New means to control spread of Brucellosis in livestock and humans

Brucellosis is among the most important zoonotic diseases. The disease, spreads when one consumes raw contaminated animal products, including milk, or comes into contact with the fluids of an infected animal. It is caused by a group of bacteria from the genus Brucella, which attacks both humans and livestock.

It affects both humans and animals thus, is a disease of immense public heath significance, prevalent in many countries, including Kenya.

There are two species circulating in several livestock hosts and humans in the country’s endemic zones.

However, this could soon be a thing of the past among Kenyan livestock farmers.

This follows a new finding paving the way for targeted control of the disease. CGS Space, a repository of agricultural research output, reveals in a study.

Titled, Molecular Epidemiology of Brucella Species in Mixed Livestock-Human Ecosystems in Kenya, the study says B. abortus and B. melitensis are the dominant Brucella species circulating in several livestock hosts and humans.

Both species of the Brucella bacteria have been detected in cattle, sheep, goats, camels, and humans.

The research was conducted by a team of scientists from the International Livestock Research Institute (ILRI) in the pastoral counties of Narok and Marsabit, where high numbers of livestock are kept in close contact with humans.

Serum samples from 228 cattle, 162 goats, 158 sheep, 49 camels and 257 humans from the two counties were collected for the study seen as a huge breakthrough in the fight against Brucellosis. The researchers also sampled information on age, location and history of abortion or retained placenta from the selected livestock. For the human participants, ILRI used data on age, gender and location of residence to come up with their findings.

According to the findings, associations between Brucella species and the different vulnerable hosts found evidence of a possible cross-transmission in areas where close interaction between different animals occurs.

“The congregation of different animal species around communal watering points, keeping of mixed herds, and sharing of grazing sites increases the chances of cross transmission of Brucella spp,’’ reads a part of  the report.

The research was conducted by a team of scientists from Afrique One-ASPIRE, Maseno University, University of Embu, Sokoine University of Agriculture, University of Liverpool, Centre Suisse de Recherches Scientifiques, Nelson Mandela African Institute of Science and Technology, Vétérinaires Sans Frontières Suisse, the University of Glasgow and ILRI.

Brucella abortus is most common in cattle and camels, while infection in sheep and goats is mainly associated with B. melitensis. Humans are exposed to both B. abortus and B. melitensis, suggesting that cattle, sheep, goats and camels could be playing a role in the zoonotic transmission.

The study further revealed that camels are more likely to test positive for Brucella than other animals due to the high frequencies of migration and sharing of grazing areas and watering points.

The authors noted that people aged between 21 and 40 in Narok and Marsabit are more likely to test positive for Brucella due to their primary responsibility of herding, milking, and helping animals to give birth. This predisposes them to exposure compared to those below 21 years.

The study is a breakthrough enabling animal and human health experts to better understand the epidemiology of brucellosis and develop targeted disease control programmes.

Detection of the two zoonotic Brucella species in humans and animals highlights the importance of One Health prevention strategies targeting multiple host species, especially in the multi-host livestock populations.