Genus: Balantidium coli
Worldwide distribution in pigs; rarely humans, other primates, rats, dogs.
Life Cycle:
• Direct.
• Transmitted through the fecal-oral route via cysts or trophozoites; cysts more
resistant to external environment.
Pathogenesis and Clinical Signs:
• Generally nonpathogenic to pigs; may invade colonic mucosa if damaged by
other pathogens.
Diagnosis
• May find trophozoites in direct smear of feces or cysts on fecal flotation.
• Trophozoites are oval, with funnel-shaped mouth, macronucleus and usually
micronucleus, covered with cilia, 30–150 25–120 μm.
• Cysts are spherical, with double membrane, 40–60 μm.
Treatment and Control:
• Generally do not treat pigs for infection.
• To prevent human infections, use good hygiene.
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Genus: Anaplasma
Species:
Anaplasma marginale and
A. centrale.
These organisms, found in the red cells of cattle, cause anaplasmosis, a
disease characterized by fever, anaemia and jaundice. Infection is transmitted by
ticks or mechanically by biting insects or even by contaminated hypodermic
needles or surgical instruments.
It infect manly the Cattles. Wild ruminants, and perhaps sheep, may act as
reservoirs of infection. The site of infection is red blood cells.
Epidemiology:
Worldwide in tropics and subtropics, including southern Europe. It is also
present in some temperate areas including parts of Iraq.
Cattle, especially adults, introduced into endemic areas are particularly
susceptible, the mortality rate being up to 80%. In contrast, cattle reared in
endemic areas are much less susceptible, presumably due to previous exposure
when young.
Life cycle:
Anaplasma can be transmitted by ticks (Intermediate hosts) and also mechanically
by biting flies or contaminated surgical instruments.
Some 20 tick species, including the one-host Boophilus, have been shown to
transmit infection experimentally. Since transovarial infection occurs in the
majority of these species, they may be considered to be intermediate hosts,
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although there is little information on the development of the parasites in the
tick.
Once in the blood, the organism enters the red cell by invaginating the cell
membrane so that a vacuole is formed; thereafter it divides to form an inclusion
body containing up to eight `initial bodies' packed together. The inclusion bodies
are most numerous during the acute phase of the infection, but some persist for
years afterwards.
Clinical Signs:
The clinical signs are usually very mild in naive cattle under one year old.
Thereafter, susceptibility increases so that cattle aged 2-3 years develop
typical and often fatal anaplasmosis while in cattle over three years the disease
is often peracute and frequently fatal.
The clinical features include pyrexia, anaemia and often jaundice, anorexia,
laboured breathing; and in cows a severe drop in milk yield or abortion. Occasionally peracute cases occur, which usually die within a day of the onset of
clinical signs.
Pathogenesis :
Typically, the changes are those of an acute febrile reaction accompanied by a
severe haemolytic anaemia. After an incubation period of around four weeks,
fever and parasitaemia appear, and as the latter develops, the anaemia becomes
more severe so that within a week or so up to 70% of the erythrocytes are
destroyed.
The infection with Anaplasma marginale more severe than infection with A.
centrale because of the role of immune response.
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Diagnosis:
1- Clinical signs
2- Blood smears, Anaplasma inclusions in the red cells are usually sufficient for
diagnosis.
3- Complement fixation and agglutination tests are available; an indirect
fluorescent antibody test
4- PCR technique by DNA probe.
Treatment:
Tetracycline compounds are effective in treatment if given early in the course
of the disease.
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