Monkey study shows dengue immunity does not affect Zika infection
A study involving rhesus macaques suggests that pre-existing dengue virus immunity does not result in more severe Zika disease, the second study this week to report this type of finding.
US researchers infected two groups of four macaques with either dengue virus (DENV) 1 or 2, according to their study, published today in Nature Communications. Through periodic blood testing for 2.5 years, the team demonstrated via cell-culture tests that antibody-dependent enhancement (ADE) occurred with Zika in vitro, meaning a stronger immune response to Zika was evident in the blood of animals that already had DENV antibodies in the blood.
But when they infected with Zika virus (ZIKV) both monkeys that had DENV antibodies and DENV-naive monkeys almost 3 years after the original DENV infection, they found that, in vivo (or live animals), the DENV antibodies did not increase ZIKV load or worsen the disease. In fact, previous exposure to DENV tended to shorten the course of ZIKV in the animals' blood compared with DENV-naive animals. They also found a lower ZIKV immune response in DENV-exposed macaques.
The authors conclude, "Results from our work may suggest that pregnant women with previous exposure to DENV may have limited ZIKV viremia and less tendency to have invasion of [the central nervous system]."
An analysis 3 days ago of blood samples in humans found no sign of ADE in those with Zika infection who had previously been exposed to DENV.
Jun 23 Nat Commun study
Jun 21 CIDRAP News scan on previous study
Taiwan, Finland report more highly pathogenic avian flu outbreaks
In new avian influenza outbreak developments, Taiwan reported six more highly pathogenic H5N2 events in poultry, while Finland detected highly pathogenic H5 in a wild bird, according to the latest reports from the World Organization for Animal Health (OIE).
In Taiwan, four of the outbreaks occurred at commercial farms and two involved slaughterhouses where authorities saw signs of illness in poultry carcasses. Five of the outbreaks involved chickens, and one occurred in turkeys. The outbreaks began between Jun 2 and Jun 15, affecting facilities in Hualien, Changhua, and Yunlin counties, plus the cities Kaohsiung and Tainan.
Between the six outbreaks, the virus killed 6,007 of 63,128 susceptible birds.
In Finland, authorities detected highly pathogenic H5 in samples from a whooper swan found sick on May 26 near the city of Sastamala in the country's southwest.
Jun 23 OIE report on H5N2 in Taiwan
Jun 22 OIE report on H5 in Finland
US bans Brazilian beef imports following food safety violations
US Secretary of Agriculture Sonny Perdue yesterday announced that the US Department of Agriculture (USDA) has banned all imports of fresh beef from Brazil because of recurring food safety issues, the agency said in a news release.
Since March, the USDA's Food Safety and Inspection Service has inspected every meat product from Brazil arriving in the United States and has refused entry on 11% of them. That compares with a 1% rejection rate on shipments from the rest of the world. The 106 rejected lots of Brazilian beef constitute about 1.9 million pounds, the USDA said.
Perdue said in the release, "Although international trade is an important part of what we do at USDA, and Brazil has long been one of our partners, my first priority is to protect American consumers. That’s what we’ve done by halting the import of Brazilian fresh beef."
The ban will remain in place until the Brazilian Ministry of Agriculture takes corrective action acceptable to the USDA. Brazil has pledged to address those concerns, including by self-suspending five facilities from shipping beef to the United States, the USDA said.
Jun 22 USDA news release