Persistence of African swine fever outbreak in a farm in Kaduna, Nigeria

PERSISTENCE OF AFRICAN SWINE FEVER OUTBREAK IN A FARM IN KADUNA STATE, NIGERIA.

NIGERIAN VETERINARY MEDICAL ASSOCIATION, 47th ANNUAL CONGRESS. “THE VETERINARIAN AND NATIONAL FOOD SECURITY”. 4-8th Oct. 2010. MAKURDI, BENUE STATE.

NVMA 47TH ANNUAL CONGRESS

SCIENTIFIC SESSION

Lazarus, D. D*., Jwander, L. D., Benshak, J. A., Agom, D., Gado, D. A., Adamu, S. S., Fasina, F. O.

AFRICAN SWINE FEVER (ASF)

AFRICAN SWINE FEVER

Is a tick bone, contagious, febrile, systemic viral disease of swine.

It may present with up to 100% mortality in pig.

Death usually results from haemorrhagic fever.

ASF VIRUS (ASFV)

Family: Asfarviridae (ASF And Related virus) Genus: Asfarvirus Only DNA arbovirus (insect virus) Only (Icosahedral cytoplasmic

deoxyribovirus) ICDV pathogenic for mammalian species.

One of the only two mammalian viruses (+Aleutian virus of Mink) that does not induce neutralising antibodies.

ASF VIRUS (ASFV)

Resistance plays a role in its epizootiology - stable in blood, urine and faeces - isolated in varying conditions including: -

70°C to +56°C, pH 3.9-13.4, dead animals exposed to trypsin, EDTA, antibiotics.

Transmitted by ticks, formites, airbone route and other animals.

ASF –NIGERIAN SITUATION

First reported initial sporadic infection in 1973.

West-African widespread epizootics started in 1996.

Nigerian pig population increased from 2 to 7 million between 1984 and 1997.

Nigerian epizootics started in 1997. Between 1997-8 lost 125,000 pigs worth

N292, million.

ASF CURRENT SITUATION

Prior to the 2007 ASF PITT between NVRI, ARCN, ILRI, CISA-INIA, Spain and ISU Global extension program Iowa, USA, no coordinated national management plan or surveillance activities was in place.

No full cost implication of ASF. Detected in pigs, bush pigs, red river hog and

warthogs. Research reports regionalised and

fragmented.

CURRENT SITUATION-VACCINE

No effective neutralising antibodies are produced against the virus.

There is no vaccine for African Swine Fever till date.

SUMMARY OF LESIONS

Dark red to purple areas of skin on ears, feet and tail.

Petechial haemorrhages on serosal surface of viscera.

Renal cortical petechial / ecchymotic haemorrhages.

Peri-renal oedema. Oedema of the gall bladder. Swollen liver. Pulmonary oedema.

CASE HISTORY

A private farm in Kaduna state reported a sudden outbreak of disease with high mortality characterised by vomiting, diarrhoea and dark red to purplish discoloration of the skin.

Five Breeder Houses were wiped off within a period of one week outbreak.

At the time of the disease investigation only one piglet was found on the farm.

CASE HISTORY

The pig was killed on the consent of the farm management and samples collected for diagnosis.

Blood was collected and serum separated for serology.

Tissue samples (lungs, liver, spleen, lymph nodes and heart) were collected for molecular analysis.

GROSS LESION

LABORATORY ANALYSIS

Serology -Indirect ELISA

LABORATORY ANALYSIS PCR

LABORATORY ANALYSIS

The test was very sensitive using the OIE primer set ASF 1/2.

The primers target a 278 bp unit of the p72 gene.

RESULTS

The serum tested positive for ASF by Indirect ELISA for ASF.

The lymph nodes tested positive for ASF by PCR.

The pooled tissues tested positive for ASF by PCR.

The same samples were tested for Classical swine fever antigen, and tested negative for CSF by Antigen ELISA for Classical swine fever.

DISCUSSION

ASF has had significant economic and social impact in Nigeria since 1997.

However, there has been no effective national response to bring it under control.

In this report, we confirm that ASF is still prevalent in Nigeria.

DISCUSSION

Movement of infected pigs seem to be the most important means of spread.

Farm-gate buyers assist the spread. Regional prevalence indicated higher % in

areas with high pig activities, nine per cent (9%) of samples and 48% of tissue samples were positive for ASF virus antibody and genome respectively (Fasina et al, 2010).

DISCUSSION Comprehensive routine surveillance and testing. Reorganisation of the market and systems for

pigs. Implementation of on-farm biosecurity protocols. Government should consider compensation

option.

ACKNOWLEDGEMENT

The management of NVRI, Vom. Numerous staff that assisted: field surveillance laboratory work

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