Increases in livestock populations linked to rise in disease epidemics

YOU can be killed by an exotic variety of diseases in India. But until recently Congo fever was not one of them. A tick-borne virus, endemic to parts of Africa, the Middle East and elsewhere, it passes easily from livestock to man, and then between humans. Horrible symptoms include fever, internal bleeding and liver failure. Some 30% of infected humans die, usually within a couple of weeks.

The authorities in Gujarat, western India, were therefore alarmed when in January a medical intern died of the disease, formally known as Crimean-Congo haemorrhagic fever. Earlier in the month it killed three others: a patient, plus a doctor and nurse who had cared for her. These appear to be the first recorded deaths in India from the illness. On February 5th doctors reported two more cases in Gujarat. The fever’s arrival is a mystery.

Nobody is predicting an imminent plague. But in a region with a booming human population, a strong agricultural (notably dairy) industry and lively trade, a virus that threatens both livestock and humans is troubling. Ticks that spread Congo fever can infect, and are spread by, many wild and domestic animals, including cattle and some birds.

Scientists spot a new disease roughly every four months. Most are trivial but a minority, such as HIV, bird flu and SARS are grave threats. Animals seem to be the main source of new infectious disease in man: in general around 60% of human pathogens are transmissible from animals; among new diseases, the rate is about 75%. Read more…