The belief is growing in me that the disease is communicated by the bite of the mosquito. She always injects a small quantity of fluid with her bite – What if the parasites get into the system in this manner? – Ronald Ross
Malaria is an ancient disease which has consumed the lives of millions over the ages. One of the goals of the World Health Assembly (which opened its annual meeting in Geneva on May 13, 2002) was to eradicate malaria from the face of the earth by the close of that decade. In 2015, thirteen years after that commendable resolution, some 214 million people were affected by malaria. It is an evil whose cause is known, thanks to the painstaking probes of scientists, but which is still haunting humanity because of ignorance, lack of education and sanitary conditions, as also shortages of resources.
According to some scientists who are studying global warming, tropical diseases like malaria will be spreading into the temperate zones before long.
An interesting question in this context is: “When and how did we come to know about what causes malaria?
This question brings us to Ronald Ross. He was born (May 13, 1857) to English parents parents living in India in the year when Indian patriots rose up in arms against British occupation of their country. His father was a general in the British Indian army. As a youth in school in England, Ronald wrote poems, composed music, and did some drawing too. But, on the advice of his father, he entered medical college and took a degree in medicine. He then became an army surgeon, traveled back and forth between India and England,
In those days it used to be thought (as the name betrays) that malaria was caused by bad air (Italian male: bad; aria: air). In the 1890s the Scottish physician Patrick Manson, who is regarded as the founder of the field called Tropical Medicine, put forward the hypothesis that parasites can flourish within mosquitoes. Tiny mosquitoes have been a nuisance in many parts of the world, as much by their annoying buzz as by their frequent stings whose purpose is simply to suck blood from the bodies of more massive creatures with a circulatory system. This is their sole mode of nourishment.
When Ross returned to India in the capacity of a medical officer of the British government, he went to many places including Bangalore where he was to report on a cholera outbreak. Next he was on assignment in a town near Ooty where he discovered a new kind of mosquito. Here succumbed to malaria and recovered. He got interested in the then emerging field of bacteriology.
Ross took blood from malaria patients and fed it to mosquitoes. It is said that Ross paid less than a tenth of a cent (by today’s reckoning) per mosquito-bite to a malarial patient, examined hundreds of the little creatures. He began his research on the subject in May 1896. He explored Manson’s idea by dissecting mosquitoes to see if they carried any disease-carrying germs. He did not find any. But he did not give up. His relentless efforts led him to the discovery that there are different types of mosquitoes. Today, entomologists say they have identified more than 3500 varieties mosquitoes.
One species, when dissected by Ross, revealed something unusual in the stomach. On 20 August 1897, Ross discovered that anopheles mosquitoes were the culprits. These are the ones that carry the malarial parasites called sporozoites. This is a stage in the life-cycle of the organism that enters into the body of the victim. It took another fifty years for scientists to uncover the various stages of the life cycle of the anopheles.
Thanks to Ross’s work, we came to know that these parasites develop within the body of the mosquito. When the mosquito sucks blood from a human, the parasites are transmitted through its saliva into the victim’s bloodstream. This was a major discovery for two reasons. First, it pointed out the cause and mode of transmission of a disease which had been taking the lives of millions of people all over the world. This knowledge helped in the prevention of the disease by getting rid of and/or keeping away from mosquitoes.
Second, it revealed how diseases may be transmitted through complex and unsuspecting modes. The idea of a disease-vector (agent) arose from Ross’s work. A politically inappropriate analogy would be that the parasites are somewhat like malevolent immigrants who come into a country with lethal weapons to cause destruction in the host country. Mosquitoes correspond to the cargo ships that bring in the agents of destruction.
Later in life Ross reflected that he had tried to better the human condition by investigating the “the causes of those diseases which are perhaps mankind’s chief enemies.” He meant physical diseases; mankind’s enemies also include mental diseases such as racism, bigotry, and religious persecution.
Ross was knighted for his achievement, and he was also one of the early recipients of the Nobel Prize for Medicine (1902).
Roland Ross met with many hurdles on his way, as reflected in the following verse in which he reveals his humility and religious inclination:
Before Thy feet I fall, Lord who made high my fate;
For in the mighty small, Thou showed’st the mighty great.
Henceforth I will resound but praises unto Thee;
Though I was beat and bound, Thou gavest me victory.
So it has been with wars against diseases. Preachers and traditions say with smugness that diseases, like earthquakes, are expressions of divine wrath at misbehaving mankind. But scientists have a different vision of Divinity, and they work hard to mitigate pain, relieve suffering, and uncover the cause rather than curse the victims as recipients of punishment for past misbehavior in the past.
It is strange that, after all the discoveries of modern science that have brought relief and cure to millions of victims of diseases all over the world, there are people who argue about the reliability, inadequacy, and truth-content of scientific knowledge, and plead for ancient worldviews as keys to unlocking the secrets of nature.
It is also one of the ironies of history that an Englishman worked to rid India and the world of the tropical disease of malaria while his country was holding the country as a colony. This is just one instance of the general truth that even unhappy historical occurrences have had some unintended positive effects.
May 13, 2016