Rift Valley Fever virus - Epidemiology

Question 1

Where and when was RVFV first characterized?

Answer 1

In the Rift Valley of Kenya in 1930-1931 by Daubney and Hudson during an outbreak on a sheep farm.

Question 2

Large Outbreaks: Kenya

Answer 2

1950-1951
1997-1998
2006-2007

Question 3

Large Outbreaks: South Africa

Answer 3

1950-1951
1973-1975
2010-2011

Question 4

Large Outbreaks: Egypt

Answer 4

1977-1979
1993
2003

Question 5

Large Outbreaks: Middle East (Saudi Arabia & Yemen)

Answer 5

2000-2001

Question 6

Large Outbreaks: Sudan

Answer 6

1973 (only animals)
2007-2008

Question 7

Large Outbreaks: West Africa (Senegal & Mauritania)

Answer 7

1987
2022

Question 8

Large Outbreaks: East Africa (Kenya, Sudan, Somalia, Tanzania)

Answer 8

1997-1998
2006-2007

Question 9

Serologic evidence for RVFV maintenance in wildlife

Answer 9

High RVFV seroprevalence in wildlife during IEPs

Question 10

Why do sheep and goats likely have lower seroprevalence during IEPs?

What does this mean?

Answer 10

High population turnover so more susceptible hosts during outbreak periods

Question 11

What is the relationship between animal and human RVFV seroprevalence?

Answer 11

Few studies have addressed this question and none have considered the wildlife factor.

Question 12

Human risk factors for RVFV seropositivity:

Answer 12

Increasing age

Sex: Male (likely occupational)

Regular contact with animals (butchering, milking, and sheltering)

Contact with aborted animal carcasses

Consumption of products from sick animals

Question 13

Where and when was most of the RVFV serological data collected?

Answer 13

East Africa, namely Kenya during the 2000s.

Question 14

Risk factors for severe RVF:

Answer 14

Data from Kenya shows association between contact with aborted tissues and severe RVF

HIV status is associated with encephalitic RVF (van Vuren, 2015).

Question 15

What is the seroprevalence of humans?

Answer 15

Varies significantly depending on the region and year.

Meta analysis using data from 1999-2021 showed 0.15% (Madagascar) - 22% (Kenya) seropositivity during IEPs.

Question 16

What is the burden of disease in humans?

Answer 16

Almost impossible to estimate given current data.

Example: During the 2007 outbreak in Sudan, there were an estimated 75,000 cases but only about 1% were laboratory confirmed.

Question 17

When was ocular disease first recognized as a complication of RVF?

Answer 17

South Africa, 1950-1951

Question 18

When were the first fatal cases of RVF recorded?

Answer 18

South Africa, 1975

Question 19

When and where was the first recorded outbreak outside of sub-Saharan Africa?

Answer 19

Egypt, 1977-1979

Question 20

When and where was the first recorded outbreak outside of the African continent?

Answer 20

Saudi Arabia & Yemen, 2000-2001