through panning (27) . Shamva District is a S. haematobium infection endemic area with the 110 highest prevalence of schistosomiasis in Zimbabwe at 62.3%, in PSAC schistosomiasis 111 prevalence was recorded to be 10% (28). 112 113 Sample size 114 Children aged five years and below with upper respiratory tract infection were recruited into 115 the study. Mothers were requested to bring their children to the clinic or to Expanded 116 Programme on Immunization (EPI) meeting points. The required sample size was calculated 117 to be 138 participants using the formula below with S. haematobium prevalence of the area 118 recorded as 10% (15): 119 ‫ܖ‬ ൌ ‫ܢ‬
Where z is the z value for the 95% confidence interval, that is alpha = 5% (z = 1.96) 120 p = proportion/prevalence of the outcome to be investigated (p = 0.10) 121 q = 1-p = 0.90 122 e = precision for the given confidence interval expected expressed as a decimal (e = 0.05) 123 n = 138 124
Using simple random sampling in the Shamva village, we recruited a total of 237 study 125 participants. 126 127 Study inclusion criteria 128 Children under five years old with signs and symptoms of an upper respiratory tract 129 infection were recruited into the study after exclusion of common non schistosomiasis co-130 . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint
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The copyright holder for this this version posted November 10, 2020. ; https://doi. org/10.1101 org/10. /2020 Auscultation: Character of breath sounds (vesicular, bronchovesicular, bronchial, tracheal) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint
The copyright holder for this this version posted November 10, 2020. ; https://doi.org/10.1101/2020.11.06.20227173 doi: medRxiv preprint ml of urine sample was collected from each participant on three consecutive days. The 180 samples were collected between 10am and 2pm, processed within two hours of collection by 181 the urine filtration method and were examined using microscopy for S. haematobium eggs 182 detection, as previously described (35). The number of eggs were reported per 10ml of urine. 183
The parasitology team recorded the results and the clinical team was blinded from them. with the arm relaxed and hanging down the body. Height and weight for age charts were used 202 to assess nutritional status. The caregivers were counseled concerning the correct nutritional 203 . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint
The copyright holder for this this version posted November 10, 2020. ; https://doi.org/10. 1101 /2020 requirements and the importance of having a balanced diet. Children with malnutrition were 204 referred to the local health facility for further management. 205 206
Data analysis was performed using IBM SPSS Statistics version 23. Initial analysis was to 208 determine an association between participants with URTI advancing to pneumonia and S. 209 haematobium infection status. The statistical methods applied were the descriptive statistics, 210 bivariate and multivariate logistic regression modelling. The multivariate logistic regression 211 models were fitted to adjust for potential confounding factors for the five manifestations with 212 three explanatory variables, that is, sex, age and schistosomiasis infection. The effect of 213 different factors on the prevalence of schistosome infection and morbidity was determined 214 using logistic regression and the results reported as adjusted ORs (AORs) and 95% CI, along 215 with the test for significance, as previously described (36). Second analysis was to determine 216 the effects of different intensities of S. haematobium infection as a risk factor for developing 217 pneumonia or severe pneumonia. We calculated the population attributable fraction (PAF) of 218 the S. haematobium infected participants with different infection intensity having pneumonia 219 using the formula: 220
Where P e = Percentage of population exposed, RR=relative risk 222
Final analysis was to determine the impact to the population of S. haematobium infection as 223 a risk factor for pneumonia. For this we used the population attributable risk (PAR) of getting 224 pneumonia in the presence of S. haematobium infection calculated using the formula 225 (37,38): 226 . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint
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Where P o = participant with the condition divided by total participants 227 P 1 = number with condition unexposed divided by total participants unexposed 228 229 Number needed to harm (NNH) in the study population was calculated using the following 230 formula: 231
S. haematobium infection was defined as the arithmetic mean egg count/10mL of at least two 232 urine samples collected on three consecutive days. 233
Demographics 235 A total of 319 children under five years from 19 Shamva district villages were screened. 236 ( Figure 1 ). Two hundred and thirty-seven preschool age children with signs and symptoms of 237 URTI were recruited into the study and followed up. The number of males was 129 (54%) 238 and females 108 (46%). The age was normally distributed with mean (SD) age of 3.2 (1.2). S. 239 haematobium prevalence was 29% (69) ( Table 1) . Amongst the study participant, 84% (201) 240 had exposure to contaminated water, whilst 15% reported no exposure to contaminated water. 241 242
After examination, 79% (182) of children had a simple cold or cough, 15% (36) had 244 pneumonia, 6.3 % (15) had severe pneumonia and 33% (5) of the severe pneumonia 245 participants deceased (Table 2) . Eighty one percent of participants with the common cold 246 . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint
The copyright holder for this this version posted November 10, 2020. ; https://doi.org/10.1101/2020.11.06.20227173 doi: medRxiv preprint were S. haematobium negative, whilst 80 % of participants with severe pneumonia were S. 247 haematobium positive and 57% of S. haematobium positive had pneumonia. 248
The study participants after adjusting for sex and age, S. haematobium infection status and 250 indoor pollution, the infected children were at higher odds of presenting with the following: 251 pneumonia (aOR = 3.61 95 % CI 1.73-7.55) and severe pneumonia (aOR =21.13(4.65-95.89) 252 and mortality (aOR = 9.79 95% CI 3.82-17.53). The risk of having pneumonia or severe 253 pneumonia in the S. haematobium infected individuals increased (Figure 2) 
Children with low intensity S. haematobium infection were at a higher risk of developing 261 pneumonia with RR=(2.62 (95% CI 1.13-6.08) (Figure 2 1. For every four children exposed one will get pneumonia 275 2. For every five children exposed to S. haematobium infection one will get severe 276 pneumonia in the event of acquiring an upper respiratory tract infection. 277
This study reveals that there is a strong association between having S. haematobium infection 280 and risk of pneumonia or severe pneumonia. In general, more than half of the severe disease 281 burden was attributable to S. haematobium infection. We also report an association between 282 high infection intensity status and development of severe pneumonia, whilst low and mild 283 infection intensity were more associated with URTI progression to pneumonia. Participants 284 who deceased all had severe pneumonia. Preschool age children with indolent 285 schistosomiasis who catch the common cold were at a higher risk of acquiring pneumonia or 286 severe pneumonia, according to our findings. This could be due to lung damage that occur 287 during S. haematobium infection predisposing the children to severe disease progression (20). 288
Pulmonary schistosomiasis occurs as early as the first exposure to infection, chest x-rays of 289 individuals with acute schistosomiasis have shown widespread non-specific infiltrates which 290 were accompanied by respiratory symptoms which include wheezes and dyspnea (39). These 291 respiratory signs and symptoms were reported to last for months after initial harm occurs 292 (19) . Despite resolution of wheezes, the infected person is still exposed to further lung injury 293 during the chronic schistosomiasis phase (40-42). 294 . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint
The copyright holder for this this version posted November 10, 2020. ; https://doi.org/10. 1101 /2020 This study shows that infection intensity was associated with URTI development turning into 296 the severe form of lower respiratory infection. Children with high intensity S. haematobium 297 infection had a significantly increased risk of severe pneumonia and death. This is in keeping 298 with previous reports on schistosomiasis and morbidity, which showed increased morbidity 299 with increased infection intensity (43-45). Schistosome eggs trapped in the host tissue are the 300 major cause of morbidity (46-48). In chronic schistosomiasis, eggs of the parasite are 301 released into the host human and are spread throughout the body and mainly into the lung 302 where they cause pulmonary arteritis (46). Infection intensity describes the parasitic load and 303 is measured as the number of eggs excreted, thus the higher the infection intensity the more 304 the associated morbidity. 305 306 To our knowledge, this is the first study to report a possible exacerbating effect of S. 307 haematobium infection on respiratory tract infection. We report S. haematobium infection to 308 have a significant population attributable fraction to severe pneumonia of 82.35% in our 309 study population. Furthermore, we found that for every four children with S. haematobium 310 infection who acquire an URTI, one will develop pneumonia. Whilst for every five S. 311 haematobium infected PSAC who acquire an URTI, one will develop severe pneumonia. is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this this version posted November 10, 2020. ; https://doi.org/10.1101/2020.11.06.20227173 doi: medRxiv preprint introduction of polymer vaccines, the numbers still remain high. Thus, including routine 320 screening and early treatment of S. haematobium infection in a schistosomiasis endemic area 321 may have immense benefits in preventing severe pneumonia. There is need for policy makers 322 in endemic areas to further strengthen the drive to screen and treat schistosomiasis in PSAC 323 in a bid to decrease the mortality and morbidity associated with respiratory infections. 324
Furthermore, in the case of a respiratory pandemic, like SARS coronavirus-2, the impact on 325 children under five in schistosomiasis endemic area has the potential to be deadly. 326 327 Limitations to our study was the fact that it was carried out during a low schistosomiasis 328 transmission season, although it was a high URTI season. Our second limitation was that the 329 type of pathogen which caused the URTI could not be identified. Study strengths include the 330 fact that our sample size was more than the calculated size and the study was done in a high 331 schistosomiasis endemic zone, thus our results may be related to other endemic areas. This 332 study is of great importance in the public health sector, since respiratory tract infections are 333 the leading cause of children under-five years, mortality after the neonatal period. . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this this version posted November 10, 2020. (24) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint
The copyright holder for this this version posted November 10, 2020. ; https://doi.org/10.1101 https://doi.org/10. /2020 Schistosomiasis in the first 1000 days. Lancet Infect Dis. 2018; 18(6):e193-203. 433 http://dx.doi.org/10.1016/S1473-3099 (17) . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint
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The copyright holder for this this version posted November 10, 2020. ; https://doi.org/10.1101/2020.11.06.20227173 doi: medRxiv preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint
The copyright holder for this this version posted November 10, 2020. ; https://doi.org/10.1101/2020.11.06.20227173 doi: medRxiv preprint 524 CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint
The copyright holder for this this version posted November 10, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint
The copyright holder for this this version posted November 10, 2020. ; https://doi.org/10.1101/2020.11.06.20227173 doi: medRxiv preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint
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The copyright holder for this this version posted November 10, 2020. ; https://doi.org/10. 1101 /2020 