Increasing incidence of pertussis in Brazil: a retrospective study using surveillance data

Abstract

BackgroundMany countries have reported an increase in the incidence of pertussis, which has become a global public health concern.MethodsIn this study, the epidemiology of pertussis in Brazil was assessed retrospectively using surveillance data gathered from case notification forms from 2007 to 2014.ResultsFrom 2007 to 2014, 80,068 suspected cases of pertussis were reported in Brazil. Of these, 24,612 (32 %) were confirmed by various criteria. The annual distribution of confirmed cases demonstrated a significant increase in incidence rate since 2012. A seasonal pattern in which cases occur most frequently between the end of spring and midsummer has been identified. Among the confirmed cases, 34.5 % occurred in infants aged 0–2 months, 22.4 % occurred in infants aged 3–6 months, 21 % occurred in children aged 7 months to 4 years, and 8 % were reported in adults >21 years. Of the confirmed cases, 47.2 % met only clinical criteria, 15.5 % met clinical and epidemiological criteria, and 36.6 % were confirmed in a laboratory. The overall case fatality rate was 2.1 %, reaching 4.7 % among infants aged 0–2 months. The complications most commonly reported in the notification forms were pneumonia, encephalitis, dehydration, otitis, and malnutrition. Of the confirmed cases, 23.1 % occurred in subjects who received at least 3 doses of the pertussis vaccine. Within this group, there were 1098 infants aged 7 to 15 months and 2079 children aged 16 months to 4 years. In 2012, 18 states did not achieve 95 % immunization coverage, a number that dropped to 10 and 6 in 2013 and 2014, respectively.ConclusionsBrazil’s main challenges in facing pertussis resurgence will be to offer the best quality medical attention to reduce mortality, to improve the infrastructure for laboratory diagnosis and to increase vaccination coverage. Additional studies to assess the effectiveness of the current vaccination schedule and basic research on the genetics and evolution of circulating B. pertussis strains are also needed.

Pertussis (whooping cough)

“…In the UK and Australia, which have an accelerated primary vaccination schedule at 2, 3, and 4 months, higher incidence and hospitalisation rate is observed in those under 3 months old compared with older infants 7. Mortality is high in this group,189 possibly due to an immature immune system and incomplete primary immunisation 10…”

“…Infants have a high risk of mortality due to pulmonary hypertension and resultant cardiac failure and shock 184950. Children are prone to dehydration and anorexia.…”

“…Children are prone to dehydration and anorexia. Rarely, seizures and encephalopathy have been reported 1152223. Acute cough-related complications include pneumothorax, aspiration, urinary incontinence, and increased risk of rib fractures, particularly in older adults 23.…”

“…Pertussis, also known as whooping cough, is caused by the Gram negative bacterium Bordetella pertussis 1. It is transmitted via airborne droplets and is highly infectious 2.…”

Immunization against Pertussis: An Almost Solved Problem or a Headache in Public Health

“…After 2014 the Brazilian National Immunization Program began to ofer Tdap to pregnant women [102]. Despite the high vaccination coverage (>95%) since 2011, a signiicant increase in the number of reported cases of pertussis in Brazil has been observed, with an incidence rate in 2013 of 14,058 conirmed cases/100,000 in infants under one year of age, the majority of cases and deaths in unvaccinated children younger than 4 months old [103].…”