Mosquitos

Mosquitos cause more human suffering than any other organism—over one million people die from mosquito-borne diseases every year. Not only can mosquitos carry diseases that afflict humans, but they also transmit several diseases and parasites that dogs and horses are very susceptible to. These include dog heartworm, West Nile Virus, and Eastern equine encephalitis (EEE). In addition, mosquito bites can cause severe skin irritation through an allergic reaction to the mosquito’s saliva—this is what causes the red bump and itching.

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Mosquito vectored diseases include protozoan diseases, i.e. malaria; filarial diseases such as dog heartworm; and viruses, such as dengue, encephalitis, and yellow fever. CDC Travelers’ Health provides information on travel to destinations where mosquito-borne diseases might be a problem.

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• West Nile Virus: According to the Centers for Disease Control, since 1999, in the state of Kansas, there have been 17 human cases of encephalitis/meningitis, 13 cases of fever, and 4 deaths from the West Nile Virus. Similar to other encephalitis strains, it is cycled between birds and mosquitos and transmitted to mammals (including horses) and man by infected mosquitos. WNV usually occurs with symptoms where the least severe are characterized by fever, headache, tiredness, and aches or a rash. These symptoms are similar to the flu and can last several days to several weeks. Other types of WNV are grouped as neuroinvasive diseases, which affect the nervous system. West Nile encephalitis affects the brain and West Nile meningitis (meningoencephalitis) is an inflammation of the brain, spinal cord, and membrane around it.

• Malaria: Malaria was, by and large, eradicated in the temperate area of the world during the 20th century with the advent of DDT and other organochlorine and organophosphate mosquito control insecticides. However, more than 3 million deaths and 300-500 million cases are still reported annually in the world. It is reported that malaria kills one child every 40 seconds.

• Dog Heartworm: Dog heartworm can be a life-threatening disease for canines. The disease is caused by a roundworm. Dogs, and sometimes other animals, such as cats, foxes, and raccoons, are infected with the worm through the bite of a mosquito carrying the larvae of the worm. It is dependent on both the mammal and mosquito to fulfill its lifecycle. The young worms (called microfilaria) circulate in the bloodstream of the dog. These worms must infect a mosquito in order to complete their lifecycle.

• Cat Heartworm: Heartworm disease is not just a canine one. Heartworm affects cats differently than dogs, the disease they cause is equally serious. Heartworm larvae induce an intense inflammatory response in the blood vessels and tissues in the lungs. Once an adult worm dies, after one to two years, there is an additional intense inflammatory reaction resulting in acute lung injury. Don’t think that your cat is safe if it is an inside only cat. In a recent study, 28% of the cats infected by heartworm disease were inside only.

• Dengue: Dengue is a serious arboviral disease of the Americas, Asia, and Africa. Although it has a low mortality rate, dengue has very uncomfortable symptoms and has become more serious, both in frequency and mortality, in recent years. Over the last 16 years, it has become more common; for example, in south Texas, 55 cases were reported in 1999 resulting in one death.

• Yellow Fever: Yellow fever, which has a 400-year history, occurs only in tropical areas of Africa and the Americas. It has both an urban and jungle cycle. Every year, about 200,000 cases occur with 30,000 deaths in 33 countries.