Before I answer your question, let me first give you a brief on bird flu.
Bird flu or avian flu, as its name implies, is primarily a disease of birds. It is caused by the Influenza A virus which has many strains. Among birds, the virus is transmitted by infected birds to healthy ones when the latter get into contact with the saliva, nasal secretions or feces of the former. Among domesticated birds and poultry, avian influenza causes widespread disease and death. Epidemics of the disease that kill millions of chickens and ducks occur periodically. In contrast, among wild birds, which also harbor and transmit the influenza virus, avian influenza usually causes only minor or no symptoms.
Bird flu started to affect humans only a few years ago. In May 1997, in Hong Kong, the first case of the disease in humans was reported following a widespread epidemic of bird flu among chickens. Apparently, a strain of the virus (H5N1) mutated and started to infect humans. By the time the outbreak was contained in early 1998 ?through the mass destruction of 1.5 million chickens, the thorough cleansing of the markets and chicken stalls, etc. ?a total of 18 human cases that resulted in six deaths had been recorded.
There have been other outbreaks of bird flu in Asia since, but most had been caused by the less lethal H5N2 and other benign strains of the avian influenza type A virus. In any case, very few human cases and deaths from the disease have been reported ?till this year.
This year, an avian influenza epidemic has raged in Asia ?specifically Thailand, Vietnam and China. To date, the epidemic has already resulted in the death of millions of chicken and at least 30 humans.
Practically all the confirmed human infections with the avian influenza have been acquired via direct contact with ?most probably, the feces of ?infected birds. As long as the transmission of the disease stays in this manner (i.e., bird to human) the disease will not become widespread among humans, because an infection has to be transmitted from person-toperson for it to reach epidemic and pandemic proportions. But ?as you have asked ?is there a possibility of an avian flu epidemic among humans? Actually, experts say there is, but the probability is low.
The possibility of a pandemic of avian influenza among humans cropped-up last month when Thailand announced that it has a confirmed case of person-to-person transmission of the disease.
Evidently, a Thai mother got sick and eventually died from avian influenza after acquiring the virus from her sick child.
Actually, this is not the first occurrence of person-to-person transmission of bird flu. Several had occurred in the past, but none had resulted in a sustained transmission of the disease. Experts are optimistic that this current case of person-to-person transmission will not result in a sustained transmission of the disease, either.
However, the possibility of a pandemic similar to the Spanish Flu pandemic of 1918 to 1919 cannot be discounted.
The Spanish Flu pandemic is believed to have been caused by a mutant virus that initially jumped from animal to man before it became capable of person-to-person transmission. Estimates of human fatalities caused by the Spanish Flu pandemic range from 20-100 million.
There is currently a worldwide effort, spearheaded by the World Health Organization (WHO), to prepare for a worst-case scenario regarding avian flu. Last month, for example, the WHO convened a meeting of the representatives of the drug industry in Geneva primarily to urge the drug companies to speed up vaccine production.
By the way, the signs and symptoms of bird flu in humans are similar to human flu: fever, malaise, muscle and joint pains, sore throat and cough. Some patients likewise develop sore eyes (conjunctivitis).
Compared to human flu, influenza A infection in human carries a higher risk for serious complications such as pneumonia, respiratory distress syndrome and kidney failure.
Address inquiries on health matters to Dr. Eduardo G. Gonzales, DLSU College of Medicine, Dasmari馻s, Cavite 4114.