Crimean-Congo haemorrhagic fever is a zoonotic disease caused by a tick-borne nairovirus, and it produces severe viral haemorrhagic fever outbreaks with a case fatality rate of 10 to 40 per cent. Its geographic range is the widest of any tick-borne virus that infects humans, and it tracks the distribution of Hyalomma ticks, its primary vector, across Africa, Asia, the Middle East and parts of Europe; migratory birds can carry the ticks into new areas. Transmission occurs through the bite of an infected tick or through direct contact with the blood or tissues of infected ticks, livestock or people, which is why workers in livestock industries, slaughterhouses and veterinary services are the highest-risk groups - and why hospital staff treating a case are themselves exposed. Symptoms begin one to thirteen days after infection: high fever, severe headache, muscle, back or abdominal pain, nausea, vomiting, diarrhoea, conjunctivitis, low blood pressure, jaundice, confusion and photophobia, with heavier bleeding and large bruises appearing three to five days in. Some infections are asymptomatic. There is no specific cure. Management is supportive - fluid balance, oxygen, blood pressure control and treatment of secondary infection - with the antiviral ribavirin showing some benefit.

CCHF is estimated to cause somewhere between 10,000 and 15,000 infections worldwide each year, a small number set against malaria or dengue but one attached to a case fatality rate that can reach 40 per cent and to a disease for which clinicians have essentially nothing specific to offer. That combination - low incidence, high lethality, no treatment - is precisely the profile that leaves a pathogen commercially unattractive and therefore under-researched, and it is why much of the antibody work in this field has come out of biodefence laboratories such as USAMRIID rather than the pharmaceutical industry. For India the stakes are concrete rather than theoretical: the vector is present, the livestock exposure pathway is ordinary agricultural work, and the 2011 Gujarat outbreak demonstrated the disease's most dangerous feature in a health-system setting, which is that the people most likely to catch it from a patient are the people treating the patient. A therapy that works after exposure, as an administered antibody would, addresses exactly that scenario.