Malaria outbreak investigation in region non-endemic of Brazil, June to August of 2021: a case–control study
- Vector-borne
- Zoonotic
- Environmental Health (Including Water & Sanitation)
- One Health
Background
Malaria cases in the extra-Amazonian region represents less than 1% of cases in Brazil. The understanding of this disease epidemiology in these areas is essential for outbreaks control. The objective was to investigate risk factors in a malaria outbreak in municipality of Itabela/Bahia state, Brazil northeast region.
Methods
A case–control study unmatched 1:3 was conducted from 4th June to 4th August of 2021. The cases were all symptomatic and from rural areas in Itabela. The controls randomly selected were malaria negatives and from the same area. Descriptive statistics were conducted for sociodemographic, environmental and behavioral characteristics. Logistic regression was performed to estimate adjusted odds ratios (AOR), 95% confidence intervals (95% CI).
Results
There were 49 individuals confirmed for Plasmodium vivax by microscopy and antigen based rapid diagnostic tests, which 40 cases were matched to 108 controls. 55.6% were males and the mean age was 35±22 years. All individuals were treated, 18.5 % were hospitalized and there were not death tolls. In multivariate analysis, using forward stepwise logistic regression, the existence of water sources near houses was associated 4.31 times odds of getting sick from malaria (95% CI=1.87-9.91) and making activities outdoor from 6 p.m. to 8 p.m. increased the chances of getting infected 2.67 times than compared to controls (95% CI=1.05-6.79). A protective factor identified were the use of alternative methods for mosquito controls (such as the use of pesticides and/or chemicals against ticks around the house and the use of smoking in the house) (AOR=0.22; 95% CI=0.09-0.58).
Conclusion
The houses’ proximity to water bodies and outdoor activities during dusk were risk factors associated with malaria outbreak in a rural area in Itabela. It was recommended maintenance controls actions implanted in the area and evaluation of the residual concentration of insecticides applied on the walls and mosquito nets.
Malaria cases in the extra-Amazonian region represents less than 1% of cases in Brazil. The understanding of this disease epidemiology in these areas is essential for outbreaks control. The objective was to investigate risk factors in a malaria outbreak in municipality of Itabela/Bahia state, Brazil northeast region.
Methods
A case–control study unmatched 1:3 was conducted from 4th June to 4th August of 2021. The cases were all symptomatic and from rural areas in Itabela. The controls randomly selected were malaria negatives and from the same area. Descriptive statistics were conducted for sociodemographic, environmental and behavioral characteristics. Logistic regression was performed to estimate adjusted odds ratios (AOR), 95% confidence intervals (95% CI).
Results
There were 49 individuals confirmed for Plasmodium vivax by microscopy and antigen based rapid diagnostic tests, which 40 cases were matched to 108 controls. 55.6% were males and the mean age was 35±22 years. All individuals were treated, 18.5 % were hospitalized and there were not death tolls. In multivariate analysis, using forward stepwise logistic regression, the existence of water sources near houses was associated 4.31 times odds of getting sick from malaria (95% CI=1.87-9.91) and making activities outdoor from 6 p.m. to 8 p.m. increased the chances of getting infected 2.67 times than compared to controls (95% CI=1.05-6.79). A protective factor identified were the use of alternative methods for mosquito controls (such as the use of pesticides and/or chemicals against ticks around the house and the use of smoking in the house) (AOR=0.22; 95% CI=0.09-0.58).
Conclusion
The houses’ proximity to water bodies and outdoor activities during dusk were risk factors associated with malaria outbreak in a rural area in Itabela. It was recommended maintenance controls actions implanted in the area and evaluation of the residual concentration of insecticides applied on the walls and mosquito nets.