Findings on FMD in Afghanistan and Pakistan

Transcription

1 Findings on FMD in Afghanistan and Pakistan Giancarlo Ferrari Project Coordinator GTFS/INT/907/ITA Controlling Trans-boundary Animal Diseases in Central Asian countries AGAH/EMPRES FAO

2 Outline of the presentation Background on GTFS/INT/907/ITA activities General approach to surveillance adopted Findings in husbandry systems such as dairy colonies (Pakistan), villages and live animal markets (Afghanistan) Conclusions

3 Background GTFS/INT/907/ITA project Controlling Trans-boundary animal diseases in Central Asian countries started its activities in 2004; It is a Regional Project supported by the Italian Government with the following beneficiary countries: Afghanistan, Pakistan, Tajikistan, Turkmenistan and Uzbekistan

4 Background Phase 1 of the GTFS/INT/907/ITA was concluded on 31 December 2007; Main objective: to demonstrate freedom from Rinderpest from the beneficiary countries; As a result during the OIE General Session of May 2008 Afghanistan, Tajikistan and Uzbekistan have been recognized officially free (Turkmenistan is still pending), while Pakistan was recognized free in 2007.

5 Background Project has been extended until 31 December 2009 and during phase 2 is focusing more on FMD and PPR; The surveillance activities have been designed in order to target different epidemiological units (namely: villages; commercial farms; slaughterhouses; live animal markets; etc..).

6 General approach to surveillance Serology: (i) NSP-antibodies detection in different epidemiological units (minimum of 48 blood samples for each epidemiological unit 16 blood samples from three different age-classes 0_1; 1_2 and > 2); (ii) Survival approach in a dairy colony (Pakistan) Virus/genome identification in both clinically and nonclinically affected animals targeting: (i) reported FMD outbreaks; (ii) Live animal markets; (iii) Dairy colonies (Pakistan).

7 General approach to surveillance An agreement has been established with both the Istituto Zooprofilattico Sperimentale della Lombardia e dell Emilia in Brescia (Italy) and with the Danish Technical University in Lindholm (Denmark) that is presently hosting two laboratory specialist from Pakistan

8 Pakistan (Dairy colonies) The dairy colony production system has some peculiar characteristics. The animals are kept on individual farms for milk production but only for the period of their lactation ( days), so recently calved and near-calving animals are purchased and brought onto the colony farms. The calves are generally not kept with and only high-yielding milking animals are maintained in this production system.

9 Pakistan (Dairy colonies) This system is dominated by the buffaloes as buffalo milk contains higher butterfat and is preferred by the customers; In order to fulfil the market demand the production level of the farm is maintained at almost constant level through an intense turn-over of animals. On average 10 to 12 per cent of animals in dairy colonies are replaced monthly.

10 Pakistan (Dairy colonies) Dairy farm in Landhi (from Soren Alexandersen) The animal population in the Landhi dairy colony is more than 200,000 heads (95% buffaloes) distributed in approximately 1,500 individual farms over an area of 6.5 sq Km (M. Afzal)

11 Pakistan (Dairy colonies) In a previous study carried out in Landhi colony in Karachi in 2006 and 2007 in collaboration with the Danish Technical University a serological investigation (among other activities on virus identification) was carried out and 180 serum samples collected (between October 2006 and April 2007) from slaughtered animals that had spent at least one lactation period into the Landhi Colony

12 Pakistan (Dairy colonies) Out of 180 samples collected 176 (98%) had detectable levels of NSP antibodies (Klein, J. et al, Virology Journal 2008, 5: 53). This finding was consistent with animals, sampled at a given point in time (slaughter) that had the common experience of having spent at least one lactation period ( days) in Landhi.

13 Pakistan (Dairy colonies) As part of the current activities and to establish the level of NSP-antibodies in animals entering for the first time the colony 179 individuals have been blood sampled (and ear-tagged) once brought into the colony (t 0 ); Animals were recruited between 26 February and 13 March 2009; Mean age = 6.15; Median = 6 Animals negative at t 0 were monitored on a monthly basis.

14 Pakistan (Dairy colonies) Date N. positive P Overall P 26 Feb % 72.6% 13 March 15 April 46* % 93.7% 17 May % 94.3% 15 Jun % 16 Jul % *3 animals were lost to observation

15 FMD in Afghanistan Village level a total of 3159 blood samples were collected from 65 villages located in the following provinces: Kabul, Nangharar, Baghlan, Pansjer, Kunduz, Balkh, Faryab, Sar-i-Pul, Samangan, Badakshan, Takhar, Heart, Badghis, Parwan, Kapisa, Jawzjan and Bamyan. The majority of the samples were collected in the period March-April 2009.

16 FMD in Afghanistan (sampling areas)

17 FMD in Afghanistan The crude results for NSP antibodies obtained were as follows: N. Positive N. Tested Proportion Age_class % Age_class % Age_class % In each single village has been found evidence of NSP Ab positive animals.

18 FMD in Afghanistan Crude data while providing evidence on the presence of animals exposed to the FMD virus cannot be used to estimate the overall proportion of positive animals in each age class for which it is necessary to weight the proportion estimated in each single epidemiological unit; As a weighting factor it has been used the total number of animals (in each age-class) in any epidemiological unit over the total number of animals of that class in all the epidemiological units sampled.

19 FMD in Afghanistan Data unadjusted (Pc) and adjusted (Pw): N. Positive N. Tested Pc Pw Age_class % 51.7% Age_class % 43.1% Age_class % 49.3%

20 FMD in Afghanistan The effect of representing crude and weighted data is better seen when attempting to find an association between history of vaccination and level of exposure to FMD virus. Out of the 65 villages sampled it was reported that in 14 of those vaccination against FMD was carried out on a regular basis (every 6 months or at least every year).

21 FMD in Afghanistan Even if it is not known if the individual animals are actually vaccinated it has been explored the existence of a difference between animals sampled in villages with history of vaccination + against those with history of vaccination - ; Vaccines reported to be used were against A, O and Asia 1 originated either from Russia or Iran.

22 FMD in Afghanistan History of vaccination + History of vaccination - Pos Tested P c Pos Tested P c Age class 1 Age class 2 Age class % % % % % %

23 FMD in Afghanistan History of vaccination + History of vaccination - Pc Pw Pc Pw Age_class % 43.3% 57.6% 53.2% Age_class % 42.6% 52.7% 43.3% Age_class % 49.2% 59.2% 49.4%

24 FMD in Afghanistan In terms of risk reduction (P vh- - P vh+ )/ P vh- Crude (village) Weighted (village) Age-class % 18.6% Age-class % 1.6% Age-class 3 2.2% 0.4% The gain, in terms of risk reduction, may be present in age-class 1 but then becomes negligible (weighted proportions).

25 FMD in Afghanistan An additional component of the surveillance activities was a regular monitoring in live animal markets on nonclinically affected animals (provided that there were no clinical cases on the day of the visit); Two markets selected one in Kabul and the other in Jalalabad; Criteria: 20 samples on a monthly basis.

26

27 FMD in Afghanistan The activity was not carried out regularly; From 23 July 2008 up to 28 April visits have been made and a total of 161 swabs collected from non-clinically affected animals (samples were stored according to a protocol established with Lindholm to preserve RNA); The main purpose was to verify (in absence of a regular notification of FMD outbreaks) the reliability of a parallel monitoring system to identify circulating strains.

28 FMD in Afghanistan Results (only on those occasions when positive results have been obtained) Date N. samples N. pos Typed Genotype 23 July 2008 (Kabul) 23 Sept 2008 (Kabul) 7 April 2009 (Kabul) IRN-05 Bar O PanAsia3? ?

29 Preliminary conclusions The level of exposure and the force of infection in husbandry systems such as the dairy colonies in Pakistan are both very high; The chain of transmission could only be interrupted targeting the breeding system that is the supplier for animals to farmers in the colony (an important socioeconomic study made by M. Afzal provides insights into the contractual system between the dairy colony farmers and breeders).

30 Preliminary conclusions The findings at village level in Afghanistan shows a high and widespread level of virus circulation and indications of recent exposure; The apparent effect of vaccination should be better studied but it appears that the gain, in terms of risk reduction, may not be significantly high;

31 Preliminary conclusions It is highlighted the need for using different criteria for sampling when wanting to detect disease or measure an effect of some hypothetical protecting factor (sometimes used interchangeably). The major drawback when using adjusted proportions is that the variance (p*q/n) also needs to be adjusted which implicates that the estimated standard error of the mean is higher if compared with crude data and consequently the statistical significance may be lost;

32 Preliminary conclusions Exposure to multiple serotypes (data not shown on this presentation but generated through the collection of 69 samples from suspected outbreaks - period 5 Jan May have proved circulation of A- IRN05/Bar08; A-IRN05/Afg07; Asia1; O PanAsia2 and O PanAsia3?). Identification of strains such as O PanAsia3(?) on 23 September and type A IRN05-Bar08 on 23 July detected earlier in live animal markets rather than attended outbreaks.

33 Preliminary conclusions If there are indications of high level of virus circulation (NSP Ab) and the reporting system is weak live animal markets may represent a monitoring site for the detection of circulating strains; Identification of two critical control points, namely: (i) live animal markets; (ii) an husbandry system such as Dairy Colonies and the need for socio-economic studies to better define the systems behind LAM and DC.

34 Preliminary conclusions Countries should be assisted in developing their national control programs, according to their resources and ability targeting specific sectors and measure the efficacy of those programs; Any external support that developing countries may receive from International organizations, NGOs, etc.. should fit into those national programs.