Elsevier

Preventive Veterinary Medicine

Volume 56, Issue 3, 30 December 2002, Pages 193-202
Preventive Veterinary Medicine

Bulk milk testing for antibody seroprevalences to BVDV and BHV-1 in a rural region of Peru

https://doi.org/10.1016/S0167-5877(02)00161-7Get rights and content

Abstract

Bulk milk from 60 herds of dairy cattle in a rural region in the central highlands of Peru was tested for antibodies to bovine viral-diarrhoea virus (BVDV) and bovine herpesvirus type 1 (BHV-1). None of the herds had been vaccinated against BVDV or BHV-1. Commercially available indirect ELISA-kits were used for antibody detection. True prevalences of BVDV and BHV-1 antibody-positive herds were 96 and 51%, respectively. A relatively low proportion of strongly positive herds suggests, however, a low prevalence of active BVDV infection. BVDV optical densities (ODs) in bulk milk increased with herd size—indicating a higher within-herd prevalence in the larger herds (probably, in part a consequence of a higher rate of animal movement into these herds). For BHV-1, this pattern was not found; a relatively high proportion of the herds was free from BHV-1 infection in each size category. This could indicate a low rate of reactivation of latent BHV-1 infection.

Introduction

Bulk milk testing for detection of antibodies is a fast, non-invasive and cost-effective method that has been invaluable in the control programmes for bovine viral-diarrhoea virus (BVDV) and bovine herpesvirus type 1 (BHV-1) in Sweden, Norway, Finland and Denmark (Bitsch and Rønsholt, 1995, Lindberg and Alenius, 1999, Nylin et al., 2000). It can be used as a first step in a control strategy to discriminate between possibly infected and non-infected herds (that is, to give a qualitative measurement of the infection status of a herd for a particular infection). Furthermore, for certain endemic infections like BVDV and BHV-1, there is also a correlation between the antibody level in a bulk milk sample and the within-herd prevalence of antibody-positive cows (Niskanen et al., 1991, Niskanen, 1993, Hartman et al., 1997, Nylin et al., 2000, Beaudeau et al., 2001). Bulk milk testing is an efficient tool to detect introduction of infections at an early stage in previously uninfected herds by detecting changes in antibody levels between paired samples (Lindberg and Alenius, 1999). The presence of only one or a few lactating individual cows with high antibody titres to BVDV within a herd of otherwise-seronegative cows will give rise to a positive bulk milk test (Niskanen, 1993).

BVDV is widespread throughout the world. The infection tends to be endemic in most populations, with 60–85% of the cattle showing neutralising antibodies to the virus. Estimations of the economic impact of the infection have been made in high milk-producing countries such as England and Denmark, with annual national losses calculated at between US$ 10 and 40 million per million calvings (Houe, 1999). Infection with BVDV results in a clinical spectrum ranging from subclinical to the highly fatal form known as “mucosal disease” (Brownlie, 1990). Infection early in pregnancy can lead to calves born immunotolerant to (and persistently infected (PI) with) BVDV (Van Oirschot, 1983). PI calves shed large quantities of virus and are the main active vectors of viral transmission within the herd (Lindberg and Alenius, 1999). Trade with PIs or with non-PI dams carrying PI foetuses (PI carriers) constitutes the major route for the transmission of virus between herds (Lindberg et al., 2001). Herds with active infection (i.e. with presence of PI animals) typically show a high prevalence of seropositive cows and thus a strongly positive bulk milk test (typically ODs>0.8 according to experiences gained in the Swedish BVDV programme) unless the PI animals were introduced only recently (Houe and Meyling, 1991, Drew et al., 1999). The presence of lactating antibody-positive PI carriers in the herd also will be reflected as a strongly positive bulk milk test, because these animals have markedly high antibody titres when sampled in late gestation (Brownlie et al., 1998, Lindberg et al., 2001).

BHV-1 is an economically important infection of cattle; it causes disease manifestations including infectious bovine rhinotracheitis (IBR) and infectious pustular vulvovaginitis (IPV)/infectious pustular balanopostitis (IBP). BHV-1 is an enzootic infection on the B list of the Office International des Epizooties (OIE), and has world-wide distribution. As with other herpesvirus, BHV-1 can establish latency (for review, see Gibbs and Rweywmamu, 1977, Kahrs, 1981, Straub, 2001). During latency, the agent is harboured in the sensory ganglia as viral DNA (Ackermann et al., 1982). Reactivation from the latent state and reexcretion of virus can occur (after stimuli such as stress or corticosteroid treatment) with the risk of transmission to susceptible animals (Pastoret and Thiry, 1985, Thiry et al., 1987). Upon introduction of the virus into a susceptible herd, the infection typically spreads rapidly and completely—resulting in clinical or subclinical disease and seroconversion (Hage et al., 1996), given that reactivation of latent infection occur.

The information on epidemiology and impact of BVDV and BHV-1 in developing countries in general, and in low-producing rural regions in particular, is limited. It seems reasonable to assume, however, that these infections have important impact on production and on economic development for the rural communities, and that a reduction of prevalence would be beneficial. Considering the economic situation in the rural regions of developing countries, any control strategy must use the available resources as efficiently as possible. By using bulk milk testing, information on the infection status in the regional population of herds is gained at a low cost. Furthermore, by using a non-invasive sampling method, the risk of iatrogenic infection transmission is reduced. This might be particularly advantageous when working among small holders in rural communities where sufficiently sterile working conditions may be hard to achieve.

Studies of individual-cow antibody prevalence of BVDV and BHV-1 have been carried out in three major dairy areas in Peru (with results ranging between 50 and 80% and between 15 and 30%, respectively; Rivera, 2001), but knowledge on incidence and regional impact is lacking. There are no official control programmes against these diseases in the country, and even though vaccination do occur in some regions, no official vaccination regimen exists.

Our purpose was to introduce the use of bulk milk testing for detection of antibodies to BVDV and BHV-1 and to investigate the current status of these infections in the Mantaro Valley (the major dairy district in the central highlands of Peru). Bulk milk testing offers a simple and inexpensive alternative to blood sampling, and could be a valuable tool for disease control in regions (such as the Mantaro Valley) with limited economic resources.

Section snippets

The region

The Mantaro Valley in the Andean Department of Junin is one of the main agricultural regions in the central highlands. It is a rural region where 30% of the economically active population has livestock production as the main economic activity (Dı́az et al., 1999), and where mixed small-scale animal and crop farming (with emphasis on dairy production) is the dominant system (Fernandez-Baca and Bojorquez, 1995). According to the national census (INEI, 1998), 40–50% of the population in these

Results

The true prevalence of BVDV antibody-positive herds was 96% (range: 89–100%), 27% of the herds had high levels of antibodies (class 3; Table 1). The median OD for the 55 positive herds was 0.42 (range: 0.07–0.97).

Twenty-seven of the 60 herds were antibody-positive to BHV-1 and the true prevalence was 51% (range: 45–57%). The median OD for the 27 positive herds was 0.85 (range: 0.10–1.99), and that for the 33 negative, 0.01 (range: 0–0.04). Interestingly to us, none of the herds had ODs between

Discussion

The selection of herds in this survey was not based on randomisation and we cannot expect the prevalences to generalise from our sample. Nevertheless, it is the largest herd-level serosurvey of BVDV and BHV-1 carried out in rural areas in Peru, and also the first to provide an estimate of the seroprevalence of dairy herds in a selected population that are likely to have had recent active BVDV infection or to contain PI animals.

In the selection, large herds were voluntarily over-represented,

Acknowledgements

The authors would like to thank Professor Stefan Alenius for comments on the manuscript. We would also like to extend our thanks to veterinary colleagues: Caroline Åkesson, Hugo Sanchez, Bety Morales, Carlos Arana de la Cruz and Charlotte Ståhl for co-operation in the Mantaro Valley, Peru, and to Martin Olin for linguistical reading of the manuscript. This work was supported by the Swedish International Development Co-operation Agency, Sida/SAREC.

References (35)

  • P.S Valle et al.

    A Bayesian approach to estimating the performance of a bovine virus diarrhoea virus (BVDV) antibody ELISA bulk-tank milk test

    Prev. Vet. Med.

    (2001)
  • J.T Van Oirschot

    Congenital infections with nonarbo togaviruses

    Vet. Microbiol.

    (1983)
  • M Ackermann et al.

    DNA of bovine herpesvirus type 1 in the trigeminal ganglia of latently infected calves

    Am. J. Vet. Res.

    (1982)
  • Armitage, P., Berry, G., 1987. Statistical Methods in Medical Research, 2nd ed. Blackwell Scientific Publications,...
  • F Beaudeau et al.

    Assessing the within-herd prevalence of cows antibody-positive to bovine viral-diarrhoea virus with a blocking ELISA on bulk tank milk

    Vet. Rec.

    (2001)
  • Bitsch, V., Rønsholt, L., 1995. Control of bovine viral-diarrhoea virus without application of vaccines. In: Baker,...
  • A Dı́az et al.

    Prevalencia del virus de la leucosis bovina (VLB) en el centro poblado menor Obenteni-Gran Pajoral-región Ucayali

    Rev. Inv. Vet. Perú

    (1999)
  • Cited by (37)

    • Prevalence of exposure to bovine viral diarrhoea virus (BVDV) and bovine herpesvirus-1 (BoHV-1) in Irish dairy herds

      2015, Research in Veterinary Science
      Citation Excerpt :

      Inclusion of both viruses allowed data on concurrent exposure to BVD and BoHV-1 to be investigated for the first time in Ireland. Although the current study has highlighted a high level of exposure to both BVDV and BoHV-1, levels are comparable to those reported for other regions (Garoussi et al., 2008; Guarino et al., 2008; Paton et al., 1998; Ståhl et al., 2002; Thobokwe et al., 2004; Van Wuijckhuise et al., 1998; Woodbine et al., 2009). It has been reported that the level of antibodies to BVDV in milk is inversely related to the amount of milk produced (Niskanen et al., 1989).

    • Bulk tank milk ELISA for detection of antibodies to Mycobacterium avium subsp. paratuberculosis: Correlation between repeated tests and within-herd antibody-prevalence

      2014, Preventive Veterinary Medicine
      Citation Excerpt :

      Bulk tank milk (BTM) testing is a frequently used tool for surveillance, monitoring or control of infectious diseases in dairy cattle, e.g. bovine herpes virus-1 (BHV-1, Nylin et al., 1999; Ståhl et al., 2002), enzootic bovine leukosis (EBL, Reber et al., 2012), bovine virus diarrhoea (BVD, Bitsch and Rønsholt, 1995; Valle et al., 2001) and Salmonella Dublin (Warnick et al., 2006).

    • Herd-level risk factors for bovine viral diarrhea virus infection in dairy herds from Southern Brazil

      2013, Research in Veterinary Science
      Citation Excerpt :

      In this situation, there is a higher probability of self-clearance of infection in smaller herds (Lindberg and Alenius, 1999). However, small herds studied in other countries in which the same test and interpretation were applied displayed higher herd prevalence (96% and 73%) than the present study (Stahl et al., 2002; Kampa et al., 2004). The cattle density of these regions is not known, but the descriptions provided indicate that these industries use more intensive rearing systems than the present region, which could partially explain the different prevalence found.

    • Association between herd exposure to BVDV-infection and bulk milk somatic cell count of Flemish dairy farms

      2013, Preventive Veterinary Medicine
      Citation Excerpt :

      The use of bulk tank milk antibody titres to estimate the BVDV seroprevalence in a herd is well established (Niskanen et al., 1991; Niskanen, 1993; Paton et al., 1998; Beaudeau et al., 2001). Moreover, for non-vaccinating herds, the level of BVDV-antibody titres in bulk tank milk corresponds with the infection status of the herd, because PI animals are most likely to be found in herds with the highest prevalence (Ståhl et al., 2002; Houe, 2005; Houe et al., 2006). As a result, herds with a current infection will have high levels of antibodies to BVDV in their bulk milk (Niskanen et al., 1991; Drew et al., 1999).

    View all citing articles on Scopus
    View full text