The Council for Scientific and Industrial Research (CSIR) is developing Lab-on-Chip (microfluidic) technologies for rapid diagnostics and identification of Brucella outbreaks in cattle at the point-of-care such as farms and abattoirs.
This month, KwaZulu-Natal was hit by the Brucella Bacteria outbreak, with over 400 confirmed cases reported.
The bacteria causes spontaneous abortions in animals and joint pains in humans.
In South Africa, Brucella is carried by cattle and is transmitted to humans commonly through unpasteurised milk. Infected mothers who are breastfeeding may transmit the infection to their infants.
Senior Researcher at CSIR’s Veterinary Molecular Diagnostics and Vaccines Unit, Dr Essa Suleman says, “These technologies would enable authorities to identify outbreaks earlier facilitating better and faster outbreak responses to limit the spread of the disease. Furthermore, the CSIR is also developing a novel plant-produced vaccine candidate against Brucella melitensis, which infects sheep that is currently undergoing efficacy trials.”
Suleman says the latest research on Brucella focuses on how pathogens cause disease in animals and humans.
He says, “There is also a significant amount of research being done to develop vaccines, particularly a human vaccine which currently does not exist, as well as research to develop rapid diagnostic and prognostic tests and the development of new therapeutics.”
Suleman says Brucellosis is a zoonotic disease (spread from animals to humans) that was first discovered during the 1850s in Malta and is also known as Malta Fever, Mediterranean Fever or undulant fever.
He says, “It is caused by members of the genus Brucella, which are small, gram-negative, non-motile, rod-shaped bacteria. Brucella abortus, B. suis, B. canis and B. melitensis are four species that can infect humans. B. melitensis primarily infects sheep and goats while B. abortus primarily infects cattle.”
Regions affected worldwide
Suleman says Brucella species are found in animals worldwide but are most common in developing countries, sub-Saharan Africa, South America, Asia, the Mediterranean and Middle East.
“Several countries in Western and Northern Europe, Canada, Japan, Australia and New Zealand are believed to be free from Brucella.”
He says Brucellosis has been a problem in many countries and regions.
“The disease has been controlled and even eradicated in some countries through expensive and lengthy animal vaccination programs followed by the culling of infected animals during later outbreaks. However, in developing countries or areas were the pathogen is endemic, eradication may be too costly or not feasible. Outbreaks in these areas have serious health and economic implications.”
Complications in humans and animals
Suleman says Brucella infection generally occurs in susceptible animals by direct contact with infected animals or via contact with discharges from infected animals which may contaminate the environment.
“ Aborted foetuses, placental membranes or fluids, and other vaginal discharges present after an infected animal has aborted or calved are all highly contaminated with infectious Brucella organisms that can be easily spread to other animals. The bacteria can survive in the environment for several months, particularly in cool, moist conditions, resulting in animals being infected by ingesting the bacteria. The bacteria also colonises the udder and contaminates milk, causing infections in calves.”
He says Brucellosis in humans primarily occurs through consumption of unpasteurised milk, milk products (e.g. soft cheeses) and undercooked meat from infected animals.
“Veterinarians, farmers, abattoir and laboratory workers are also vulnerable to infection as they handle infected animals, aborted foetuses and tissues. Human to human transmission of Brucella does not usually occur, although this may be possible under certain scenarios e.g. blood transfusion, organ transplants, sexual contact and breastfeeding.”
Suleman says in humans, symptoms may develop several days to months after initial infection and may include intermittent or irregular fever, headache, weakness, depression, profuse sweating, chills, weight loss and general aching.
“Muscular pain, night sweats (often very foul-smelling perspiration) are classical signs of infection. The duration of the disease can vary from a few weeks to many months or even years (if not treated). In animals, the most important symptoms are abortion, weak offspring, arthritis, infertility and reduced milk production.”
He says the best way to prevent human Brucellosis is by controlling infections in animals.
“However, this requires extensive and lengthy vaccination programs combined with the culling of infected animals which is very costly and thus not feasible in many countries. Additionally, control and prevention may be difficult in countries where Brucella species are endemic and that have certain wildlife species (e.g. buffalo) that can act as reservoirs for the disease. Proper pasteurisation of milk also significantly reduces risk of human infections. “
Suleman says there is no treatment for the disease in animals. “ In humans, antibiotics (e.g. rifampicin, doxycycline, tetracycline etc.) have proved effective in treating the disease but may cause side effects such as vomiting, nausea and loss of appetite. Despite antibiotic treatment, relapse may still occur in some patients. “
He adds that generally, the mortality rate from Brucellosis is very low, however, complications associated with Brucellosis, including endocarditis, myocarditis and pericarditis can result in death.
Department of Agriculture and Rural Development’s Dr Themba Sikhakhane says the outbreak of Brucella Bacteria in the northern part of KZN has the potential to affect red meat production: