NEW YORK (TheStreet) -- Shares of molecular diagnostic company Nanosphere  (NSPH) plummeted 42.1% to 71 cents in afternoon trading Tuesday after the World Health Organization said the number of new Ebola cases in the hardest-hit areas is declining.

The WHO reported 8,914 suspected or confirmed Ebola cases and 4,447 resultant deaths. This trend is "relatively flat" at approximately 1,000 new cases per week for the last three to four weeks, according to Bruce Aylward, the WHO assistant director-general who oversees the organization's operations in West Africa.

However, the WHO also noted the virus continues to spread throughout a wider geographical region, such as the Ivory Coast border, and continues to spread throughout some capital cities in Africa.

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Nanosphere shares had skyrocketed 88% Monday after it received FDA clearance for additional viral targets for its Verigene Enteric Pathogens Nucleic Acid test. Investors anticipated demand for Verigene, which could detect and diagnose the Ebola virus in patients at an earlier stage.

More than 6.8 million shares had changed hands as of 2:37 p.m., compared to the average volume of 987,403.

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