JUAN O. TAMAYO

 They have long been a staple of the Cuba-U.S. conflict: Havana's allegations that
 Washington used biological weapons to attack the island's people, animals and
 crops.

 But an exhaustive study by an independent U.S. researcher has concluded that
 the outbreaks of disease were almost certainly the work of nature or bad
 decisions by President Fidel Castro -- not the CIA.

 The charges were so clearly unfounded that even Cuba's own scientists did not
 endorse them, wrote Raymond Zilinskas, senior scientist in residence at the
 Washington-based Monterey Institute for International Studies.

 Yet Havana has made the charge so often that it may be weakening efforts to
 control the proliferation of biological weapons around the world, Zilinskas wrote in
 the quarterly, Critical Reviews in Microbiology.

 The 60-year-old microbiologist was a member of two U.N. inspection missions
 sent to Iraq in 1994 in the wake of the Gulf War.

 His 55-page article represents the most comprehensive attempt yet to gather
 published information on the Cuban allegations, test them against known facts
 and reach conclusions on their truth.

 He did not travel to Cuba but culled information on Havana's charges from official
 Cuban documents, Castro's speeches and several Cuban reports to the United
 Nations.

 NATURE OR ACCIDENT

 It is impossible to disprove the 12 allegations made by Cuban officials since 1962,
 Zilinskas wrote, but his study showed that ``none . . . was likely to have resulted
 from biological attack by the U.S.

 ``The most likely explanation for all of them is that they were caused by nature or
 were accidentally brought on by human activity such as trade and commerce, he
 wrote.

 Ills that Havana blames on the United States include dengue fever and
 hemorrhagic conjunctivitis in 1981 and optical neuropathy in 1992, plus viral and
 fungal outbreaks among chickens and pigs and sugar cane, tobacco and other
 plants from 1962 to 1996.

 Cuba believes it has reason to worry about U.S. biological attacks because of
 well-publicized CIA plots in the 1960s to poison Castro, Zilinskas said.

 Yet Havana has never made public the most basic scientific data for its
 allegations, he added, and in the dengue case even declined to provide blood
 samples that would have helped trace the epidemic to its source.

 TRADE A SUSPECT

 Most of the human, animal and crop diseases that Havana complained about
 were present in neighboring countries and could easily have jumped to Cuba
 aboard travelers, ships, airplanes and wind currents, he said.

 The alleged ``biological sabotage of a Cuban-made vaccine that spread Newcastle
 disease through the poultry industry in 1962 was more likely the result of ``poor
 manufacturing practices and/or quality control, he wrote.

 One human disease, optical neuropathy, is caused by a combination of diet and
 lifestyle factors, not any kind of biological agent that could have been introduced
 to Cuba, the researcher noted.

 Castro probably made the epidemics worse, he added, by deciding to import
 fewer insecticides in the late 1970s, when mosquito populations were down, and
 ordering workers to plant a sugar cane variety that produces more sugar but is
 more susceptible to the fungal rust disease that erupted in 1979.

 SCIENTISTS ABSTAIN

 Zilinskas noted that with a single exception -- Dr. Pedro Kouri, head of Cuba's
 Tropical Medicine Institute -- no Cuban scientists have lent their names to the
 Havana charges of biological attacks.

 ``There is a positive aspect to this otherwise sorry history of untrue allegations by
 the Cuban government -- the behavior of the Cuban scientific community has been
 honorable and commendable, he wrote.

 Cuba took only one of its charges to the United Nations for review under the
 Biological and Toxin Weapons Convention -- a 1996 allegation that a U.S. crop
 duster sprayed a bug, thrips palmi, on its crops. The eight Western nations on
 the 10-nation review panel found the charge was false or lacked proof. China and
 Vietnam said they could not draw ``definite conclusions from the evidence
 presented.

 Zilinskas cautioned that making such false charges before the United Nations
 could make it harder to control the proliferation of biological and chemical
 weapons around the world.

 ``It gives publicity to these kinds of charges and gives the impression that they
 might be true, he told The Herald, ``and in doing so may get some governments
 thinking about the need to obtain their own biological weapons.

                     Copyright 1999 Miami Herald