Serodiagnosis of Toxoplasma gondii infection in dairy cows in Thailand.

Toxoplasma gondii is a zoonotic protozoan parasite of both medical and veterinary importance worldwide. The parasite can cause severe complications in immunocompromised individuals such as AIDS patients and transplant recipients, where up to 25% of patients will develop toxoplasmic encephalitis. Toxoplasmosis is a zoonosis that causes a public health concern in both developed and developing countries such as Thailand. Livestock development particularly in dairy cows of Thailand have been hampered by low production of milk and slow growth rate because of many pathogens including T. gondii. The objective of this study was to evaluate the serodiagnostic tool to be used for detection of T. gondii infection in dairy cows of Thailand. During 2006-2007, the sera of 700 cows from 55 small farm holders of the highest number of dairy cow population in the northern provinces were collected and analysed. Antibodies to T. gondii were assayed by latex agglutination test (LAT), enzyme-linked immunosorbent assay (ELISA) and indirect fluorescent antibody test (IFAT). The overall prevalence of T. gondii infection in dairy cows was 9.4% (66/700) by LAT and 17% (119/700) by ELISA. Sixty-three seropositive samples by LAT (95.5%) and 107 by ELISA (89.9%) were confirmed by IFAT. These results demonstrated that LAT had the highest specificity for detection of T. gondii infection.

Seroprevalence of Cryptosporidium parvum infection of dairy cows in three northern provinces of Thailand determined by enzyme-linked immunosorbent assay using recombinant antigen CpP23.

Cryptosporidium parvum is the most frequent parasitic agent that causes diarrhoea in AIDS patients in Thailand. Cryptosporidiosis outbreaks in humans may be attributed to contamination of their drinking water from infected dairy pastures. A 23-kDa glycoprotein of C. parvum (CpP23) is a sporozoite surface protein that is geographically conserved among C. parvum isolates. This glycoprotein is a potentially useful candidate antigen for the diagnosis of cryptosporidiosis by enzyme-linked immunosorbent assay. Therefore, we investigated the seroprevalence of C. parvum infection in dairy cows in northern Thailand using an ELISA based on recombinant CpP23 antigen. Sera were randomly collected from 642 dairy cows of 42 small-holder farmers, which had the top three highest number of the dairy cows' population in Northern Thailand, that included Chiang Mai, Chiang Rai and Lumpang provinces. The overall seroprevalence of the infection was 4.4%, and the seropositive rates for the three provinces were 3.3% in Chiang Mai, 5.1% in Chiang Rai and 3% in Lumpang. These results suggest that cattle could play a role in zoonotic cryptosporidiosis in Thailand.