Flu Scan for Sep 23, 2014

More H5N6 in Vietnam
;
Global flu report
;
Flu in pregnant women

Vietnam reports two more H5N6 outbreaks in ducks

Two more outbreaks of highly pathogenic H5N6 avian flu have occurred in central Vietnam, leading to the death of thousands of domestic birds, according to a Sep 20 report from the World Organization for Animal Health (OIE).

One outbreak, in Quang Ngai province, killed 300 birds out of a flock of 1,000. The remaining 700 were destroyed. The other outbreak, in Quang Nam province, killed 600 out of a flock of 2,000 birds, with the remaining 1,400 destroyed.

The apparent morbidity rate was 100%, the apparent mortality rate 30%, and the apparent case-fatality rate 30% in the two outbreaks taken together.

A Sep 22 story from the Chinese news agency Xinhua says more than 3,100 40-day-old ducks at a commune in Quang Nam were infected with H5N6. This is presumably the same outbreak as reported by the OIE, because Xinhua says 2,000 birds at the commune had tested positive for H5N6 last week.

The Xinhua story also says Nui Thanh district's veterinary center vaccinated 50 flocks of ducks and disinfected all farms in the commune.

H5N6 avian flu was first reported in China in April. Laos reported its first outbreak just last week, and Vietnam has seen several outbreaks since the first one there was reported Aug 8.

The UN Food and Agriculture Organization (FAO) issued a statement of concern just yesterday about the potential impact of H5N6 on Southeast Asian animal health and its potential for transmission to humans.
Sep 20 OIE report
Sep 22 Xinhua article
Sep 22 FAO statement

 

Southern Hemisphere flu activity shows mixed pattern

Seasonal influenza is ongoing in the Southern Hemisphere, with some areas seeing decreasing activity but some, including Australia and tropical South America, experiencing increasing or high levels, according to a global flu update yesterday from the World Health Organization (WHO) based on data from 50 reporting countries.

Australia is seeing continuing high activity of the 2009 H1N1 and H3N2 strains. New Zealand has ongoing activity with the same two strains, and the consultation rate for influenza-like infections is above the seasonal threshold and slightly above the average epidemic curve.

Most tropical South American countries are seeing increased levels of flu. Bolivia has had co-circulation of H3N2 and 2009 H1N1, but that trend has reportedly decreased since mid-August. Colombia is seeing a predominance of H3N2, while Peru has lower flu activity than it did last year. Brazil's flu activity is decreasing overall but less so in the southeastern region, where H3N2 is most common.

Flu activity is variable in Central America and the Caribbean, with influenza B predominant and co-circulating with 2009 H1N1 in Guatemala and with H3N2 in the Dominican Republic and Honduras. Panama is seeing decreasing levels of flu B in recent weeks, and Cuba is seeing increased severe acute respiratory infections, but respiratory syncytial virus (RSV) is the main causal organism.

Eastern Asia has low flu activity, with H3N2 the most common strain. That strain, along with influenza B, also continues to circulate in southern China.

Central Africa and western Asia have had low flu activity. India, Nepal, and Singapore are seeing decreased activity, mainly from H3N2. South Africa's flu activity remains high, with H3N2 most common.

Decreasing levels of flu activity are occurring in the temperate region of South America, where H3N2 has also been the predominant strain.

Flu activity in Europe, North America, northern Africa, and central Asia remains at interseasonal levels.

Worldwide, influenza A accounted for 81% of specimens tested and influenza B for 19%; of subtyped type A specimens, H3N2 accounted for 69.9% and 2009 H1N1 for 30.1. Nearly all (98.5%) of subtyped type B specimens were of the Yamagata lineage.
Sep 22 WHO global flu update

 

Study: Pregnant women mount strong immune response to flu

A study from Stanford University suggests that certain immune responses to influenza in pregnant women are unusually strong, which contradicts conventional thinking and may help explain why they tend to get sicker with flu than other adults.

The established view is that immune responses are suppressed by pregnancy to prevent the woman's body from rejecting her fetus, which would explain pregnant women's increased risk of severe illness.

In the study, published yesterday in the Proceedings of the National Academy of Sciences, researchers collected immune cells from 21 pregnant women and 29 healthy, nonpregnant women and exposed them to 2009 H1N1 and H3N2 flu viruses in the lab. The cells were gathered from blood samples taken before and 7 days after the women received flu vaccines and again 6 weeks after they gave birth.

The researchers found that pregnancy enhanced the immune response of natural killer (NK) cells and T cells to H1N1, according to a Stanford press release. Compared with the same cells from nonpregnant women, pregnant women's NK and T cells produced more cytokines and chemokines, which help attract other immune cells to an infection site. Too many cytokines and chemokines can lead to excessive inflammation in the lung, making the illness worse.

Both H1N1 and H3N2 also caused NK and T cells to be activated in a greater variety of ways in pregnant women than in nonpregnant women, according to the release.

The authors also found that the pregnant women's NK and T cells showed reduced responses to stimulation by certain chemicals—the type of finding that led to the conclusion that the cells are suppressed during pregnancy. "Clearly this conclusion is not correct relative to the more biologically relevant assays described here," they wrote.

"Robust cellular immune responses to influenza during pregnancy could drive pulmonary inflammation, explaining increased morbidity and mortality," the report states.

"If our finding ends up bearing out in future studies, it opens the possibility that we can develop new immune-modulating treatment approaches in the setting of severe influenza, especially in pregnant women," Alexander Kay, MD, instructor in pediatric infectious diseases and the study's lead author, said in the release.
Sep 22 PNAS abstract
Sep 22 Stanford press release

 

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