Contagions Round-up 21: From Old Tombs to New Viruses

Its been a while since I’ve done a round-up. Here are some of the posts that caught my attention in the last couple weeks. I am going to start restricting these round ups to topics more closely related to Contagions – history of medicine, bioarchaeology and infectious disease. I’m still reading all the rest and I will occasionally include something off topic.

Mia D’ Ambrigo of Notes from the Field brings us news of the possible discovery of the tomb of the last Inca emperor and she also looks at recent claims for the earliest Christian tomb in Jerusalem.

Rosemary Joyce of Ancient Bodies, Ancient Lives writes about new research on Mayan women.

Kristina Killgrove of Powered by Osteons writes about Roman reproductive votives.

Katy Meyers of Bones Don’t Lie looks at osteoporosis in ancient populations.

Lindsey Fitzharris wrote about syphilis and “syphilophobes” in early modern England on Wonders and Marvels.

Caroline Rance of The Quack Doctor brings us a cute lyrics to a folksong on quack medicines.

I’ve been writing here at Contagions about all different types of things: new ways to detect plague proteins with Immuno-PCR, what our long term immune response to plague looks like, archaeological evidence for malaria in Anglo-Saxon England, and the way plague historiography has shaped views of medieval history.

Michael Walsh of Infection Landscapes is working his way through the worms with posts on hookworm, and whipworm. With Otzi the Iceman’s metagenome in the news this week, I did have to wonder if any of the ‘other eurkaryote’ sequences found were worms.

Vincent Racaniello of The Virology Blog keeps us up to date with the H5N1 influenza controversy with posts on new estimates of human infections and new information on the controversial H5N1 ferret experiments.

Tara Smith of Aetiology wrote about a whole new family of influenza in bats and some of her work on the human origins of ‘pig’ Staph ST398. Maryn McKenna of Superbug writes more about the pig staph as well and more about resistant bacteria on meat.

Connor Bamford of Rule of 6ix writes about the interactions between prions and our immune system and  the new Schmallenberg virus causing epizootics in Europe; Maryn McKenna of Superbug first broke the story on the blogs with her round-up of information on the Schmallenburg virus.

Plague Detection by Immuno-PCR

Once again the Marseille research group is pushing the bounds of plague detection. This time their target is looking for a more sensitive method of detecting non-nucleic acid biomolecules from Yersinia pestis, ‘the plague’. We have now moved into an era where PCR is being used in the mechanics of testing, rather than amplifying the ultimate target of the test.

Immuno-PCR

The immuno-PCR (iPCR) method is outlined in the figure. The selective component of the assay is the mouse polyclonal anti-Yersinia pestis antibody. Polyclonal antibodies are the products of several different B lymphocytes reacting to the same antigen, protein in this case. This means the antibodies in preparation will bind to different parts (epitopes) of the same protein. This should be an advantage in working with badly degraded material.

In iPCR the selective reagent is the non-human antibody generated against the microbial target. The second antibody is against the non-human antibody (mouse, rabbit, etc) and carries biotin as a marker. These biotinylated antibodies are a very common and widely available immunology reagent. The third antibody is against the biotin and carries a reporter sequence of DNA. Quantitative real-time PCR is then done on the reporter DNA sequence attached to the antibody. This amplified reporter DNA can easily measure very tiny amounts of DNA. The iPCR system utilizes advances in PCR technology to measure specific protein levels.

Malou et al (2012) took  known positive and negative teeth, and subjected them to iPCR, PCR and the standard ELISA antibody assay.   They first determined the detection limit for ELISA and iPCR, and set a threshold for a positive iPCR result with 10 known negative teeth (5 ancient and 5 modern). They then coded and randomized  34 historically known positive teeth, the 10 negative teeth (5 ancient and 5 modern) and two blanks for testing with ELISA, PCR, and iPCR. The results and how they compare are shown in the diagram below. The ELISA only picked up four teeth with one being a known negative resulting in a sensitivity of 9% and specificity of 90%. Of the three ELISA true positives, two were from a 17th century site at Lariey and one from a 6th century site at Sens, both in France. For the iPCR, 14 of 34 exceeded the threshold and were considered positive for a 41% sensitivity with a 100% specificity (all positives were historically positive, no false positives). These teeth came from Lariey, Bourges, Sens, Bondy, and Venice with a date range from the 6th to 17th century. Traditional PCR identified 10 out of 34 historically positive teeth fora  sensitivity of 29% with 8 of 10 also being identified by iPCR.

Venn diagram of positive teeth detected by ELISA, PCR, and iPCR.

Immuno-PCR compares well with the efficiency and specificity of standard PCR for Yersinia pestis DNA and is more sensitive than the standard ELISA antibody assay. A standard ELISA produced the worst results. Although not quantitative, it would have been interesting if they had also done the Rapid Diagnostic Dipstick Test (RDT), another antibody based protein detection method, that has been used in several studies.  They are suggesting that iPCR be added to traditional PCR as a method of further confirmation of Yersinia pestis at a site. Immuno-PCR can be done on the same teeth as traditional PCR and should be easily doable with the expertise and equipment in labs that conduct traditional aDNA PCR.  By identifying both aDNA and protein, the confirmation of Yersinia pestis in the ancient remains should become quite strong.

Reference:

Malou, N., Tran, T., Nappez, C., Signoli, M., Le Forestier, C., Castex, D., Drancourt, M., & Raoult, D. (2012). Immuno-PCR – A New Tool for Paleomicrobiology: The Plague Paradigm PLoS ONE, 7 (2) DOI: 10.1371/journal.pone.0031744

 

Mapping Malaria in Anglo-Saxon England

Guthlac at Croyland in the marshes of the Wash.

England once looked very different. Much of southern Britain was marshland for most of the island’s occupied history. These bogs, fens, and marshes ensured that areas of virtual wilderness persisted  from before Roman Britain through the Norman period and beyond. Despite the difficulties of using fenlands, these areas were not only occupied throughout the Anglo-Saxon period, but important centers like Croyland, Bardney, and Ely eventually developed in the marsh.

The largest fenland region was known as ‘the Wash’.  This low-lying region drained four rivers into  a square bay of the North Sea that forms the corner between Lincolnshire and Norfolk. In Anglo-Saxon times, this tidal marsh and bog was a vast border region between the region of Lindsey and East Anglia.  Places like Croyland and Ely were islands in the wetlands.  The eighth century Life of Guthlac describes the environment of Croyland when Guthlac arrived:

There is in the Midland district of Britain a most dismal fen of immense size, which begins at the banks of the river Granta not far from the camp which is called Gronte (Cambridge) and stretches from the south as far north as the sea. It a very long tract, now consisting of marshes, now of bogs, sometimes with black waters overhung by fog, sometimes studded with woodland islands and traversed by the windings of tortuous streams. (Hill, 1981:11 cited in Gowland & Western, 2011).

These marshes are ideal for malaria, but evidence of malaria in Anglo-Saxon England has been lacking. It is supposed that malaria would have been brought to Britain with the Romans (1). Unfortunately, there is no evidence that I know of that malaria became endemic in Roman Britain much less lasted into the early medieval (Anglo-Saxon) period. It has also been speculated that ‘spring fever’ (lecten adl) found in Anglo-Saxon leechbooks is the spring manifestation of tertian malaria (1) caused by Plasmodium vivax. This would fit the pattern of malaria in cool or cold climates like that found in Finland discussed in a recent post. Indoor transmission in Anglo-Saxon earthen floored, open structured wooden homes with thatched roofs would be an ideal way to concentrate malaria in a thinly populated marsh.  (Without chimneys homes had to open enough to allow smoke to escape from a central hearth.)

Incidence of Malaria in England, 1840-1910 (2)

It has long been known that Britain can environmentally support endemic malaria. Malaria was fairly wide-spread in 19th century Britain when it was first mapped (figure to left) (2). The upper black area on the map includes much of ‘the Wash’. However, proof of malaria is more tenuous for the medieval period.  Together with the unhealthy reputation of the brackish marshlands there is at least enough evidence to suggest that endemic malaria reached back into the late medieval period.

Malaria went by a variety of local names before the early modern period. Malaria-like fevers are mentioned in literature from Geoffrey Chaucer to William Shakespeare (2, 3). Terminology for malaria was not settled upon the Italian ‘malaria’ until the early modern period. Before then, it went by a variety of terms the most universal being ‘ague’, meaning the shakes, and sometimes  ‘fever and ague’ referring to the cyclic breaking of a fever.

Gowland and Western (2011) took a new approach to finding evidence of malaria in Anglo-Saxon England (400-1100 AD) (4). Malaria caused by Plasmodium vivax causes chronic hemolytic anemia that may result in cribra orbitalia due to expansion of the bone marrow in the cranium. Gowland and Western correlated the presence of cribra orbitalia in Anglo-Saxon skeletal remains with the presence of the malarial vector Anopheles atroparavus and reports of ‘ague’ in 19th century England.

The Anglo-Saxon cemeteries used in their study are mapped in the figure below on the left. Note that not many cemeteries are located near the modern coastline of ‘the Wash’. This area would have likely been too wet for settlement.

Anglo-Saxon cemeteries (4)

Map of A. atroparvus with 19th century "ague" records. (4)

Gowland and Western  determined areas capable of sustaining malaria by mapping the presence of A. atroparvus from a 1900 AD British Museum survey (shown above on the right) (4).  The darker the shading the more reports of mosquitoes. This survey was reported to not have been systematic, so they augmented it with 19th century ‘ague’ reports (triangles).  There are some notable areas with high levels of mosquitoes that lack ague reports. This map was use to determine malarial regions for correlation with either cribra orbitalia or the poor nutrition control enamel hypoplasia. It also roughly correlates with the 1840-1910 malaria incidence in the color map above by Kuhn et al (2).

An inverse distance map showing A. atroparus incidence vs. hot and cold spots for cribra orbitalia. (4)

In this last map, malarial areas are plotted with hot and cold spots for cribra orbitalia.  Purple and blue areas on the map indicate the highest areas of A. atroparvus in 1900, while red and orange circles indicate the cribra orbitalia ‘hot’ spots. Areas of cribra orbitalia correlate very well with malarial areas around the Wash.  Cribra orbitalia ‘cold’ spots (blue circles) correlate with areas of low A. atroparvus. They found no correlation between enamel hypoplasia with either ‘malarial’ or ‘non-malarial’ areas (4).

If this cribra orbitalia is due to malaria, it is likely an underestimate of the amount of malaria in the English wetlands. Cribra orbitalia forms in children so it will not indicate adults who contract malaria. Communities like Ely, Croyland and Peterborough were large monasteries who probably drew many into the marsh as adults.

Confirmation of malaria in Anglo-Saxon England will have to wait for molecular evidence, but this skeletal evidence strengthens the hypothesis that it was endemic in early medieval Britain. It also should be informative for the areas to concentrate efforts to find molecular evidence.

References:

(1) Cameron, M.L. (1993, repr. 2006) Anglo-Saxon Medicine. Cambridge University Press.

(2) Kuhn, K., Campbell-Lendrum, D., Armstrong, B., & Davies, C. (2003). Malaria in Britain: Past, present, and future Proceedings of the National Academy of Sciences, 100 (17), 9997-10001 DOI: 10.1073/pnas.1233687100

(3) Reiter P (2000). From Shakespeare to Defoe: malaria in England in the Little Ice Age. Emerging infectious diseases, 6 (1), 1-11 PMID: 10653562

(4) Gowland RL, & Western AG (2011). Morbidity in the marshes: Using spatial epidemiology to investigate skeletal evidence for malaria in Anglo-Saxon England (AD 410-1050). American journal of physical anthropology PMID: 22183814