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.

Respiratory syncytial virus infection of camels (Camelus dromedaries).

This study aimed to investigate the occurrence of respiratory syncytial virus (RSV) infections in camels in Sudan. A total of 272 camel lung specimens showing pneumonia were collected from slaughter houses at four different areas in Sudan, additionally 8 specimens were collected from outbreaks of respiratory infection in camels. Using sandwich ELISA kits for RSV antigen detection 4 out of 280 tested lungs (1.4%) were positive, all were from Central Sudan (Tambool slaughter house). FAT was used to confirm the ELISA positives. Polymerase chain reaction RT/PCR was applied for the detection of RSV genome in camel lungs; 1 out of 4 ELISA positives was positive by RT/PCR. Using indirect ELISA kits 135 out of 495 (27.3%) camel sera showed antibodies to RSV, highest prevalence was observed in Western (33.5%) then Central (31.6%) and Eastern Sudan (23.5%). Based on the manufacturer specified calculations for OD readings, most of positive sera (90/135) were low reactive (1+). This is the first report for the detection of RSV antigen, genome and antibody in camels in Sudan.

Respiratory infection of camels associated with parainfluenza virus 3 in Sudan.

This study was undertaken to investigate the role of parainfluenza virus 3 (PIV3) in respiratory infection of camels. A total of 273 lung specimens from camels with pneumonia lesions were collected from slaughterhouses in four different areas of Sudan. In addition, eight specimens were collected from outbreaks of respiratory infection in camels. Using antigen detection sandwich ELISA kits, six out of the 281 specimens tested were positive for the PIV3 antigen (2.1%); the highest prevalence was noted in Eastern Sudan (4.2%), then in Central and Northern Sudan (1.4%). The direct immunofluorescent test (FAT) was used to confirm the positive reactions for PIV3 by ELISA. The polymerase chain reaction (RT-PCR) was applied for the detection of the PIV3 genome in lungs of camels; two out of four samples which were positive by the PIV3 ELISA were also positive by RT-PCR. Virus isolation was attempted for PIV3 in MDBK cells; four specimens yielded cytopathic virus when inoculated onto the cell culture. The cytopathic effect (CPE) consisted of cell rounding, multinucleated cells, sloughing and elongation of cells, and some syncytia were observed on the 3rd to 7th day post-inoculation. Using commercially available indirect ELISA kits for antibodies to PIV3, 495 camel sera were tested, and the seroprevalence detected was 82.2%. The highest seroprevalence was observed in Central (92.6%), then in Eastern (92.2%) and Central to South Sudan (82.5%); the lowest prevalence was found in Northern Sudan (64.8%).

Phylogenetic analysis of rabies viruses from Sudan provides evidence of a viral clade with a unique molecular signature.

Rabies is endemic in Sudan and remains a continual threat to public health as transmission to humans is principally dog-mediated. Additionally, large-scale losses of livestock occur each year causing economic and social dilemmas. In this study, we analysed a cohort of 143 rabies viruses circulating in Sudan collected from 10 different animal species between 1992 and 2006. Partial nucleoprotein sequence data (400 bp) were obtained and compared to available sequence data of African classical rabies virus (RABV) isolates. The Sudanese sequences formed a discrete cluster within the Africa 1a group, including a small number of sequences that clustered with sequences from Ethiopian RABV. These latter sequences share an Aspartic Acid at position 106 (Asp(106)) with all other Africa 1a group members, in contrast to the remaining Sudanese strains, which encode Glutamic Acid at this position (Glu(106)). Furthermore, when representatives of other African and European lineages were aligned, Glu(106) is unique to Sudan, which supports the concept of a single distinct virus strain circulating in Sudan. The high sequence identity in all Sudanese isolates studied, demonstrates the presence of a single rabies virus biotype for which the principal reservoir is the domestic dog.

Natural exposure of Dromedary camels in Sudan to infectious bovine rhinotracheitis virus (bovine herpes virus-1).

The occurrence of bovine herpes virus-1 (BHV-1) in camels was studied. A total of 186 pneumonic camel lungs were collected from slaughter houses at four different areas in Sudan during 2000-2006. Using sandwich ELISA 1.6% of 186 tested lungs were found positive for BHV-1 antigen, all were from Tambool at Central Sudan. Direct fluorescent antibody test (FAT) was used to confirm the BHV-1 ELISA positives, all ELISA positives were also positive. PCR was used to detect BHV-1 genome with three positive results. BHV-1 was isolated from two camel lungs in MDBK cells. Isolates were identified using ELISA and FAT. Indirect ELISA was used to detect antibodies to BHV-1 in 260 camel sera; 76.9% were found positive. Highest prevalence was observed in sera from Kordofan (84%) then Blue Nile (80%) and Tambool (76.3%). This is the first report for the detection of BHV-1 antigen, genome using PCR, isolation in cell culture and antibodies in camels in Sudan.

Synchronous cycles of domestic dog rabies in sub-Saharan Africa and the impact of control efforts.

Rabies is a fatal neurological pathogen that is a persistent problem throughout the developing world where it is spread primarily by domestic dogs. Although the disease has been extensively studied in wildlife populations in Europe and North America, the dynamics of rabies in domestic dog populations has been almost entirely neglected. Here, we demonstrate that rabies epidemics in southern and eastern Africa cycle with a period of 3-6 years and show significant synchrony across the region. The observed period is shorter than predictions based on epidemiological parameters for rabies in domestic dogs. We find evidence that rabies prevention measures, including vaccination, are affected by disease prevalence and show that a simple model with intervention responses can capture observed disease periodicity and host dynamics. We suggest that movement of infectious or latent animals combined with coordinated control responses may be important in coupling populations and generating synchrony at the continental scale. These findings have important implications for rabies prediction and control: large-scale synchrony and the importance of intervention responses suggest that control of canine rabies in Africa will require sustained efforts coordinated across political boundaries.

Molecular epidemiology of canid rabies in Sudan: evidence for a common origin of rabies with Ethiopia.

Rabies is an endemic zoonosis in Sudan with the principal reservoir species being the domestic dog. A panel of rabies virus isolates from dogs in Sudan have been used to establish a molecular phylogeny based on a partial sequence of the viral nucleoprotein. These isolates were then compared to those from countries bordering Sudan in north-east Africa. The Sudanese viruses form a tight cluster of isolates with a single outlier. When compared to other African viruses, the Sudanese isolates cluster most closely with isolates from Ethiopia to the East suggesting a common origin for rabies in both countries which supports historical records of the movement of rabies into Sudan. The Sudanese group of viruses belong to the Africa 1a group of viruses that are present throughout much of north Africa.