Increasing Acai Sales Demands Vigilance for Chagas Disease

Teresa Santos and Ilana Polistchuck, MD

October 13, 2017

Between 100 and 150 new cases of acute Chagas disease are reported every year in Brazil, with most outbreaks linked to food transmission[1].Although the confirmation of food as the mode of transmission is still a challenge, new tools are starting to change this scenario.

At a symposium conducted during the 20th Brazilian Conference on Infectious Disease, held in Rio de Janeiro, Dr Maria Aparecida Shikanai Yasuda of Sao Paulo University commented that real-time quantitative polymerase chain reaction assays can detect the presence of Trypanossoma cruzi in food products such as acai[2].

The number of Chagas cases tends to increase between July and December, the dry season, during which its vector (Triatoma infestans, "barber bug") is most greatly dispersed, but "the increase of the acai palm trade now demands year-round vigilance," Dr Aparecida said.

Other foods also need evaluation, such as bacaba (a fruit similar to the acai palm, originating in the Amazon), heart of palm, and sugarcane, given that once they are infected with parasites or feces, or with the infected secretions of marsupials, they can also transmit the disease[3]. Colombia and Venezuela have already experienced outbreaks related to the consumption of contaminated guava, orange, and tangerine juice[4,5].

According to Dr Aparecida, "These days, the oral transmission of Chagas disease outbreaks is a reality throughout Latin America, and not necessarily in endemic areas alone."

Features of Oral Transmission

A case is considered to be under suspicion of oral transmission when there are clinical displays (swollen faces or limbs, exanthema, adenopathy, splenomegaly, acute heart disease, bleeding, jaundice, Romana's sign, or inoculation chagoma), and the absence of other probable forms of transmission. Confirmation via direct parasitologic examination, with the probable absence of other transmission forms, and the simultaneous occurrence of more than one case with epidemiologic links constitute a case of probable oral transmission.

In addition to confirmation by direct parasitologic examination, when other transmission channels can be excluded and the epidemiologic evidence in a certain food can be determmined as a source of transmission, then a case of oral transmission can be confirmed[3].

The incubation period for oral transmission is between 3 and 22 days, which is longer than for vectorial transmission (4 - 15 days) but shorter than blood transmission (30 - 112 days)[6]. An in vitro study of acai palm pulp proved that T cruzi can survive or maintain its virulence in that food under various conditions, and neither refrigeration nor freezing is adequate to prevent acute Chagas disease transmitted by food[7]. Heating acai palm pulp above 43°C for 20 minutes has been shown to be an efficient way to prevent the transmission of the disease[8].

Women of Childbearing Age

One of the main problems associated with orally transmitted Chagas disease outbreaks is, according to Dr Aparecida, its unpredictability. Data from the World Health Organization (WHO) indicate that there are between 8 and 10 million people infected with T cruzi in Latin America, 1.8 million of them women of childbearing age (15 - 44 years old).

A systematic review and a meta-analysis revealed that in 2010, there were 34,629 pregnant women in Brazil infected with T cruzi, and between 312 and 1073 infants were born with a congenital infection[9].

According to Dr Aparecida, maternal-fetal transmission depends on a few variables, among them, the level of parasitemia, the mother's immunologic status, infectious strain, and placental factors. Currently, treatment of patients with acute Chagas disease is based on the administration of benznidazole, a drug incorporated into the Brazilian Unified Health System.

"The problem right now is that we just do not have the drug for all patients," said Dr Aparecida, emphasizing the importance of the Chagas Disease Clinical Protocol and Therapeutic Guidelines[10].

This article was originally published in Medscape's Portuguese edition .

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