First H7N9 case offers vital clues to fight flu

By Lai Shiow-suey 賴秀穗  / 

Wed, May 08, 2013 - Page 8

A Taiwanese businessman working in China, surnamed Lee (李), has been confirmed as the first H7N9 avian influenza case in Taiwan. The case has provided us with a lot of valuable information about how the H7N9 virus infects humans.

Lee stayed in Suzhou in China’s Jiangsu Province, for two weeks, was not in contact with birds or poultry and played golf once during the stay. This shows that in an H7N9-infected area, there is a constant risk of infection.

His falling ill after returning to Taiwan on April 9 shows that the virus’ incubation period is longer than that of a normal flu virus. During the early onset of the infection, he developed a light fever and experienced minor cold sweats and fatigue. During this period, a throat examination did not show any signs of the virus, which shows that a fever drives out none or only very little of the virus and thus will not infect others at this time.

The patient’s symptoms intensified rapidly and within a week of their appearance, the patient experienced lung and heart failure, and without extracorporeal membrane oxygenation it would have been difficult to save him. Only then was the virus discovered after examining a sputum specimen, which implies that the patient was beginning to secrete the virus and may have been able to infect someone coming into physical contact with him.

The H7N9 epidemic in China will not disappear in the near term and it could spread to southern provinces, such as Guangdong and Guangxi, and maybe even on to Hong Kong, as well as Taiwan. One can only hope that the disease prevention authorities have comprehensive response measures in place and that Taiwanese businesspeople and tourists traveling between Taiwan and China know how to protect themselves.

Questions about the source of H7N9, whether it spreads from person to person and how Lee contracted the virus during his two-week stay in Suzhou all remain unanswered. It has been two months since the virus first appeared in eastern China and it is now slowly spreading to the country’s northern and southern provinces. This means that the amount of people in the areas exposed to the virus is now in the hundreds of millions. Considering the virus’ infectiousness, one cannot help but wonder if the number of infected people is really just 120.

Given that the H7N9 virus is a composite of three different avian flu strains and that it has spread to an area covering hundreds of thousands of square kilometers in seven provinces, it appears that the source of the virus would be a poultry farm. There are close to 20 billion chickens in the affected areas, and these birds are required for the virus to grow enough so that it can infect humans.

Furthermore, the virus can be contained in poultry feces, which, when dry, become a powder that can be spread to remote places by the wind. Chicken droppings are rich in organic substances that can sustain the virus.

As for proof of whether the virus will spread between people, the Department of Health can test for that. Blood samples can be taken from people that visited the patient after he became seriously ill, such as family members, medical staff or friends who visited him within two to three weeks after they were tested for the virus. If the samples contain antibodies, that would be proof that the virus can spread from person to person, but that the excreted virus is not sufficient to cause infection or that the disease did not break out due to individual differences. If there were no antibodies, that would indicate that at the current stage, the H7N9 virus does not spread from person to person.

Lai Shiow-suey is an honorary professor in the Department of Veterinary Medicine at National Taiwan University.

Translated by Perry Svensson