CSF surveillance

1. Surveillance of classical swine fever in Costa Rica, since 1997
Dr.Dagoberto Méndez - National Swine Health Program-MAG/ Senasa. Costa Rica 2013
Background
Classical swine fever (CSF), appeared in our country in early 1994 and the last outbreak was detected in Upala city, north border with Nicaragua, in October 1997, which was removed by stamping out. Today, Costa Rica is free of disease and submitted its self declaration on September 17, 2009, (Decree: No. 35552-MAG), after a great effort in organizing and tracking of different activities aimed at implementing an efficient organization based on current legislation, the implementation of activities performed based on a protocol detailing the responsibilities of the different actors in the system related to the prevention and control situations that could jeopardize the re-entry disease into the country.
National swine production
In the country, were processed in the year 2011, a total of 683,711 heads of swine of which 321,106 were in rural slaughterhouses and 362,606 heads in "packing plants." ( (National Production Council, 2012).
Legislation
Classical swine fever is a notifiable disease within the national territory as established by Executive Decree No. 23368-MAG of June 14, 1994, as amended by Executive Decree No. 24407-MAG of 8 June 1995 and Executive Order No. 34669-MAG of 8 July 2008, published in “La Gaceta No. 156 of August 13, 2008”. Lastly it lists the notifiable animal diseases, including Classical Swine Fever and reaffirms the obligation of all citizens to report cases of CSF. Legislation is available on the website of the SENASA .
Besides, SENASA Act, 8495 (Gazette May 93 -16 2006), is a specialized and technical entity which obeys national and international norms.
As a public body, the work of SENASA is regulated by various national laws such as: Law on Public Financial Management and Budget, Public Procurement Act, Internal Control Act, against Corruption and illicit enrichment.
In addition to the above technical competence SENASA is regulated by other laws and international treaties approved by Costa Rica, among which should be mentioned in a particular Act 7473, known as Law Enforcement Agreements of the Uruguay Round, which indicates Ministry’s implementation of the obligations and exercise the rights provided in the Agreement on the Application of Sanitary and Phytosanitary Measures. To meet the obligations of SENASA, the 8495 Act provides in Article 14 that the SENASA will have financial resources such as items that are assigned annually in ordinary and extraordinary budgets of the Republic, among others.

2. Epidemiological Surveillance
Since 1997 a continuous CSF epidemiological surveillance has been maintained in Costa Rica, together with training activities for pig producers, based on the appropriate use of biosecurity measures at farm level with informative material that seeks prevention of the disease into the country.
Passive surveillance for CSF in Costa Rica is based on claims of veterinarians, hog farmers or any other citizen, and active surveillance field, according to a sampling plan on subsistence farms and technified pig farms in risk areas and the rest of the country.
In order to demonstrate the absence of CSF virus in the country, some additional surveys were made in two different periods.
A national survey, conducted in 1999.
For the second national study, executed in 2008, a design was done for technified and subsistence farms in two stages: first identifying the technified sector farms according to a list frame and then the grids (geographical units 5X5 km2) with subsistence pig populations both in the border area as the rest of the country.
For technologically advanced farms: Prevalence among farms of 5% and a confidence level of 95% Intra-farm prevalence of 15% with a confidence level of 95% For subsistence farms: Prevalence among grids 10% 95% confidence level Prevalence 15% intra-grid 95% confidence level
A total of Sample distribution by province in the 2008 study:
Province Samples Percentage San Jose 379 13% Alajuela 1458 50% Cartago 101 3% Heredia 22 1% Guanacaste 417 14% Puntarenas 322 11% Limon 192 7%
Total 2891 100%
Passive Surveillance
Veterinarians and pork producers or any other citizen should report any suspected

3. disease of pigs that could be CSF, more so if clinical symptoms or findings in slaughterhouses support it, according to Executive Decree .34669-MAG.
These cases should be investigated by the official veterinarian to confirm or rule out the CSF or other pig diseases of official interest. All cases will be documented including the results of laboratory tests as implemented control measures.
In case of clinical suspicion (passive surveillance), tests are used to detect viruses: Diagnosis in parallel: They mount the two tests simultaneously PrioCheck CSFV Ag ELISA test for the detection of Ag (Virus) and RT-PCR for Pestivirus, any positive test gives a probable case. In this case, samples are sent to the reference laboratory of CSF (in Nicaragua). PrioCheck CSFV Ag ELISA according to manufacturer's specifications: Sample type Sensitivity Specificity Fabric 76% 100% Blood 62% 98% Plasma Data not available 94% Serum 97% Data not available RT-PCR for Pestivirus: if the result is positive, makes the following two tests: a. Study of restriction enzyme b. sequencing If one of the two positive tests, is considered a probable case subject to confirmation in Nicaragua. Sensitivity and specificity could not be determined yet.
Active Surveillance
1 - Field Surveillance Active surveillance for CSF in Costa Rica is based on the detection of infection with a statistical design on technologically advanced and subsistence farms. Sampling in subsistence farms is divided in two groups: the protection zone of 20 km wide adjacent to the border with Nicaragua, and backyard farms in the rest of the country. As it is not known the exact location of population and backyard pigs, the sampling unit was "Grids", which are areas of 5 km x 5 km (25 km2). The sample design was as follows: Fig 1-Prevalence assumed to detect infection at farm and animal in the different strata.
LEVEL
Tech. farms
Subsistence grids
Protection zone
Rest of the country
Farms
15%
10%
15%
Animals
20%
20%
20%
Samples are taken on farms by SENASA officials trained for that purpose. The routine diagnosis is based on detection of antibodies (ELISA PrioCheck) in porcine sera, and is performed in SENASA officials laboratories; confirmation tests are performed in the LANASEVE and when applied to a reference laboratory abroad. In this case the Central Veterinary Diagnostic Laboratory MAGFOR - Managua in Nicaragua.

4. Sampling in slaughterhouses was part of the active surveillance plan.
Samples analyzed since 1967
In the year 2008 the number of samples was 281+2891=3172
In the year 2012
Laboratory
N° Farms tested
N°of samples
Regional Laboratory (North region)
283
1241
LANASEVE(Central- San Jose)
39
249
Regional Laboratory (South region)
6
58
Total
328
1548
Keeping a surveillance program by testing swine in high risk areas, allows early detection of CSF virus in case of introduction into Costa Rica swine population,. This program is implemented in cooperation with private sector, National Laboratory of Animal Health, UNA University and International Cooperation organization like OIRSA,FAO ,USDA.
Source: National Swine Health Program-MAG/ Senasa. Costa Rica 2013
Province
2007
2007
2008
(first semester)
2008
(first semester)
2009
2009
2010
2010
2011
2011
Farm
Sample
Farm
Sample
Farm
Sample
Farm
Sample
Farm
Sample
San José
30
155
10
44
17
543
22
248
16
445
Alajuela
464
652
66
79
24
43
107
525
97
171
Cartago
2
4
1
1
3
332
6
71
63
181
Heredia
70
73
31
12
5
58
7
41
52
67
Guanacaste
198
185
125
83
97
92
102
238
87
120
Puntarenas
26
119
16
45
21
116
16
163
17
92
Limón
46
51
26
17
20
178
15
85
21
255
Total
836
1239
275
281
187
1362
275
1371
152
1331