Brazil records increase in number of human brucellosis cases due to vaccine accident

Publicação: 7 de November de 2017

According to infectious diseases and human brucellosis expert, Dr. Marcos Vinícius da Silva, the vaccines used for animals, both cattle and goats, can develop the disease in humans

We do not have information about the real number of human brucellosis cases, we are not aware of the dimensions of this problem, only about those that reach us

Characterized as an important zoonosis spread worldwide, brucellosis a serious public health issue. Although many countries have achieved great progress controlling the disease, there are still places where the infection persists among domestic animals and, consequently, the transmission to humans take place. In Brazil, renowned infectious diseases and human brucellosis expert, Dr. Marcos Vinícius da Silva, believes the number of cases are increasing, since besides the natural transmission, currently the number of cases due to vaccine accidents have increased, since the vaccines used in veterinary medicine, both for cattle and for goats, can develop the disease in humans.

Physicians’ unfamiliarity with the disease and difficulty performing laboratory diagnosis make human brucellosis a neglected zoonosis. “It is unknown by a considerable amount of health professionals” Signs and symptoms are polymorphic, reason why it is also known as the ‘Thousand faces diseases’. Information about the patient’s epidemiological background can help in diagnostic suspicion, but this rarely happens, especially because currently we do not know de origins of our food, including meat, milk and their byproducts”, he stresses while adding a second problem diagnosing the disease, which is the low sensitivity of bacteria culture methods from patient biological samples. “Brucella is a bacteria of high infection risk for laboratory personnel handling it, requiring biosafety level (BSL) 3 laboratories. Another difficulty is the absence of good immunological laboratory tests able to diagnose both the disease originated from smooth and rough Brucella strains”, he adds.

According to estimates from the World Health Organization (WHO), the human brucellosis incidence could be five times or greater than the official numbers. Doctor Marcos Vinícius states that there is no information about the real number of cases. “We do not know the real dimension of this problem, only part of it which are the cases that reach our Tropical Diseases, Zoonosis and Unknown Fevers Ambulatory at the Emilio Ribas Infectology Institute or appointments by other health professionals that forward patients to us”, he regrets. Still according to him, human brucellosis is many times diagnosed as tuberculosis with negative smears and molecular tests. Since the symptoms of these two diseases may confused, under suspicion of tuberculosis without laboratory confirmation, a therapy scheme is introduced with rifampicin, a drug also used in brucellosis treatment. Since the TB treatment is long, it may treat brucellosis and neither the doctor nor the patient would know that in reality it was brucellosis and not TB.

In 2001, the Ministry of Agriculture, Livestock and Supply (MAPA) launched the National Program for Brucellosis Eradication and Control. According to doctor Marcos Vinícius, after this program was launched, initially we became aware of the extension and dimension of cattle brucellosis, as result of inquiries performed by that Ministry in great part of the Country. One of the measures put in practice was intensifying cattle vaccination against brucellosis and alongside, increasing cases of vaccine accidents and cases of the diseases by this transmission form. Besides brucellosis transmitted by cattle, it is also transmitted by pigs, sheep, goats and dogs, the latter totally unknown and with punctual concerning veterinary medical papers.

Only a few countries are officially free of the disease, although some cases in people returning from endemic regions are still reported. Despite advances, human brucellosis is still an important disease in several parts of the world, especially in the Mediterranean, European Countries, North and East Africa, Middle East, South and Central Asia, Central and South America, where many times it is not recognized and reported. The expansion of international travel, use of exotic products that may be infected, and import of such food also contribute the growing concerns around human brucellosis.

The disease’s prevention and control requires immediate action supported by several sectors, including those in charge of food safety and consumer education. “To avoid the disease, the first step would be reporting it among public health professionals in order for physicians to be able to recognize it. Secondly, having good sensitivity and specificity laboratory diagnostic methods with broad access to them. Thirdly, disclosing wide information to the population and veterinary medicine professionals about the disease’s epidemiology, transmission, symptoms, diagnostic, treatment and transmission by vaccine accident”, he finishes.