Bulgaria–United States relations to work. Bulgaria became a member of the Warsaw Pact on May 14, 1955. Though no Soviet troops were stationed on Bulgarian soil, in 1968, Zhivkov sent a Bulgarian division to join Polish, Hungarian and Soviet troops to crush a popular uprising in Prague. In 1978, the Bulgarian secret police were implicated in the assassination in London of Georgi Markov, a Bulgarian dissident who was a correspondent for the BBC World Service, Deutsche Welle radio and the U.S. sponsored Radio Free Europe. Markov was assassinated with a poisoned umbrella on September 7, Zhivkov's birthday. The rise of democratic movements across
Ricin exposure occur, ricin can cause an allergy to develop. This is indicated by edema of the eyes and lips; asthma; bronchial irritation; dry, sore throat; congestion; skin redness (erythema); skin blisters (vesication); wheezing; itchy, watery eyes; chest tightness; and skin irritation. An antidote has been developed by the UK military, although it has not yet been tested on humans. Another antidote developed by the U.S. military has been shown to be safe and effective in lab mice injected with antibody-rich blood mixed with ricin, and has had some human testing. Symptomatic and supportive treatments are available for ricin poisoning. Existing