Third Pandemic

From ArticleWorld

Historically, and to this day, the spectre of the plague haunts societies, with good reason. The most recent plague pandemic, called the Third Pandemic, started in Yunnan province in China in the 1850s, spread to every inhabited continent, killed millions, and was only considered over in 1959 when, according the the World Health Organization, the number of deaths worldwide dropped to below to 200. Like most pandemics, this one spread and endured for so long because of political, technological, and economic changes.

Trajectory

The bubonic plague was endemic to rodents in Central Asia, but remained confined to that region until political change displaced thousands of people, many of whom found their way south to Yunnan, where the disease broke out in 1854. Again, it was limited to the region until a political uprising drove people south and east to Canton 40 years later. Canton, today Guangzhou, was a major port and trading centre, and just across the water from Hong Kong, which was a vital node in the commercial interests of the British empire, and therefore in international trade. As in previous centuries, ships and their cargo – which often carried infected rats – spread the disease to India, Egypt, Tunisia, Madagascar, Paraguay, Europe, Russia, Australia, the Caribbean, and the US West Coast. In China and India alone 12 million people died from the bubonic plague.

Plague vectors and research

It was not until the 1890s that scientists began to understand the transmission methods of the plague, and find that it was caused by a bacillus. Fittingly, it was in Hong Kong that a scientist, Alexandre Yersin, identified the bacillus, and how it was transmitted, contrubuting to not just our understanding of the plague, but also antibiotics and vaccines.

The plague is often endemic to populations of rats. When there is an outbreak of disease among rats, especially black rats, the fleas that normally feed on them must find alternative sources of nutrition. The fleas are the vectors that carry the Yersinia pestis bcateria and transmit it through their bites. Of rats start to die, the fleas bite other animals, including humans, thus transmitting the plague, an animal disease, to the human population.

Contemporary fears

The plague is still prevelant in some parts of Asia, Africa, and South America, and according to the World Health Organisation, there have been on average close to 2,500 reported cases annually from 1985-2005. There have a been a couple of small outbreaks in Brazil and neighboring countries, north India, and Central and Southern Africa, with the most cases reported in southern Africa, and Madagascar alone accounting for almost 55% of reported cases, according to the WHO. Of greater concern is the potential avian influenza pandemic.