Maternal transmission of Small Ruminant Lentivirus has no epidemiological importance

Area of Science:

• Veterinary Virology
• Epidemiology of Infectious Diseases

Background:

• Small ruminant lentivirus (SRLV) causes maedi-visna in sheep and goats.
• The transmission dynamics between maternal and horizontal routes are not well understood.
• Understanding transmission is crucial for effective disease control strategies.

Purpose of the Study:

• To evaluate the relative importance of maternal versus horizontal transmission of SRLV.
• To determine the impact of maternal transmission on SRLV outbreak dynamics.
• To identify the most effective strategies for controlling SRLV spread.

Main Methods:

• Literature review on SRLV transmission.
• Theoretical modeling of disease spread dynamics.
• Analysis of transmission efficiency rates.

Main Results:

• Maternal transmission of SRLV is inefficient, infecting 10-25% of lambs from infected ewes.
• Maternal transmission alone is insufficient to initiate or sustain outbreaks.
• Maternal and horizontal transmissions are additive, with horizontal transmission being the primary driver of outbreaks.
• Preventing maternal transmission aids in creating clean flocks but does not control outbreaks if horizontal transmission is prevalent.

Conclusions:

• Control strategies for SRLV (maedi-visna) must prioritize minimizing horizontal transmission.
• While reducing maternal transmission is beneficial for flock health, it is not the key to outbreak control.
• Focusing efforts on preventing horizontal spread is essential for effective management of SRLV.