Animals Play Key Role in Flu Pandemics

15 January (Reuters Health [David Fo-garty])—Scientists are investigating if the deaths of 3 people in Vietnam from bird flu could be the start of a new pandemic. In most pandemics, animals, such as chickens and pigs, have played a role in creating deadly new strains of influenza viruses.

That is what is alarming scientists in Asia after an outbreak of bird flu has killed millions of poultry in Vietnam, South Korea, and Japan. The World Health Organization (WHO) says 18 people in Vietnam are suspected to have been infected with bird flu, including the 3 confirmed infections.

But the WHO stresses there is a lack of evidence of human-to-human transmission in Vietnam. The case resembles an outbreak of bird flu in Hong Kong in 1997, when 18 people were infected with avian influenza virus A (H5N1), 6 of whom died. That outbreak did not spread because the virus could not pass from one human to another.

The danger is when a new virus can cross from person to person. Animals play a key role here because they become breeding grounds for new strains of flu that contain changes in the genetic structure that the human immune system cannot recognize.

According to the science journal Nature, flu viruses originate in wild birds and are thought to become lethal when they cross into poultry or pigs. In cells infected with another flu variety, the viruses pick up genes that enable them to infect humans.

Pigs can be infected with human and avian influenza viruses in addition to swine influenza viruses. Infected pigs get symptoms similar to humans, such as cough, fever, and runny nose.

Because pigs are susceptible to a variety of flu viruses, they potentially may be infected with viruses from different species, such as ducks and humans, at the same time. If this happens, it is possible for the genes of these viruses to mix and create a new virus.

In Vietnam, hundreds of pigs have also died of flu.

Dr. Veronica Chan, head of the microbiology and parasitology department at the University of the Philippines' College of Medicine, said humans would have no protection against a new strain of flu.

The virus behind the last major flu outbreak, the Hong Kong flu pandemic of 1968, is thought to have originated with wild aquatic birds, such as ducks. Nature journal reported last year that the next killer influenza strain might leap directly from ducks to humans.

Editor's comment. As of 21 January 2004, there have been 5 confirmed cases of influenza virus H5N1 infection in humans in Vietnam, with more cases suspected. To put the potential danger of a pandemic in perspective, I have included a comment from Craig Pringle that appeared in a ProMED-mail article from 17 January 2004 (see ProMed-mail archive number 20040117.0181 [http://www.promedmail.org]):

While not wishing to diminish legitimate concerns [about the potential of widespread human to human transmission of infection] …, it should be remembered that genetic interactions between avian and human influenza A viruses have been rare and the evolution of hybrid viruses endowed with the potential to spread from person to person has been even rarer. It is likely that multiple genetic changes are necessary to produce an influenza A virus with pandemic potential. The recent occurrence of cases of human infection by avian influenza A viruses (H5N1 and H9N2 in Asia, and H7N7 in Europe) during the course of outbreaks of influenza in domestic poultry has not been accompanied by significant spread from person to person. Furthermore the pathogenesis of influenza in birds is different from that in mammals, in that virus replication occurs in the intestinal tract as well as the respiratory tract. Consequently the exposure of humans to avian influenza viruses may well not be by a respiratory route, further limiting potential for onward transmission.

Fatal Diphtheria Case Highlights Importance of Vaccination for Travelers

8 January (Reuters Health)—In a new report, the Centers for Disease Control and Prevention (CDC) describes a fatal case of respiratory diphtheria involving a US traveler. “The case highlights the need for all international travelers to be up-to-date with all recommended vaccinations, including a primary series of diphtheria toxoid-containing vaccine,” the CDC emphasizes.

The case involved a 63-year-old Pennsylvania man who traveled to Haiti last October. The man was previously healthy but had never been vaccinated against diphtheria.

On day 6 of the 1-week trip, the man developed a sore throat. Soon after returning to Pennsylvania, he presented to a local emergency room (ER) complaining of difficulty swallowing in addition to the sore throat. Group A strep and heterophile agglutinins tests were negative, and the patient was treated with oral amoxicillin/ clavulanate.

Two days later, the man's condition had deteriorated—on return to the ER, he now had chills, sweating, restlessness, difficultly breathing, nausea, and vomiting. Physical examination revealed stridor, a swollen neck, expiratory wheezing, diminished breath sounds in left lung base, and no fever. The patient was admitted to the intensive care unit (ICU) and intubated.

A yellow tonsillar exudate was seen during intubation, but a swab specimen tested negative for Corynebacterium diphtheriae. However, methicillin-susceptible Staphylococcus aureus was isolated from the sputum. Over the next 4 days, the patient was treated with a variety of antibiotics and steroids but became hypotensive and febrile.

On day 8 of the acute illness, the man was transferred to a tertiary care center, where tracheostomy was performed. During the procedure, a white exudate consistent with C. diphtheria infection was seen. Although culture testing failed to reveal the pathogen, C. diphtheria genes were found on PCR analysis.

The patient died on day 17 of cardiac complications.

In an Editorial Note, the authors point out that only 30% of US adults age 60– 69 have protective levels of diphtheria antibodies. They remind readers that, after the childhood vaccination series, adults should have diphtheria toxoid boosters every 10 years.

Source: MMWR Morb Mortal Wkly Rep CDC Surveill Summ 2004; 52:1285–6.

Editor's comment. I wonder how many of the members of the Infectious Diseases Society of America have kept their tetanus and diphtheria immunizations up to date. I plead guilty

U.K. Suspects First VCJD Case Transmitted by Blood Transfusion

17 December (Reuters Health)—Britain said [17 December] it has identified the world's first possible case of variant Creutzfeldt-Jakob disease (vCJD) transmitted via blood transfusion.

A patient who received a transfusion from a donor, who was later found to have vCJD, died from the illness, said Health Secretary John Reid.

He said a donor, who at the time showed no signs of vCJD, gave blood to the National Blood Service in 1996, and that it was in turn given to a patient shortly afterwards.

The donor developed the disease in 1999 and died from it. The recipient of the blood died earlier this year.

He also said it was possible both individuals separately acquired vCJD by eating meat or meat products from animals with bovine spongiform encephalopathy, also known as mad cow disease.

There is as yet no blood test for vCJD, so there is no way of screening blood donations for the presence of CJD. Reid said, however, that the government has set up a range of precautionary measures since 1997.

Reid said there have been 143 cases of vCJD reported in the United Kingdom.

Who Confirms New Polio Cases in West Africa

13 January (Reuters Health)—The World Health Organization (WHO), battling to eradicate polio worldwide by the end of the year, confirmed [13 January] that the disease had resurfaced in Cameroon and Benin.

The United Nations health agency said 1 case had been identified in each of the West African states and had spread there from neighboring Nigeria.

Once one of the world's most devastating and widespread diseases, polio is now endemic in only 6 countries—India, Pakistan, Nigeria, Afghanistan, Niger, and Egypt—but stamping it out completely has proved difficult.

Over 650 cases were reported in 2003, Nigeria topping the list with 300, followed by India with 214 and Pakistan with 96. But the total was sharply down on the 1918 recorded in 2002.

The fight against polio ran into trouble in the mainly Muslim north of Nigeria in late 2003 when local religious leaders forced the suspension of an immunization program because they feared the vaccine spread AIDS and infertility

When the WHO launched its campaign to wipe out polio in 1988, the disease affected more than 100 countries.

Trinity'S Rapid HIV Test Gets U.S. Approval

29 December (Reuters Health)—Trinity Biotech plc. said it received U.S. regulatory approval to market its rapid HIV test in the United States.

The Ireland-based company said the product, Uni-Gold Recombigen, is approved for the detection of antibodies to HIV in human serum, plasma, or whole blood and that it is the first to be approved for use with all 3 sample types.

The company said Uni-Gold Recombigen, which is already used in Africa, requires only 1 step and produces a result within 10 minutes. The test can be conducted in a doctor's office.

Government research and HIV programs have indicated that as many as 40% of those taking lab tests do not return for their results.

New Rapid Test Developed to Detect Chlamydia

16 December (Reuters Health [Patricia Reaney])—An international team of scientists has developed an easy-to-use, rapid test for chlamydia.

The “Firstburst” test gives results in less than 25 minutes and will cost as little as 70 US cents in developing countries.

The dipstick test picks up the bacterium in urine samples from men and from a vaginal swab in women. It is designed to be used in clinics, but Dr. Helen Lee, of the University of Cambridge, England, who headed the research team, said her ultimate goal is that women will be able to test themselves.

Dr. Ted Bianco, of the Wellcome Trust charity, which funded the research, said the test has the potential to help millions of people.