Study site and design
The study was conducted in Shamva District in Mashonaland Central Province of Zimbabwe, with the highest prevalence of schistosomiasis in Zimbabwe at 62.3%. Children were recruited from 19 different villages in Shamva district and Shamva district hospital. All children were assessed for schistosomiasis, upper respiratory tract infections, dermatophytosis and malaria. Clinical screening was done by experienced clinician and laboratory work was done by experienced laboratory scientist.
Study inclusion criteria
Participants recruited into the study were residents of the Shamva district in Zimbabwe. The PSAC were aged between 1 to 5 years and met the following inclusion criteria: 1. Be lifelong residents of the study area 2. Had no previous anti-helminthic treatment exposure 3. Parental/guardian consent to participate 4. Be negative for Schistosoma mansoni and geohelminths 5. Be negative for the ToRCHeS (toxoplasmosis, rubella, cytomegalovirus, hepatitis and syphilis) screen 6. Be HIV negative 8. Have a widal TO ratio <1:160 9. Mantoux test reaction <5mm 10. Had a normal nutrition status
Ethical statement
Ethical approval was obtained from Medical Research Council of Zimbabwe (MRCZ/A/2435). Gatekeeper approval was obtained from the Provincial and District Medical Directors and Community Leaders. Written informed consent was obtained from the parents or guardians of the children. All participants with confirmed infections were offered treatment.
Data collection
A questionnaire was administered and medical records assessed for those who were admitted. Information was extracted from the demographic and health survey- Zimbabwe statistics (13). The coinfections were selected from top morbidity causes in children under-five years old in Zimbabwe (12).
Clinical examinations
The clinical examinations were conducted on PSAC (n = 415) by two medical practitioners independent of each other according to a protocol (Figure 1)
S. haematobium infection diagnosis
Urine samples collected were examined for macrohematuria using the Uristix reagent strips (Uripath, Plasmatec, UK) dipped into fresh, well-mixed urine for 40 sec and the test area was compared with a standard colour chart as per manufacturer’s instructions. The parasitology team conducted parasitology examination and results were recorded separately, not accessed by the clinical team. Approximately 50 ml of urine sample was collected from each participant on three consecutive days. The samples were collected between 10am and 2pm and processed within 2 hours of collection by urine filtration method and were examined using microscopy for S. haematobium eggs detection. The number of eggs were reported per 10ml of urine.
Diagnosis of other infections
Upper Respiratory Tract Infection
URTI was diagnosed on clinical signs and symptoms after excluding allergy and influenza (14–16). Severe pneumonia was defined as per WHO guidelines (17,18).
Fever of unknown origin (FUO)
FUO was defined as children who within the past six months had been admitted with a temperature of 38.5oC and no other diagnosis found after blood, urine and stool cultures as represented from their medical records (19). Seizures were described as change in movement, attention or loss of consciousness in a child diagnosed with FUO, with no family history of febrile seizures (20).
Malaria
Thick and thin blood film slides were stained using the geimsa stain and examined for malaria parasites using microscopy, as previously described(21). Complicated malaria was described as per WHO guideline for severe malaria (18,22).
Dermatophytosis
Skin scraps were collected from individuals with signs of dermatophytosis, examined on a warmed potassium hydroxide treated slide for microscopy(23). Severe dermatophytosis was described as ringworms covering greater than 20% surface area using the paediatric burns chart (24).
Statistical method
Data analysis was performed using STATA version 15. The statistical methods applied were descriptive statistics providing relative risk and regression analysis for odds ratio. Results were reported as adjusted ORs (AORs) and risk ratios (RR) with 95% confidence interval (CI), along with the test for significance, as previously described (25). Infection intensity for S. haematobium was defined as the arithmetic mean egg count/10ml of at least two urine samples collected on three consecutive days.