Tag Archives: fever

Dengue vaccine approved for use in Mexico, Brazil and Philippines

Scientific American recently reported that the three countries most affected by dengue fever have approved the use of the first vaccine against this affliction. Officials from Mexico, Philippines and Brazil hope that this will curb the nearly 400 million new infections each year, 22,000 of which result in death.

Dengue symptoms include fever (sometimes as high as 105°F/40°C), pain in muscles, bones and joints, headaches, nose and gum bleeds and other similarly pleasant manifestation. The disease is caused by a virus which spreads through mosquito-bites and is closely related to the Zika virus. It emerged as a worldwide problem in the 1950s and up to now, apart from trying to keep the insects at bay, there was not much people could do to avoid infection.

The countries and areas at risk of dengue transmission are shaded in orange, and the geographical extension of dengue is indicated in red. Data are from the World Health Organization, 2007.
Image via nature

Although dengue rarely occurs in the continental United States, it is endemic in many parts of the world. Clocking in at a staggering 400 million new infections per year, an efficient vaccine for dengue could make a huge difference in the livelihood of those living in high-risk areas.

Enter Sanofi. While it’s not 100 percent effective against dengue infection, trials show that it reduces the chances of contracting the virus from infected mosquitoes by 60 percent (in patients over the age of 9.)

But, more importantly, the drug is 95.5 percent effective in treating dengue hemorrhagic fever, a deadly form of the disease that affects an estimated 500,000 people each year. Sanofi has the potential to drastically reduce incidents of DHF, saving countless lives.

Experts project the first Sanofi inoculations in Brazil, the Philippines and Mexico will take place this year, after each country completes negotiations with Sanofi’s parent company. The World Health Organization will examine the vaccine in April before making global recommendations.

Researchers have described the mechanism of formation for a key substance that triggers fever. Image: Flickr

The origin of fever: study shows it stems from the brain

Researchers have described the mechanism of formation for a key substance that triggers fever. Image: Flickr

Researchers have described the mechanism of formation for a key substance that triggers fever. Image: Flickr

Occasionally we’re hit by fever. Nobody likes it, most sane people actually hate it, but it’s important to note that it’s an important part of the healing process. Fever is a result of the immune response by your body to foreign invaders like viruses, bacteria, fungi, drugs, or other toxins. Research showed that it is triggered by an onset of the signaling substance prostaglandin. For some time, researchers have been debating where this signal originates, but new developments at the Linköping University in Sweden have finally settled the matter: prostaglandin originates in the brain. This key insight could pave way for a new class of drugs that suppress certain fever symptoms, but keep the ones that are essential to healing.

From the brain to the rest of the body

Aspirin is great for fever and researchers should it works its magic by suppressing prostaglandins producing throughout the body. Thus all inflammation symptoms are eased simultaneously: fever, pain, loss of appetite and so on. In some cases though, it might not be desirable to get rid of all these symptoms. After all, the body’s responses to invaders isn’t there for nothing – it fits a purpose.

”Perhaps you want to inhibit loss of appetite but retain fever. In the case of serious infections, fever can be a good thing,” says David Engblom, senior lecturer in neurobiology at Linköping University.

Actually, Engblom discovered the mechanism behind the formation of prostaglandin E2 during fever some eleven years ago. He found the signaling molecules are unable to pass the blood-brain barrier, which protects the brain from hazardous substances. What he found instead is that prostaglandin can be synthesized from two enzymes in the blood vessels inside the brain, before reaching the hypothalamus where the body’s thermostat is located.

Many years later, Engblom and colleagues finally confirmed their theory was correct. The researchers made tests on mice that lack the enzymes COX-2 and mPGES-1 in the brain’s blood vessels. When they were infected with bacterial toxins the fever did not appear, while other signs of inflammation were not affected, proving that the hypothesized mechanism is correct.

”This shows that those prostaglandins which cause fever are formed in the blood-brain barrier – nowhere else. Now it will be interesting to investigate the other inflammation symptoms. Knowledge of this type can be useful when developing drugs that ease certain symptoms, but not all of them,” explains David Engblom.