Epidemic nephritis in Nova Serrana, Brazil

• Published in: The Lancet (British edition) Vol. 355; no. 9217; pp. 1776 - 1780
• Main Authors: Baiter, Sharon, Benin, Andrea, Pinto, Sergio Wyton Lima, Teixeira, Lucia Martins, Alvim, Gladstone Gripp, Luna, Expedite, Jackson, Delois, LaClaire, Leslye, Elliott, John, Facklam, Richard, Schuchat, Anne
• Format: Journal Article
• Language: English
• Published: London Elsevier Ltd 20-05-2000; Lancet; Elsevier Limited
• Subjects: Adolescent; Adult; Animals; Bacteria; Biological and medical sciences; Brazil - epidemiology; Case-Control Studies; Cattle; Cheese; Disease Outbreaks; Female; Food Microbiology; Glomerulonephritis; Humans; Male; Medical sciences; Nephritis - epidemiology; Nephritis - microbiology; Nephrology. Urinary tract diseases; Nephropathies. Renovascular diseases. Renal failure; Pasteurization; Streptococcal Infections - epidemiology; Streptococcal Infections - microbiology; Streptococcus equi - isolation & purification; South America; Brazil; America; Nova Serrana Brazil; Kidney disease; Human; Glomerulonephritis; Urinary system disease; Etiopathogenesis; Case control study; Epidemiology; Infection; Streptococcaceae; Streptococcus equi subsp. zooepidemicus; Geographical division; Outbreak; Public health organization; Environment impact; Bacteriosis; Bacteria; Micrococcales; Public health
• ISSN: 0140-6736; 1474-547X
• DOI: 10.1016/S0140-6736(00)02265-0

Outbreaks of nephritis have been rare since the 1970s. From December, 1997, to July, 1998, 253 cases of acute nephritis were identified in Nova Serrana, Brazil. Seven patients required dialysis, and three patients died. We did a case-control study to investigate the cause of the outbreak.
Using a matched cluster design, we examined seven recent patients, their family members (n=23), and members of neighbourhood-matched control households (n=22). We subsequently interviewed 50 patients and 50 matched controls about exposure to various dairy products. We also cultured dairy foods and took udder-swab and milk samples from cows.
Throat cultures indicated that nephritis was associated with group C
Streptococcus equi subspecies zooepidemicus, a cause of bovine mastitis.
S zooepidemicus was detected in four of seven case households (six of 30 people) and no control households (p=0·09). Patients were more likely than matched controls to have consumed a locally produced cheese called
queljo fresco (matched odds ratio 2·1, p=0·05). The nephritis attack rate was 4·5 per 1000 in Nova Serrana but 18 per 1000 in the village Quilombo do Gaia (p=0·003). The largest supplier of unpasteurised
queijo fresco was a farm in Quilombo do Gaia.
S zooepidemicus was not detected in food samples or in swabs collected from cows in August, 1998, although mastitis was evident among cows on the suspected farm. Throat cultures of the two women who prepared cheese on this farm yielded the outbreak strain of
S zooepidemicus. After the cheese was removed from the distribution system, no further cases were reported.
A large outbreak of glomerulonephritis was attributed to
S zooepidemicus in unpasteurised cheese. This outbreak highlights the dangers of consuming unpasteurised dairy products and need for global efforts to promote food safety.