Page 146 - The Veterinary Laboratory and Field Manual 3rd Edition

Parasitology 115

In the last few decades it has become more samples need to be picked up from the ground,
widely accepted that helminthic infection is not care must be taken to avoid environmental con-
always harmful. The beneficial role of helminths tamination as free-living helminths may appear
for host health has been documented through similar and complicate the diagnosis. If possible,
the ‘hygiene hypothesis’ developed to explain at least 10 g of faeces should be submitted for
the steep increase in inflammatory bowel disease laboratory examination. All samples should be
and allergic response in hosts that are devoid of collected into plastic screw cap containers or in
parasitic infections. Nevertheless, treatment or securely sealed, labelled plastic bags (Figures
control measures are warranted when helminth 3.1 and 3.2), filling the container to the brim
infection is perceived to be the cause of poor and securing it. Containers should be air tight
animal health or is documented to significantly to create anaerobic conditions and prevent egg
decrease the production of a livestock unit. hatching and subsequent larval development. If
a delay of 1–4 days is expected, samples should
be stored at 4°C. For long-term storage, samples
A sound helminth control strategy requires can be fixed in a preservative such as 70% alco-
breaking the life cycle(s) of the species impli- hol or 10% formal saline. If molecular testing
cated. The majority of helminth parasites is planned, samples are required to be saved in
have a life cycle that has an environmental 70% alcohol. The animal(s) identification, date
component (for example, egg development of sample collection and the name of the owner
and hatching of larvae), which may require (or submitter) should be marked on the con-
a specific range of temperature and humid- tainer label. At the laboratory, if it is necessary
ity. Environmental conditions will, therefore, to make an accurate assessment of the number
influence the number of infective stages of
the parasite which can successfully develop
to infect the host and this must be taken
into consideration when implementing any
sort of helminth control program in livestock.

collection and preservation of faecal
samples

As with any samples sent to the laboratory,
it is important to submit full details of the Figure 3.1 Various plastic bottles and bags may be
animal(s) sampled (that is, species, age, sex, suitable for collecting faecal samples. Regardless
breed) and a description of any clinical find- of shape or size, specimen bottles should have a
ings, recent use of anthelmintic(s), ectoparasite wide neck to allow easy access and a thread cap for
control or other treatment. The date of collec- secure closure. If plastic bags are used for sample
tion and the name of the submitting animal collection these should be sealed and placed inside
health officer or veterinarian should be clearly another bag to ensure that leakage does not occur.
marked on the submission form. For detec- Label all containers to provide a clear identification
tion of parasite eggs, and lungworm larvae, it and record relevant details (that is, reference num-
is important that fresh faecal samples are col- ber, animal identification and specimen details and
lected rectally. In situations where fresh faecal so on) at the time of sample collection.

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