Vol. V, No. 10~ EINet News Briefs ~ May 31, 2002
The EINet listserv was created to foster discussion, networking, and collaboration in the area of emerging infectious diseases (EID's) among academicians, scientists, and policy makers in the AsiaPacific region. We strongly encourage you to share their perspectives and experiences, as your participation directly contributes to the richness of the "electronic discussions" that occur. To respond to the listserv, use the reply function.
In this edition:
1. OVERVIEW OF INFECTIOUSDISEASE INFORMATION
Below is a semimonthly summary of AsiaPacific emerging infectious diseases.
Brazil (Mato Grosso do Sul) Leishmaniasis
Control measures implemented in 2000 included a serosurvey of dogs,
spraying of residual insecticides in houses, and health education
campaigns. The Centre for Control of Zoonoses of Campo Grande confirmed
leishmaniasis in 16.5 percent of dogs tested in the first three months
of 2002 compared to 2.1 percent of dogs tested in the year 2001. In
December 2001 diagnostic kits and drugs for treatment were distributed
and in January 2002 a course in diagnosis and treatment was held for
health workers of the Basic Health Network. On 22 May 2002 the Manager
of the Visceral Lieshmaniasis Control Program will visit Tres Lagoas
to evaluate the situation. On 7 June 2002 there will be a seminar
for health workers in Campo Grande on surveillance, treatment and
United States Imported Hantavirus Pulmonary Syndrome
England Drugresistant Bacteria
Foot and Mouth South Korea
Four new cases of FMD occurring between 19 May and 20 May 2002 in pigs were confirmed by South Korea, bringing the total number of cases since the outbreak started on 4 May 2002 to 12. The Agriculture Ministry has reported that authorities have gathered, as of 22 May 2002, more than 110,000 animals in their efforts to contain the disease. According to Agriculture Minister Kim Dongtae, the current FMD situation is under government control and South Korea has only detected cases in a limited area. Of the total positive cases, 10 are located in a 12mile diameter zone between YongIn and Ansong cities in Kyonggi province around Seoul. The remaining two cases are outside the town of Chinchon in Chung Chong province. In addition to managing outbreak investigations, South Korea is making efforts to stop the leakage of bloody water from one of the animal burial pits. According to reports, vinyl wrapper in one of the pits was torn when animals were transferred into it. Currently the government is disinfecting the bloody water leaked from the pit and deodorizing the surrounding areas. South Korea plans to kill and bury 16,286 more animals, bringing the total to almost 127,000. According to reports there have been no new reports of suspected FMD.
On 22 May 2002 South Korean police arrested the owner of the first
farm infected in the recent foot and mouth disease (FMD) outbreak.
According to the Kyonggi provincial police agency, the owner allegedly
buried more than 200 dead pigs near his farm between 27 April and
2 May 2002 without notifying officials.
Hong Kong H5N1 Avian Influenza Outbreak
Hong Kong has been hit by three major outbreaks of avian influenza
in the past five years. This year, over 900,000 chickens were killed
and in both 1997 and 2001 the entire chicken population of over one
million birds was slaughtered. In the 1997 outbreak of avian influenza
A (H5N1) infection was confirmed in 18 individuals, six of whom died.
In that outbreak humans acquired infection directly from chickens,
without an intermediate host. The slaughter of over 1.5 million chickens
helped stop the outbreak. Recommendations proposed by the investigation
team to decrease the likelihood of an outbreak include the avoidance
of contact with markets by farmers, discontinuation of movement of
materials between farms, an increased supply of chilled poultry, and
introduction of an additional market "rest day" each month
for the disinfection of retail markets.
Brazil (Sao Paulo) Hantavirus
Development of Ebola Vaccine
New DTP Vaccine
The FDA has approved Daptacel for the first four consecutive doses
of the childhood immunization series, but the fifth dose remains to
be licensed by the FDA. The results of a recent randomized trial published
in the New England Journal of Medicine (N Engl J Med 334:349𤭓)
suggest that the vaccine has a high level of protection against pertussis.
The trial, sponsored by the National Institute of Health, was doubleblinded
and placebo controlled. According to a company statement, supplies
are expected to be available by midJune. Daptacel is also licensed
for use in Canada.
Genetically Engineered Malariaresistant Mosquito
Researchers at Case Western Reserve University in Ohio, United States, and the Universitat Bayreuth in Bayreuth, Germany have taken a transgenic approach to preventing transmission of the malaria parasite Plasmoidium. It is estimated that malaria causes 0.7 to 2.7 million deaths a year; however, this number is thought to be underestimated due to underreporting and difficulties of diagnosis. Control of the disease has been difficult due to drug resistance in the parasites, insecticide resistance in the mosquitoes, and lack of an effective vaccine. The scientists introduced a synthetic gene in to the germline of culicine and anopheline mosquitoes in order to express antiparasitic peptides in the midgut of mosquitoes. Once inside a mosquito, the malaria parasite needs to cross gut epithelium and into the blood in order to fully develop. JacobsLorena and colleagues identified a peptides called SM1 that attaches itself to the gut wall of the mosquito and essentially acts by blocking the parasite. They then constructed a synthetic gene that produces SM1 when the mosquito feeds on contaminated blood.
Through their research, which has been published in the May 23rd issue
of Nature (Nature 417:387פ), the scientists found that expression of
the SM1 peptide in the mosquito midgut inhibited Plasmodium development.
The genetically modified mosquitoes were less susceptible to infection
after feeding on a malariainfected mouse and were far less able to transmit
the malaria parasite to mice than normal mosquitoes. Both groups of mosquitoes
studied were unable to transmit the parasite and one group had a 50 percent
reduction in transmission. The study investigated transmission in mice
so it is not yet known if SM1 will block transmission of human malaria
parasites. Another major obstacle in the use of these genetically modified
mosquitoes is that it is not clear if there is a safe and effective way
to spread foreign genes across mosquito populations. What's more, because
the technique was not fully effective at blocking transmission, resistant
variants may be selected and little is known about how genetically engineered
mosquitoes may affect the genes of mosquitoes in the wild.
Timing and Effectiveness of Measles Vaccination
Results of the study by Dr. Gregory A. Poland of the Mayo Clinic in the
United States and colleagues suggest that children who are vaccinated
closer to 15 months of age may gain better protection against measles
compared with those who are immunized around 12 months of age. Investigators
evaluated 333 children who were immunized against measles at 12 months
and 719 children immunized closer to 15 months. All of the children were
between the ages of 6 and 11 years and had only one dose of measles vaccine,
as had been recommendations at that time. Overall, 87 percent of the US
children and 76 percent of the Canadian children had measlesfighting
antibodies in their blood (P< 0.001). After adjusting for time from
immunization and age of immunization, differences in seropositive rates
were no longer significant (OR = 1.53, 95%CI = 0.87מ.69). However, the
researchers observed a significant doseresponse relationship between
the age at immunization and the likelihood of being seropositive after
immunization. The authors concluded that the current US policy of immunizing
with a first dose at 12 months of age may be less effective than immunizing
at 12 to 15 months of age.
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© 2002, The University of Washington