Volume 23, Number 9—September 2017
Research
Convergence of Humans, Bats, Trees, and Culture in Nipah Virus Transmission, Bangladesh
Table 1
Characteristic |
Villages with cases, n = 60 |
Nearby control villages, n = 73 |
p value† |
Distant control villages, n = 74 |
p value‡ |
Human population | |||||
No. persons in village | 1,476 (1,202–1,749) | 1.389 (1,102–1,676) | 0.20 | 1,392 (1,010–1,774) | 0.10 |
No. persons/km2 |
1,168 (1,167–2,169) |
1,173 (592–1,754) |
0.78 |
1,335 (456–2,213) |
0.95 |
Pteropus bat population | |||||
Proportion of villages where P. medius bats were observed roosting or within 5 km of village boundary | 0.85 (0.76–0.94) | 0.86 (0.78–0.94) | 0.86 | 0.76 (0.66–0.86) | 0.19 |
No. bats roosting in village or within 5 km of village boundary |
554 (319–789) |
620 (364–875) |
0.60 |
407 (226–587) |
0.37 |
Proportion of respondents reporting large fruit bats | |||||
Roosted nearby during the day in past month | 0.25 (0.17–0.34) | 0.37 (0.29–0.45) | 0.060 | 0.40 (0.31–0.49) | 0.024 |
Fly overhead at dusk | 0.51 (0.43–059) | 0.64 (0.56–0.70) | 0.019 | 0.77 (0.71–0.83) | <0.001 |
Visit fruit trees at night | 0.43 (0.35–0.51) | 0.52 (0.45–0.60) | 0.10 | 0.53 (0.45–0.61) | 0.090 |
Date palm sap and fruiting trees | |||||
No. trees in village within a 500-m radius of village boundary | 120 (88–152) | 95 (78–111) | 0.91 | 101 (65–138) | 0.14 |
Proportion of households with fruiting trees on premises | 0.97 (0.94–0.99) | 0.97 (0.94–0.98) | 0.81 | 0.94 (0.92–0.96) | 0.14 |
No. fruiting trees on each household premise |
56 (46–68) |
52 (43–61) |
0.81 |
108 (45–170) |
0.47 |
Human behavior | |||||
Proportion of villages with >1 date palm sap collector | 0.60 (0.47–0.63) | 0.40 (0.29–0.52) | 0.026 | 0.51 (0.40–0.63) | 0.32 |
No. sap collectors in villages | 4.5 (1.8–7.3) | 2.3 (1.0–3.6) | 0.41 | 3.7 (1.9–5.6) | 0.54 |
Proportion of villages with >1 fresh date palm sap seller | 0.38 (0.28–0.51) | 0.32 (0.21–0.43) | 0.45 | 0.39 (0.26–0.51) | 0.92 |
No. (%) fresh sap sellers in villages | 1.9 (0.6) | 0.9 (0.2) | 0.16 | 2.4 (0.6) | 0.47 |
Proportion of households where >1 person drank raw sap | 0.61 (0.54–0.68) | 0.49 (0.42–0.56) | 0.014 | 0.31 (0.24–0.39) | <0.001 |
Proportion of households where someone drank raw sap >1×/wk during the past harvest season | 0.35 (0.27–0.43) | 0.29 (0.23–0.35) | 0.26 | 0.21 (0.16–0.27) | 0.005 |
No. household residents who drank >1 glass of raw date palm sap when in season | 3.3 (2.7–3.9) | 2.1 (1.8–2.5) | 0.001 | 1.5 (1.1–1.9) | <0.001 |
Proportion of villages where >1 household fed raw date palm sap to livestock | 0.16 (0.10–0.21) | 0.12 (0.06–0.18) | 0.66 | 0.14 (0.08–0.21) | 0.78 |
Proportion of villages where >1 person hunted bats | 0.53 (0.40–0.66) | 0.64 (0.53–0.75) | 0.22 | 0.27 (0.17–0.38) | 0.002 |
Proportion of households that reported residents ate bitten fruits dropped on the ground | 0.42 (0.37–0.48) | 0.58 (0.53–0.62) | <0.001 | 0.66 (0.61–0.71) | <0.001 |
*Values are mean (95% CI) except as indicated.
†Comparison of villages with cases of Nipah virus infections with nearby control villages by using generalized linear models that account for correlations within villages for characteristics measured in household surveys.
‡Comparison of villages with cases of Nipah virus infections with distant control villages by using generalized linear models that account for correlations within villages for characteristics measured in household surveys.
1Current affiliation: Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA.
2Current affiliation: University of Michigan School of Public Health, Ann Arbor, Michigan, USA.
3Current affiliation: Medical Research Council, Banjul, The Gambia.
4Current affiliation: University of Florida, Gainesville, Florida, USA.