Veterinary World, EISSN: 2231-0916 Available at www.veterinaryworld.org/Vol.6/Oct-2013/23.pdf RESEARCH ARTICLE Open Access

unrestricted use, distribution and reproduction in any medium, provided the work is properly cited. GO (2013) Seroprevalence of peste des petits ruminants among domestic small and large ruminants in semi-arid region of northeastern Nigeria, Veterinary World 6(10): 807-811. Abstract Background: Recent changes in the host range of peste des petits ruminants (PPR) virus coupled with the presence of a huge ruminant population in the study area has stimulated our interest to carry out a sero-survey for PPR among the different domestic ruminant populations of semi-arid region of Northeastern (NE) Nigeria.


Introduction
the peste des petits ruminants (PPR) [7].This disease is among the greatest threats to the successful livestock Ruminants are a major component of the production and food security in the affected areas [8, livestock sub-sector in most parts of the world 9].PPR is an economically important, rapidly including Nigeria [1].Nigeria is blessed with abundant spreading, acute or subacute viral disease of domestic livestock resources with most of the animals being and few wild small ruminants [10,11].The disease is concentrated in the northern parts of the country [2].
characterized by high morbidity and heavy mortality, The semi-arid zone of north-eastern (NE) Nigeria is with symptoms ranging from depression, pyrexia, reported to account for about 25% of each of the oculo-nasal discharges, pneumonia, stomatitis, to ruminant population of Nigeria which is estimated at diarrhea [9,10,12,13].This disease was found to occur 13.3 million cattle [3]; 20.1 million sheep and 34.5 in most of the African countries that are situated in a million goats [4,5].Efforts to improve the productivity wide belt between the Sahara and the Equator, Middle of livestock in Nigeria have been hindered by a variety East, Arabian Peninsula and south India [14-16].The of factors including infectious diseases that results in disease is now spreading from Afghanistan into the countless number of animal deaths [6].In an economic neighbouring countries of the former Soviet Union and point of view, one of the important of these diseases is has recently entered China.This disease is proving to be costly with an increasingly significant impact on economy of these countries [14,16].It is considered as one of the most important health constraints in the rearing of small ruminants [14, 17] with a significant England and supplied by BDSL, were provided by impact on the financial status of rural farmers [18,19].
LANAVET Garoua Cameroon.The c-ELISA used for For a better understanding of the epidemiology of the detection of antibodies to PPR and RP in the serum PPR among the ruminant populations of the semi-arid samples is based on two specific monoclonal NE region of Nigeria, both large and small ruminants antibodies against the hemagglutinin (HA) protein of were sampled and analysed serologically for evidence PPR virus and the other one specific against HA protein of PPR.
of RP virus.The tests detect only antibodies to specific virus and gives no cross reactivity between the two

Materials and Methods
viruses.The samples with PI (full form of PI) >50% Test sera: Blood samples were collected randomly by were considered as positive venipuncture method from sheep, goats, cattle and Statistical analysis: The data were analyzed camel that had no previous history of vaccination statistically using student t-test and at a 5% level of against PPR or rinderpest (RP) at slaughter houses, statistical significance.watering points and individual flocks in the semi-arid NE region of Nigeria.A total of 2,879 samples

Results
consisting of 1,571 goats, 1,008 sheep, 192 cattle and A total of 2,879 serum samples, comprising of 108 camels were collected.Blood samples were 1,571 goat sera, 1,008 sheep sera, 192 cattle sera and allowed to clot and then stored at 4°C overnight.Sera 108 camel sera were tested for PPR antibodies using were harvested from the clotted blood after VNT and c-ELISA.The results of the VNT revealed centrifugation at 1,500 rpm for 10 minutes, and stored PPR antibody prevalence rates of 51.6%, 76.5%, in sterile 2ml cryotubes.The sera were stored at -20°C.
16.7% and 27.8% for goats, sheep, cattle and camels, The samples were collected from slaughter houses, respectively.While the c-ELISA showed a organised farms, rural dwellings, and at watering sites.seroprevalence of 50.4%, 73.2%, 16.7% and 25.9% for The serum samples were subjected to virus goats, sheep, cattle and camels, respectively (Table 1).neutralization test (VNT) and competitive enzyme-Significant difference (P<0.05) was noted in the linked immunosorbent assay (c-ELISA).
percentage of seroprevalence between males and females in both goats and sheep (Figure 1).The age Virus neutralization test: Vero cells (R133), PPR ® distribution showed significant difference in vaccine virus (Capripestovax LANAVET Garoua, percentage of seroprevalence among the different age Cameroon), RP vaccine virus, PPR and RP positive groups of goats with seroprevalence being increased sera were obtained from LANAVET Garoua, with an increase in age (Figure -1).Sheep that are aged Cameroon.Both vaccine viruses were used at 3 above two years showed statistical difference in 10 TCID .The test sera used in this study were heat 50 prevalence when compared to the other age groups of °inactivated at 56 C for 30 minutes prior to using them.
sheep tested (Figure -1).The seasonal distribution of The neutralizing antibody titres of serum samples were the positive samples among the small ruminant species determined according to the protocol described in OIE did not show any statistical difference (P>0.05)(Figure manual [20].The reciprocal of the highest dilution of -1).When the PPR positive samples were tested for RP sera showing complete inhibition of cytopathic effect antibodies using VNT and c-ELISA, it was observed was recorded as VN titre.
that 64.8% and 63.8% of the PPR positive goat and Competitive enzyme-linked immunosorbent assay: sheep samples were found to cross neutralise with RP The PPR and RP competitive ELISA kits manufactured using VNT, but none of these positive samples was by the Institute for Animal Health Pirbright Surrey, found to be positive for RP antibodies using c-ELISA (Table -2).No such cross-reactivity was observed study agrees well with the findings of 55.2% in Uganda among the cattle and camel samples.

Discussion
but disagrees with 1.7% in Ethiopia [27].Our results This sero-epidemiological survey for PPR show how vulnerable the small ruminant populations antibodies among goats and sheep in the Sahel region of this region could be to other secondary infections as of NE Nigeria revealed that PPR infection of the two a result of infection with PPR virus.This is because species is widely distributed with sheep showing a PPR virus like most morbilliviruses is known to induce higher percentage of prevalence rate than goats.The immunosuppression in its natural host [28,29].Some prevalence of PPR antibodies in some parts of Borno workers have however, reported differences in the state of Nigeria were earlier reported by Taylor [21] virulence of the different lineages of the PPR virus.For who also observed a higher prevalence in sheep than in example, the lineage I (e.g.Cote d'Ivoire 89, Guinea goats.On the other hand, Shamaki et al. [4] observed Conakry, Bissau Guinea, etc.) cause per acute to acute an opposite trend in these prevalence rates.
disease, lineage II (e.g.Nigeria 75/1) cause mild to in Nevertheless, it is important to note that both the apparent disease, lineage III (e.g.Sudan Sennar) cause workers reported a high prevalence of PPR among the acute to mild disease and lineage IV (e.g.India two species in this area.The differences between the Calcutta) cause acute disease [22].Furthermore, present observation and that of these workers could be because goats are more susceptible to PPR than sheep, primarily because they sampled goats of different it is likely that the number of goats carrying PPR virus breeds that belong to other parts of the southern regions neutralising antibodies observed in this study were the of the state unlike our study where the samples were ones that survived a previous infection.While the high collected from NE region.A difference in the neutralising PPR antibodies in the sheep may be sensitivity to PPR virus, which was correlated to breed because sheep only suffer mild to inapparent infection rather than to the virus, was reported among various with the virus or this may be attributed to a higher breeds of goats [22,23].PPR is the singular most recovery rate and a greater longevity of sheep verses important cause of morbidity and mortality among goats which is similar to the serological profile small ruminants, for which the most effective form of reported earlier by some workers [30,31,32]

Figure- 1 .
Figure-1.Gender, age and seasonal distribution of PPR VN antibodies among small ruminants in the semi-arid NE zone of Nigeria

Table - 1
. Some protection is through vaccination or an eventful workers have reported a PPR outbreak in a flock of recovery from natural infection.Because there is no sheep and goats with only the goats being affected [33, history of vaccination against PPR in the present study 34].Similar to the reports of Luther et al. [35] and area, the prevalence of high PPR antibodies in the Abdalla et al. [25] we have also observed a significant population from this region is a clear indication of a statistical difference in the age and sex specific PPR high activity of the virus in this particular environment.prevalencerates among either species of animals.In The overall seroprevalence of 55% observed in this the present study, there was no significant difference in .Prevalence of PPR VN antibodies in the sera of some ruminants in the semi-arid region of NE Nigeria

Table - 2
. Results of VN test and c-ELISA in differentiating PPR from RP antibodies in the sera of some ruminants in the semiarid region of NE Nigeria * c-ELISA -The numbers indicates samples that were positive for PPR using c-ELISA out of the corresponding samples that were positive at that ** titre using VN test; -= Negative; RP -Rinderpest; PPR -Peste des petits ruminants