We are going to focus on 2 types of Vector Borne disease - Summer Mastitis and Infectious Bovine Keratoconjunctivitis. 

Summer Mastitis

Summer mastitis generally occurs in non-lactating animals (cows and heifers) during the summer months. It is a bacterial disease caused by a number of bacteria acting together (synergistically).  It is believed to be spread primarily by the fly Hydrotea irritans.

In cattle, large numbers of this fly cluster on the ventral abdomen and udder and the bacteria is mechanically transmitted from animal to animal.  

The fly Hydrotea irritans lives in sheltered areas such as bushes/trees and only has the ability to fly in very calm, damp, humid conditions. As a result of this, the incidence of summer mastitis is highly variable and tends to be associated with ‘problem fields’ e.g. adjacent to woodland.

Disease may be present for up to a week before the animals appears systemically ill which is why it is important to check stock frequently during high risk periods. Be observant and look for swollen/enlarged teats - the consequences of summer mastitis are severe and animals may abort/die if untreated.

Flies can also be involved in causing other cases of mastitis in lactating cattle, both by direct transmission and irritation/trauma to teats, so it is important to ensure good fly control in milking as well as dry cows.

Infectious Bovine Keratoconjunctivitis

This disease is usually called ‘New Forest Eye’ or ‘Pink eye’.  It is a highly infectious disease caused by the bacteria Moraxella bovis.  It can spread rapidly during the summer months and is more common in young stock.

Head and nuisance flies act as mechanical vectors for the spread of this disease. The ocular lesions are very painful and disrupt grazing patterns resulting in poor performance and weight loss, and can cause blindness if left untreated.