Risk Factors Associated With Infection By Neospora Caninum In Dual- Purpose Cattle In The Central Region Of Veracruz, Mexico
J V., E S., J M.
dual-purpose cattle, mexico, neospora caninum, risk factors
J V., E S., J M.. Risk Factors Associated With Infection By Neospora Caninum In Dual- Purpose Cattle In The Central Region Of Veracruz, Mexico. The Internet Journal of Veterinary Medicine. 2012 Volume 9 Number 1.
The aim of the present study was to determine the frequency of
In dairy cattle, the frequency of animals positive for neosporosis by serological tests varies considerably throughout the world. For example, in Sweden and Germany frequencies of 1.3% and 1.6%, respectively, have been recorded (Bartels et al. 2006), while in Uruguay and Argentina the seroprevalence is 61.3% and 64.5%, respectively (Venturini et al
With regard to the Mexican state of Veracruz, a study performed by Romero-Salas et al
Previously-identified risk factors associated with bovine neosporosis include (1) the presence and abundance of dogs or wild canids on farms, which can result in environmental contamination with oocytes (Paré et al. 1998; Bartels et al. 1999; Mainar-Jaime et al
Determination of the risk factors for
The aims of the present study were to determine the frequency of
Materials and methods
Spatial location of farms
The study examined dual-purpose cattle from the Mexican municipalities of Jamapa and Veracruz that are located in the central region of the state of Veracruz (Figure 1). Using the Köppen climate classification modified by García (1973), this zone is characterized by a warm, humid climate with a dry season (Aw). The geographic coordinates of the examined farms were established by global positioning system (GPS).
Minimum sample size and sampling design
Sampling was performed on 28 farms from the two municipalities, which at the time of the study had a population of 1889 cattle. A pilot study was performed with 100 cattle with the aims of estimating the frequency of
The median coccygeal artery or adjacent vein was punctured for blood collection using a vacutainer. Each sample was identified individually and transported to the parasitological laboratory in Torreon del Molino, Faculty of Veterinary Medicine and Zootechnics of the Universidad of Veracruz (FMVZ-UV). Samples were centrifuged at 6,04 X g for 5 min, and the serum was removed and stored at –20°C.
Serum samples were tested using an indirect ELISA test (Pourquier Institute version: P00511/01) for the detection of antibodies against
manufacturer’s instructions (Hall et al. 2006). These tests were performed in the immunohistochemical and molecular biology laboratory of the Pathology Department of the Faculty of Veterinary Medicine and Zootechnics of the National Autonomous University of Mexico (UNAM).
Herd surveys gathered the following information: the presence of dogs and/or wild canids, occurrence of abortions and neonatal deaths in the cattle, origin of herd replacements, and feeding and vaccination programs. A database was developed using Epi Info version 3.4.3 to analyze each factor (variable). Each variable was evaluated to measure the strength of its association with the serological test result through univariate analysis of the odds ratio (OR), and its statistical significance was measured using chi-square or Fisher’s exact tests. Variables with P ≤ 0.05 were included in multivariate logistic regression analyses.
Serum samples from one or more animals from 23 of the 28 farms evaluated (82%) were positive for antibodies against
Division of the serum samples based on municipality indicated that 23.92% (89 of 372) of the samples from Jamapa were seropositive for
Figure 1 indicates the GPS location of the 28 farms examined and the frequencies of animals seropositive for
Table 2 displays the results of the univariate analysis for the determination of risk factors associated with the presence of
Further logistic regression analysis of the variables indicated that the risk factors associated with cows that have presented abortion and farms that obtain cattle replacements from another Mexican state were statistically significant (P ≤ 0.05) (Table 3).
Although seroepidemiological studies performed in Mexico have demonstrated the presence of neosporosis and its association with abortions in dairy cattle (Morales et al. 2001; Garcia-Vázquez et al. 2002, 2005; Sanchez et al. 2003; Gutiérrez et al. 2007), there is not much information with regard to dual-purpose and beef cattle. A study performed in the state of Nuevo Leon on beef cattle indicated that 10% of cattle in Linares (3/29 animals from two herds) and Pesqueira (3/30 animals from one herd) were seropositive for
The frequency of
With respect to the risk factors analyzed in the present study, the statistical significance of a history of abortion [OR = 7.34; IC95% = 2.35–22.92; P < 0.05] suggests that cattle could be previously infected with neosporosis (6 times more likely to be seropositive for
The other factor that was significant in this study was obtaining replacement animals from other Mexican states [OR = 2.23; IC95% = 1.13–4.39; P < 0.05]. Cattle from farms that obtained replacements from another state were 1.2 times more likely to be seropositive than were cattle from farms that did not buy heifers from other states. This result suggests that the replacement cattle from other states or regions of high
With regard to the other factors that were evaluated in the present study, there was no association with seropositivity for the presence of owned or alien dogs or wild canids. Although there are no epidemiological studies in these canids of this region, this result suggests that the prevalence of neosporosis in these animals is low. This finding was similar to those of Fischer et al. (2003) and Hobson et al. (2005). Additionally, there was no association between seropositivity and the types of feeding and vaccination programs. These findings were different than those reported for dairy cattle, which could be attributable to the different production systems used. Dual-purpose cattle are generally managed in extensive systems where the animals are fed mainly with green forage rather than stored feed, which may decrease the intake of food contaminated with the feces of dogs or wild canids. There are few reports of naturally-infected dogs that eliminate oocysts. However, some epidemiological studies have indicated that the presence of dogs on dairy farms is a risk factor for neosporosis in cattle, and this is still an economically-important transmission route (Bartels et al. 1999; Dijkstra et al. 2002; Sanchez et al. 2003). Infected cattle may be present even when there are no dogs on a production unit. Therefore, endogenous transplacental transmission is a very effective way for the parasite to be maintained within a herd (Basso et al. 2001; McGarry et al. 2003; Schares et al. 2005; Cedillo et al. 2008).
Currently, there is no worldwide general strategy or program for the control of bovine neosporosis because there are great differences in the epidemiology of the infection and regional differences in zoosanitary procedures. Therefore, for the development of a prevention and control program, it is important to determine the current state of the infections at a regional and local level, or at least at the level of the production unit (Dubey et al. 2007).
Dual-purpose cattle from the municipalities of Jamapa and Veracruz, Veracruz, Mexico, have been exposed to
Finally, to identify other risk factors that have not been examined, additional epidemiological studies are needed within municipalities near the municipalities examined here, as well as municipalities in other Mexican states with similar geographic conditions, types of animals, and management systems.
This project was financially supported by the Program of Support to Projects of Investigation and Technological Innovation (PAPIIT) IN210207.