News Scan for Nov 21, 2017

Zika spread, complications
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Monkeypox in Nigeria
Filed Under
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Animal Zika studies shed light on transmission, paralysis complications

Experiments in guinea pigs to explore possible routes of Zika transmission found that infected animals can pass the virus to healthy cagemates, perhaps through tears or saliva, researchers from China reported today in Nature Communications.

Zika transmission through sexual contact has been clearly established, but much less is known about other routes of human-to-human spread. The case of a US man from Utah who contracted the virus in 2016 after caring for his sick father has confounded researchers.

In the new report, the study team first confirmed that guinea pigs were susceptible to Zika infection after subcutaneous injection. Then when they place infected animals in cages with healthy animals, all of the uninfected animals readily developed viremia at levels similar to the experimentally infected animals. After just 1 day, Zika RNA was found in blood, saliva, and tears.

Researchers compared two Zika strains, one from 2010 in Cambodia and the other from 2016 in Venezuela. Response in guinea pigs to the earlier strain was slightly attenuated.

Another round of experiments showed that guinea pigs can be infected with Zika through intranasal inoculation, with virus found in several tissues, including the brain and parotid glands. In experiments with macaques, the team found that the animals can efficiently contract Zika after intranasal and intragastric inoculation.

The authors concluded that more evidence from animal models and clinical settings are needed to tease out close contact routes of transmission from other known routes.
Nov 21 Nat Commun abstract

In other Zika research developments, researchers from Yale University yesterday reported that the immune response to Zika, rather than the virus itself, may be responsible for some of the neurologic complications of the disease such as Guillain-Barre syndrome. They reported their findings in Nature Microbiology. Based on experiments with mice engineered to be susceptible to the disease, the investigators found that when Zika spread through blood to the brain, it triggered a flood of CD8 T immune cells, which have the capacity to limit nerve cell infection but can also trigger Zika-related paralysis.
Nov 20 Nat Microbiol abstract
Nov 20 Yale University press release

 

Nigeria confirms 4 more monkeypox cases but notes slowdown

The Nigerian Centre for Disease Control (NCDC) confirmed four more monkeypox cases but said the number of suspected cases has declined over the last 3 weeks. There are now 42 confirmed and 146 suspected cases reported since outbreak began in October.

All confirmed cases have been found in the 10 southernmost states of Nigeria. A total of 22 states have reported suspected cases.

The report said 9 of 12 swabs that were negative for monkeypox were positive for chickenpox.

So far there have been no deaths attributed to monkeypox, a rare virus closely related to smallpox. This outbreak, however, is Nigeria's largest to date. More men than women have been infected, and most patients have been between 21 and 30 years of age.

The NCDC said they will be taking a One Health approach to monitoring the outbreak. Humans contract monkeypox from infected animals.
Nov 19 NCDC update

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