- Source: Xinhua News Agency online
- The 2 latest confirmed cases of human bird flu in Thailand
might be [the result of] human-to-human transmission, a senior health official
has said. Dr Charoen Chuchottaworn, an avian influenza expert at the Public
Health Ministry's Department of Medical Services, said doctors concluded
after reviewing the history of the past 2 cases that both victims presented
very mild symptoms of avian influenza and neither had any physical contact
with chickens or birds.
- One of the victims was a boy in Bangkok and the other
was an 18-year-old man from Nonthaburi province, The "Nation"
newspaper reported on Fri 2 Dec 2005.
- This left doctors no clues as to where the patients became
infected with the H5N1 virus and showed that avian influenza had moved
from causing severe human infection to milder cases.
- Charoen, who is also a member of the National Committee
issuing guidelines for the treatment of avian influenza, made the remarks
on Thu 1 Dec 2005 at the Joint International Tropical Medicine Meeting
2005 in Bangkok. Dr Kamnuan Ungchusak, Director of the Epidemiology Bureau,
challenged Charoen's assertion about human-to-human transmissions.
- He told The Nation newspaper that while neither of the
patients had direct contact with chickens, they lived in an environment
where the virus was prevalent. "Chickens were dying near their homes
and chicken droppings were everywhere around their neighborhood,"
he said. "They might have contracted the virus through contaminated
- Dr Charoen said the milder the symptoms, the harder it
is for doctors to diagnose infection. This means that a lot more advanced
laboratory facilities are needed with a testing technique called RT-PCR
to confirm cases and decide if patients should be treated with the antiviral
Tamiflu (oseltamivir phosphate). He said this meant that avian influenza
could become asymptomatic now. The only tool [Tamiflu] available in Thailand
to fight H5N1 infections at the moment is insufficient, he said. At present,
Thailand has about one million capsules for 100 000 treatments of Tamiflu,
but it is estimated that about 120 million capsules of the drug will be
- Only severe cases of human bird flu have previously been
detected in Thailand simply because patients went to hospital for treatment.
But doctors believe that there have been many cases with mild symptoms
of the disease. "We believe that this is the tip of the iceberg,"
he said. Signs of possible human-to-human transmission were closely observed
in Vietnam, where 10 clusters of probable human transmissions were detected
in which the victims had no contact with infected poultry, Charoen said.
Thailand and Indonesia had one official cluster, he said, but the Indonesian
cluster showed clear-cut evidence because a child contracted H5N1 without
going to an infected area, as her father had.
- (No human cases of avian influenza had been reported
from Thailand for more than one year before mid-October 2005. It is not
clear from the text of this report whether the 2 cases described above
are new cases or are 2 of the 4 cases previously described since mid-October.
The mildness of the 2 cases described above may be significant, in that
asymptomatic human cases could have gone undetected in the intervening
period. This situation further emphasizes the need for comprehensive serological
surveys of the general population in East Asian countries.
- >From an analysis of a cluster of 3 cases in the same
family in 2004, it was concluded previously that person-to-person transmission
may have occurred in Thailand at an earlier phase of the outbreak. 2 family
members (a mother and an aunt) appeared to have contracted infection from
a critically ill index patient, but onward transmission was not observed
(see: Avian influenza, human - East Asia (18): Thailand 20050124.0258).
- The recent identification of 2 unrelated avian influenza
cases without known contact with poultry may not be an indication of imminent
widespread person-to-person transmission of avian influenza virus in Thailand.
The alternative view is that there may be significant environmental contamination
with virus where there are high numbers of poultry in the vicinity. The
available information does not allow firm conclusions about the source
of the virus. - Mods.MPP/CP)
- Patricia A. Doyle, DVM, PhD Bus Admin, Tropical Agriculture
- Please visit my "Emerging Diseases" message
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