We performed a retrospective study of laboratory reports of 2011 to 2015 from hospitals of 3rd and 2nd line situated in different geographical areas of Cochabamba. Bolivian health system, based on Primary Health Care (PHC), has a basic level of care close to the most remote populations as a first line, a second line offers more complex services (e.g. laboratory) and third line are hospitals of more complexity and capacity usually located in big cities (11). Areas considered were: high valley with an altitude of 2761 m. (meters) with average of humidity of 40% and variation from 6 to 23°C of temperature according to the season; Low valley, between 2200 to 2700 m. with an average of humidity of 55% and variation from 10 to 26°C of temperature; semi-tropical area, from 1800 to 900 m., has an average of humidity around 60% and variation from 25 to 30°C of temperature and finally, the tropical area under 900 m. with an average humidity of 70% and temperature variations from 21 to 35°C (8).
One of the greatest difficulties of the Bolivian health system is the dispersion of its population. The difficulty of access and road communication makes people look for the nearest primary health centre. In most of the cases, a laboratory is offered from the second level forward (11). Thus, the cases collected from second line hospitals can be considered as the closest and most representative to their area. We choose reference centres in each areas taking into account the availability of reports of the period for the study:
- The third line hospital of the main city (Cochabamba) is the only third line public centre in Cochabamba city and in the department. Therefore it is the reference hospital for all the population with no social insurance (80% of the population): more or less 1 500 000 habitants depend on it. People living in the city represent 60% of the patients and the other 40% come from different areas of the department. Only two years of reports were available (2014 and 2015).
- Four second line hospitals from each geographical region of the department; we have:
High valley area: Hospital of Punata that corresponds to eight first line centres and 40288 habitants.
Lower valley area: Hospital of Vinto that corresponds to seven first line centres and seven points of health care and 46924 habitants.
Semi-tropical area: Hospital of Mizque with seven first line centres and 40173 habitants.
Tropical area: Hospital of Ivirgarzama that assembles other seven first line centres and 25094 habitants.
From the laboratory reports, we obtained data from stool samples that were requested in medical consultation for detection of parasites, results are registered in handwritten books at the time of receiving samples. No link to the medical records of each patient was possible because of the absence of digital systematization of laboratory or medical records in public health system. We included samples of children from 0 to 12 years old. We included one stool sample per child, per year and the first sample of the year, regardless of the result. This means that a child could have repeated samples within the period of 5 years but not a repeated sample in one year. This was ensured by Government insurance identification system for children with the birthdate and initials of their first and last names, which allows in a certain way to measure the number of visits that a child makes to a centre, however, it is not systematized and a child can be taken as new if he visits another establishment. A child can visit the first level as a new case and if he does not find a solution, he is referred to the second line and he will also be counted as a new case, hence the importance of only taking the data corresponding to second level hospitals and / or third level.
It was excluded illegible, incomplete or confusing data. We also excluded samples from patient whose age data was missing. Only available data at the hospitals were digitized for this study.
The technique for stool samples analysis were direct simple examination and direct serial examination (one stool sample per day during three days). Incomplete serial procedures (only 2-stool examination) were classified as a direct simple examination and we considered a positive result even if just one of the two samples was positive or negative in case the two samples were negative. Other kinds of process, like concentrated technique (Ritchie), ELISA (Enzyme-Linked ImmunoSorbent Assay) just for Entamoeba histolytica/dispar or a method similar to a culture for Strongyloides stercoralis (Dancescu method) in stool were also included in the collecting data.
For this study, enteroparasites considered as pathogenic are Complex Entamoeba histolytica/dispar, Giardia lamblia, Ascaris lumbricoides, Ancylostomidae (Ancylostoma duodenal/Necator americanus), Trichuris trichiura, Strongyloides stercoralis, Taenia solium, Enterobious vermicularis and Hymonolepis nana. All the other intestinal parasites reported were considered as commensals and were not detailed in our description: Blastocystis hominis, Entamoeba coli, Chilomastix mesnilli, Iodamoeba bütschlii and Endolimax nana. These parasites were not considered pathogenic for this study because they are not considered for treatment either in the epidemiological surveillance of the Bolivian PHC (12).
It is worth mentioning that most of the secondary care centers use simple examination as the main diagnosis technique, techniques with higher sensitivity such as Ritchie concentrated technique, molecular tests are barely used and for this reason is not possible to distinguish between E. histolytica and E. dispar.
Most hospitals of the public health services in Bolivia do not have a digital system but handwriting notebooks of monthly reports. The third line hospital (city hospital) was able to keep the reports only for two years (2014 and 2015). Transcribing and cleaning process was developed by the main researcher. This study has the approval of the ethical committee of the University of San Simon and the local health direction of the department of Cochabamba.
Descriptive data such as mean, standard deviation for age variable and frequencies for the others: area (high valley, low valley, semi-tropical, tropical and city), group of parasites (helminths, protozoan), diagnosis (pathogenic, non-pathogenic, non-parasites observed), season (spring, summer, autumn, winter) and age groups used for analysis took account the paediatric classification used in Bolivia to follow child development. For so we have:
Minor infant: From day zero to 12 months (0–1 year old).
Older infant: From 12 months 1 day to 24 months (1.1–2 years old).
Pre-school age child: From 24 months 1 day to 48 months (2.1–4 years old).
School age child: From 48 months 1 day to 12 years old (4.1–12 years old).
The association of available variables (gender, age group, area, and season) with presence of pathogenic parasites were analysed using binary logistic regression model and the degree of associations were expressed in odds ratio (OR). The defined value of p < 0.05 were considered as statistically significant.