Postnatal neosporosis in dairy cattle in northeast Thailand.

A total of 83 dairy cows in Loei Province (Muang) and Nong Bua Lamphu (NBL) Province, northeast Thailand were sampled three times within 6 months in 1998 and their sera were examined for antibodies to Neospora caninum at a dilution of 1:100 in the indirect fluorescent antibody test (IFAT). In Muang the seroprevalence of N. caninum was 37.5% (June), 60% (August), and 62.5% (November). In NBL the prevalence was 50% (August) and 70% (November). In both areas abortions were observed between 1 and 3 months after the introduction of these cattle from another area. Nine of 14 and seven of 17 calves were descendants of seropositive dams, of which only two calves from Muang and two calves from NBL were positive for N. caninum antibodies. These findings suggest postnatal N. caninum transmission.

Influence of Trypanosoma evansi infection on milk yield of dairy cattle in northeast Thailand.

Effect of subclinical Trypanosoma evansi infection on the milk yield of newly introduced Holstein Friesian dairy cattle were investigated. Five hundred pregnant heifers were introduced in Loei Province, northeast Thailand and a total of 168 blood samples were collected at 20 farms during 6 visits over 2 years. Trypanosomes were found in cattle in June and November 1996, after which the parasite was rarely seen. On the other hand, the infection prevalences by antigen-detection ELISA (Ag-ELISA) were around 40% from the first sampling through October 1997; then, antigenemic cattle decreased to 20% by June 1998. Milk yields of the cattle with detectable parasitaemia in June and November 1996 were significantly lower than those of the non-infected cattle by Student's t-test. Similarly, the milk yields of Ag-ELISA positive cattle were lower than those of negative cattle at every sampling and significant differences were observed during the first year and in February, 1998 (tested by 2-way ANOVA; T. evansi status and herd as factors). This study suggested that subclinical trypanosomosis caused decrease in milk yield of newly introduced dairy.

Seroprevalence of antibodies to Neospora caninum and associated abortion in dairy cattle from central Thailand.

A total of 904 sera from dairy cattle in 11 provinces of central Thailand were tested for antibodies to Neospora caninum employing the indirect fluorescent antibody test (IFAT). Fifty four (6%) cattle were positive in IFAT, titres of 1:200 (16 cattle), 1:400 (9 cattle), 1:800 (14 cattle), 1:1600 (7 cattle), 1:3200 (6 cattle) and two positives. No significant difference was observed among the provinces. The seropositivity for Toxoplasma gondii by a commercial latex agglutination test was 4% (2 out of 50) in positive sera, 2.9% (2 out of 69) in negative sera for anti-Neospora antibodies and 3.4% (4 out of 119) in total. The results of the IFAT were not associated with the presence of antibodies to T. gondii in bovine sera. Furthermore, the cause of abortions experienced in neighbouring three areas in the northeast, where pregnant heifers were newly introduced into small-scale farms from the central region, was investigated. The positive rates for anti-N. caninum antibody were 12, 28 and 44% at a cut-off titre of 1:200, and cattle were suspected to be infected after the introduction. In the area with the highest rate, seven out of eight aborting cattle were positive for antibodies to N. caninum while other two areas had similar abortion rates in both negative and positive cattle. However, in the latter two areas, positive rates for Trypanosoma evansi antigen along with parasitaemic animals were observed by an antigen-detection ELISA, but not for the former area. Considering the endemic diseases of the areas, Neospora was presumed to be responsible for the abortions in the former area while the examination results pointed out T. evansi as the most probable cause in the latter two areas. This is the first report of Neospora-associated abortion in Southeast Asia.

Natural infection of trematodes in Lymnaea (Radix) auricularia rubiginosa in water reservoirs in Amphoe Muang, Khon Kaen Province.

Lymnaea (Radix) auricularia rubiginosa (Michelin, 1831) was surveyed in 54 reservoirs of 18 districts in Amphoe Muang, Khon Kaen Province during February to May 1994. Lymnaeid snails were found in the water of 20 reservoirs, of which 16 reservoirs contained clear water and 4 turbid water. Two of the four turbid water reservoirs received drainage water from Khon Kaen Town. Two thousand four hundred and eight L. auricularia rubiginosa were collected and examined by shedding and crushing. Trematode infection occurred in 163 (6.77%) of 2,408 L. auricularia rubiginosa and some snails were infected with more than one cercarial species. Ninety-nine snails (4.11%) were infected with echinostomes, while mixed infection of echinostomes with Fasciola gigantica and with schistosomes was found in 5 snails (0.21%) and 2 snails (0.08%), respectively. Only 1 snail (0.04%), 19 snails (0.79%) and 37 snails (1.54%) were infected with F. gigantica, schistosomes and unidentified species, respectively. The mean size of infected snails was 6.89 +/- 2.02 mm (6.20-22.36) while the mean of sampled snails was 13.46 +/- 3.64 mm (4.00-26.55). The water plants which were found in reservoirs and presented with snails, were creeping water primose (Jusstaea repens), water lily (Nymphaea sp), water hyacinths (Eichornia crassipes) and grass.

Immunization: full coverage the aim.

PIP: In November 1988, nursing students at Khon Kaen University in northeast Thailand conducted a baseline survey in 16 villages before a retraining program for village health workers began. It consisted of a 1-week intensive training program and meetings between officers and village health workers. The goal was to achieve full immunization coverage for children under 5. After retraining, the workers implemented their health education and immunization recruitment programs with a refresher course 4 months later. The nursing students conducted a follow-up survey in June 1989 so researchers could compare the effects of the 8 intervention villages with data collected in the 8 control villages. The intervention indeed brought about improvement in immunization coverage, mother's and health worker's knowledge, and health worker participation in program planning and coordination in the case villages. For example, full immunization coverage among children under 1 increased from 65% to 89% while in the control villages it remained at 56%. It also increased among children over 5 (30-81%) but in the control villages it only rose slightly (23-31%). The percentage of mothers who were very knowledgeable about infectious diseases increased from 1% to 8% yet in the control villages it decreased from 2% to 0. Mothers with high level of knowledge about immunization was higher in the 2nd survey in both groups, but the increase was greater in the intervention villages (12-33% vs. 14-21%). High level of knowledge about infectious diseases among health workers grew considerably (3-72%) in the case villages but in the control villages it decreased from 10% to 2%. In addition, health workers in the case villages improved their contact with health officers but not those in the control villages (47-64% vs. 70-36%). Program participation increased in the intervention villages (11-36%) but fell in the control villages (22-13%).^ieng

Health programme effects upon acceptance of immunisation in northeast Thailand.

PIP: As every year 5 million children die in developing countries because of infectious diseases, the government of Thailand in 1976 initiated an expanded program for immunization. Although vaccine coverage of the under 1 year of age population with BCG, diphtheria, pertussis, and tetanus is over 80%, the dropout rates are high and over 40% are without complete immunization. The availability and accessibility of immunization and the efficacy of health care delivery is analyzed. Group sessions were carried out with mothers of children under 4, with village health communications (VHCs) and village health volunteers (VHVs). 2 provinces with the highest immunization coverage and 2 with the lowest were selected. 608 women from 16 villages provided the sample as well as a total of 128 VHVs and VHCs. Distance to health center showed a significant relationship with completion of immunization (in contrast to travel time). The rate of complete immunization was higher for those who received regular information from VHVs and VHCs and who themselves contacted this personal than for those who never contacted the VHVs and VHCs. The most important factor of completion of immunization was the VHV/VHC contact. High immunization areas were highly correlated with high level of VHV/VHC knowledge about infectious diseases. The frequency of VHV/VHC reporting to subdistrict health officers also increased immunization coverage. Household visits were utilized by 54.6% of VHVs and VHCs in high immunization areas and by 15/7% only in low average areas. In high coverage areas, 13% of them were not instructed about dissemination of information as compared with 27.4% of them in low immunization areas. The 2nd phase of the study will consist of the measurement of intervention impact on immunization acceptance.^ieng