Like Typhus, but also Not
Joe Biden’s great-great-great-grandfather, Edward Blewitt, was overseer at the Ballina Union Workhouse in County Mayo from 1848 to 1850 during the Great Irish Famine. Many died in the workhouse and others perished in the temporary fever hospital built against one of its walls. With his family, Blewitt emigrated to Pennsylvania in 1851. He did well, despite the political power of the anti-Catholic, anti-Irish Know Nothing movement, a nationalist and Protestant political party, which in the 1850s had a hundred congressmen, eight state governors, and a controlling position in half-a-dozen state legislatures. Before his job at the workhouse, Blewitt had been an engineer for the Irish Ordnance Survey; in Pennsylvania he helped to lay out the new mining town of Scranton.
The Irish famine stands as the most lethal pandemic in the British islands since the Black Death. The four cholera pandemics that struck between 1831 and 1866 killed 113,000 in England and Wales. The 1918-19 influenza pandemic killed 179,624 in Britain and Ireland. Covid-19 has so far killed 58,245 in the UK and 2052 in Ireland. One million died in Ireland during the famine.
The famine’s cause was the fungus Phytophthora infestans, genotype HERB-1, which came from the tubers of wild potatoes growing in the Toluca Valley in central Mexico. It spread to the US in 1843, causing potato blight, and south to the Andes. It then travelled to Belgium, and moved on to Ireland in 1845, when it caused a big potato crop failure, repeated in the next three years. 1846 and 1848 were particularly disastrous. The acid Irish soil, the wet sunless climate and environmentally efficient lazy beds suited potato cultivation perfectly. The crop was nutritious and needed little preparation, and until 1845 the favoured variety, the lumper, was disease free. About three million people ate little else, a working man getting through five kilos a day. Lumpers also fed the pigs and chickens.
The Phytophthora-induced failure killed men, women and children. Some starved to death and some got scurvy, but the majority died of typhus. Others were carried off by relapsing fever. Both diseases were spread by lice, and were known as famine fevers because their incidence escalated from endemic to epidemic in such bad times, as well as during wars. Others died of dysentery, the bloody flux. Cholera came from Scotland in late 1848, peaking in May 1849, but it had nothing to do with the famine.
By the later years of the 19th century, it was established that typhus mortality increased steadily with age, being about 2 per cent for patients aged 10 to 15, and rising to 67 per cent for those over 60. In the voluntary hospitals it was lower in paying patients (15 per cent) than in parochial paupers (28 per cent). In the United States it was much higher in blacks than whites, and in Britain was higher in the very fat. Covid-19 is extraordinarily similar, in spite of typhus being caused not by a virus but by a bacterium that infects its victims when they scratch their skin in areas contaminated with the faeces of infected lice. Breathing in bits of dried louse faeces was another transmission route. Workhouse staff, clergymen and doctors usually caught typhus this way; many of them died during the famine. Edward Blewitt was lucky. Why typhus and Covid-19 mortalities vary in the way they do is a mystery.
By the 1920s typhus mortality in Britain had fallen to zero. The concept of herd immunity was first fully defined during that decade, and it was pointed out that the herd was now immune to typhus, not because the individuals comprising it had specific immunity, but because most members of the herd were not lousy. Even if the organism was imported, it could not spread, despite all in the herd being fully susceptible. Covid-19 isn’t like that. The only kind of herd immunity we can rely on to control Covid-19 depends on making individuals insusceptible to infection by developing specific immunity. Vaccination may deliver this. It is too early to tell whether it will.
Predicting the emergence of new pathogens with pandemic potential is enormously difficult. The Phytophthora pandemic exemplifies the challenge. It came out of Mexico more than a century before potatoes were cultivated there for sale (Mexicans have traditionally preferred maize). The small tubers of its wild hosts in the Toluca valley were not commercially marketable. But to start the pandemic, soil containing Phytophthora spores or live infected tubers had to be transported to the United States and Europe, an extremely unlikely event, which explains why blight did not appear in Europe for more than 250 years after the introduction of cultivated potatoes from South America in the late 1500s.
Evolution means that even detecting and characterising a new pathogen at the beginning of a pandemic will be an insecure foundation on which to make predictions. The Phytophthora HERB-1 genotype that caused the famine lasted only fifty years. Twentieth-century strains of the fungus have the US-1 genotype. But they haven’t lost their virulence, and remain the most destructive disease of the world’s third largest food crop, causing losses that could feed hundreds of millions of people. For Covid-19, attention has focused on the Spike protein, and whether mutations will diminish vaccine efficacy.
One worry is that genetic changes will increase virulence. This hasn’t happened in a coronavirus that infects pigs. Transmissible gastroenteritis virus (TGEV) remained unchanged for at least forty years, until the RNA coding for its Spike protein lost bits of its gene sequence, and its name changed in the 1980s to porcine epidemic diarrhoea virus (PEDV). Both viruses caused acute diarrhoea and vomiting and high mortality in suckling pigs. After another twenty years, the RNA coding for the Spike protein lost more genetic information, and the virus became less virulent, killing only 5-10 per cent of infected piglets. Optimism that Covid-19 might behave in the same way must be very guarded; not only does PEDV causes a very different disease in a different host, but attempts to develop effective vaccines against it have not been particularly successful, and it has been shown to spread on the wind from farm to farm as far as ten miles.
The political reputations of Jacinda Ardern and Nicola Sturgeon have been enhanced by their handling of the Covid-19 pandemic; not so those of Boris Johnson or Donald Trump. Enormous sums of money have been borrowed to alleviate the economic effects of lockdowns. In Ireland during the famine, maize and corn were bought in. Public works and soup kitchens were funded by loans. Enormous temporary fever hospitals were built. Unlike the 2020 Nightingale Hospitals, they were used to the full. But outlays during the famine were only about 2 to 3 per cent of public expenditure. Folklore has it that the gombeen men, the meal-mongers, made big profits during the famine, like the purveyors of personal protective equipment in 2020.
It is too early to tell what long-term political impacts the current pandemic will have. The revolutions of 1848 did not reach Ireland; there was no equivalent of the Habsburg Empire’s abolition of the Robot (unpaid forced peasant labour). But the acceleration of the diaspora coincided with the establishment of the Irish as a political force in the United States. After Biden’s election win, a piece of old footage emerged from last January, when a BBC reporter asked the then primary candidate for ‘a quick word’: ‘The BBC?’ Biden replied. ‘I’m Irish.’ It took him a second to break into a grin.