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| | ==Life Cycle== | | ==Life Cycle== |
| − | D immt adults reach sexual maturtyF in tth plmonary
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| − | arteries and right ventricle of the dog. After
| + | Dirofilaria immitis adults reaach maturity and sexually reproduce in the right ventricle and the pulmonary arteries. After mating, female worms release larvae known as microfilariae into the circulation. When a mosquito takes a blood meal from the infected dog or cat, microfilariae are ingested. Mosquitos are true intermediate hosts for Dirofilaria immitis, and microfilariae require a variable period of maturation in the vector depending upon environmental conditions. For example, maturation at 30°rees;C takes around 8 days, but when temperatures are down to 18°rees;C, this takes around one month<sup>ferasin</sup>. Below 14°rees;, development is halted and resumes when temperatures rise. In cooler climates, this means that transmission of heartworm disease to new canine or feline hosts can only occur in warmer months. |
| − | mating, the female nematodes rea e immature larvae | |
| − | (LI or micrflria into the crulation. Mkrofilariae
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| − | are eventually ingeste bymosquitoes during
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| − | a blood meal. Msqito0ear not o*nya v or but | |
| − | also an obligatory iemei os
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| − | heartworm diease could t be it.
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| − | ingested micraoariaae require a perio f maturtion
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| − | in the insect, which varies depending on enronmental | |
| − | conditions. This development canntot otur beow | |
| − | the threshold temperature of 14C When the cycle
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| − | is temporarily suseded until warmer conditions
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| − | resume. At an average dily temperature of 30W,
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| − | maturation can bte complete in eight days; howr, | |
| − | maturation takes approximately moe month at an
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| − | environmental tempratu Of 18C. Transmission of
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| − | infecive larvae is therefore limitd to warm month
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| − | and varies depending on geographical location. | |
| − | also on the season, and this is a key consideration when
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| − | screening for the disease or planning a chemoprophylactic
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| − | schedule.
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| − | Although heartworm disease has been diagnosed in
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| − | the UK in dogs imported from abroad, the disease is
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| − | unlikely to spread in this country despite the presence of
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| − | potential vectors and a large canine population. In fact,
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| − | the low average daily temperature does not allow larval
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| − | maturation within the mosquito, even in summertime.
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| − | In the mst mir o-aseo
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| − | larva stage(V12 ad,eventaly,tothe inetv 0~tg
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| − | .When the 130ta s drelav
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| − | from the tubules to the ines
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| − | subseqnt blood meal on an ap rt enter
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| − | the bite wound, colnising the local connetivethisses
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| − | Atr aoxi one vwek, the larvae matuWe fom
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| − | L3 to L4 and, follobwig ctinu migration for two to
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| − | three months in the subcutaneous tisse reac the final
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| − | stage of immature aduts (1. The 1 larvae penetrate
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| − | a systeic vein; and migrate to the right heart and pulmonary
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| − | ateries ithin a few days they Mature
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| − | and mate after around6 tree to six mont releasing
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| − | microfilariae into th cicltion to complet the biological
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| − | cyle. The average prepatent period about six
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| − | months in dog and eigh onths in cat.
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| − | Adult D immitisay survive for up to five year in
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| − | dg; inats; the w0orms p more slowlyad surve
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| − | f*r approximat two years. The slower devlopmnent
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