**9. The boat cough11**

234 Biodiversity Loss in a Changing Planet

In contrast to such episodes, in 1727 an outbreak of possible smallpox on St Kilda killed nearly the entire population. Ninety-four deaths in a population of 132 were recorded,

Neil MacKenzie, minister on St Kilda from 1829 to 1843, writing a hundred years later stated *'Death after death followed. At last there were scarcely sufficient to bury the dead… There were 94* 

A small party of three men and eight boys were marooned on Stac an Armin, a 196-metre high sea stack, where they had been taken to collect birds and birds eggs, but also survived through an Atlantic winter till rescued on 13 May 1728 in a little known epic tale of endurance in adversity. A small bothy gave limited shelter, and the group lived off the stack's fresh water supply, birds and their eggs and fish caught with a bent nail, though they were noted to have lost weight. They patched their clothes as well as possible with birds' skins. Although the greater resources of Boreray Island were 100 yards away, the vertical

A decade earlier Lady Mary Wortley Montagu, wife of the ambassador to Turkey discovered there the procedure of variolation, or intradermal inoculation of smallpox scabs. This caused a moderate infection with a mortality rate of 0.5–2%, compared with a death rate of 10% from the actual disease, She variolated her own children, and though sceptical of

physicians there, hoped to introduce the process into England, writing

Severe symptoms preceding the infectious rash, with isolation preceding infectivity.

Deterioration and death of only a few of those infected with smallpox.

*deaths… those who had been left on Stac an Armin returned mostly to empty houses'.* 

 Greater vulnerability in children than adults Relatively slow spread to household contacts

Fig. 14. Stac an Armin

rock face prevented ascent from the water.

Most of those infected survive mild but obvious disease

leaving four adult and twenty-six children as the survivors.

Another well documented infection peculiar to the inhabitants of St Kilda was called by the native Gaelic speakers '*cnatan-nagall'* or the strangers' cough. 10

Martin during his visit to the island in 1697, did record details of this boat cough. He wrote:

*'They [the islanders] contract a cough as often as any strangers land and stay among them, and it continues for some eight or ten days; they say the very infants on the breast are affected by it.8*

The Reverend Macaulay arrived in St Kilda in 1758, and related his experience as follows:

*'When I landed, all the inhabitants, except two women in child-bed enjoyed perfect health.... On the third day after I landed, some of the inhabitants discovered evident symptoms of a violent cold, such as hoarseness, coughing, discharging of phlegm, etc. and in eight days, they were all infected with this un-common disease, attended in some with severe head-aches and feverish disorders'*.5

Limited Bio-Diversity and Other Defects of

cell function.

Fig. 15. Chloracne

the Immune System in the Inhabitants of the Islands of St Kilda, Scotland 237

system. Animal studies have also shown that dioxin toxicity can cause thymic involution, decreased antibody production with thymic dependent and independent antigens reduced function of the HLA system producing some lymphocyte subsets and reduced cytotoxic T-

The question therefore arises if the dioxin pollution was a contributory factor to the infections experienced by the inhabitants of St Kilda. Comparison with the major known leak of the dioxin, TCDD (2,3,7,8-Tetrachlorodibenzo-p-Dioxin) from Seveso near Milan in 1976, suggests this is unlikely. The soil levels of dioxin in Italy were considerably higher, yet careful follow up over many years in Seveso found no acute increase in the incidence of acute infections, but there was an increase in carcinomas of the gastrointestinal tract and lymphatic systems and an increase in the death rate from respiratory disease. Dioxins are

Chloracne, an acne-like skin eruption, most marked behind the ears, on the cheeks and in the axilla and groin, affected a significant number of Seveso's inhabitants ( 42 of 214 children in the most contaminated Zone A.) Viktor Yushchenko, past President of the Ukraine, is considered to suffer from this condition, following an acute illness in 2004 in which his face became disfigured, scarred and pockmarked. Levels of dioxin in his blood were reported to be 6,000 times above the safe minimum, but the veracity of these tests are debated by toxicologists, and the possibility of deliberate poisoning is debated in political circles.

Another dioxin leak, probably with TCDD, occurred Germany in 1953. Again chloracne occurred, and acute respiratory tract infections were more common only in the group with severe chloracne. Photographs on the St Kilda population from the late 19th century show no evidence of chloracne in the women and children. Although the men have heavy beards, there is no visible evidence on photographs of chloracne around the neck, nor reports suggesting this dermatological disease. Dioxin toxicity on St Kilda appears a most

Chloracne has become the '*sine qua non'* of dioxin poisoning.

improbably contributory factor to the infections suffered by the islanders

believed to be carcinogenic, but cancers were not a common problem on St Kilda.

Macaulay noted that once this epidemic had resolved it did not recur without further visitors. Three episodes were once noted to occur within eight weeks following three separate visits from other islands, making the usual suggestion of influenza unlikely, as this organism does not mutate into a new infecting subtypes as quickly as this.

Human rhinoviruses (HRV), with 110 serological types, are the most common worldwide infective viral agents in humans, causing 30–50% of all cases of upper respiratory infection based on viral cultures, or an even higher percentage using improved detection techniques including reverse transcription-PCR. The short incubation period and recurrent infections with severe cough and profuse sputum, plus some cases of pneumonia and rare deaths, strongly support rhinovirus as the cause of the boat cough. Although adults with an averagely robust immune system usually experience one brief episode per year, the prolonged and recurrent bouts experienced by the St Kildans again support some problem in their immune systems. 10
