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03 December 2008

Future flu havoc in SA?

With human cases of the H5N1 virus increasing steadily, a global flu pandemic could be on the cards. But would South Africa be able to handle it?

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South Africa and other African countries have stockpiled just enough of the anti-flu medication Tamiflu to cover the needs of less than 5% of their populations if a worldwide outbreak should occur.

If no one receives treatment during such an epidemic in this country, up to 32 000 people could die and 34% of the population could become ill.

Human cases of bird flu (H5N1) have been increasing steadily since it was first reported in Vietnam in 2003.

At the end of last month, 292 people in 12 countries had already become ill and 172 had died, according to the World Health Organisation (WHO). The danger of a new virus, against which the human body has no resistance, is still a troublesome reality.

Should H5N1 mutate and become a worldwide pandemic, only 5 million units of Tamiflu will be available through the WHO.

The rest of the units needed by individual countries would have to come from their own stockpiles. This is where Africa and Asia – regarded as high-risk areas – are lagging far behind.

Stockpiling up to individual governments
Mr William Burns, CEO of Roche, who manufactures Tamiflu, said at a news conference in Basel, Switzerland it is unlikely that, in the case of an epidemic, countries would be prepared to share their stockpiled units with each other. “It is really up to individual governments to decide to what extent they want to be prepared.”

According to a report from the WHO, it appears that only one African country, Algeria, has ordered Tamiflu, or its active ingredient oseltamivir, for more than 5% of its population. The rest of the orders by 80 countries worldwide are all from Europe, the Middle East, Australasia and the USA.

Mr David Reddy, Roche’s team leader for pandemics, told Die Burger that there was “very limited interest” in the remedy from countries south of the Sahara. “We have not really received any significant orders.”

In the meantime, Roche has awarded Aspen a licence to produce more of the oseltamivir for its generic format in order to cover the needs of the African market.

Research published last year in the technical periodical Nature predicted that if, in a given country, no one were treated with oseltamivir, up to 6.8 out of every 1 000 people would die. This means that, in South Africa, about 32 000 people would die and 34% (around 7 million) would become ill.

If 29% of the population were treated, the estimated number of deaths is only 3.2 out of every 1 000 people – 32% would still get sick, because the main focus would be on the reduction of the number of deaths. If 57% of the population were treated (this includes preventive treatment of everyone in the household who had any contact with the sick person), the estimated number of deaths is 2.2 out of every 1 000, and 22% would become ill.

If all sick people and everyone who came into contact with them were to be treated, the estimated death rate would be 1.3 out of every 1 000 and 13% would get sick.

According to Burns, Roche is capable of producing 400 million units of Tamiflu per year, but governments and corporations have as yet only ordered 215 million. The company is therefore considering scaling down production. If a pandemic were to break out, the company could attain full production again within a month.

SA's plan of action
Prof Barry Schoub, head of the South African National Institute for Communicable Diseases, says the country has a plan of action, which would be set into motion in case of such a flu epidemic. The plan was worked out by the Department of Health in collaboration with his institute.

This action plan is available on the Department of Health’s website and can be found by searching under the word “influenza”.

Schoub said that the possibility of a flu pandemic, whether caused by a mutation of H5N1 or by a virus that is still unknown, is of great concern for South Africa. It is regarded in a very serious light by the authorities.

According to Schoub, South Africa definitely has a stockpile of Tamiflu, but probably not enough of the medication to provide for more than 5% of the population. He is not sure how much the Department has ordered.

Schoub says the reasons for this is that Tamiflu only has a five-year shelf life and that funds for such purposes are limited. South Africa also has other health priorities that require urgent attention.

Schoub added, “We are not entirely sure if Tamiflu would be effective in the case of a pandemic. It is, however, the only remedy that is currently available and it proved to be effective against H5N1 in studies on animals. At the moment, there is no vaccine available. I therefore assume that Tamiflu would be effective.”

If a pandemic broke out, Roche would only be able to develop a vaccine within six months after the identification of the specific flu strain.

Schoub points out that the last pandemic occurred in 1968 and that it is likely that there will be others. It is just not possible to predict where it will happen and what strain would be involved.

How the flu is transmitted
H5N1 is a type-A influenza virus. Certain sub-strains of the A-flu virus are limited to certain species, with the exception of birds, which host all known sub-types of this flu. A-flu viruses that are normally found only in one species may sometimes be transmitted to other species. There are two ways in which transmission may take place:

  • through direct contact between an infected bird and a human being (the person would need to have had close contact with the bird and/or its droppings); and
  • by means of a mediator-host, like a pig.

It is important to remember that bird flu cannot be transmitted from one sick person to another – at least not in the current form of the virus.

The greatest danger lies in the mutation of the H5N1-virus. If this should happen, it could be transmitted directly from person to person. Countries will have to be prepared to treat the sick and have plans in place to prevent the spread of the disease.

A-type flu viruses have eight different genetic segments. This segmented genome allows flu viruses from different species to combine to form a new A-type flu virus. This happens when viruses from two different species infect the same person or animal.

It could happen as follows: a pig becomes infected with the human A-type virus as well as bird flu. The genetic material of the two viruses is combined, creating a new virus.

The new virus would contain mainly genetic material particular to human flu – it would however also contain some elements of the other virus.

A person who already has human flu could also contract bird flu.

The two viruses could mutate and create a new deadly virus.

The genetics of the new virus could cause it to become transmittable from person to person. Once it becomes contagious, the virus will spread like wildfire.

The new H5-virus would probably make one extremely sick and people would pass it on to each other. The virus would contain proteins that were previously unknown in human flu viruses. This great change in A-flu viruses is known as an antigenic shift. – (Elsabé Brits, Die Burger, May 2007)

- (Sources: Roche, WHO, American Association for the Advancement of Science, USA Centre for Disease Control)

Read more:
What is Tamiflu?

 
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