Agriculture Reference
In-Depth Information
3.
Ancylostoma caninum
and
Ancylostoma braziliense
CLM is a relatively common clinical entity in humans caused by larval migration of zoonotic
hookworms, mainly
A. braziliense
but also
A. caninum
and a few other species. Infective
larvae penetrate the skin and migrate through the epidermis, but are usually confined to the
dermis and do not develop into adult worms. Less common clinical manifestations are
eosinophilic pneumonitis, localized myositis, folliculitis and erythema multiforme but eye
involvement is rarely reported. Larval infection of humans with
Anc. ceylanicum
may
occasionally give rise to adult worms that inhabit the small intestine and may cause
abdominal discomfort and eosinophilic enteritis. The presence of immature
Anc. caninum
worms in the intestinal lumen of humans has rarely been reported (Bowman et al., 2010).
Infection of both definitive and paratenic hosts with these nematodes is most commonly
acquired when third-stage hookworm larvae penetrate in their skin, although these infective
larvae may also be ingested. In adult dogs infected with
Anc. caninum
, some larvae may
undergo somatic migration and subsequently infect puppies by the transmammary route
(Bowman et al., 2010; Soulsby, 1982). These larvae invade the skeletal muscle or gut wall and
remain in an arrested state, becoming reactivated during the last two weeks of pregnancy
(Barriga, 1988). Adult worms inhabit the small intestine of the definitive hosts (dogs for
Anc.
caninum
,
Anc. braziliense
,
Anc. ceylanicum
and
U. stenocephala
; cats for
Anc. tubaeforme
,
Anc.
braziliense
,
Anc. ceylanicum
and
U. stenocephala
) and may cause blood loss and anemia.
Female worms shed eggs, typically two weeks after ingestion of larvae and about one month
after skin penetration, which are passed in the host's feces. Once in the soil, first-stage larvae
hatch and develop into infective third-stage larvae (Figure 2).
Fig. 2. Simplified life cycle of
Ancylostoma braziliense
and
Anc. caninum
. Adapted from CDC
(2011).
