The Challenges of Containing Mosquito-Borne Diseases

The Zika Virus continues to dominate the news.  The virus is now being spread by mosquito vectors within the United Sates, and authorities are wondering how to secure regions as large as the entire state of Florida.  History may provide a clue.

I have previously blogged about Sir Ronald Ross, the man who discovered mosquito vectors.  Today I highlight two other pioneers in this field.  Coincidentally, they both celebrate birthdays this week.

Scottish physician Sir Patrick Manson (born October 3, 1844) is considered the “Father of Tropical Medicine.”  How smart was he?  He was memorizing church sermons at the age of five.  He completed his university medical courses at the age of 19, earning a Master of Surgery, Doctor of Medicine and Doctor of Law.

Manson studied tropical medicine in China, where his gardener was infected with filaria (a worm that causes elephantiasis).  Manson would have mosquitoes feed on the gardener’s blood while he was sleeping (!) so Manson could dissect the insects and study the blood.  This is how Manson discovered that mosquitoes play a role in spreading tropical diseases.

Manson’s work was leveraged by William Gorgas, who was born exactly 10 years later on October 3, 1854.  As a U.S. Army physician, Gorgas combatted tropical diseases in Florida and Cuba.  When he heard about a project to build a canal in Panama, he volunteered for duty there.

At the time, there was huge controversy over Walter Reed’s recent announcement that mosquitoes were also responsible for the spread of malaria and yellow fever.  When Gorgas proposed a $1 million plan to fumigate the entire Panama isthmus, he was met with considerable political opposition.  Sound familiar?

After a quarter of U.S. workers deserted the canal project following a yellow fever scare, U.S. President Theodore Roosevelt finally received a personal appeal from his own physician: “You are facing one of the greatest decisions of your career.  If you fall back on the old methods, you will fail.  If you back Gorgas, you will get your canal.”

Roosevelt granted the funding, and Gorgas began one of the most extensive sanitary campaigns in history.  With a “mosquito brigade” that included 4,000 people, 120 tons of insecticide, 600,000 gallons of oil, 4,000 buckets and 1,000 brooms, Gorgas fumigated, drained ponds and swamps, and implemented mosquito netting.  These measures saved thousands of lives and enabled the successful construction of the Panama Canal.

Agilent solutions are used to research Zika, malaria and other vector-borne diseases.

Brazilian researchers were able to detect and sequence the Zika virus genome in the amniotic fluid of two pregnant women whose fetuses were diagnosed with microcephaly.  (The virus was not detected in their urine or serum.)  The results suggest that the virus can cross the placental barrier.  The researchers used an Agilent Bioanalyzer system and High Sensitivity DNA Kit in their work.

In a separate study, Brazilian researchers used an Agilent Bioanalyzer system to discover how a patient had contracted Zika.  They concluded that it was a possible transmission through blood transfusion.  The patient had received a blood product from an infected donor, most likely in the incubation period after infection but prior to disease onset.  The study emphasizes the importance of diligence – for both donors and recipients – during outbreaks of potentially blood-borne infections.

Malaria is actually transmitted by Plasmodium, a parasite carried by mosquitoes.  The Enterobacter bacterium Esp_Z can inhibit the development of Plasmodium without harming mosquito fitness.  Researchers at Johns Hopkins University investigated whether exposing mosquitoes to Esp_Z can interrupt malaria transmission.  They used an Agilent Bioanalyzer system, microarray and scanner in their work.


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