Mosquito repellant is essential virtually everywhere in India, except very high in the Himalayas although I’ve even seen mosquitos in Leh, Ladakh, which has an elevation of 11,500′! Although I haven’t heard of any outbreaks of mosquito-borne diseases there, it’s certainly a possibility.
Most people recommend DEET-based repellants. The trouble with DEET, however, is that it’s toxic to humans. It gets absorbed through the skin, so it has a stronger effect on children because of their higher skin-to-body-mass ratio. Not good. Just because the effects don’t usually show up immediately, except in people who tend to be more sensitive, doesn’t mean it isn’t harmful. There is reason to think that it is extremely harmful, and that frequent use could even be lethal. Even the advocates of DEET recommend using it as sparingly as possible.
Possible side effects of DEET include memory loss, fatigue, headache, tremors, muscle and joint pain, general weakness and shortness of breath. Such symptoms may not be evident until months or even years after exposure, making accurate diagnosis difficult. However, these symptoms are consistent with those reported by soldiers who used DEET during the Persian Gulf War. Studies on rats showed that DEET caused brain cell death and behavioral changes. (Ref: http://www.quantumhealth.com/ news/dangers_of_DEET.html)
Because of false information that has been widely propagated, many people have been conditioned to think that natural substances can’t be as effective as chemical ones. This simply isn’t true. The chemical industry has a vested interest in promoting this lie, for which reason it puts a lot of money into trying to discredit the efficacy of anything natural. (Incidentally, this is also true of the health care and agro industries, as you may know.)
You really don’t have to use DEET, and it’s not even the most effective thing, anyway. DEET is thought to work by masking human odors, and there are certainly better (not to mention safer and more pleasant) ways to achieve that! Moreover, there are other substances that mosquitoes evidently avoid because they don’t like the odor. Two oils in particular are getting rave reviews, and are considerably BETTER at keeping mosquitoes off than DEET. Without the harmful side effects. And they don’t have that creepy feeling on your skin that DEET has.
A study that was done at Iowa State University showed that catnip oil is about ten times more effective than DEET in repelling mosquitoes. It can be applied to the skin without the dangers associated with DEET.
Neem oil is another particularly effective oil. The neem tree is indigenous to India, so it’s readily available here, though you can also find it at garden centers in other countries, as it’s commonly used in the garden. One particular component of Neem seed oil has also been found to be more effective than DEET at repelling mosquitoes, according to researchers at the Malaria Institute in India. Both the U.S. National Research Council and the Journal of the American Mosquito Control Association have confirmed this finding. [Ref: http://www.discoverneem.com/natural-mosquito-repellent.html]
Other oils that you can also use include citronella oil, rosemary oil, eucalyptus oil, lemongrass oil, pennyroyal, tea tree oil and lavender oil. You can make a blend of oils using another oil such as apricot oil or coconut oil as a carrier. Some people like to mix some essential oil with water and glycerine, or grain alcohol or a light massage oil and use it as a spray. Citronella oil can be applied to your clothing and mosquito net. Some people use the essential oils directly, but others find that they are too strong if not diluted. Even as little as 1% seems to be enough.
Many people swear by Avon’s Skin So Soft bath oil as a mosquito repellant. I don’t recommend it because it is loaded with chemicals whose effects are unknown, but it’s probably a big improvement over DEET in any case. However, so many people have recommended this that I felt it was worth a mention.
An excellent product that’s available in India, and which I have found to be effective, is an herbal mosquito repellant spray made by Aromance. The main active ingredient is citronella.
Incidentally, not everyone finds the same level of efficacy in any given oil or product. I think this must be because each person’s body chemistry is a little different, so that it makes some subtle change in how any given oil smells to mosquitoes. Since mosquitoes evidently find their victims by smell, their sense of smell must be exceptionally acute.
Ultimately, the only way to be sure of avoiding malaria and dengue fever is to avoid getting bitten. Preventative medicines just aren’t all that effective, and they are very likely to make you feel sick. Mosquito nets will certainly help avoid malaria because it’s the night-feeding mosquitoes that are the carriers, but the day-feeding mosquitoes are the ones that carry dengue fever, so you also need to avoid their bites. For this reason you need to have a good mosquito-repellant.