Figure

Figure. Acute form of African swine fever in wild boars. A) Petechial and larger ecchymotic hemorrhages beneath the epicardium. B) Severe hyperemia and petechial and larger ecchymotic hemorrhages in mucosa of urinary...

The wild boar population in northwestern Iran is 12,000–13,000. Boars affected by ASFV show weakness, difficulty walking, dragging of the hind legs, dysentery, and sudden death. The first report of dead boars came from 2 villages (Oshdibin and Namngah) in the Jolfa area and then from other cities such as Ahar, Sarab, Maragheh, and Marand. The disease spread to the city of Khoie, located in another province (West Azarbaijan). Postmortem histopathologic investigations of tissue samples of 3 dead, female, wild boars found characteristic signs of ASF, such as disseminated intravascular coagulation with multiple hemorrhages (Figure).

Viral DNA from 6 tissue samples (kidney, liver, lung, large intestine, heart, and spleen) from the 3 dead boars was extracted by using the JETQUICK Tissue DNA Spin Kit (GENOMED GmbH, Lohne, Germany) according to the manufacturer’s instructions. ASFV was detected by PCR and SYBR Green real-time PCR on a Rotor-Gene 65H0 (Corbett Life Sciences, Sydney, New South Wales, Australia) in all samples from each boar; primers used were P72 D, U (major capsid protein), and PPA_1,2 (in the viral protein 73 coding region of the genome) (6,9). Melting curve analysis showed that an elevated temperature of 86.7°C could generate a specific peak in this curve. The sequences of the PCR products derived by using PPA primer pairs were analyzed by using BLAST (www.ncbi.nlm.nih.gov/blast/Blast.cgi) and showed 100% similarity to submitted sequences of Georgia isolates. A partial sequence of the isolates from Iran has been submitted to GenBank under accession no. FJ897727.

To confirm a specific pathogen and trace the possible sources of infection, genetic characterization of the virus strain associated with disease is crucial (1,2). Real-time PCR and PCR are the most practical ways to differentiate infectious agents that cause similar clinical signs (5,6,9). The 100% similarity between our isolates and those from Georgia suggests that they might have originated from Georgia, probably brought into Iran by infected wild boars crossing the Aras River during the disease incubation period.

The main obstacles to ASF eradication are wildlife reservoirs, limited ability to control movement of infected pigs and wild boars, inadequate laboratory support for rapid and accurate diagnosis, and lack of an effective vaccine (4). Ornithodoros spp. ticks may contribute to virus persistence in the Caucasus region, including northwestern Iran. Although in our study ticks were not detected on the boar carcasses, they should be considered as potential transmission vectors. O. lahorensis ticks are found in areas with a cold climate and are mainly found near sheep and cows, so they are not likely to be isolated from an animal. In the absence of Ornithodoros spp. ticks, transmission to pigs could occur through contact with infected pigs or through feeding of virus-contaminated products (7,8).

The pig industry differs among Caucasus countries. In Azerbaijan, Chechnya, and southern Russian Federation, the pig industry is not as large as it is in Georgia and Armenia (7). In these countries with limited or no pig farms, the virus could be spread by infected wild boars, and the disease could become endemic as it has in Spain and Sardinia (3,7,8,10–12). Because Iran has no commercial pig facilities, the ASFV reservoir would be wild boars, which could transmit disease to neighboring countries that have pig industries, resulting in considerable economic losses.