URL: http://effectmeasure.blogspot.com/2005/04/h7-in-north-korea.html

<p>Effect Measure 

   <p>Effect Measure is a forum for progressive public health discussion and
   argument as well as a source of public health information from around
   the web that interests the Editor(s)

<h>H7 in North Korea

   <p>Reports from Pyongyang, North Korea today seem to indicate that the
   unidentified bird flu strain afflicting North Korean poultry is of the
   H7, not H5, sub-type. AP says this has been confirmed by FAO, but New
   Scientist says evidence is "indirect" (according to a different FAO
   source), where "indirect" means the North Koreans prepared a vaccine
   from the sick birds and the vaccinated birds showed antibodies to H7.
   
   <p>If the infection is with H7 subtype this would seem to be good news as
   human cases with H7 have not been particularly severe. H7N2 has been
   reported in poultry in the US (Delaware) and H7N7 caused a large
   outbreak in poultry in 2003 in The Netherlands which jumped to humans.
   Most cases manifested as conjunctivitis ("pink eye") and a small
   number (3) showed typical influenza-like symptoms (cough, fever,
   muscle aches). The only serious case involved a veterinarian who
   visited one of the farms and developed fatal respiratory distress
   syndrome.
   
   <p>Relatively mild disease, yes. But the fly in the ointment is that this
   avian virus also showed itself to be quite transmissible to and among
   people. Eighty-three cases were reported initially among poultry
   workers with three possible subsequent transmissions to family
   members. A follow-up blood study with 500 farmers, their families and
   workers involved in the massive cull initially showed no antibodies to
   H7, even in those with confirmed infection. It turned out the
   hemagglutination assay (to see if a subject's blood serum made red
   blood cells clump together, a standard test for prior infection)
   worked with horse red blood cells, not the standard turkey rbcs. Even
   using horse rbcs, only about 50% of the previously infected patients
   showed agglutination, still not very sensitive. Using the modified
   assay, Dutch investigators estimated that at least 1000 and perhaps as
   many as 2000 people may have been infected. More importantly, close
   family contacts of poultry workers had a 59% seroprevalence of H7
   antibodies, suggesting person to person transmission on large scale.
   Some other pertinent technical results:

     <p>. . . having measurable antibodies was associated with having
     conjunctivitis (RR 1.72; 95% CI 0.99-2.99), and a lower proportion
     of the exposed persons who took prophylactic antiviral medication
     developed antibodies (corrected OR 0.48; 95% CI 0.25-0.89).
     
	 <p>Neither poultry farmers nor those engaged in controlling the
     epidemic complied satisfactorily with preventive measures. Only 6%
     of farmers reported consistent use of facial masks and 1% reported
     consistent use of goggles while working with infected poultry. In
     cullers, compliance was only slightly better: 25% consistently used
     facial masks and 13% used goggles. The results of the
     epidemiological study suggest that oseltamivir protected against
     conjunctivitis (corrected OR=0.14; 95% CI=0.08C0.27) as well as
     against infection without specific symptoms. No protective effect
     was demonstrable for safety goggles or mouth-nose masks.

   <p>Meanwhile, the North Koreans are declaring the outbreak over (Right.
   Maybe they want to sell me a bridge over the Yalu?). Even if true,
   questions remain, as New Scientist notes:

     <p>But this is a mystery, as an outbreak of H7 has never been recorded
     in east Asia before. âThe North Koreans say they have destroyed all
     the sick chickens, and the outbreak is now over,â says [the FAO
     scientist]. âThatâs good for the Koreans. But weâd like a sample of
     tissue from the infected birds so we can isolate the virus.â
     A genetic sequence might help trace the strainâs origins, and
     whether it has mixed with other Asian strains.

   <p>So the evidence has been destroyed? I'll bet it's still there. The
   problem will be getting it before it migrates elsewhere.

   
   <p>In epidemiology an effect is the endpoint of a causal mechanism. An
       effect measure is anestimate of the influence of a particular
       factor on a population's health. The Editors of Effect Measure are
       seniorpublic health scientists and practitioners. Their names
       wouldbe immediately recognizable to many in the public health
       community.They prefer to keep their online and public lives
       separate to allow maximum freedom of expression. Paul Revere was a
       member of the first local Board of Health in the United States
       (Boston, 1799). The Editors signtheir posts "Revere" to recognize
       the public service of aprofessional forerunner better known for
       other things.