Leishmaniasis is a parasitic disease that occurs in the Mediterranean basin and South America and can affect dogs and humans, and is one of the best known human parasitic diseases. It is transmitted by the bite of a phlebotomine sandfly, a type of mosquito that bites mammals and birds. In addition, other animals (up to 70 species are counted), such as hares, rats or opossums, act as reservoirs, i.e. they are intermediaries in the transmission of the disease.
What does the body of the leishmaniasis mosquito look like?
The phlebotomine sandfly that transmits leishmaniasis is a small insect, about 2-3 mm long, which does not emit a buzzing sound. It is light brown to yellowish and has a hair-covered body and wings, long thin antennae and a proboscis that is longer than the head and is used by females to suck blood. The wings adopt a 45° angle when the mosquito is biting while perched on the animal’s skin. There are more than 90 different species of sandflies that transmit leishmaniasis.
How does the leishmaniasis mosquito work?
It is active from dusk until dawn, and the rest of the day it remains hidden in dark and cool places. It is more common in areas with vegetation and in places where the minimum temperatures do not usually fall below 15 ºC. For this reason, fluctuations in temperature can greatly affect the development of the parasite inside the mosquito’s body causing it to be transmitted in areas where the disease was not previously present. In addition, it also needs moisture for the eggs to survive; it lays them in cracks, holes, animal burrows and tree roots. After peak rains, populations are reduced due to lack of daytime resting sites for adults and because heavy rains lead to the death of immature stages. It cannot fly if there is a strong wind and the flight distance is very short; it looks for food no more than 50 meters from its breeding site.
What are the life stages of the leishmaniasis mosquito?
Its life cycle goes through four stages: egg, larva, pupa and adult. One week after sucking blood, the female lays about 60-80 eggs, elongated and of an intense brown color, in humid places rich in organic matter. The eggs hatch, releasing the larvae, only half a millimeter long, a week after laying. The pupa is light yellow and retains the larval cuticle. The adult is fully developed about 2 months after the eggs are laid.
How does the leishmaniasis mosquito transmit the disease?
To bite the dog, the female phlebotomine sandfly, which needs to suck blood to feed and form eggs, lands on the dog’s skin. The transmission of leishmaniasis takes place through this bite when the sandfly has previously bitten an infected dog. Each female sandfly usually bites 3 or 4 times and then dies, usually before she is two weeks old.
How can we control the leishmaniasis mosquito?
The usual way is to spray homes and animal shelters with insecticides. And if it is known where the mosquitoes rest, it will also be useful to fumigate these places.
As for prevention in dogs, it is best to use authorized insecticides or repellents (collars or sprays, for example) during periods of sandfly activity. It is also important to bear in mind that if we introduce infected dogs into areas free of leishmaniasis, we should take extreme precautions against sandflies, since we will have a real risk of spreading the disease to previously free areas. In this sense, it is essential to apply repellents to control the disease collectively.
And finally, it is also interesting to remember that walks with dogs should preferably take place in areas away from rivers, stagnant waters, swampy areas, etc., and during the day, trying to avoid the hours between sunset and sunrise, since during these hours mosquitoes are more frequent.