Leptospirosis

Leptospirosis is a type of disease that appears in cattle, especially during wet weather.

There are over 200 types of Leptospira, which are small, spiral-shaped bacteria. The two most important types that affect cattle are L. Pomona and L. hardjobovis. These bacteria can also infect humans, making this disease a concern for the health and safety of people working in rural areas.

Causes

The bacteria are found in the kidneys of cattle but can also be in the reproductive tract in females. It can stay in the animal's body for a long time and spread through urination, birth, or abortion. The disease can also spread through contaminated water, food, soil, and pasture.

Animals and humans can catch the disease through the:

• mouth
• eyes
• nose
• broken skin
• contact with contaminated water or afterbirth.

Both animals and humans need protection and intervention in these areas to prevent infection.

The bacteria can live for a long time in a moist environment. That's why this disease can suddenly appear and spread during wet conditions. The disease can also spread more during floods, heavy rain, or runoff.

Some animals that appear healthy can still carry the bacteria. Other animals such as sheep, goats, and horses, can also get this disease. However, they're less likely to be affected than cattle.

Signs and symptoms

The signs of Leptospirosis in a cattle herd vary depending on the strain:

• hardjobovis causes symptoms of mastitis, especially in dairy cattle, where it is easy to see problems with milk production.
• Pomona affects pigs and calves. This strain can spread through wild pig populations, making them a constant source of infection. Calves with L. Pomona often have high fevers, jaundice, and red-brown urine, which is why the disease is sometimes called 'red water'. This strain can be fatal to calves.

Both strains cause cattle to have abortions, usually in the last 3 months of pregnancy. If the herd hasn't had the disease before, there can be many abortions at once, called 'abortion storms'. These abortions happen a few weeks after the cattle are exposed to the bacteria, which build up in their reproductive organs.

The number of abortions may reduce as the disease spreads through the herd and the cattle build immunity. This immunity isn't permanent, and the disease will come back in cycles, with different levels of impact. The immunity will only protect against the specific strain of bacteria they were exposed to.

Diagnosing an infected animal is usually completed through a blood sample. Samples can also be taken from aborted foetuses, afterbirth, or urine cultures to detect the disease. These are usually harder to collect.

Impacts

This disease causes production losses and can have a huge impact if people catch it. In humans, the disease can cause severe flu-like symptoms. In serious cases, it can lead to neurological problems. Mild cases may recover in 1-2 weeks, while severe cases might prevent a person from working for months.

Some producers may experience financial losses due to the disease among their cattle.

Treatment

Controlling and preventing the disease through vaccination is the most cost-effective option. The Leptospirosis vaccine is available commercially in a 2-strain form. It can also be combined with vaccines for other diseases to save time and effort in managing livestock.

Use the following guides to vaccinate cattle:

• For unvaccinated herds, the first vaccination requires 2 shots given 4-6 weeks apart, followed by an annual booster. Animals new to the property need the same vaccination program before joining the herd.
• To maintain immunity, vaccinate cows and heifers 4-6 weeks before calving to protect the calf.
• Calves from mothers vaccinated late in pregnancy need vaccination at 3-4 months old.
• Calves from unvaccinated mothers need vaccinating from one month old. Calf vaccinations also need 2 doses.

Herds at high risk may need the annual booster every 6 months to ensure strong immunity.

While vaccination can prevent the infection, it might not eliminate the bacteria from all animals.