Study of H7N9 clusters finds no change in risk of human-to-human spread
An analysis of 40 human H7N9 avian flu clusters from five waves of disease activity in China found a stable pattern in number and size, suggesting that the human-to-human transmission risk hasn't changed since the virus emerged in 2013. A team from China and their collaborators at the US Centers for Diseases Control and Prevention reported its findings yesterday in Emerging Infectious Diseases.
Often, patients infected with H7N9 in China have similar exposure to poultry and live-poultry markets, so it can be difficult to sort out which clusters reflect human-to-human transmission. Of the 40 clusters, the authors considered 14 (35%) probable and 26 (65%) as possible in terms of person-to-person spread. The proportion of clusters didn't vary significantly by wave, and there was no spread beyond second-generations infections.
Of the probable clusters, 4 were linked to household exposure and 10 were related to healthcare settings, including 4 during the fifth and biggest wave in 2016-17. Case-fatality rate was similar to sporadic cases. Index case-patients were significantly more likely than those with secondary infections to need mechanical ventilation.
Despite the surge in H7N9 activity during the fifth wave, cluster patterns were similar to earlier waves, suggesting no change in transmission risk over time, the group concluded, adding that the increase this past season probably reflects increased transmission from poultry over a wide geographic area.
Nov 21 Emerg Infect Dis study
Estimates reveal proposed malaria funding cuts could lead to spike in cases
The US Congress has proposed cutting by 44% the President's Malaria Initiative (PMI), one the chief sources of funds in the global battle against the disease, which if enacted could lead to an estimated 67 million more cases over the next 4 years, according to a modeling study published yesterday in PLoS Medicine.
The PMI, established in 2005, supports malaria control programs in 19 African countries and is the largest funder of malaria prevention and treatment.
In its calculations, the research team from the United Kingdom took into account transmission dynamics, as well as data about epidemiology, interventions, and PMI financing.
Gauging potential impacts of PMI funding, the team said maintaining current levels has the potential to avert 162 million more cases and save 692,589 lives from 2017 through 2020, compared with no PMI support. If the 44% in cuts are enacted, in addition to the steep rise in cases, an estimated 290,649 more deaths could occur from 2017 throgh 2020 compared with keeping the current funding level.
The authors said that PMI funding is highly cost-effective and has averted an estimated 185 million cases and 940,040 deaths since it began in 2005.
"Our results provide a conservative estimate of the overall impact of PMI funding, as we do not capture the impact of all PMI-associated activities," the group wrote. "PMI's ongoing support... in countries of high burden or strategic importance is vital in order to avoid a rapid erosion of the progress made in the last 15 years on the road towards malaria eradication."
Nov 21 PLoS Med study
Nov 21 PLoS press release
Case series details high public health cost of measles investigations
Investigating and responding to measles cases, even just single ones, puts a high burden on health departments, researchers from Colorado reported today in their breakdown of two recent unrelated cases in the Denver area, according to their report in Morbidity and Mortality Weekly Report (MMWR).
One of the patients was a 14-month-old baby who got sick after traveling to India, and the other was a 33-year-old man whose symptoms began after he traveled to Thailand.
Both cases resulted in hundreds of exposures and triggered complex responses by multiple public health agencies. Between them, the responses cost $68,000, accounting for personnel time, vaccination, postexposure prophylaxis, and lab costs. The cost in responding to the man's measles infection was less, because of a delay in reporting that put contacts beyond the recommended prophylaxis window. No secondary cases were linked to either of the infections.
The team said in both cases, failure to recognize measles early in the disease course is a reminder that health providers might not be familiar with the clinical signs or be aware of the risk for transmission during international travel. More awareness is needed for both patients and providers about international travel recommendations to prevent imported infections.
"Even a single measles case can impose high economic and programmatic burdens on public health agencies," the team wrote.
Nov 24 MMWR report
Protection via 1 dose of oral cholera vaccine drops after 2 years, study finds
New research from an international team of scientists shows that a single dose of oral cholera vaccine (OCV) confers 87% protection against the illness 2 months after administration, but that number drops to 33% after 2 years. The research was published yesterday in Clinical Infectious Diseases.
The authors of the 23-study meta-analysis said their work shows that a single dose of OCV may be useful in an outbreak setting, or when supplies of the vaccine are limited, but should not be relied upon for long-term immunity. Two doses of cholera vaccines are generally recommended.
"Protection, even short-term, from a single dose of OCV provides a way forward in considering alternative vaccine strategies to contain cholera outbreaks," the authors concluded. "For example, during cholera outbreaks with logistic challenges or insufficient OCV doses, single-dose coverage of a population at high-risk for cholera using all immediately available vaccine could be implemented rapidly, followed by administration of a second dose when feasible."
Recent cholera outbreaks in Haiti and Yemen have highlighted the need for cholera vaccination campaigns. And the authors cautioned that although hygiene, safe water, and other public health measures are the cornerstones of cholera prevention, outbreaks should be expected in areas shaken by political unrest or natural disasters.
Nov 21 Clin Infect Dis study