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| − | == Nematodes of Dogs == | + | {{frontpage |
| − | In Britain, the most important nematode of dogs is the ascarid, ''Toxocara canis''. Almost all puppies harbour this worm, which in large numbers can cause serious disease during the first weeks of life. ''T. canis'' larvae can also invade human tissues - impairment of vision is a possible outcome.
| + | |pagetitle = Dog Nematodes |
| | + | |contenttitle=Content |
| | + | |pagebody = |
| | + | |contentbody = |
| | + | <big><b> |
| | + | <br> |
| | + | [[Nematodes of Dogs Overview|Overview]] |
| | | | |
| | | | |
| − | Other veterinary clinical problems associated with nematodes, such as hookworm and whipworm, are largely confined to large kennels or dogs in rural areas. Overseas, however, there are two nematode diseases of major significance in small animal practice. These are the hookworm, ''Ancylostoma'', and the canine heartworm, ''Dirofilaria''.
| + | ''[[Ancylostoma caninum]] |
| | | | |
| | + | ''[[Angiostrongylus vasorum]] |
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| − | {| style="width:75%; height:200px" border="1"
| + | ''[[Dirofilaria immitis]] |
| | | | |
| − | !
| + | ''[[Filaroides osleri]] |
| − | !'''Small Intestine'''
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| − | !'''Caecum'''
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| − | !'''Lungs'''
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| − | !'''Heart'''
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| − | |-
| + | ''[[Toxascaris leonina]] |
| − | |'''Nematode Species'''
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| − | |
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| − | *''Toxocara canis''
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| | | | |
| − | *''Toxascaris leonina''
| + | ''[[Toxocara canis]] |
| | | | |
| − | *''Uncinaria stenocephala''
| + | ''[[Trichuris vulpis]] |
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| − | *''Ancylostoma caninum'' (rare in UK)
| + | ''[[Uncinaria stenocephala]] |
| − | |
| + | <br> |
| − | *''Trichuris vulpis''
| + | <br> |
| − | |
| + | </b></big> |
| − | *''Filaroides (Oslerus) osleri
| + | |logo=Dog-logo.png}} |
| − | | | |
| − | *''Angiostrongylus vasorum''
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| | | | |
| − | *''Dirofilaria immitis'' (not in UK)
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| − | |}
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| | | | |
| − | == Nematodes of Dogs - the ASCARIDS ==
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| − | === '''''TOXOCARA CANIS''''' ===
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| − | ==== Recognition ====
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| − | ''T. canis'' is a typical ascarid. The fleshy adult worm may be up to 18cm long and lives in the small intestine of the dog, fox and other canidae. It is slightly bigger than the other canine ascarid species (''Toxoscaris leonina'' - up to 10cm). Female ''T. canis'' produce characteristic dark eggs with a pitted surface
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| | | | |
| − | ==== Significance ====
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| − | *Almost all puppies are born with ''T. canis'' infection.
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| − | *Small numbers of worms are usually asymptomatic.
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| − | *Larger numbers cause pot-belly, diarrhoea, vomiting, weight-loss and other clinical signs in young puppies; intestinal obstruction may occur in severe cases.
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| − | *It is also an important '''zoonosis'''.
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| | | | |
| − | ==== Life-Cycle ====
| + | [[Category:Dog Parasites]] |
| − | *''T. canis'' has a complicated life-cycle.
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| − | *The behaviour of the parasite changes as the dog becomes older.
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| − | | |
| − | '''In pups under approximately 2-3months of age''':
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| − | *After ingestion of embryonated eggs or larvae:
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| − | **''T. canis'' larvae migrate via the hepato-tracheal route to the small intestine, where they become adults, and eggs are then passed in faeces
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| − | **the prepatent period is about 4-5weeks
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| − | **after approximately 6weeks of age there is a spontaneous expulsion of worms from the intestine.
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| − | | |
| − | '''In older dogs''':
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| − | *Larvae migrate to the liver, via the heart, and then on to the lungs (hepato-tracheal migration), where they stay in the blood stream.
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| − | *They then migrate back to the heart and then on to somatic tissues (such as the liver, kidney, musculature etc.), where granulomatous reactions may occur. This is called the 'waiting phase'.
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| − | *'''Somatic ('waiting') larvae''':
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| − | **do not develop or grow (size = approximately 0.5mm)
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| − | **but metabolically, they are highly active:
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| − | → large quantities of excretory/secretory (ES) antigens
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| − | | |
| − | → spread over the cuticle
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| − | → immune evasion: rapid turnover
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| − | → sloughing of antibody and immune cells (also mimic some host proteins)
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| − | **somatic larvae '''wait for pregnancy to occur'''.
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| − | *After approximately 42nd day of gestation:
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| − | **a proportion of the somatic larvae are activated
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| − | **the majority of activated larvae migrate to the placenta, and gain access to the foetuses - this is '''prenatal infection'''
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| − | **the remainder of the activated larvae migrate to the mammary gland, and get passed to the puppies via colostrum and milk - this is '''transmammary infection'''
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| − | **larvae not activated in the first pregnancy may be activated in subsequent pregnancies.
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| − | | |
| − | '''In warm-blooded non-canid animals''':
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| − | *Events occur just as in the older dog, i.e. larvae migrate → liver → lungs → heart → somatic tissues → granulomatous reactions → 'waiting phase'; but in this case, the somatic larvae are waiting for the animal that they are in (which is acting as a '''paratenic host''') to be eaten by a dog, fox, wolf or other canid, where they will establish as adults or somatic larvae (depending on the age of the predator).
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| − | *This explains how humans (as warm-blooded non-canid animals) enter into the epidemiological picture.
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| − | | |
| − | ==== Epidemiology ====
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| − | *Infection of dogs is by ingestion of the L2 larvae, which can occur in four ways:
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| − | 1) ingestion of the embryonated egg
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| − | 2) prenatal infection
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| − | 3) transmammary infection
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| − | 4) ingestion of a paratenic host.
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| − | *Infection of a paratenic host can occur by:
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| − | 1) ingestion of the embryonated egg
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| − | 2) ingestion of larvae in the tissues of another paratenic host.
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| − | | |
| − | *Each female ''T. canis'' can lay up to 250,000 eggs per day:
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| − | **the eggs are not infective until the L2 is fully developed
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| − | **this process takes a few weeks in summer, but many weeks in the winter
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| − | **the embryonated egg is tough and can survive for 4-5years
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| − | **eggs therefore accumulate in the environment, and can easily be demonstrated in soil scrapings from, for example, breeding kennels or city parks
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| − | **when eggs from the environment are swallowed by a bitch, larvae accumulate in her somatic tissues - to be activated during pregnancy
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| − | **at birth, prenatally derived larvae are already migrating through the pups' liver and lungs
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| − | **adult worms reach the intestine and start to lay eggs when the pups are 2-3weeks old
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| − | **pups are therefore a potent source of environmental contamination (particularly in breeding kennels) until spontaneous expulsion occurs after approximately 6weeks of age.
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| − | **in general, only approximately 15% of adult dogs have patent infection - an exception is nursing bitches, who often pass large numbers of eggs
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| − | **up to 45% of foxes have patent infection, and are therefore a potent source of eggs in urban areas.
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| − | | |
| − | ==== Human Infection ====
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| − | *Humans are infected by swallowing embryonated eggs from the environmental reservoir.
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| − | *This is most likely to happen in young children.
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| − | *Most infections are asymptomatic.
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| − | *Approsimately 2.5% of the British population are seropositive.
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| − | | |
| − | ==== Efficacy of Anthelmintics Against Life-Cycle Stages of ''T. canis'' ====
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| − | {| style="width:75%; height:200px" border="1"
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| − | !'''Compound'''
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| − | !'''Trade-Name'''
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| − | !'''Intestinal Worms'''
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| − | !'''Migrating Larvae'''
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| − | !'''Somatic Larvae'''
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| − | '''Piperazine'''
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| − | '''Pyrantel'''
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| − | '''Pyrantel + Febantel'''
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| − | '''Fenbendazole'''
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| − | '''Mebendazole'''
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| − | '''Flubendazole'''
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| − | '''Nitroscanate'''
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| − | '''Selamectin'''
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| − | '''Milbemycin'''
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| − | '''Moxidectin'''
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| − | ==== Control of ''T. canis'' ====
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| − | *The only satisfactory way of breaking the life-cycle in breeding kennels and reducing zoonotic risk is to eliminate ''T. canis'' eggs from the environment.
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| − | *Hygiene is important (but note that the eggs stick to surfaces and that few disinfectants will kill them).
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| − | *To prevent dogs excreting eggs, pups must be dosed regularly from 2weeks of age.
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| − | *Most anthelmintics are only active against adult worms in the intestine.
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| − | *These adult worms are quickly replaced by developing larvae that survived treatment.
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| − | *Therefore, pups should be dosed at 2, 4, 6, 8 and 12weeks of age.
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| − | *Fenbendazole is active against both adults and larvae.
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| − | *So, an equivalent result can be obtained with just two treatments: one in the third week of life, and again 3weeks later.
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| − | *Nursing bitches should also be treated.
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| − | *Otherwise, adult dogs should be dosed 2-4times a year.
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| − | *Current anthelmintics at normal dose-rates will not kill somatic larvae.
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| − | *This can be done, however, with daily high doses of fenbendazole.
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| − | *Pregnant bitches are given daily doses (25mg/kg) from the 42nd day of pregnancy.
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| − | | |
| − | ==== ''T. canis'' in Veterinary Public Health ====
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| − | ''T. canis'' is associated with at least three disease syndromes in humans:
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| − | 1) '''visceral larval migrans''' (VLM) (→ eosinophilia, hepatomegaly, fever, asthma)
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| − | 2) '''ocular larval migrans''' (OLM) (→ unilateral partial impairment of vision)
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| − | 3) '''covert toxocarosis''' (non-specific clinical signs associated with high antibody titre)
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| − | Around 55cases, mostly OLM, are diagnosed in the UK each year.
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| − | === '''''TOXOSCARIS LEONINA''''' ===
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| − | ''T. leonina'' is a little smaller (up to 10cm), but otherwise similar in appearance to ''T. canis''. With a female worm, the easiest way to tell them apart is to cut it open and examine the eggs under the microscope. The eggs of ''Toxoscaris'' are smooth and pale; whilst those of ''Toxocara'' species are dark and pitted.
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| − | | |
| − | The biology of ''T. leonina'' is generally similar to that of ''T. canis'', '''except''':
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| − | *it infects both felidae and canidae
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| − | *in the final host:
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| − | **there is '''no prenatal transmission'''
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| − | **there is '''no transmammary transmission'''
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| − | **there is '''no hepato-tracheal migration'''
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| − | *in 'paratenic' hosts:
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| − | **develops to L3 in tissues (the 'paratenic' hosts therefore are really facultative intermediate hosts).
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| − | | |
| − | Transmission is via ingestion of the embryonated egg or an infected 'paratenic' host. The zoonotic potential is uncertain, but ''T. leonina'' is not thought to be as hazardous as ''T. canis''.
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| − | | |
| − | | |
| − | == Nematodes of Dogs - the HOOKWORMS ==
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| − | The hookworms are 1-2cm long bursate nematodes. They are easily identified under the microscope, as they have a large buccal cavity with teeth, and the mouth points dorsally. Some have teeth around the rim of the mouth which can be used for identification, and which are used to embed the head deeply into the mucosa of the small intestine. The life-cycle is typical for the superfamily.
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| − | | |
| − | As with all hookworms, the L3 can penetrate the skin. A protective immunity develops, and so enteric disease is largely confined to pups. Some dogs develop a hypersensitivity, leading to a pedal dermatitis which can affect all ages.
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| − | | |
| − | In the UK, ''Uncinaria stenocephala'' is commonly found in greyhounds, hounds, sheepdogs and other country dogs, but is relatively non-pathogenic. It is a plug-feeder, causing a protein-losing enteropathy. Heavy infections leads to intermittent diarrhoea, causing reduced growth-rate.
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| − | | |
| − | ''Ancylostoma caninum'' is found rarely in Britain, but is a major pathogen of dogs in many warmer regions of the world. It may be brought into the UK with dogs entering from abroad. ''A. caninum'' is an avid blood-sucker, so heavy infections lead to severe anaemia, especially in unweaned pups.
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| − | Key features of hookworms of the dog:
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| − | {| style="width:75%; height:200px" border="1"
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| − | !'''''Ancylostoma caninum'''''
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| − | !'''''Uncinaria stenocephala'''''
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| − | |-
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| − | *Warm and hot climates
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| − | *Avid blood sucker → anaemia
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| − | *Teeth around mouth
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| − | *Infection mostly percutaneous
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| − | *Causes pedal dermatitis
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| − | *Transmammary infection
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| − | *Cool and cold climates
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| − | *Protein leak → diarrhoea
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| − | *Cutting plates
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| − | *Infection mainly by mouth
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| − | *Causes pedal dermatitis
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| − | *No vertical transmission
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| − | |}
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| − | == Nematodes of Dogs - the WHIPWORM ==
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| − | *''Trichuris vulpis'' is a typical whipworm in every way.
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| − | *It causes intermittent diarrhoea in dogs.
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| − | *Typical eggs may be shed in faeces, but are not always easy to find, so it may be necessary to examine several repeat samples if infection is suspected.
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| − | | |
| − | | |
| − | == Nematodes of Dogs - LUNGWORMS ==
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| − | === '''''ANGIOSTRONGYLUS VASORUM''''' ===
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| − | *Infects dogs and foxes.
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| − | *A typical metastrongyloid, with the adult worms living in the pulmonary arteries and the right side of the heart.
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| − | | |
| − | ==== Life-Cycle ====
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| − | Adults (approximately 2cm), produce anticoagulants to reduce thrombus formation leading to coagulation disorders:
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| − | → eggs laid into pulmonary arteries
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| − | → trapped in lung capillaries
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| − | → larvae (with merastrongyloid kinky tail) hatch out
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| − | → alveoli (causing a small injury)
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| − | → trachea
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| − | → swallowed
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| − | → passed in faeces
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| − | → slug (intermediate host)
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| − | → eaten by dog or fox (final hosts)
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| − | → larvae migrate via mesenteric lymph nodes
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| − | → blood stream
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| − | → heart.
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| − | ==== Epidemiology ====
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| − | Once restricted to Southern Ireland and Cornwall, this lungworm is spreading across the British Isles and is now endemic in the South-East. The fox may act as a reservoir of infection.
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| − | | |
| − | === '''''FILAROIDES (= Oslerus) OSLERI''''' ===
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| − | *''F. osleri'' is atypical of the Metastrongyloidea in almost every way.
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| − | *Adults (approximately 1cm) are found in dogs clustered in fibrous nodules (few mm - 2cm) on tracheal wall (near bifurcation of trachea).
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| − | *This means that small numbers of L1 are found in the sputum, and can either be passed to the skin during grooming, or can be passed in the faeces (dead-end for life-cycle).
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| − | *Transmission from bitch to pups occurs during grooming via transfer of sputum.
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| − | *Horizontal transmission rarely, if ever, happens.
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| − | *Infection is usually asymptomatic, but if symptoms are present, there is a chronic, dry, debilitating cough - performance of greyhounds may be affected.
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| − | == Treatment of Hookworms, Whipworms and Lungworms in Dogs and Cats ==
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| − | {| style="width:75%; height:200px" border="1"
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| − | !'''Compound'''
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| − | !'''Trade-Name'''
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| − | !'''Hookworms'''
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| − | !'''Whipworm'''
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| − | !'''Lungworm'''
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| − | '''Piperazine'''
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| − | '''Pyrantel'''
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| − | '''Pyrantel + Febantel'''
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| − | '''Fenbendazole'''
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| − | '''Mebendazole'''
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| − | '''Flubendazole'''
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| − | '''Nitroscanate'''
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| − | '''Selamectin'''
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| − | '''Milbemycin'''
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| − | '''Moxidectin'''
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| − | '''Emodepside'''
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| − | various (high dose needed)
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| − | Strongid (dogs only)
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| − | Drontal (various combinations)
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| − | Telmin
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| − | == Nematodes of Dogs - CANINE HEARTWORM ==
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| − | *''Dirofilaria immitis'' is one of the most important causes of morbidity and mortality in dogs in many regions of the world that have a warm, humid climate, including parts of southern Europe, USA and Australia.
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| − | *The presenting signs are usually those of heart failure, but sudden collapse may occur in heavily infected dogs.
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| − | *The endemic zone for canine heartworm disease is spreading as people increasingly travel with their pets.
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| − | *Strains of ''D. immitis'' are adapting to cooler climates.
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| − | *It is not endemic in the UK, but more infected dogs are likely to be imported now that the quarantine regulations have been relaxed.
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| − | *It has a very long prepatent period, so clinical signs may not appear for many months after importation.
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| − | *Although primarily a canine parasite, cats and ferrets can become infected.
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| − | *Owners taking their pets into endemic regions require advice on how the disease can be prevented.
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| − | | |
| − | '''''Dirofilaria immitis''''':
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| − | *a filarial worm
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| − | *females: up to 30cm long; males: up to 15cm long
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| − | *life-span 5-7years
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| − | *up to 250 worms may establish in the heart and pulmonary arteries
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| − | *produce microfilariae, not eggs.
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| − | | |
| − | '''Microfilariae''':
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| − | *in peripheral circualtion
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| − | *periodicity - maximum numbers in blood evening/night
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| − | *greater than 300µm long
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| − | *life-span 2years
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| − | *present in approximately 60% of infected dogs
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| − | *microfilariae are absent from the circulating blood if:
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| − | **only immature worms present
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| − | **only one worm present
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| − | **only one sex
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| − | **microfilariae killed by immune response (in 15% of dogs)
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| − | **females sterilised by chemotherapy (e.g. ivermectin).
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| − | | |
| − | '''Intermediate hosts''':
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| − | *many, but not all, species of mosquito.
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| − | | |
| − | '''Local Epidemiology''':
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| − | *determined by feeding preferences of local species, and population density.
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| − | *up to 45% of non-protected dogs infected in some parts of USA.
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| − | | |
| − | '''In mosquito''':
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| − | *microfilariae → L1 → L2 → infective L3
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| − | *this takes 1week at 30°C, or 4weeks at 18°C - there is no development below 14°C.
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| − | *when mosquito next feeds:
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| − | **L3 moves to mouthparts
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| − | **up to 12 L3 deposited on skin
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| − | **enter body via puncture wound.
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| − | | |
| − | '''In dog''':
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| − | *larvae migrate through connective tissues and moult twice
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| − | *immature adults (L5) are 1-5cm long → caudal distal pulmonary arteries in 4months → diffuse eosinophilic reaction in lung parenchyma, then migrate back towards right ventricle
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| − | *start producing microfilariae 6-7months post-infection.
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| − | | |
| − | '''Zoonotic hazard''':
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| − | *human infection can occur, but few cases are diagnosed
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| − | *this usually happens when a radio-opaque plaque is detected in the lung, and further investigation shows it to be caused by a trapped ''D. immitis'' larva.
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| − | | |
| − | === Pathology ===
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| − | '''Worms produce''':
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| − | *substances that are:
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| − | **antigenic
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| − | **immunomodulatory
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| − | **pharmacologically active.
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| − | | |
| − | '''Lesions are''':
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| − | *'''not''' confined to the location of the worms
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| − | *also caused by shear stress of high blood flow.
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| − | | |
| − | '''Severity''':
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| − | *not associated with the number of worms
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| − | *exacerbated by exercise (i.e. by high blood flow rate)
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| − | *sedentary dogs often asymptomatic - symptoms most commonly associated with racing greyhounds.
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| − | | |
| − | '''Acute prepatent disease''':
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| − | *immature adult worms in caudal distal pulmonary arteries
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| − | *leads to intense diffuse eosinophilic reaction, which in turn leads to coughing.
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| − | | |
| − | '''Chronic disease''':
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| − | *mature worms in right heart and pulmonary arteries
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| − | *endothelial swelling and sloughing
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| − | *increased permeability → inflammation → periarteritis
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| − | *platelets/white blood cells activated → thrombosis
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| − | *proliferation of smooth muscle, thickening of media:
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| − | | |
| − | → impairment of blood flow
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| − | | |
| − | → pulmonary hypertension
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| − | | |
| − | → right ventricular strain
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| − | | |
| − | → right ventricular hypertrophy and right-sided heart failure
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| − | *insufficient blood pumped through pulmonary capillary bed → insufficient preload for left ventricle.
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| − | | |
| − | '''Post Caval Syndrome (Dirofilarial haemoglobinuria)''':
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| − | *can be acute or chronic
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| − | *heavy heartworm infestation:
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| − | **entangled clumps of worms → impaired closure of tricuspid valve → post-caval stagnation → hepatic congestion and hepatic failure
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| − | *this is accompanied by increased red blood cell fragility, haemolytic anaemia and haemolobinuria.
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| − | | |
| − | '''Clinical signs''':
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| − | *often sudden onset severe lethargy and weakness, but:
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| − | *signs variable, reflecting multiple system dysfunction - pulmonary circulation, heart, liver and kidneys:
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| − | **lung damage (severe pulmonary hypertension; thromboembolism)
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| − | **heart failure (right-sided congestive)
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| − | *therefore, '''not''' pathognomonic
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| − | *acute prepatent = coughing
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| − | *chronic = exercise intolerance, sometimes with ascites
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| − | *acute post caval syndrome = collapse (dyspnoea, pale mucous membranes or jaundice, haemoglobinuria)
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| − | | |
| − | '''Diagnosis''':
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| − | *Physical examination:
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| − | **signs of heart disease
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| − | **lung involvement
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| − | *Radiography:
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| − | **enlargement of right heart, main pulmonary arteries; arteries in lung lobes with thickening and tortuosity; inflammation in surrounding tissues
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| − | *ECG:
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| − | **right axis deviation → deep S waves
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| − | *Echocardiography:
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| − | **if post caval syndrome suspected - right ventricular enlargement with worms in ventricle appearing as parallel lines.
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| − | | |
| − | '''Clinical pathology''':
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| − | *needed alongside physical examination and other tests to determine treatment strategy and prognosis.
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| − | | |
| − | '''Parasite detection''':
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| − | *methods for demonstrating microfilariae in blood:
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| − | **wet blood smear (okay for quick look, but insensitive) = ''D. immitis'' not progressively motile
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| − | **Knott's test = red blood cells lysed; stained sediment examined
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| − | **micropore filter = blood forced through; microfilariae held on filter; stained and examined
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| − | **antibody detection ELISA = not reliable in dogs, but it is the best for cats (although some false positives)
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| − | **antigen detection ELISA (using specific antigen from adult female worm) = reliable positives from 5-7months post-infection in dogs; although occasional false negatives occur → '''not''' useful for cats
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| − | *the immunochromatographic test (ICT) uses coloured gold colloidal particles tagged to monoclonal antibodies to visualise the presence of adult worm antigen - performance similar to antigen detection ELISA, but quicker and easier to do (but not as quantitative as some ELISAs are)
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| − | *operator error can give false positives, therefore best to confirm result with another test.
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| − | | |
| − | '''Chemotherapy''':
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| − | *three treatment objectives needing different approaches:
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| − | | |
| − | 1) '''Adulticidal'''
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| − | *risk that dead worms → thromboembolism → respiratory failure
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| − | *therefore, hospitalise and strict exercise restriction for at least 3weeks post-treatment
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| − | *organic arsenicals for adulticidal therapy:
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| − | **'''Thiacetarsamide''' (2.2mg/kg IV bid for 2days) - hepatotoxic; skin sloughing
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| − | **'''Melarsomine''' (2.5mg/kg IM sid for 2days) - generally safer, but greater risk of thromboembolism
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| − | | |
| − | NB - Ivermectin preventative doses over 16months reduces adult worm numbers
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| − | | |
| − | 2) '''Microfilaricidal'''
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| − | *start 3-6weeks after adulticidal therapy:
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| − | **'''Ivermectin''' (50µg/kg)
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| − | **'''Milbemycin oxime''' (0.5mg/kg)
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| − | NB - risk of reaction to dead microfilariae in sensitised animals (lethargy, retching, tachycardia, circulatory collapse) - observe for 8hours post-treatment
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| − | | |
| − | 3) '''Preventative (prophylactic)'''
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| − | *objective = kill migrating L4 before they reach the heart
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| − | *monthly treatments are 100% effective and safe if used properly, but often fail because of inadequate owner compliance
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| − | *test for adult infection/microfilarie before start and annually thereafter:
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| − | **'''Ivermectin''' (6µg/kg monthly) - blocks maturation of larvae; these die only after several months
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| − | **'''Selamectin''' (6mg/kg monthly)
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| − | **'''Moxidectin''' (injectable formulation - 0.17mg/kg gives 6months protection)
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| − | **'''Milbemycin oxime''' (0.5mg/kg monthly) - care → kills microfilarie, therefore risk of reaction
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| − | **'''DEC (diethylcarbamazine)''' daily - care → kills microfilarie, therefore severe risk of reaction
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| − | | |
| − | '''Treatment of Post Caval Syndrome''':
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| − | *surgical removal with forceps via jugular vein
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| − | *usually very successful, but:
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| − | *do not crush or fragment worms
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| − | | |
| − | → massive release of antigen
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| − | | |
| − | → cardiac failure and acute respiratory distress
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| − | | |
| − | → rapid death
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| − | | |
| − | '''A typical therapy protocol''':
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| − | | |
| − | 1) Pre-treatment evaluation
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| − | | |
| − | 2) Adulticide: 4-6weeks restricted exercise
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| − | | |
| − | 3) Microfilaricide: 3weeks after adulticide
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| − | | |
| − | 4) Initiation of monthly preventative treatments
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| − | | |
| − | 5) Check for microfilariae after 2weeks
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| − | | |
| − | 6) Check for adults (ELISA) 4-6months after adulticide, and before start of each subsequent mosquito season.
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| − | [[Category:Dog]] | |
