Update on the BTV situation in the Netherlands
GD and the Veekijker monitor the situation regarding bluetongue in the Netherlands closely. All available information, including the latest details, can be found on our website, www.gddiergezondheid.nl/blauwtong
Data analysis: Increases in E. coli and E. coli K99 infections in young calves
In the second quarter of 2024, pathological examinations showed an increase in the percentage of calves submitted from dairy farms with proven E. coli infections. E. coli was detected in 26.3 per cent of submissions in the second quarter, compared to 13.0 and 12.9 per cent in the second quarters of 2023 and 2022 respectively.
This increase mainly affected calves in the category aged 0–30 days, with most cases occurring in the first few days after birth (Figure 1). These E. coli cases were diagnosed e.g. in sepsis, pneumonia or polyserositis. In that same quarter, there was also an increase in the percentage of submissions for pathological examination diagnosed with E. coli K99, which is an intestinal pathogen and the causative agent of diarrhoea in calves up to 10 days of age. Due to the fact that E .coli K99 has a different clinical presentation, it was analysed separately and therefore does not play a role in the observed increase in the E. coli statistics mentioned above. The percentage of cases in which E. coli K99 was diagnosed was 29.6 per cent in the second quarter of 2024, as compared to 15.6 and 9.4 per cent in the second quarters of 2023 and 2022 respectively.
The rising trend in the percentage of calves submitted with E. coli or E. coli K99 infections has not continued in the third quarter of 2024: the number of detections is similar to the number of infections detected in the third quarter of 2023. We have no explanation for the observed increase in the percentage of calves submitted with E. coli or E. coli K99 infections. We will continue to monitor the trend closely.
Moulds on sweet potatoes
In mid-July, the Veekijker received a call from a practising veterinarian about a dairy farm where two cows and a calf had died in just a short period. One calf had become peracutely short of breath, had subcutaneous emphysema of the thorax and a rectal temperature of 38.2 degrees Celsius. This calf died shortly after the clinical examination. One cow had a fever (temperature of 40.1 degrees Celsius) and a bronchoalveolar lavage sample had already been submitted for bacteriological examination because of suspected Mannheimia haemolytica. The sample did not show Mannheimia haemolytica or any other respiratory bacteria. Three weeks before the symptoms appeared, a batch of sweet potatoes had been delivered to the premises to be fed to the cows. That batch was now showing mould growth. Despite the mould, the cows were happy to eat the sweet potatoes and, although it was not meant as feed for the calves, the young animals were walking about with the cows and could therefore also get at the sweet potatoes. The farmer himself had linked the symptoms to the mould growth on the sweet potatoes after finding a post by GD on the internet about a similar case in 2017. Sweet potatoes contaminated with the mould Fusarium solani
can contain the toxin 4-ipomeanol, a compound that may cause acute respiratory distress, pulmonary oedema and pulmonary haemorrhage. This toxin is produced when the mould converts compounds that are naturally present in the sweet potato plant into 4-ipomeanol. This can happen at any point: not only in the living plant but also during storage and conservation of sweet potatoes. As a general rule, the risk of mould growth increases if the plant is bruised or damaged. In the lungs, 4-ipomeanol is converted by certain enzymes into a highly reactive metabolite that binds to large protein molecules. This generates a massive inflammatory response that includes pulmonary oedema. To confirm the hypothesis that mouldy sweet potatoes in the feed had caused the mortality and to discuss the options for diagnosis and treatment, Veekijker consulted GD’s toxicologist. As far as we are aware, there is no test for 4-ipomeanol available in the Netherlands.
Where cattle are already exhibiting severe symptoms, it is possible to start symptomatic therapy, but the prognosis is very limited. It is therefore sensible to consider euthanising the animals in severe
cases. In milder cases and in cattle without symptoms that have ingested the mouldy product, 1 gram of activated charcoal per kilogram bodyweight can have a protective effect. Steps must of course be taken immediately to ensure that the cattle cannot get to the product; in this case, that had already been done. The toxicity itself stops as soon as absorption of the toxine stops (i.e. when the sweet potatoes are no longer being fed), but the lesions that have arisen still need time to heal. In severe cases, the lungs can be so badly damaged that they never recover.
In this case, a total of three cows and one calf died. There were no new cases of animals with respiratory problems after the sweet potatoes were removed. The livestock farmer in question has stated that he will no longer use sweet potatoes as feed. It is important to note that the picture described here only occurs with sweet potatoes and not with the common potato varieties fed to cows in the Netherlands.
Data analysis: Higher mortality ear-tagged dairy calves and suckler calves
The mortality among ear-tagged calves up to fourteen days of age in each quarter was calculated as the number of dead calves with tags collected by Rendac divided by the total number of calves with ear-tags. The mortality among ear-tagged calves aged 15 to 56 days and aged 56 days to one year was calculated for each quarter as the number of dead calves divided by the total number of
calves in the age category concerned. This was corrected for the number of days that the calves were present on the farms in the quarters in question. In the second quarter of 2024, the mortality of ear-tagged dairy calves and suckler calves in all age categories was slightly higher than expected compared against the same quarter in 2023 and 2022, and when compared against the
five-year trend (see Table). Mortality is highest in the second quarter every year. It is not known why the mortality figure for this year is a little higher than in other years. It is possible that the health of calves from mothers infected with BTV-3 in 2023 may be impaired.
Table 1: Mortality percentages for ear-tagged suckler calves and dairy calves in various age categories during the second quarters of 2024, 2023 and 2022.
* Note: the quarterly mortality rates cannot be added up to give annual figures
Health of cattle in the Netherlands, third quarter of 2024
VETERINARY DISEASES
Implementing Regulation (EU) 2018/1882 of Animal Health Regulation (AHR)
(category A disease)
Lumpy Skin Disease (LSD) Viral infection. The Netherlands is officially disease-free. A, D, E No infections ever detected.
Foot and Mouth Disease (FMD) Viral infection. The Netherlands has been officially disease-free since 2001. A, D, E No infections detected.
Implementing Regulation (EU) 2018/1882 of Animal Health Regulation (AHR)
Bluetongue (BT)
Bovine genital campylobacteriosis
Bluetongue serotype 3 outbreak in the Netherlands since September 2023 (see §3.2.1).
Bacterium.
The Netherlands has been disease-free since 2009. Monitoring of AI and embryo stations and of animals for export.
Bovine Viral Diarrhoea (BVD) Viral infection.
Control measures are compulsory for dairy farms but voluntary on beef cattle farms.
Brucellosis (zoonosis, infection through animal contact or inadequately prepared food)
Bacterium.
The Netherlands has been officially diseasefree since 1999. Monitoring via antibody testing of blood samples from aborting cows.
Enzootic bovine leukosis Viral infection.
The Netherlands has been officially diseasefree since 1999. Monitoring via antibody testing of bulk milk and blood samples from slaughtered cattle.
Epizootic Haemorrhagic Disease (EHD) Viral infection. Detected since 2022 in cattle in Europe (Spain, Italy, Portugal and France).
Infectious Bovine Rhinotracheitis (IBR) Viral infection. Control measures are compulsory for dairy farms but voluntary on beef cattle farms.
Anthrax (zoonosis, infection through contact with animals)
Bacterium. Not detected in the Netherlands since 1994. Monitoring through blood smears from fallen stock.
(categories B to E)
C, D, E The remuneration rules for PCR on necropsy material has stopped, follow-up of vaccinated beef cattle farms, vaccination survey, study of vertical transmission in living calves.
D, E Campylobacter fetus spp. Veneralis not detected.
C, D, E The status* of 90 per cent of dairy farms is ‘BVD-free’ or ‘BVD unsuspected’.
The status of 20 per cent of all non-dairy farms is favourable (BVD-free or BVD unsuspected).
* The BVD status as determined according to the GD programme.
B, D, E No infections detected.
C, D, E No infections detected.
D, E No infections detected.
C, D, E The status of 82 per cent of dairy farms is ‘IBR-free’ or ‘IBR unsuspected’.
The status of 21 per cent of all non-dairy farms was favourable (IBR-free or IBR unsuspected).
D, E No infections detected.
VETERINARY
Implementing Regulation (EU) 2018/1882 of Animal Health Regulation (AHR) 2016/429 (categories B to E)
Paratuberculosis
Rabies
(zoonosis, infection through bites or scratches)
Bovine tuberculosis (TB) (zoonosis, infection through animal contact or inadequately prepared food)
Trichomonas
Q fever
(zoonosis, infection through dust or inadequately prepared food)
Bacterium.
In the Netherlands, the control programme is compulsory for dairy farms. 99 per cent take part.
Viral infection.
The Netherlands has been officially diseasefree since 2012 (an illegally imported dog).
Bacterium.
The Netherlands has been officially diseasefree since 1999. Monitoring of slaughtered cattle.
Bacterium.
The Netherlands has been disease-free since 2009. Monitoring of AI and embryo stations and of animals for export.
Bacterium.
In the Netherlands, this is a different strain to the one on goat farms and a relationship with cases of disease in humans has not been established.
From the first quarter of 2023 onwards, this is once again part of the standard post-mortem protocol when cows calve prematurely
E The PPN (Paratuberculosis Programme Netherlands) status of 82 per cent of dairy farms is ‘A’ (‘unsuspected’).
B, D, E No infections detected.
B, D, E No infections detected.
C, D, E Tritrichomonas foetus not detected.
E Two infections detected in aborted foetuses.
Article 3a.1 Notification of zoonoses and disease symptoms, ‘Rules for Animal Husbandry’ from the Dutch Animals Act Leptospirosis
(zoonosis, infection through animal contact or inadequately prepared food)
Bacterium.
Control measures are compulsory for dairy farms but voluntary on beef cattle farms.
Listeriosis (zoonosis, infection through inadequately prepared food)
Salmonellosis (zoonosis, infection through animal contact or inadequately prepared food)
Yersiniosis (zoonosis, infection through animal contact or inadequately prepared food)
Bacterium.
Infections have occasionally been detected in cattle.
Bacterium. Control measures are compulsory for dairy farms but voluntary on beef cattle farms.
Bacterium.
Infections detected occasionally in cattle, mostly in aborted foetuses.
- The status of 98.5 per cent of dairy farms is ‘leptospirosis-free’.
The status of 30 per cent of non-dairy farms is ‘leptospirosis-free’.
Animals are still arriving with a leptospirosis status poorer than ‘free’ though fewer than in the previous quarter.
Two dairy farms with leptospirosis infections.
- No infections detected.
- The bulk milk results of 93.5 per cent of dairy farms are favourable (nationwide programme).
- Five infections detected.
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VETERINARY DISEASES SITUATION IN THE NETHERLANDS
Regulation (EC) no. 999/2001
Bovine Spongiform Encephalopathy (BSE)
Prion infection.
The OIE status for the Netherlands is ‘negligible risk’. Monitoring has not revealed any further cases since 2010 (total from 1997 to 2009: 88 cases).
Other infectious diseases in cattle
Malignant Catarrhal Fever (MCF)
Viral infection.
There are occasional cases in the Netherlands of infection with type 2 ovine herpes virus.
Liver fluke Parasite.
Liver flukes are endemic in the Netherlands, particularly in wetland areas.
Neosporosis Parasite.
In the Netherlands, this is an important infectious cause of abortion in cows.
Category (AHR)
Table continuation
Surveillance – Highlights Third Quarter 2023
- No infections detected. Classical BSE detected in a cow in Scotland.
Tick-borne diseases
External parasite that can transmit infections.
Ticks infected with Babesia divergens, Anaplasma phagocytophilum and Mycoplasma wenyonii can be found in the Netherlands.
- Three infections confirmed upon necropsy.
- Infections were detected at twelve farms and in two cows presented for necropsy.
- No infections detected in aborted foetuses submitted for necropsy.
- No samples submitted for examination.
Animal health monitoring
Since 2002, Royal GD has been responsible for animal health monitoring in the Netherlands, in close collaboration with the veterinary sectors, the business community, the Ministry of Agriculture, Nature and Food Quality, vets and farmers. The information used for the surveillance programme is gathered in various ways, whereby the initiative comes in part from vets and farmers, and partly from Royal GD. This information is fully interpreted to achieve the objectives of the surveillance programme – the rapid identification of health problems on the one hand and the following of more general trends and developments on the other. Together, we team up for animal health, in the interests of animals, their owners and society at large.