Intestinal parasites in public transport buses from the city of Diamantina, Minas Gerais, Brazil

Abstract

Background: Intestinal parasites’ eggs, larvae, or cysts can be carried in public transport buses, and contribute to the increased incidence of diseases. This study aimed to detect biological forms of intestinal parasites in samples from public buses in the town of Diamantina, Minas Gerais, in order to know the local situation and propose interventions to improve public health.

Materials and methods: In November 2014, six samples were obtained in buses of the two stations by using Graham method, in duplicate, by affixing a 6×5 cm clear tape, six times on each collection site of the bus, in an area of ~30 cm². Then, each tape was positioned longitudinally on a slide microscope, and the identification of the biological forms of the parasites was performed with the aid of a 40× objective optical microscope.

Results: A total of 216 slides were analyzed, of which 86 (39.8%) were positive for at least one intestinal parasite. Cysts of Entamoeba coli were the most frequently found in this study (52.1%), followed by Endolimax nana cysts (30.7%), Iodamoeba butschlii(6.5%), helminth larvae (4.7%), Giardia lamblia cysts (3.6%), Hymenolepis nana eggs (1.2%), Enterobius vermicularis eggs (0.6%), and Entamoeba histolytica cysts (0.6%). Top right handrails and right stanchions had the highest occurrence of biological forms, with 18.3% and 14.8%, respectively.

Conclusion: The results indicated the need for better cleaning of the buses and better personal hygiene by users, since pathogenic and non-pathogenic intestinal parasites were found, suggesting fecal contamination of these sites, representing a risk to public health.

Introduction

Intestinal parasitoses or enteroparasitoses is a group of diseases caused by helminths or protozoans affecting ~2 billion people worldwide, reaching high prevalence rates in some regions.¹ In Brazil, the occurrence of these diseases may vary according to sanitation conditions, socioeconomic level, and population health habits, becoming a major public health problem in the country, mainly in large cities' peripheries.²

Intestinal parasites have a direct physiological effect on the health and nutritional balance of infected individuals.³ The vulnerable populations, living in regions with inadequate sanitation conditions, in need of effective health education are the most affected by these pathologies.⁴ Diarrhea, for example, is one of the conditions in children contributing to malnutrition, affecting both growth and cognitive development of infected individuals, among other complications.^5–7

The spread of infectious forms of intestinal parasites is a determining factor for the increased incidence of intestinal parasites in Brazil. The eggs, larvae, or cysts of parasites, can be spread in several ways: greens and vegetables sold in street fairs,^8,9 money (paper bills),^10–12 mechanical vectors,^13,14 pacifiers,¹⁵ school toilets,¹⁶ health basic units,¹⁷ public transportation buses,¹⁸ among others.

Public transport buses can be an important source of transmission of infectious forms of parasites, since a large number of passengers are in constant contact with these internal parts of the vehicle. Thus, the aim of this study was to investigate biological form occurrences of intestinal parasites present in transport buses from the city of Diamantina, in order to assess the local current situation and propose interventions aiming to improve local public health.

Materials and methods

The town of Diamantina (Lat 18º14'58" S and Long 43º36'01" W) (Figure 1) located in the Jequitinhonha River Valley has become historically famous for its mineral riches, such as gold and diamonds. Diamantina is currently one of the most visited cultural and tourist spots in Brazil. It has a population of 45,880 inhabitants,¹⁹ built on large quartzite formations composing the Espinhaço Mountain Range.

Figure 1 Diamantina (Lat 18º14'58' S and Long 43º36'01' W).

The Universidade Federal dos Vales dos Jequitinhonha e Mucuri, 5 km from the center of Diamantina, has two bus lines which transport students, staff, and others who use the services of the university. The buses serve ~5,000 users daily, comprising people from different social classes and hygiene habits.

In November 2014, six samples were collected using the Graham method,²⁰ by affixing a 6×5 cm clear tape, in duplicate, six times on each collection site in an area of ~30 cm². Biological material was collected in six buses of the Rio Grande line and six buses of the Largo Dom João line. Nine areas in the buses were selected: top handrail (right and left), seat grab rails (right and left), door handholds, stanchions (right and left), and seats (right side and left). Samples were collected after a work day and before the bus cleaning was done. Thereafter, each tape was placed longitudinally on a microscope slide, and identification of the forms of parasites found (eggs, larvae, or cysts) was conducted with the aid of an optical microscope with a 40× objective. This methodology was similar as performed by Pereira et al.²¹

Absolute values were subjected to analysis of variance, and the means were compared by the Tukey's test, with a significance level of 5% (p≤0.05) by using SISVAR version 5.0 software.²²

Results

A total of 216 slides were analyzed, of which 86 (39.8%) were positive for at least one intestinal parasite. A total of 169 biological forms of intestinal parasites were detected. Cysts of Entamoeba coli were the most frequently found in this study (52.1%), followed by Endolimax nana cysts (30.7%), Iodamoeba butschlii (6.5%), helminth larvae (4.7%), Giardia lamblia cysts (3.6%), Hymenolepis nana eggs (1.2%), Enterobius vermicularis eggs (0.6%), and Entamoeba histolytica cysts (0.6%). Top right handrails and right stanchions had the highest occurrence of biological forms, with 18.3% and 14.8%, respectively (Table 1).

Table 1 Frequency of intestinal Parasites found in some areas inside public buses from the city of Diamantina, Minas Gerais (November 2014)

Table 2 shows the mean frequency of biological forms found per sample in the buses in the town of Diamantina. The results also showed that the Rio Grande and Largo Dom João had a very similar ratio of biological forms, but the mean frequency for G. lamblia and I. butschlii showed a statistically significant difference (p≤0.05) between the stations (Table 2).

Table 2 Mean frequency of intestinal Parasites found per sample in public bus stations from the city of Diamantina, Minas Gerais (November 2014)

Discussion

Parasites' eggs, larvae, and cysts may be spread in many ways. This work shows that public buses can be one of the sources of infection for passengers who use this means of transportation. Users with poor personal hygiene contaminate the internal parts of the vehicle with their dirty hands, enabling the transmission of pathogens and non-pathogens to other passengers.

The protozoans E. coli and E. nana showed high occurrence in the examined sites. Although they are not considered pathogenic, the presence of these organisms makes fecal contamination of human origin evident. The detection of G. lamblia and E. histolytica is worrying as these agents are considered pathogenic and cause symptoms such as diarrhea, abdominal pain, and cramps in the infected individuals.²³

When analyzing surfaces at a school in the same locality, Pereira et al²¹ verified the marked presence of E. coli (50%), as evidenced in the present study. Another fact that deserves attention is the similarity of the results when we analyze the percentage of I. butschlii, which is also practically the same in both studies. As it is a collective line of buses and school goers enjoy this type of transport, it may be that the same users are circulating in both environments.

H. nana eggs were observed in this work, but in a smaller number. This species of tapeworm has often been identified in samples of feces from hospitalized children and Indians,^24,25 in Minas Gerais. H. nana detection also indicates users' poor hygiene, which may increase the risk of transmission in the endemic area.²⁶

Borges et al,²⁷ in a study conducted in Uberlândia, Minas Gerais, also found a positive result for E. vermicularis on the buses analyzed there. Enterobiasis, despite being more common in children, can also affect adults in their reproductive age and cause acute pain and discomfort. This study showed the presence of this helminth's eggs, which hampers good hygiene maintenance and eases transmission.²⁸

The most contaminated parts of the buses in this study were the top handrails and stanchions, these data corroborate work from Murta and Massara,¹⁸ who found the highest infection rates in these bus points. These internal parts are in direct contact with people's hands that constantly hold them as safe support during transportation.

Finally, the results indicate the need for better cleaning of the buses and an implementation of educational campaigns to improve users' personal hygiene as pathogenic and non-pathogenic intestinal parasites were found, suggesting fecal contamination of these sites, representing risk to public health.

Acknowledgments

We would like to thank Ms Rosalva de Freitas Oliveira (Centro de Idiomas/UFVJM) who kindly revised the English language version of the manuscript.

Disclosure

The authors report no conflicts of interest in this work.

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