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Volume 30, Number 9—September 2024
Research

Lower Microscopy Sensitivity with Decreasing Malaria Prevalence in the Urban Amazon Region, Brazil, 2018–2021

Priscila T. Rodrigues, Igor C. Johansen, Winni A. Ladeia, Fabiana D. Esquivel, Rodrigo M. Corder, Juliana Tonini, Priscila R. Calil, Anderson R.J. Fernandes, Pablo S. Fontoura, Carlos E. Cavasini, Joseph M. Vinetz, Marcia C. Castro, Marcelo U. FerreiraComments to Author , and on behalf of the Mâncio Lima Cohort Study Working Group1
Author affiliations: Centro Nacional de Pesquisa em Energia e Materiais, Campinas, Brazil (P.T. Rodrigues); University of São Paulo, São Paulo, Brazil (P.T. Rodrigues, I.C. Johansen, W.A. Ladeia, F.D. Esquivel, R.M. Corder; J. Tonini, P.R. Calil, A.R.J. Fernandes, P.S. Fontoura, M.U. Ferreira); State University of Campinas, Campinas (I.C. Johansen); Universidade Federal do ABC, Santo André, Brazil (J. Tonini); Instituto Federal de Educação, Ciência e Tecnologia de Minas Gerais, Belo Horizonte, Brazil (A.R.J. Fernandes); Ministry of Health, Brasília, Brazil (P.S. Fontoura); Faculdade de Medicina de São José do Rio Preto, São José do Rio Preto, Brazil (C.E. Cavasini); Yale School of Medicine, New Haven, Connecticut, USA (J.M. Vinetz); Universidad Peruana Cayetano Heredia, Lima, Peru (J.M. Vinetz); Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA (M.C. Castro); Global Health and Tropical Medicine, NOVA University of Lisbon, Lisbon, Portugal (M.U. Ferreira); Institute of Hygiene and Tropical Medicine, NOVA University of Lisbon (M.U. Ferreira)

Main Article

Table 2

Factors associated with Plasmodium spp. infection and clinical malaria, as revealed by mixed-effects multiple logistic regression analysis, in the urban population of Mâncio Lima, Brazil, 2018–2021*

Factor Outcome
P. vivax infection
 P. falciparum infection
 Clinical malaria
OR (95% CI) p value OR (95% CI) p value OR (95% CI) p value
Individual-level variables
Age
<10 Referent Referent Ref 1 Ref
10–19 3.35 (1.99–5.67) <0.0001 2.48 (0.97–6.33) 0.057 3.49 (1.01–12.11) 0.048
20–29 4.00 (2.22–7.19) <0.0001 3.57 (1.38–9.25) 0.009 6.24 (1.82–21.46) 0.004
30–39 3.39 (1.99–5.80) <0.0001 2.29 (0.90–5.83) 0.082 4.34 (1.31–14.41) 0.017
40–49 3.40 (1.83–6.33) <0.0001 3.35 (1.21–9.26) 0.020 6.97 (2.16–22.53) 0.001
50–59 2.71 (1.38–5.31) 0.004 3.11 (1.10–8.81) 0.032 4.98 (1.27–19.53) 0.021
>60 3.94 (2.07–7.49) <0.0001 3.74 (1.41–9.91) 0.008 8.56 (2.52–28.98) 0.001
Trend
0.003
0.011
<0.0001
Sex
F Referent Referent Referent
M
 1.04 (0.79–1.38)
 0.767
1.72 (1.20–2.47)
 0.003
0.72 (0.48–1.06)
 0.095
Any past malaria
No Referent Referent Referent
Yes
 2.39 (1.70–3.34)
 <0.0001
3.27 (1.93–5.52)
 <0.0001
4.29 (2.58–7.12)
 <0.0001
Bed net use past night
No Referent Referent Referent
Yes, not treated 0.70 (0.48–1.02) 0.063 0.74 (0.40–1.34) 0.318 0.42 (0.23–0.76) 0.004
Yes, insecticide-treated
 0.91 (0.67–1.23)
 0.530
0.84 (0.52–1.37)
 0.494
0.59 (0.35–1.00)
 0.051
Household-level variables
Wealth index quartile
1, poorest Referent Referent Referent
2 0.60 (0.44–0.82) 0.001 0.53 (0.31–0.90) 0.019 0.52 (0.28–0.93) 0.028
3 0.46 (0.30–0.71) <0.0001 0.63 (0.36–1.07) 0.092 0.52 (0.29–0.94) 0.029
4, wealthiest 0.39 (0.22–0.71) 0.002 0.51 (0.23–1.12) 0.094 0.39 (0.12–1.27) 0.118
Trend
<0.0001
0.064
0.018
Presence of eave gaps
Yes Referent Referent Referent
No
 0.71 (0.42–1.19)
 0.194
0.47 (0.24–0.95)
 0.034
0.11 (0.03–0.46)
 0.002
Study wave number and dates
1, Apr–May 2018 Referent Referent Referent
2, Sep–Oct 2018 1.61 (1.05–2.49) 0.030 2.26 (1.17–4.34) 0.014 3.78 (1.91–4.50) <0.0001
3, May–Jun 2019 1.50 (0.96–2.33) 0.073 2.29 (1.27–4.13) 0.006 2.15 (0.97–4.75) 0.058
4, Sep–Oct 2019 0.77 (0.48–1.25) 0.294 1.18 (0.56–2.49) 0.664 0.56 (0.20–1.60) 0.283
5, Oct–Nov 2020 0.54 (0.32–0.92) 0.025 0.68 (0.29–1.59) 0.378 0.48 (0.16–1.41) 0.183
6, Apr–May 2021 0.24 (0.13–0.42) <0.0001 0.43 (0.17–1.05) 0.063 0.10 (0.01–0.83) 0.032
7, Oct–Nov 2021
 0.26 (0.15–0.47)
 <0.0001
0.34 (0.11–1.02)
 0.053
0.56 (0.18–1.71)
 0.308
No. observations† 11,676
 11,615
 11,569

*Infection is defined as a positive genus-specific PCR result confirmed by species-specific TaqMan assay positive for Plasmodium vivax or P. falciparum, regardless of any symptoms. Clinical malaria is defined as a positive genus-specific PCR result confirmed by species-specific TaqMan assay positive for P. vivax or P. falciparum. in a study participant who reported symptoms (fever, chills, or headache) within the previous 7 days. Note that clinical malaria may be due to P. vivax, P. falciparum, or both species (mixed infections). OR, odds ratio. †The numbers of observations differ among outcomes because some exposure categories were dropped from the analysis in order to allow logistic models for P. falciparum infection and clinical malaria to converge.

Main Article

1Group members are listed at the end of this article.

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