Study suggests prior dengue infection doesn't increase Zika viral load
An analysis of blood samples from Brazilian patients seen in an emergency department for acute febrile illness found no sign of antibody-dependent enhancement (ADE) in those with Zika infection who had previously been exposed to dengue virus.
Both viruses are flaviviruses, which are known for enhancing immune response. As part of their work on Zika virus vaccines, scientists have been trying to tease out how and if ADE impacts Zika severity and if cross-infection with dengue or other flaviviruses worsens the disease.
A Brazil-based research team examined samples from 65 patients who were evaluated at a hospital in Sao Paulo state during the first half of 2016, when the area was experiencing a Zika outbreak. To explore any connection between ADE and both dengue and Zika, the researchers examined patients' viral loads and their cytokine profiles during acute infection. They published their findings yesterday in Clinical Infectious Diseases.
For patients diagnosed as having acute dengue or Zika infections, the researchers didn't see higher viremia levels in those who had previously been infected with dengue, but they noted that the study had only enough power to detect the difference with Zika virus.
In the cytokine analysis part of the study, the investigators looked at patterns with 10 cytokines, finding a significant difference in only one: IL-1-beta, which was lower in patients with acute dengue infections who had been infected with dengue previously. Again, the researchers said the power to detect differences between the groups was low, but in the Zika patients they did see a significant positive association between IL-1-beta and viral load.
The authors said they will continue to evaluate the group of patients to assess if earlier dengue infection protects against future Zika infections or illnesses involving other dengue serotypes. They also said they will explore other immunoglobulin subclasses and different immune cell subsets to better understand the mechanisms of the findings they observed in the patients.
Jun 20 Clin Infect Dis abstract
New MERS case reported in Riyadh
Saudi Arabia's Ministry of Health (MOH) reported one new MERS-CoV case yesterday in an update dated Jun 19.
The patient is a 42-year-old male expatriate from Riyadh. He did not have any symptoms of MERS-CoV (Middle East respiratory syndrome coronavirus) infection and is in stable condition. He's listed as a secondary household contact of a previously reported case.
The MOH reported no new cases in an update dated yesterday and of this writing had not issued a Jun 21 report. Before yesterday, the agency reported new cases on 19 straight days.
As of yesterday, Saudi Arabia's MERS-CoV cases since 2012 total 1,656, including 676 deaths. Seventeen people are still being treated for their infections.
Jun 19 MOH report
Nonmedical vaccine exemptions linked to pertussis outbreaks
A study yesterday in Proceedings of the National Academy of Sciences used geospacial data to show that US counties with more kindergartners with nonmedical vaccine exemption status have higher rates of pertussis outbreaks in the United States.
The data come from 2012, when the national incidence rate for pertussis was 15.4 per 100,000 people, the highest since 1955. The researchers compared reports of nonmedical vaccine exemption statuses of kindergarteners during the 2011-12 and 2012-13 academic years with statistically significant geographic clusters of pertussis cases in 2012 for two different age-groups (5 years and younger and 10 to 14 years), reported at the county level.
They found that relative risk for pertussis outbreaks increased in counties that had more unvaccinated kindergartners. On average, the proportion of kindergarteners with nonmedical vaccine exemptions was 2.8 times larger in counties reporting a pertussis vaccine cluster.
"Although we recognize that correlation does not establish causation, the findings from this investigation are consistent with previous suggestions that geographic clusters of nonmedical vaccine exemptions and waning immunity may have been two of several factors that contributed to community-level pertussis outbreaks," the authors concluded.
Jun 20 Proc Natl Acad Sci study
Ricin vaccine candidate received more funding
The National Institute of Allergy and Infectious Diseases (NIAID) is providing, additional money for animal testing of the novel ricin poison treatment and vaccine, RiVax, according to a company news release.
The NIAID will provide Soligenix, the maker of RiVax, with approximately $2 million in additional funding, bringing the total amount awarded to date under this contract to $18.7 million, according to the release.
The company specializes in making products that treat rare diseases. If all contract options are exercised, the total award of up to $24.7 million will support preclinical, manufacturing, and clinical development.
Ricin is a toxin that could be weaponized. The plant-derived poison is lethal in doses as small as a grain of salt and can be dissolved in water. There are no current treatments for ricin poisoning, but RiVax acts as a medical countermeasure to prevent the effects of ricin exposure.
Jun 21 Soligenix press release