Lab notes: How bacteria cause premature births, dangers of the dengue vaccine and more

Toxic bacterial sacs trigger pre-term births

India accounts for 35% of all the pre-term births in the world and is the biggest contributor to the global incidence of such events. Researchers from the Indian Institute of Science, Bombay and Mumbai’s National Institute for Research in Reproductive Health have now discovered the mechanism by which pre-term births may be triggered.

Pre-term births are those that occur at between 28 weeks and 38 weeks. The researchers found for the first time that a gram-positive bacterium normally found in the human vagina, the Group B Streptococcus or GBS, could be responsible. The bacteria produce small balloons-like membrane vesicles containing toxins that kill both foetal and maternal cells. The toxins also destroy the collagen that binds the cells together leading to loss in elasticity and weakening of the amniotic membrane. The weak membrane is susceptible to rupture as the foetus grows.

The researchers injected vesicles into 15 pregnant mice, all of which gave birth to preterm babies of which nearly 40% were stillborn. The baby mice, that were much smaller and unhealthier than normal, were born two days preterm, which is equal to two months in human gestation. The study was published in the journal PLOS Pathogens.

Dangers from the new dengue vaccine

The first and newly approved dengue vaccine could lead to more dengue cases instead of preventing them, according to a new study published in Science. British and American public health researchers analyzed data from clinical trials of Dengvaxia, the vaccine produced by Sanofi Pasteur.

The live attenuated virus used in the vaccine acts like a silent natural infection, the study says. The nature of the disease is such that a second infection is much worse than the first and so use of the vaccine among people who had not been previously exposed to the disease could lead to a larger number of cases of people who got a more severe attack of dengue.

In moderate transmission settings, the study predicts positive impacts overall but increased risks of hospitalization with dengue disease for individuals who have not been previously exposed to the virus. However, in high-transmission settings, vaccination benefits the whole population.

The vaccine has been approved in six countries – Brazil, Paraguay, El Salvador, Mexico, Singapore and the Philippines.

The human cost of hartal

Scientists have now quantified the potential impact of hartals on healthcare delivery in government hospitals to show that hartals do not only cost the state but the sick as well.

Using data from 16 government health centers in Kerala during four state-wide hartals, researchers from the University of Kentucky found that the number of outpatient visits dropped by half on hartal days compared with a non-hartal day.

While this may seem obvious the data also showed that no surge in outpatient visit the day after the hartal, indicating that people may not have simply postponed their visits to health centres but cancelled them entirely. The drop in outpatient visits was seen across all types of government health centers, in primary, secondary and tertiary care facilities.

Data on emergency visits to the casualty showed a small but not statistically significant reduction in the number of visits. Although the study does not look at private hospital sector, the study hypothesises that many of these facilities may be under-staffed on hartal days, and the burden of caring for the sick may fall on government health centers. The team says that the study proves hollow the claim that governments make governments and political ogranisations make that “emergency services and healthcare is exempted from hartal.”