Antibody seroprevalences against Peste des Petits Ruminants (PPR) virus in sheep and goats in Sudan

Counter immnuo-electrophoresis (CIEP) and Competitive ELISA (C-ELISA) tests were employed for seroprevalence of Peste des Petits Ruminants (PPR) infection in Sudan. The result of both tests showed high prevalence of PPRV antibodies in sheep and goats sera collected from six different regions of Sudan. Of the 519 serum samples examined for the presence of PPRV antibodies 307(59.15%) were positive by CIEP while 263(50.67%) were positive by C-ELISA. CIEP technique was shown to be more sensitive than C-ELISA technique for detection of PPRV antibodies (Kappa statistics 0.259). C-ELISA allowed rapid, simple, specific, sensitive and differential sero-diagnosis of PPRV and RPV in sheep, goats and cattle. CIEP is, unlike competitive ELISA, is group-specific test and can not differentiate between PPR and RP infections. Despite its low specificity CIEP can be a useful indicative screening test for PPRV antibodies in flocks that neither been vaccinated nor otherwise exposed to PPR or RP virus. Results obtained suggest that CIEP, like the HI test, could be a useful screening test where it is not possible to use C-ELISA.     

The detection of antibody against peste des petits ruminants virus in Sheep,Goats, Cattle and Buffaloes

Monoclonal antibody-based competitive ELISA (C-ELISA) has been used for the specific measurement of antibodies to peste des petits ruminants (PPR) viruses in sheep, goats, cattle and Buffalo. Serum samples from sheep (n = 232), goats (n = 428), cattle (n = 43), buffalo (n = 89) were tested. The animals had not been vaccinated against rinderpest or PPR. Findings suggested that the sero-positive cases were significantly higher in sheep (51.29%) than in goats (39.02%) (P = 0.002). The overall sero-prevalence of PPRV in small ruminants was 43.33%. The PPR antibodies seroprevalence was 67.42% in buffalo and 41.86% in cattle which was significantly higher in buffalo (P = 0.005). The overall sero-prevalence of PPRV in large ruminants was 59.09%. Cattle and buffalo sera showed a high prevalence of antibody against PPR virus which may explain the difficulty experienced in achieving high post-vaccination immunity levels against rinderpest. Because antibodies against PPR virus are both cross-neutralizing and cross-protective against rinderpest virus, further vaccination in the presence of antibodies against PPR virus may be a waste of national resources. It was also suggested that antibodies to PPR virus could prevent an immune response to the rinderpest vaccine. This paper presents serological evidence for the transmission of PPR virus from sheep and goats to cattle and buffalo and highlights the need to include PPR serology in the sero-monitoring programme to give a better indication of national herd immunity of sheep and goats against PPR.     

Prevalence and distribution of Peste des petits ruminants virus antibodies in various districts of Tanzania

Despite the widespread prevalence of infection with Peste des petits ruminants virus (PPRV) in goats and sheep industry in Asia and sub-Saharan Africa, there have been few, if any, structured population-based studies examining the epidemiology of this infection in Tanzania. In this study, we investigated the seroprevalence, and risk factors, of Peste des petitis ruminants(PPR) in sheep and goat flocks from seven different geographical administration authorities (Ngorongoro, Monduli, Longido, Karatu, Mbulu, Siha and Simanjiro) located in Northern Tanzania. Serum samples from 657 and 892 sheep and goats, respectively, corresponding to 91 sheep/goat flocks and 43 villages were collected. Competitive enzyme linked immunosorbent assay (c-ELISA) was used to detect the presence of antibodies in the serum against PPRV. Chi-square analysis and multivariable logistic regression model were used to identify risk factors for PPRV seropositivity. Findings suggested that the sero-positive cases were significantly higher in goats than in sheep (49.5% versus 39.8%; P = 0.002). The overall seroprevalence of PPRV infection in small ruminants was 45.8%. Highest seroprevalence (42.6–88.02%) was observed in Mbulu, Siha, Longido, Ngorongoro districts, while antibodies less than 40% to none were found in serum from Monduli, Karatu and Simanjiro, respectively. These findings confirm natural transmission of PPRV under field condition for the first time in Tanzania. Results may be correlated with variations in the sheep and goat husbandry practices within different geographic localities, the uncontrolled movement of animals, the levels of natural immunity and the sharing of grazing field amongst agro and pastoralists.     

Serological studies with peste des petits ruminants and rinderpest viruses in Nigeria

One hundred and ninety-five goat and 67 sheep sera collected from various parts of southern Nigeria were screened for neutralising antibodies to both the peste des petits ruminants (PPR) and rinderpest viruses. Neutralising antibodies against both viruses were found in the sheep and goat sera examined. Parallel titration of samples which neutralised both viruses indicated a primary infection with the PPR virus (PPRV). However, some samples which failed to neutralise PPRV neutralised the rinderpest virus (RV) indicating RV activity in sheep and goats in Nigeria. These findings are discussed in relation to the diagnosis of PPRV infection and the recent reappearance of bovine rinderpest in Nigeria.     

Peste des petits ruminants infection in domestic ruminants in Sudan

The existence of peste des petits ruminants (PPR) in domestic ruminants and camels in Sudan during 2008–2012 was investigated. Lung tissues and serum samples were randomly collected from sheep, goats, cattle, and camels at different areas of Sudan. A total of 12,384 serum samples were collected from clinically healthy 7413 sheep, 1988 camels, 1501 cattle, 1459 goats, and 23 gazelles at different areas in the Sudan. They were examined for PPR antibodies using competitive ELISA (cELISA). The overall detected seroprevalence of PPR in tested sera was 49.4%; seroprevalence values within species were 67.1, 48.2, 25.8, 2.1, and 21.7% in sheep, goat, cattle, camels, and gazelles, respectively. The highest seroprevalence (68.1%) was observed in sera collected from Darfur states, then the central states (54.3%). A total of 1276 lung tissue samples (623 sheep, 324 cattle, 220 camels, and 109 goats) were collected. The majority of lung samples were collected from clinically healthy animals that showed lesions on PM in slaughterhouses (95%) and during PPR outbreaks; samples were tested for PPR antigen using immunocapture ELISA (IcELISA). PPR antigen was detected in 233 out of the 1276 tested samples (18.3%). Positive results were observed in samples collected from clinically healthy and diseased animals. The observed prevalence values in each species were 33.6, 21.1, 15.4, and 12.3% in camel, goat, sheep, and cattle, respectively. PPR antigen was detected in samples from different areas; however, the highest prevalence (63.9%) was found in samples collected from the eastern states, then Khartoum state (28%). Trials for virus isolation were done in different cell cultures. Out of 30 IcELISA-positive samples inoculated in primary bovine and ovine kidney cells, Vero cells, the PPR virus was successfully isolated from 15 (eight sheep, five camels, and two goats) samples in the three cell culture types. Using RT-PCR, PPRV nucleic acid was detected in all 25 IcELISA-positive tested samples.     

Post-vaccination antibodies profile against Peste des petits ruminants (PPR) virus in sheep and goats of Punjab,Pakistan

A total of 70 sheep and 330 goats were selected randomly. All the animals were kept under same housing and management conditions. Serum samples were collected from all the animals and tested for the presence of antibodies against Peste des petits ruminants (PPR) virus using competitive ELISA (cELISA). All the animals were found negative showing percentage inhibition (PI) values <50. The animals were vaccinated against PPR with Nig/75/1 strain vaccine of PPR Serum samples were collected from randomly selected 12 sheep and 30 goats at 10, 30 and 45 days post-vaccination. The samples were subjected to cELISA to determine the presence of antibodies against PPRV. The samples with PI >50 were considered as sero-positive. The sheep found positive at 10, 30 and 45 days post-vaccination were 1(8.3%), 7(58.3%) and 12(100%) respectively. In case of goats 3(10.0%), 29(96.6%) and 27(90.0%) animals gave positive results at 10, 30 and 45 days post-vaccination respectively. Mean PI values in sheep at 10, 30 and 45 days post-vaccination were recorded as 37, 65 and 91 respectively, whereas in goats these values were 43, 78 and 86 respectively.     

Rapid detection of <Emphasis Type="Italic">Peste des Petits Ruminants</Emphasis> (PPR) virus antigen in Sudan by agar gel precipitation (AGPT) and haemagglutination (HA) Tests

AGPT and HA tests were employed for rapid diagnosis of PPRV infection in sheep and goats in Sudan. Forty lymph nodes and spleen samples from suspected cases of PPR in both sheep and goats were examined by AGPT and HA tests for detection of PPRV antigen. Viral antigen was detected from (77.5%) of the samples tested by AGPT and (92.5%) tested by HA test. The results of both tests revealed that HA test was more sensitive than AGPT for detection of PPRV antigen (Kappa statistics 0.4366). Another advantage of the HA test over AGPT was that it can differentiate PPRV from RPV. Thus the HA test represents a quick, easy, simple, cheap and reliable confirmatory test for the diagnosis of PPR and differential diagnosis of PPRV and RPV. The HA test was carried out using chicken, goat and pig RBCs. Chicken RBCs were found to be the most sensitive for detection of PPRV antigen, followed by goat then pig RBCs. The HA time when using chicken RBCs was 20–25 minutes, using goat RBCs was 25–30 minutes and using pig RBCs was 40–45 minutes. The distribution of PPR infection in four different regions of Sudan was investigated.     

PPR virus infection on sheep in blacksea region of Turkey: Epidemiology and diagnosis by RT-PCR and virus isolation

In this study, a totally 164 materials (lung, spleen, lymph node, nasal and ocular swap, blood and samples from oral lesions) from sheep and lambs (n = 57) in the 34 flocks suspected the PPRV infection as clinically and macroscopic pathologic remarks, housed in the 4 different provinces in the Middle and Eastern Blacksea Region were used for RT-PCR and virus isolation. Additionally, serum samples randomly collected from 892 sheep were tested for the detection of PPRV seroprevalance in the same regions. The seroprevalance were estimated as 14,9% and 3,5–38,2% in the sampled animals and sampled province, respectively. While no virus isolated in Vero cell cultures, PPRV nucleic acid was detected in 26 of 164 materials by RT-PCR. According to the result of RT-PCR, the PPRV infection were diagnosed in 44,1% (15/34) and 31,5% (18/57) of the flocks and sampled animals, respectively. Diagnostic value of necropsy materials such as lymph node, spleen, lung and of clinical samples such as nasal swap and conjunctival swap were determined more valuable diagnostic materials in the diagnosis of PPRV infection by RT-PCR. Data showed that PPRV infection was widespread in the Middle and East Blacksea Region and that the prevalence of the infection in the region varies in accordance with the factors such as geographical conditions (climate, etc.) and the method of breeding. Additionally, it is determined that RT-PCR is sensitive and reliable method in the diagnosis of PPRV infection.     

Antibody seroprevalences against peste des petits ruminants (PPR) virus in camels, cattle, goats and sheep in Ethiopia

A questionnaire-survey data indicated that 26% of 276 farmers reported the presence of respiratory disease in their herds in 2001. The incidence was perceived as "high" in small ruminants and camels, but as "low" in cattle. Simultaneously, 2815 serum samples from camels (n=628), cattle (n=910), goats (n=442) and sheep (n=835) were tested. The peste des petits ruminants (PPR) antibody seroprevalence was 3% in camels, 9% in cattle, 9% in goats and 13% in sheep. The highest locality-specific seroprevalences were: camels 10%, cattle 16%, goats 22% and sheep 23%. The animals had not been vaccinated against rinderpest or PPR. Antibody seroprevalences detected in camels, cattle, goats and sheep confirmed natural transmission of PPR virus under field conditions.     

Current situation of Peste des petits ruminants (PPR) in the Sudan

The current situation of PPR in Sudan was investigated. A total of 61 tissue samples were collected from various PPR suspected outbreaks in sheep in Sudan during 2008. Collected tissue samples were tested for PPR antigen using IcELISA, PPR antigen was detected in 26 out of 61 samples (42.6%). Highest antigen detection rate was in specimens collected from western Sudan. A total of 1198 serum samples were collected from sheep (n = 500), camels (n = 392), and goats (n = 306) from different areas in Sudan (Khartoum, Gezira, Tambool, River Nile, Kordofan, White Nile, Blue Nile, Gedarif, Kassala, Halfa ElGadida, Port Sudan). Collected sera were examined for PPR antibodies using cELISA, a total of 336 (67.2%) sheep, 170 (55.6%) goat and 1 (0.3%) camel samples were found to be positive.     

Evidence of mixed infection of peste des petits ruminants virus and bluetongue virus in a flock of goats as confirmed by detection of antigen, antibody and nucleic acid of both the viruses

A mixed infection with peste des petits ruminants virus (PPRV) and bluetongue virus (BTV) occurred in goats which exhibited symptoms characteristic of PPR. A number of samples were collected from ailing or dead goats for labrotory diagnosis. Antibody to BTV and PPRV was detected in sera samples by competitive ELISA. No PPRV antigen was detected in tissue samples like lung and spleen, however, presence of PPRV antigen in some sera samples was confirmed by sandwich ELISA. All the blood samples collected from the ailing animals were found positive for BTV antigen by a sandwich ELISA. BTV- and PPRV nucleic acids were amplified from the pooled blood and tissue samples respectively by RT-PCR assays. The identity of the amplicons was confirmed by cloning and sequencing. All these tests confirm that the goats were infected with PPRV and BTV simultaneously. Isolation of viruses from the clinical samples is underway.     

Evidence of peste des petits ruminants virus (PPRV) infection in Sindh Ibex (<Emphasis Type="Italic">Capra aegagrus blythi</Emphasis>) in Pakistan as confirmed by detection of antigen and antibody

An outbreak resulting in mortality in Sindh Ibex (Capra aegagrus blythi) was investigated. There was a history of about 36 deaths (both young and adult) during the period of 1 month. Disease appeared in a generalized form, affecting the respiratory and digestive systems. Major lesions were respiratory distress, pustules on and in the mouth, ocular–nasal discharges, and severe diarrhea. The most significant lesion was the oculonasal discharges and diarrhea. Deaths were mainly due to blindness, anorexia, diarrhea, and respiratory arrest. Both adult (mortality = 21) and young (mortality = 15) animals were affected with the disease. Peste des petits ruminants virus (PPRV) antigen was detected in the spleen, lung, lymph node, and swab samples by immunocapture enzyme-linked immunosorbent assay. Spleen and lung samples were also tested and found positive for the presence of F-gene of PPRV by polymerase chain reaction. Thirteen of 20 serum samples from nearby sheep and goats were found positive for antibodies to PPRV. The disease threatened the huge population of ibex in the wild life park, which was spread over a large area, but vaccination of the domestic population of sheep and goats in the surrounding villages appeared to control the disease.     

Evaluation of a commercially available enzyme-linked immunosorbent assay for detecting antibodies to Fasciola hepatica and Fasciola gigantica in cattle, sheep and buffaloes in Australia

A commercially available ELISA for detecting antibodies to liver fluke was evaluated for use in Australia. Milk and serum samples from cattle and sheep in which infection with Fasciola hepatica was confirmed by detection of eggs in faeces were used to estimate sensitivity. Similar samples collected from cattle and sheep outside the F. hepatica-endemic area were used to estimate specificity. The ELISA was also evaluated for detecting antibodies to F. hepatica in milk from sheep and antibodies to Fasciola gigantica in sera from cattle and buffaloes, but with small numbers of samples. In cattle, the sensitivity and specificity of the ELISA were 98.2% and 98.3% using serum and 97.7% and 99.3% using milk. In infected herds, 41.4% and 41.5% of animals were positive in the serum and milk ELISAs, respectively, whereas F. hepatica eggs were found in faecal samples from 26.5% of animals. In sheep, the sensitivity of the ELISA was 96.9% and the specificity was 99.4%. In infected flocks, 60.2% of animals were positive in the serum ELISA and F. hepatica eggs were found in faecal samples 52.2% of animals. There was perfect agreement in the ELISA between paired serum and milk samples collected from ewes. The assay detected antibodies in sera from cattle and buffaloes with natural and experimental F. gigantica infections. In the experimentally infected animals, antibodies were detected 2 weeks post-infection. We conclude that the ELISA will be a valuable tool for diagnosing F. hepatica infections in cattle and sheep. The assay may also be useful for diagnosing F. gigantica infections but further studies are required to establish sensitivity and specificity.     

Development of a monoclonal antibody based competitive-ELISA for detection and titration of antibodies to peste des petits ruminants (PPR) virus

Peste des petits ruminants (PPR) is an acute febrile, viral, disease of small ruminants with great economic importance. A competitive-ELISA (c-ELISA) test was developed for detection of antibodies to PPR virus in the sera samples of goats and sheep. The test uses monoclonal antibody to a neutralizing epitope of haemagglutinin protein of the virus. Based on the distribution of known negative sera samples (n=933) in respect of PPR virus antibodies in the test, a cut-off value was set as 38%. This value was the result of mean of negative population added with two times the standard deviations. A total of 1668 sera samples from goat and sheep and 32 sera from cattle were screened by c-ELISA and virus neutralization test (VNT). Efficacy of c-ELISA compared very well with VNT having high relative specificity (98.4%) and sensitivity (92.4%). The sensitivity of c-ELISA for PPR sero-surveillance could further be increased (95.4%), if the target population is non-vaccinated. c-ELISA test correlated well with VNT (r=0.845) for end-point titration of PPR virus antibody in 64 goat sera samples. It could clearly separate infected population from uninfected in field sera. Using c-ELISA test paired sera samples from 13 goats provided a clear diagnosis of PPR virus infection. Furthermore, antibodies to PPR virus could be successfully detected during 1 year after vaccination in four goats inoculated with an experimental PPR vaccine. Findings suggest that the c-ELISA test developed can easily replace VNT for sero-surveillance, sero-monitoring, diagnosis from paired sera samples and end-point titration of PPR virus antibodies.     

Sero-epidemiology of peste des petits ruminants (PPR) in Pakistan

A sero survey was conducted during 2005-2006 to estimate the sero prevalence of PPR in the small ruminant population of Pakistan. A total of 2798 samples were collected including goats (1979) and sheep (819) from villages in 27 randomly selected districts. These were tested by cELISA for PPRV and true prevalence estimates were calculated by Rogan and Gladen estimator. Overall, 1273 (45.5%) were found positive; 980 (49.5%) of 1979 samples from goats and 293 (35.8%) of 819 serum samples from sheep were positive. The true sero-prevalence of PPR was estimated to be 48.5% (95% CI, 46.6-50.3), and 52.9% (95% CI, 50.7-55.1) and 37.7 (95% CI, 34.4-41.0) for goats and sheep, respectively. PPR virus is widely distributed all across Pakistan and has become an endemic infection of small ruminants. Since it is one of the leading causes of morbidity and mortality in small ruminants, it poses a serious threat to food security and the rural economy in Pakistan.     

Prevalence of peste des petits ruminants among sheep and goats in India

This study measured the clinical prevalence of peste des petits ruminants (PPR) among sheep and goats in India between 2003 and 2009 by analyzing clinical samples from suspected cases of PPR that were submitted to the Rinderpest and Allied Disease Laboratory, Division of Virology, IVRI, Mukteswar for PPR diagnosis. PPR outbreaks were confirmed by detecting PPR virus (PPRV)-specific antigen in the clinical samples. Clinical samples (blood, nasal swabs, spleen, lymph node, kidney, liver, intestine, and pooled tissue materials) were taken from a total of 592 sheep and 912 goats in different states of India and screened for the presence of PPRV antigen using a monoclonal antibody-based sandwich ELISA kit. A total of 20, 38, and 11 laboratory-confirmed PPR outbreaks occurred among sheep, goat, and combined sheep and goat populations, respectively. Our findings provide evidence of widespread PPR endemicity in India. The underlying reasons could be variations in husbandry practices in different geographical regions, agro-climatic conditions, and livestock migration. Furthermore, decrease in the number of PPR outbreaks over time might be due to the effectiveness of current live PPR vaccines and timely vaccination of target species. Vaccination against PPR has been practiced in India since 2002 to control this disease.