Advances in research

A brief review of some recently published scientific papers as examples of the impact and scope of veterinary research:

Analysis of equid herpesvirus 1 strain variation reveals a point mutation of the DNA polymerase strongly associated with neuropathogenic versus nonneuropathogenic disease outbreaks.

J. Nugent et al [1]

Equid herpesvirus 1 (EHV-1) is known to cause a wide range of clinical signs, including respiratory disease, abortion, neonatal foal death and neurological disease. Researchers from the Animal Health Trust, Newmarket, and Maxwell H. Gluck Equine Research Center, Kentucky, analysed the complete genome sequence of the V592 strain of virus which has been shown experimentally to cause predominantly respiratory signs, rarely can be associated with abortion, but does not cause neurological disease. They compared this with a previously published sequence of the EHV-1 strain Ab4, which is known to cause severe clinical disease including a relatively high frequency of abortion and neurological disease. Thirty one out of the 76 proteins encoded by EHV-1 were found to differ between these two strains of the virus. The researchers examined 16 of the changes using a panel of EHV-1 strains, and correlated DNA sequence with the geographical origin of the virus and disease characteristics. They report that certain strain groups are recovered mainly from either Europe or North America, suggesting geographical restriction of EHV-1 strains. Most interestingly, they found a variation of one particular amino acid in the DNA polymerase protein of the virus is strongly associated with either neurological or non-neurological disease outbreaks, providing the first molecular epidemiological data to support suspicions that disease manifestations of EHV-1 outbreaks are associated with distinct strains of the virus.

No increase in human cases of Mycobacterium bovis disease despite resurgence of infections in cattle in the United Kingdom.

Jalava, K. et al (in press) [2]

This paper assessed the impact of the steady increase in the number of cattle herds infected with Mycobacterium bovis in the United Kingdom on the number of reported cases of M. bovis infection in humans. A human case of M. bovis infection was defined as a culture positive M. bovis case reported through Mycobnet (UK Mycobacterial Resistance Network) since 1993 or through enhanced surveillance of M. bovis since 1998. This was compared to the number of cattle herds testing positive for M. bovis, obtained from the UK State Veterinary Service Vet Net electronic database. There were 315 M. bovis cases in humans reported between 1993 and 2003, with the highest number of cases in London. Consumption of unpasteurised dairy products was reported by 49% of cases, and 46% had occupational contact with cattle. However, as the title of the paper suggests, despite a five fold increase in the number of cattle herds infected with M. bovis in the 1990s, there was no increase detected in the number of reported human cases of infection. The authors conclude that the measures taken in the UK to prevent M. bovis transmission from cattle to humans have been effective.

Prevalence, risk factor analysis and follow-up of infections caused by three feline hemoplasma species in cats in Switzerland

Willi, B. et al [3]

This paper described disease caused by the three feline hemoplasma species in Switzerland. Hemobartonella felis, the cause of feline infectious anemia, has recently been reclassified as a hemoplasma. Three different species of hemoplasma affecting felines were investigated by the authors: Mycoplasma haemofelis, "Candidatus Mycoplasma haemominutum" and "Candidatus Mycoplasma turicensis". The paper reports the outcome of a study involving RT-PCR tests on 996 feline blood samples from 86 healthy and 627 ill cats in Switzerland. "Candidatus Mycoplasma haemominutum" was the most commonly detected species, and "Candidatus Mycoplasma turicensis" the rarest. No significant difference was detected between hemoplasma prevalence in ill and healthy cats, and hemoplasma infection was not associated with anaemia, leading to suggestions that cofactors, such as infection with FeLV or FIV, are required for development of disease. Evidence was presented that "Candidatus Mycoplasma haemominutum" and "Candidatus Mycoplasma turicensis" infections may be responsive to treatment with antibiotics. The authors recommended screening of blood donor cats for all three feline hemoplasma species.

A low cost decision support tool for the diagnosis of endemic bovine infectious diseases in the mixed crop-livestock production system of sub-Saharan Africa

Eisler, M.C. et al (in press) [4]

A shortage of qualified veterinarians in sub-Saharan Africa has led to the use of animal health auxiliaries to diagnose, treat and control diseases of livestock. This paper describes the development of a decision support card for these auxiliaries, to aid in distinguishing between endemic bovine diseases. The prototype card listed eight endemic bovine diseases in sub-Saharan Africa: anaplasmosis, babesiosis, cowdriosis, fasciolosis, parasitic gastroenteritis, schistosomosis, theileriosis, and trypanosomosis. Questionnaires from 32 veterinary research scientists and 14 veterinary practioners were used to assign symptoms to each disease, and this information was added to the card in a colour coding system, allowing a most likely diagnosis to be determined for any given combination of 16 clinical symptoms. Initial preliminary tests of the card were encouraging, and full field-based validation is currently underway in eastern Uganda.

[1]        Nugent, J. et al. (2006) J Virol 80, 4047-60.

[2]        Jalava, K., Jones, J.A., Goodchild, T., Clifton-Hadley, R., Mitchell, A., Story, A. and Watson, J.M. (2006) Epidemiol Infect, 1-6.

[3]        Willi, B. et al. (2006) J Clin Microbiol 44, 961-9.

[4]        Eisler, M.C., Magona, J.W., Jonsson, N.N. and Revie, C.W. (2006) Epidemiol Infect, 1-9.