydatid cyst-infected sheep/rodents. In the Irish examples, infestation could have occurred where dogs scavenged sheep carcases or were fed on uncooked offal from sheep with hydatid cysts. The examples of hydatid cysts at Caherquin and Moorabbey occur in rural locations where there would have been regular contact with farm dogs. In a large town such as Cork in medieval times, the local dogs could have been infected when scavenging refuse-tips, or by the common practice of feeding on uncooked and raw sheep and cattle offal. Human infection would possibly have been enhanced by the commonly occurring polluted streets in which dog faeces and human faeces created a significant degree of contamination of watercourses and of the general environment. In the past, especially in medieval times, it was customary to tip refuse from the house directly on to the street. Cork would have been a place where livestock was brought into town on the hoof from the countryside. Many of these animals would have been slaughtered in unregulated slaughterhouses, and offal would have been fed to dogs and disposed of as general refuse. These Irish cases of human hydatidosis are probably the first recorded examples from Irish archaeological sites. They indicate the presence of hydatid disease in Ireland as early as medieval times and continued well into the 18th or 19th century.
The recognition and documentation of human parasitic infection in Ireland is important. In each of the Irish skeletal cases having calcified hydatid cysts, probably as a result of infection with the eggs of the tapeworm E. granulosus, it is most likely that the affected humans harboured these cysts for some 10 to 15 years. The cysts, depending on their location and size may not have caused any symptoms or may have resulted in chronic disease and the eventual death of the person concerned.
I would like to thank Professor V.R. O’Sullivan, Department of Anatomy, of Bahrain Royal College of SI, for his advice and information on the first case of the disease which I observed, i.e. the Moorabbey example. Thanks are also due to Dr Edmond O’Sullivan, veterinary inspector, Cork County Council,
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