BEHAVIOUR OF HAEMONCHUS CONTORTUS AND HAEMONCHUS PLACEI INFECTIONS IN LAMBS
Autor(es): Michelle Cardoso dos Santos, Jorge Konrado Xavier, Mônica Regina Vendrame Amarante, César Cristiano Bassetto, Alessandro Francisco Talamini do Amarante
BEHAVIOUR OF HAEMONCHUS CONTORTUS AND HAEMONCHUS PLACEI INFECTIONS IN LAMBS
» Área de pesquisa: HELMINTOLOGIA
» Instituição: Universidade Estadual Paulista, Botucatu, SP
» Agência de fomento e patrocinadores: FAPESP - Fundação de Amparo a Pesquisa do Estado de São Paulo.
Haemonchus species may exhibit more generalist or more specialist behaviour concerning host specificity. This trial aimed to study the prepatent and patent periods of Haemonchus contortus and Haemonchus placei after a single infection in sheep and also whether serial infections with both species confer protection against homologous or heterologous challenges. In the first trial five lambs received a single infection with 4000 H. contortus-infective larvae (L3), and another five received a single infection with 4000 H. placei L3. H. contortus presented patency earlier than H. placei. Animals infected with both species shed a large number of eggs in the faeces for several months. H. contortus eggs were detected in the faeces for a minimum of 302 days and a maximum of 538 days post infection, while the H. placei patent period lasted from 288 to 364 days. In the second trial, lambs serially infected with H. placei and then challenged with the same species presented the most intense immune response with the highest levels of anti-parasitic immunoglobulin and number of inflammatory cells in the abomasal mucosa. As a result, this group had the lowest rate of parasite establishment (2.68% of the 4000 L3 given), but this phenomenon did not occur in animals single challenged with H. placei, in which the rate of establishment was relatively high (25.3%). However, when the animals were previously serially infected with H. placei and then challenged with H. contortus, no evidence of significant protection was observed (establishment of 19.18%). The results showed that after a single infection, both H. contortus and H. placei may survive over one year inside of a host sheep. In contrast, a strong immune response to H. placei occurs in lambs after serial infections.
