L L Walters — Page 2 | PubMed Health

PubMed1981

Endemicity of Dirofilaria immitis and Dipetalonema reconditum in dogs of Pleasants Valley, Northern California.

A house-to-house survey of dogs in a 26-km2 area of Pleasants Valley (Northern California) was done to determine the prevalence of the filariids Dirofilaria immitis Leidy and Dipetalonema reconditum Grassi in the canine population. Blood samples were taken from the cephalic vein of 97 dogs (greater than or equal to 5 months of age) and were tested for the presence of microfilariae, using a modification of the Knott technique. Two dogs with autochthonous D immitis (2.1% of the dogs examined) were discovered. These dogs were outdoor-housed working or sporting dogs, 5 to 8 years old, 1 female and 1 male. Five male dogs, greater than 2 years of age (5.1%), were positive for Dip reconditum microfilariae. Mixed infections were not detected.

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Leishmania differentiation in natural and unnatural sand fly hosts.

Leishmania differentiation in the gut of phlebotomine sand flies was evaluated based on five light and electron microscopic studies of natural (Leishmania panamensis/Lutzomyia gomezi, Leishmania chagasi/Lutzomyia longipalpis) and unnatural (Leishmania mexicana/Lutzomyia abonnenci, Leishmania panamensis/Phlebotomus papatasi, Leishmania major/Lutzomyia longipalpis) life cycles. In the bloodmeal, transformation of amastigotes into stumpy promastigotes occurred before or during division. Further division in pairs or rosettes resulted in the development of spatulate and/or elongate nectomonad (free-swimming) promastigotes. Elongate, short, and metacyclic nectomonad promastigotes, and nectomonad paramastigotes were present in the midgut lumen. Dividing short promastigotes predominated in the cardia, and appeared to generate metacyclic forms which were observed in three life cycles. Haptomonad (attached) forms of Leishmania panamensis in the hindgut were primarily spatulate promastigotes (natural host) or pear-shaped promastigotes (unnatural host); paramastigotes and dividing forms were rare. At the stomodeal valve, short haptomonad promastigotes predominated in unnatural hosts, while both short and pear-shaped haptomonads were abundant, along with paramastigotes in natural hosts. Haptomonad paramastigotes and pear-shaped promastigotes colonized the esophagus, while paramastigotes predominated in the pharynx. Metacyclics were free-swimming in the lumen of the foregut.

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