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Teileriose em bovinos de carne na região do Ribatejo
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Resumo(s)
A Teileriose é uma doença parasitária causada por Theileria spp., transmitida por vectores
da família IXODIDAE. Esta hemoparasitose representa uma ameaça à produção de bovinos,
em diferentes países, conduzindo a elevadas perdas económicas. São conhecidas várias
espécies de Theileria, sendo as mais patogénicas Theileria annulata, agente da Teileriose
Tropical ou Mediterrânica, e Theileria parva, agente da Febre da Costa Oriental.
Em Portugal, o Ribatejo e o Alentejo são consideradas regiões endémicas de Teileriose
Mediterrânica, devido à elevada ocorrência de ixodídeos do género Hyalomma. Os
objectivos deste estudo foram: (i) avaliar a presença de Theileria spp. em 112 bovinos de
aptidão carne de uma exploração da região do Ribatejo; (ii) estabelecer níveis de infecção
para os géneros de hemoparasitas encontrados e (iii) identificar uma amostra de ixodídeos,
recolhidos da população em estudo. Através da observação microscópica de esfregaços
sanguíneos, detectou-se que a prevalência de Theileria spp. foi de 100%. O género
Anaplasma também foi identificado em todos os bovinos estudados. Relativamente aos
níveis de infecção de Theileria spp., concluiu-se que o nível I (1-10 merozoítos/10 campos)
foi o mais prevalente, tanto nos bovinos reprodutores, com 87,5% (84/96), como nos vitelos,
com 37,5% (6/16) dos animais infectados. Estes dados sugerem que a maioria dos animais
apresentava infecção subclínica, constituindo um grupo de portadores assintomáticos. Os
níveis de infecção II (11-20 merozoítos/10 campos) e III (> 20 merozoítos/10 campos)
tiveram uma maior expressão nos vitelos, com 31,3% (5/16) em cada nível, do que nos
animais adultos, em que 12,5% (12/96) estavam infectados em nível II e nenhum animal se
encontrava infectado em nível III. Os níveis de infecção mais elevados nos vitelos estão de
acordo com a maior susceptibilidade destes animais a Theileria spp.. Quanto a Anaplasma
spp., o nível de infecção I foi o mais frequente, tanto nos animais reprodutores (60,4%),
como vitelos (50%). Dos 92 ixodídeos identificados, 65% (60/92) pertenciam ao género
Hyalomma e 35% (32/92) eram Rhipicephalus spp., reconhecidos como vectores de
Theileria spp..
Os dados obtidos neste estudo realçam a importância da Teileriose em Portugal. Desta
forma, conclui-se ser necessária uma maior investigação acerca da epidemiologia e
patogenia da doença.
ABSTRACT - THEILERIOSIS IN BEEF CATTLE IN THE RIBATEJO REGION - Theileriosis is a tick-borne disease caused by Theileria spp. protozoa and transmitted by vectors from IXODIDAE family. This parasitic disease constitutes a threat to cattle production in different countries, leading to economic losses. There are various species of Theileria, being T. annulata, the most pathogenic agent in Tropical or Mediterranean Theileriosis, and T. parva, the agent of East Coast Fever. In Portugal, Ribatejo and Alentejo regions are considered endemic for Mediterranean Theileriosis due to the high incidence of ticks of the genus Hyalomma. The aims of this study were: (i) to evaluate the presence of Theileira spp. in 112 beef cattle from a farm located in endemic region of Ribatejo; (ii) to establish blood infection levels and (iii) to identify the genus of the ticks collected in the studied population. Microscopic blood smears observation, showed that Theileria spp. prevalence was 100% either in adults and in calves. The genus Anaplasma was also identified in all the studied animals. Concerning Theileria spp. levels of infection, level I (1-10 merozoits/10 fields) was the most prevalent, both in adult cattle and calves, with 87,5% (84/86) and 37,5% (6/16) respectively. These data suggest that most of the animals had subclinical infection, constituting a group of asymptomatic carriers. Infection levels II (11-20 merozoits/10 fields) and III (> 20 merozoits/10 fields) had a higher expression in calves with 31,3% (5/16) in both, than in adult animals, in which 12,5% (12/96) were infected at level II and no adult animal was infected in level III. The infection levels are highest in calves since these animals are more susceptible to Theileria spp. infection. In relation to Anaplasma spp. infection, level I was the most frequent, in both breeding animals (60,4%) and calves (50%). Of the 92 ticks identified, belonged to the genus Hyalomma, 65% (60/96) and to Rhipicephalus 35% (32/96) recognized as vectors of Theileria spp.. Data obtained in this study emphasizes the importance of theileriosis in Portugal. In this way, further investigation on spreading and pathogenesis of theileriosis is needed.
ABSTRACT - THEILERIOSIS IN BEEF CATTLE IN THE RIBATEJO REGION - Theileriosis is a tick-borne disease caused by Theileria spp. protozoa and transmitted by vectors from IXODIDAE family. This parasitic disease constitutes a threat to cattle production in different countries, leading to economic losses. There are various species of Theileria, being T. annulata, the most pathogenic agent in Tropical or Mediterranean Theileriosis, and T. parva, the agent of East Coast Fever. In Portugal, Ribatejo and Alentejo regions are considered endemic for Mediterranean Theileriosis due to the high incidence of ticks of the genus Hyalomma. The aims of this study were: (i) to evaluate the presence of Theileira spp. in 112 beef cattle from a farm located in endemic region of Ribatejo; (ii) to establish blood infection levels and (iii) to identify the genus of the ticks collected in the studied population. Microscopic blood smears observation, showed that Theileria spp. prevalence was 100% either in adults and in calves. The genus Anaplasma was also identified in all the studied animals. Concerning Theileria spp. levels of infection, level I (1-10 merozoits/10 fields) was the most prevalent, both in adult cattle and calves, with 87,5% (84/86) and 37,5% (6/16) respectively. These data suggest that most of the animals had subclinical infection, constituting a group of asymptomatic carriers. Infection levels II (11-20 merozoits/10 fields) and III (> 20 merozoits/10 fields) had a higher expression in calves with 31,3% (5/16) in both, than in adult animals, in which 12,5% (12/96) were infected at level II and no adult animal was infected in level III. The infection levels are highest in calves since these animals are more susceptible to Theileria spp. infection. In relation to Anaplasma spp. infection, level I was the most frequent, in both breeding animals (60,4%) and calves (50%). Of the 92 ticks identified, belonged to the genus Hyalomma, 65% (60/96) and to Rhipicephalus 35% (32/96) recognized as vectors of Theileria spp.. Data obtained in this study emphasizes the importance of theileriosis in Portugal. In this way, further investigation on spreading and pathogenesis of theileriosis is needed.
Descrição
Dissertação de Mestrado Integrado em Medicina Veterinária
Palavras-chave
Bovinos de carne Theileria spp. Anaplasma spp. Prevalência Níveis de infecção Hyalomma spp. Beef cattle Prevalence Levels of infection
Contexto Educativo
Citação
Fernandes, J.I.M. (2010). Teileriose em bovinos de carne na região do Ribatejo. Dissertação de Mestrado. Universidade Técnica de Lisboa, Faculdade de Medicina Veterinária, Lisboa.
Editora
Universidade Técnica de Lisboa. Faculdade de Medicina Veterinária