Dr. Jason Chan presented on the outbreak of Lumpy Skin Disease (LSD) in feral cattle populations in Hong Kong from 2020-2021. The key points were: 1) The initial outbreak was reported in October 2020 across multiple country parks. Disease investigation found that 72% of cattle in one herd showed skin lesions and 84% were seropositive. 2) By March 2021, no new clinical cases were reported. Surveillance since found 14 juveniles seronegative, suggesting LSD may have disappeared due to lack of susceptible newborn cattle. 3) Continued clinical and serological surveillance is important since Hong Kong has a small teaching farm. No urgency exists currently to declare freedom

1. Lumpy Skin Disease Symposium in Rome, Italy (14-16 March 2023)
Lumpy Skin Disease in Hong Kong
Dr. Jason Chan
Veterinary Officer (Stray Cattle Management)
Agriculture, Fisheries and Conservation Department
The Government of HKSAR, China

2. Lumpy Skin Disease Symposium in Rome, Italy (14-16 March 2023)
Contents
1. Background information
2. Time course of initial outbreak
3. Disease investigation
4. Disease control and surveillance

3. Lumpy Skin Disease Symposium in Rome, Italy (14-16 March 2023)
Background information
 No Commercial cattle farms in Hong Kong
 Two types of bovine species in Hong Kong –
Brown Cattle (local Chinese breed) and
Asian Water Buffaloes (Bubalus bubalis)
 All feral, living in the wild
 Staying in the country park areas but do
accidentally venture into urban areas
 Believed to be a signature of many
country parks in Hong Kong – they shall
be protected and conserved

4. Lumpy Skin Disease Symposium in Rome, Italy (14-16 March 2023)
Background information – number and distribution
Source: AFCD cattle/ buffalo population survey
Population survey in 2022 -
860 brown cattle and 180 buffaloes
Central New
Territories
(Tai Mo Shan,
Shing Mun, Tai
Lam)
Cattle Buffalo
240 55
Northeast New
Territories (Sha
Tau Kok, Plover
Cove)
Cattle
120
Lantau Island
Cattle Buffalo
120 125
Sai Kung
Cattle
380

5. Lumpy Skin Disease Symposium in Rome, Italy (14-16 March 2023)
Time course of initial outbreak in brown cattle
27km
25km
36km
9/11/2020
➢ Lam Tsuen
Country Park
➢ Seen cattle
with skin
lesions during
operation
20/10/2020
➢ Government
Operation Centre
➢ First cow in the
Centre
4/10/2020
➢ Sai Kung Country Park
➢ First ever report by
public – cattle with skin
lesions
2/11/2020
➢ Lantau Island
➢ Reported by public –
cattle with skin lesions
30/10/2020
➢ Two cattle were
euthanised
➢ Post-mortem at
Government Vet Lab

6. Lumpy Skin Disease Symposium in Rome, Italy (14-16 March 2023)
Disease investigation – pathological findings
Enlarged prescapular lymph node
Histopathology: Virus inclusion
TEM: Poxvirus virions
Source:
Tse A.C. et al. (2022). Lumpy Skin Disease in a Cow.
Brazilian Journal of Veterinary Pathology, 15(2), pp.
114 – 117.

7. Lumpy Skin Disease Symposium in Rome, Italy (14-16 March 2023)
Disease investigation
 Two different herds were sampled
 All the cattle in each herd have similar epidemiological risk
 Always together in a set territory
 Seldom mix with other herds
 These two herds were chosen because:
 Less timid and more docile
 Can be attracted through giving hay
➢ Mui Wo - 25
cattle
➢ Lantau Island
(Southwest
border of Hong
Kong)
➢ Pak Lap - 31 cattle
➢ Sai Kung Country Park (Eastern
border of Hong Kong)

8. Lumpy Skin Disease Symposium in Rome, Italy (14-16 March 2023)
Disease investigation
 Mui Wo Herd, Lantau Island (Southwest border of Hong Kong)
 First report received on 2/11/2020
 Sampling period: 20/1/2021 – 2/3/2021
 25 cattle in total
 4/25 were seronegative (16%) (but 2 with skin lesions <50%>)
 21/25 were seropositive (84%)
 5 out of these 21 seropositive > generalised skin lesions (23.8%)
 11 out of these 21 seropositive > mild skin lesions (52.4%)
 5 out of these 21 seropositive > no skin lesions (23.8%)

9. Lumpy Skin Disease Symposium in Rome, Italy (14-16 March 2023)
Disease investigation
 Pak Lap Herd, Sai Kung Country Park (Eastern border of Hong Kong)
 First report received on 4/10/2020
 Sampling period: 1/2/2021 – 26/4/2021
 31 cattle in total
 13/31 seronegative (42%) (but 7 with skin lesions <54%>)
 18/31 seropositive (58%)
 5 out of these 18 seropositive > generalised skin lesions (27.8%)
 5 out of these 18 seropositive > mild skin lesions (27.8%)
 8 out of these 18 seropositive > no skin lesions (44.4%)

10. Lumpy Skin Disease Symposium in Rome, Italy (14-16 March 2023)
Disease investigation
 In summary:
 As high as 72% of cattle in a herd showed suspicious skin lesions
 As high as 84% of cattle in a herd were seropositive
 Comparing clinical surveillance findings with serological testing results:
 Up to 72% of cattle in a herd having both testing results in line with each other
 The consistency dropped over the course of disease outbreak (skin lesions
might have healed or become less obvious; antibody level might have dropped)
 Clinical surveillance assisted by public members
 Many public members concern about animal welfare in Hong Kong – they
wanted those skin lesions to be treated
 The government only a phone call away
 Most initial disease outbreak reports in October and November 2020 were
lodged by public members

11. Lumpy Skin Disease Symposium in Rome, Italy (14-16 March 2023)
Disease investigation
 Last report by public members in March 2021
 No suspicious cases after March 2021
 Water buffaloes in Hong Kong seemed to be unaffected, both
clinically and serologically

12. Lumpy Skin Disease Symposium in Rome, Italy (14-16 March 2023)
Disease control and surveillance
 Was disease control possible in the feral cattle population?
 Vaccination
 Movement control and zoning
 Vector control
 Stamping-out
 Fortunately, natural herd immunity seemed to build up
 No clinical cases since March 2021
 Affected animals recovered
Unfortunately not
Not feasible
Not feasible
Not feasible
Practically feasible, but public perceptions are of major concern

13. Lumpy Skin Disease Symposium in Rome, Italy (14-16 March 2023)
Disease control and surveillance
 Clinical surveillance
 During our population control program
 Animal welfare groups
 Public members
 Serological surveillance
 Purpose: to see if LSD is still present in the feral population
 Sampling target: all the cattle that were born after March 2021 (just less
than 2 years old) but older than 3 months old
 Sampling period: started after October 2022
 Target sample size vs convenient sampling

14. Lumpy Skin Disease Symposium in Rome, Italy (14-16 March 2023)
Disease control and surveillance
 Serological surveillance: target sample size vs convenient sampling
 To calculate a target sample size:
 Estimated population of calves and juveniles: 120 (Population survey in 2022)
 ELISA sensitivity: 80 – 98.6% (ESFA, 2018; ESFA, 2020; Ibrahim A.I. et al., 2022 )
 Design prevalence: 3.5% (ESFA, 2018)
 Sample size: 64 - 79 (RiBess+)
 Convenient sampling: so far 14 calves/juveniles sampled (all without any clinical signs and
all seronegative)
Unable to sample 64 - 79 calves/juveniles within a short period

15. Lumpy Skin Disease Symposium in Rome, Italy (14-16 March 2023)
In summary……
1. Has LSD disappeared in Hong Kong?
 Not many newborns? Calves and Juveniles only about 10% of the population
> no susceptible animals before the disease dies out > breaks the
transmission cycle???
 Continue to perform both clinical surveillance and serological surveillance
through convenient sampling
2. Fortunately, no urgency to declare “freedom of disease”
 No commercial cattle farms in Hong Kong
 No cattle exports
 Closest commercial cattle farm is about 430 km away
3. Having said that, one farm is being set up in Hong Kong
 An university teaching farm
 Vaccination program and movement control are in place

16. Lumpy Skin Disease Symposium in Rome, Italy (14-16 March 2023)
References
 EFSA (European Food Safety Authority), Calistri P, DeClercq K, De Vleeschauwer A, Gubbins
S, Klement E, Stegeman A, Cortinas Abrahantes J, Antoniou S-E, Broglia A and Gogin A,
2018. Scientific report on lumpy skin disease: scientific and technical assistance on control
and surveillance activities. EFSA Journal 2018;16(10):5452, 46 pp.
https://doi.org/10.2903/j.efsa.2018.5452
 EFSA (European Food Safety Authority), Calistri P, De Clercq K, Gubbins S, Klement E,
Stegeman A, Cortinas Abrahantes J, Marojevic D, Antoniou SE and Broglia A, 2020.
Scientific report on the lumpy skin disease epidemiological report IV: data collection and
analysis. EFSA Journal 2020;18(2):6010, 36 pp. https://doi.org/10.2903/j.efsa.2020.6010
 Ibrahim A.I. et al. (2022). Serodiagnosis of Lumpy Skin Disease Using Sheep Pox Virus
Compared to a Commercial ELISA Kit. Journal of Applied Veterinary Sciences, 7(1), pp. 46-
52.

17. Lumpy Skin Disease Symposium in Rome, Italy (14-16 March 2023)
Any questions?