Over the last three years, CPW has received over 14,000 reports of sightings and conflicts with bears. In 2022, CPW will be offering financial resources to communities in an effort to reduce conflicts with bears across Colorado. We discuss that, the sources of conflict and the behavior of bears in this episode with Area Wildlife Manager Adrian Archuleta.
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Most evidence on the association between malaria in pregnancy and adverse pregnancy outcomes focuses on falciparum malaria detected at birth. We assessed the association between the number and timing of falciparum and vivax malaria episodes during pregnancy on small-for-gestational-age (SGA) and preterm birth.
There are few prospective studies assessing the effects of malaria during pregnancy in relation to gestational age [8, 11,12,13,14,15,16,17,18,19,20,21,22], especially for vivax malaria [8, 20, 21], and these studies have reached conflicting conclusions (Additional file 1). Falciparum malaria detected at delivery, but not during pregnancy, has consistently been associated with preterm birth [12, 17], and falciparum malaria during pregnancy and at delivery has consistently been associated with fetal growth-related outcomes (LBW, SGA, and IUGR) [11, 13, 15,16,17,18,19, 22]. However, the gestational age at which falciparum malaria is most strongly associated with these adverse outcomes varies between studies. Few of these studies looked at falciparum malaria in early pregnancy [14,15,16], only one looked at the effect of falciparum malaria within gestation windows of less than 3 months [18], and only one was conducted outside of Africa [21]. Several, but not all [13] studies have also shown a cumulative association between the number of falciparum malaria episodes detected and fetal growth-related outcomes (Additional file 1) [11, 14, 15, 22,23,24,25]. There have been no studies on the effect of the number of vivax malaria episodes in pregnancy and fetal growth-related outcomes or of falciparum malaria outside of Africa where transmission is low and falciparum and vivax malaria coexist.
Understanding how the consequences of malaria in pregnancy differ by the number of episodes and the gestational age at detection and treatment is important for the design and timing of interventions to prevent or control malaria in pregnancy. Here, in refugee and migrant women attending antenatal clinics (ANCs) on the Thailand-Myanmar border, we assess the rates of both vivax and falciparum malaria throughout pregnancy and also study how the number of episodes and the gestational age at detection and treatment affect the risk of SGA and preterm birth.
Women were encouraged to attend antenatal care early and return weekly throughout their pregnancy for malaria screening (finger-prick blood sample examined by trained microscopists) because there were no suitable preventive interventions for malaria in this region [25, 26]. Syphilis and HIV were not routinely tested for, but prevalence is very low [27]. When malaria parasites were detected, information on species, symptoms, fetal viability, and gestational age were recorded. Malaria was defined as the presence of asexual parasites in the peripheral blood and was counted per 500 leucocytes or 1000 erythrocytes. Women were also asked about recent antimalarial treatments administered at other clinics, and information on these malaria episodes was recorded retrospectively. Genotyping data were not available to classify recurrent episodes, which could be either novel, recrudescent, or a relapse in the case of vivax malaria [28].
Of the 8221 women with malaria, 3138 (38%) had falciparum malaria only, 3592 (44%) had vivax malaria only, and 1491 (18%) had both vivax and falciparum malaria (either sequential or mixed infections). Women with both vivax and falciparum malaria in pregnancy were excluded from subsequent analyses because of unknown interactions. Recurrent falciparum malaria (either novel or recrudescent) occurred in 860 women (27%): 602, 180, and 78 women had two, three, or four or more falciparum malaria episodes, respectively. Recurrent vivax malaria (either novel, recrudescent, or relapse) occurred in 1335 women (37%): 710, 322, and 303 women had two, three, or four or more vivax malaria episodes, respectively.
One inevitable limitation is that only the time of malaria detection (rather than actual timing of infection) and corresponding gestational age was known. Some women did not attend every week as recommended. But as most women attended weekly or fortnightly and blood smears were taken on every occasion, the inaccuracy in ascribing the timing of patent malaria infection is likely to be small. Inaccuracies in estimates of gestational age may have biased our results; however, we previously found that all estimation methods perform remarkably well in this population [29]. It should also be noted that these data were collected over a 30-year period, and the influence of changes over time in malaria transmission, methods used to estimate gestational age, antimalarials, and the quality of antenatal and obstetric care on our results is unknown, and is a key limitation. Although there are slight differences in results between sub-group analyses pre- and post-2001 (when ultrasound was introduced), these differences do not change our conclusions (Additional file 7). Genotyping data were not available to classify recurrent episodes, which could have been either novel, recrudescent, or a relapse in the case of vivax malaria [28]. We have also made many comparisons by assessing the association between malaria within monthly intervals, with differentiation by species and symptoms, and three adverse outcomes. We have addressed this by considering the magnitude of associations, their 95% confidence intervals and p values, and by focusing on trends in associations rather than on single associations within specific gestation windows. Reduced power to detect associations between malaria very early in pregnancy and adverse outcomes is another limitation.
Several previous studies have found that the effect of falciparum malaria in reducing birthweight increases with the number of episodes [11, 14,15,16], and one study in Africa found that the effect of falciparum malaria on intrauterine growth restriction was also cumulative [23]. In Malawi, there was no association between the number of falciparum malaria episodes and SGA; however, this was in the context of women receiving malaria screening and three-dose IPTp-SP [13]. We found a cumulative effect of the number of malaria episodes on the risk of SGA, for both falciparum and vivax malaria. Surprisingly, this cumulative effect was greater for vivax malaria than falciparum malaria. This is concerning, because the propensity for vivax malaria to relapse is high, occurring in more than half the cases in this region, and 8-aminoquinolines cannot be used in pregnancy (Fig. 2). 2ff7e9595c
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