Mosquito bites man, what follows is a medical enigma

Mosquito bites may be one of the most common bites but have you ever heard of a mosquito transmitting a worm in human host? Strange but true. Meet 82-year-old Sohanlal Agarwal, who recently not only battled this one of the most rare eye conditions but also successfully overcame it.

The octogenarian or even the doctor had not imagined that a mosquito bite would be responsible for a 3- cm-long worm in his eye. In a rare case which has affected only a few humans world wide, a mosquito (Aedes Albopictus) transmitted a larvae into the patient's eye which had to be surgically removed.

Animals, mostly dogs, are the hosts of the worm. A Hinduja hospital microbiologist described the rare infection as dirofilariasis. Centres for Disease Control and Prevention too said dirofilariasis is a rare happening in humans.

Dr Jayashree Thakore, eye surgeon at Lotus Eye Hospital, Andheri said, "Sohanlal came to us on December 31 with severe pain and redness in right eye. First I thought there was a cyst formation on the eye ball and there was some kind of discharge. However, the very next moment I realised something was moving behind the conjunctiva."

Recalling the visit to the doctor, Sohanlal said, in fraction of seconds, Dr Thakore's consulting room turned into a war zone with she and her team running for forceps, needle, blade etc. "She told me there is some creature in my eyes and not to panic. I was calm and was only happy to get rid of the severe pain," he said.

Within seconds, Dr Thakore removed the 3-cm-long worm. "The moment I realised that it was possibly a worm, I administered local anaesthesia to sedate the creature so that I get enough time to remove it. But within seconds, it was again moving, running behind the eye ball," said Dr Thakore.

With the help of needle and forceps, Dr Thakore removed the transparent worm handed it over to Hinduja Laboratory for further investigation. "The worm was like a thin thread and transparent. Dr Thakore's surgical skill are praiseworthy as she managed to remove the entire worm. It helped us identify the worm," said Dr Ami Varaiya, microbiologist and infection control officer at Hinduja Healthcare in Khar.

Dr Varaiya's department later got in touch with the Bombay Veterinary College to confirm the findings. "We took help of Dr ML Gatne from Bombay Veterinary College who confirmed that the worm was an adult male Dirofilaria which is commonly seen in dogs and other canines. While in animals, the worm is not known to cause any problem, human being is unusual host and can harm. It can even lead to blindness," said Dr Varaiya.

Dr Varaiya said Aedes Albopictus is known to bite tender skin on the face. "In Sohanlal's case too, the mosquito must have bitten him on the face and the larvae travelled to his right eye and grew there. He had a similar pain three months back but nothing was detected then," said Dr Thakore.

Taking the uniqueness of the disease into consideration, Dr Thakore has decided to send the case study to medical journals. "There are handful of cases reported across the world. This infection needs more awareness so that it is curbed at the earliest," said Varaiya.

All about the disease
The disease is caused by Dirofilaria roundworms. The main natural host is dog and wild canines. Infection can result in nodules under the skin or conjunctiva and lung granulomas (small nodules formed by an inflammatory reaction). Aedes albopictus feeds on a wide range of hosts. It is also known to be a significant biting nuisance, with the potential to become a serious health threat as a bridge vector of zoonotic pathogens to humans. This mosquito species is a known vector of chikungunya virus, dengue virus and dirofilariasis.