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What is hemorrhagic septicemia in buffalo, and how do you prevent it?

Hemorrhagic septicemia is a fast, often fatal bacterial disease of cattle and buffalo. Signs, why it peaks in the rains, and Thailand's yearly vaccine.

Beginner8 min read

On this page
  1. What causes hemorrhagic septicemia?
  2. Why are buffalo hit harder than cattle?
  3. Why does HS break out in the rainy season?
  4. What are the signs of hemorrhagic septicemia?
  5. When should buffalo be vaccinated against HS, and how often?
  6. What should you do if you suspect HS?
  7. Can people catch hemorrhagic septicemia?

Hemorrhagic septicemia (HS) is a bacterial blood infection of cattle and water buffalo. In Thai it is usually called rok kho buam, "swollen-neck disease", after its most visible sign. Sick animals run a high fever, breathe hard and noisily, develop a hard swelling of the throat, neck or brisket, and often die in less than two days. The main protection is a yearly vaccine given before the rains, plus keeping animals out of the situations that stress them when the weather turns.

Thailand's National Institute of Animal Health (NIAH), part of the Department of Livestock Development (DLD), notes that HS outbreaks are most common at both the start and the end of the rainy season. This post collects what a buffalo or beef cattle keeper needs to know, using DLD documents and the standards of the World Organisation for Animal Health (WOAH).

A timeline in weeks: the HS dose goes in more than a month before the rains, protection starts about three weeks later and lasts through the rainy season, and the next dose comes a year later

What causes hemorrhagic septicemia?

HS is caused by a few serotypes of the bacterium Pasteurella multocida: mainly B:2 in Asia and E:2 in Africa, according to WOAH's disease page. The NIAH newsletter of October–November 2024 gives the same two serotypes.

What makes HS hard to keep out is that the bacteria are often already in the herd. WOAH says P. multocida lives mostly as a commensal in the nasopharynx of animals, without causing disease. The DLD explains the next step: when a carrier animal is stressed, it sheds bacteria into feed and water; other animals swallow them, fall sick, and shed more in nasal discharge, saliva and dung.

How long the bacteria survive outside the animal

Why are buffalo hit harder than cattle?

Buffalo are more susceptible. WOAH's Terrestrial Manual chapter on HS states that water buffaloes are generally more susceptible than cattle and show more severe disease. A 2020 notice from the Udon Thani provincial livestock office says the same in local terms: buffalo have higher sickness and death rates than cattle.

The 2020 outbreak in north-eastern Thailand shows what that looks like. In late July 2020 the DLD Director-General reported 28 sick and 25 dead buffalo in Maha Sarakham, and 4 sick buffalo, 1 dead buffalo and 1 dead beef animal in Khon Kaen. By 31 July the DLD's count across three provinces (Maha Sarakham, Khon Kaen and Udon Thani) was 13 farmers, 51 sick animals and 34 deaths.

In areas where HS is endemic, WOAH notes that deaths are largely confined to older calves and young adults. That lines up with the DLD's vaccination age of four months and up.

Why does HS break out in the rainy season?

Because the start and end of the rains bring sudden weather changes, stressed animals and wet ground, and HS needs both stress and moisture. WOAH says that in many Asian countries outbreaks mostly occur in monsoon conditions of high humidity and high temperature.

DLD documents list the same stress triggers: the start or end of the rainy season, moving animals, and working them too hard. In a December 2022 warning the Director-General added going without feed, explaining that a weakened animal falls sick and sheds bacteria into feed and water.

On a farm, those are recognisable weeks: buffalo working the paddies, the herd moved to high ground ahead of flooding, animals trucked to a market or a new owner, and the stretch when there is not enough grass to go round.

What are the signs of hemorrhagic septicemia?

High fever, laboured breathing, drooling, and a hard swelling of the throat, head or brisket, usually followed by death in less than two days. The incubation period is three to five days.

The signs as listed in the Udon Thani notice and on the NIAH disease page:

  1. High fever (NIAH gives 104–107 °F), dullness, reluctance to move.
  2. Drooling, nasal discharge, no cud-chewing.
  3. A hard, hot swelling of the throat, head, shoulders and brisket.
  4. Open-mouth breathing with the neck stretched forward; deep, fast, noisy breaths.
  5. Bloating, dung with blood-stained mucus.
  6. Going down and dying 6 to 24 hours after the first signs.

The NIAH newsletter gives a similar window, with most animals dying within 18 to 30 hours of showing signs, and some dying suddenly before any sign is seen. In the less acute form, NIAH says death follows in two to three days.

There is very little time to act. WOAH puts the case fatality rate at close to 100% if treatment does not start at the initial stage, and notes that HS can follow an outbreak of foot-and-mouth disease as a secondary complication.

When should buffalo be vaccinated against HS, and how often?

Vaccinate cattle and buffalo from four months of age, once a year, at least a month before the rains. That is the advice on the NIAH disease page and in the NIAH newsletter.

The DLD vaccine

The HS vaccine made by the DLD's Bureau of Veterinary Biologics is an inactivated, oil-adjuvanted vaccine given by deep intramuscular injection. The label information on the NIAH page:

Item NIAH page
Starting age 4 months and older
How often Once a year
Protection starts 3 weeks after the dose
Protection lasts 15 months

I've left out the dose and injection technique on purpose. The livestock officer or vet who gives the vaccine should follow the label of the batch they are using.

Why vaccinate every year if the label says 15 months?

Because a young animal's first dose may not last that long. WOAH states that a single dose in calves four to six months old protects for 3–4 months with alum-precipitated vaccine (APV) and 6–9 months with oil-adjuvanted vaccine (OAV). Its recommended routine is a dose of OAV at four to six months, a booster three to six months later, and yearly revaccination after that.

Where it isn't practical to reach animals one by one at the right age, the same chapter recommends vaccinating every animal over four months once a year, and giving all calves under one year a second dose six months later. In my view, that makes it worth asking the district livestock office when a calf that has had its first dose should get its booster, rather than waiting for the next year's campaign.

What you might see after vaccination

WOAH notes that oil-adjuvanted vaccine leaking under the skin can occasionally leave a fibrous lump at the injection site, and APV may occasionally cause shock reactions. Report anything unusual to whoever gave the vaccine.

Vaccination records and compensation

According to the NIAH newsletter, only animals that were vaccinated against HS qualify for compensation under the law if they die of the disease. Keep each animal's vaccination record somewhere safe.

What should you do if you suspect HS?

Separate the sick animal, call the livestock officer straight away, and stop moving animals, because antibiotics only work if they start early. NIAH says treatment works well when given as the animal starts to show signs.

WOAH advises choosing antibiotics from susceptibility test results, because multidrug-resistant strains are emerging, and the NIAH newsletter stresses the right drug, dose and duration. Buying antibiotics and injecting them yourself puts both the animal and future treatment at risk.

Steps when an animal is sick or has died

  1. Separate the sick animal and report to the local veterinary officer quickly.
  2. The DLD's December 2022 warning listed these channels: livestock officers or volunteers, the village or subdistrict head, the local council, the DLD 4.0 app, or the hotline 06-3225-6888.
  3. Do not eat animals that died; bury or burn them.
  4. After handling a sick animal, shower and change clothes and boots before going into a pen of healthy animals.
  5. During an outbreak, keep animals off fields, paddies and wallows that sick animals have used.

What officials do in an outbreak area

HS is a listed epidemic disease under Thailand's Animal Epidemics Act B.E. 2558 (2015). The district livestock officer can declare a temporary epidemic zone, inside which no cattle, buffalo or carcasses may be moved in, out or through without a vet's written permission.

In the July 2020 outbreak, the DLD took samples for culture and drug-sensitivity testing, declared temporary zones, ordered animals held in place, set up checkpoints, vaccinated cattle and buffalo within 5 km of each outbreak, and buried carcasses and disinfected the sites. Its 31 July summary counted 9,676 animals vaccinated around the outbreak sites and 67,565 more in a mass campaign in neighbouring areas.

Can people catch hemorrhagic septicemia?

There is no confirmed human infection with the HS serotypes. WOAH states there are no confirmed reports of human infections with P. multocida B:2 and E:2, but other serotypes do infect people, so it advises precautions to avoid exposure when handling sick animals or carcasses. The DLD's 2020 statement also described HS as an animal disease that does not infect people.

Before next year's rains: a checklist

  • Every animal four months or older has had its HS vaccine, at least a month before the rains.
  • Calves that had a first dose: ask the district livestock office about the booster.
  • Each animal's vaccination record is kept.
  • Pens have a roof against rain and wind and bedding, and are cleaned and disinfected regularly, as the DLD Director-General recommends.
  • Clean water and enough feed are on hand, so animals don't go hungry during heavy rain or floods.
  • Animals are not bought, sold or trucked while there are outbreak reports nearby.
  • The district livestock office's number is saved, and the DLD 4.0 app is installed.

Sources

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