**3.2 Clinical and laboratory diagnosis of STH infections**

Though clinical diagnoses of STH infections are based on the signs and symptoms accompanying the disease after the establishment of an infection, infected persons usually remain clinically asymptomatic, and the diseases rarely cause mortality. When present, clinical symptoms may include non-specific gastrointestinal symptoms, such as acute abdominal pain, diarrhoea or intestinal obstruction. Chronic symptoms may present as iron-deficiency anaemia, malnutrition, retarded growth, cognitive impairment, particularly in children, and pre-term delivery, low-birth weight babies, and impaired lactation in pregnant/post-natal women. These clinical manifestations as well as self-reported cases, need to be confirmed by identifying infective stages like eggs, ova, or larvae in bowel contents collected from suspected patients with clinical illness or from asymptomatic persons.

Laboratory diagnosis for confirmation of STH infections can be done by using diverse methods with varying sensitivity and specificity [19–21]. The two most effective methods are direct parasitological, using microscopy (i.e., sedimentation concentration, McMaster, Kato Katz, FLOTAC) and molecular methods (i.e., polymerase chain reaction). The different diagnostic methods, STH detected, usefulness, and disadvantages are summarised in **Table 1**. Culture techniques and serological assays are less preferred methods in STH infection diagnosis, compared with microscopy and molecular techniques. The choice of a particular diagnostic method requires paying considerable attention to factors such as rapidity of obtaining test results, availability of infrastructure, cost of assay, ease of performance, and level of application in the field (**Table 1**). Other conditions such as proper training of laboratory personnel and strict compliance to quality control or quality assurance procedures could enhance the performance of diagnostic methods to confirm STHs. Confirmed diagnosis helps to ascertain individual infection status, and to estimate the incidence, prevalence, and intensity of infections among populations at risk. The outcomes of diagnosis can again be used to evaluate the effectiveness of parasite control measures like parasite clearance, the reduction in incidence or prevalence, and the intensity of infections. The benefit of laboratory findings is also to provide context-based policy guidance on the frequency of anti-helminthic treatment or prophylactic therapy in affected geographical areas.

#### **3.3 The specific case of STH infections in an African LMIC**

A longitudinal study conducted by Kretchy et al. [7], showed 4.3% incidence rate and low intensity of infections with the STH, *Trichuris trichiura* (*T. trichiura*) among waste handlers in a large coastal peri-urban settlement in Southern Ghana, six months post-treatment with albendazole (400 mg single oral dosage). This incidence rate for *T. trichiura* was, however, higher compared with the national average in an adult population (1.2%) and among non-school going children (0.8%) in endemic communities in Kintampo, Ghana [22, 23]. This could mean that waste handlers were at higher risk of infection with *T. trichiura* compared with the adult population of an endemic area in Ghana due to their occupational exposures. However, a similar study conducted in endemic communities in India by Narain et al. [24] among a group of teenagers found a higher incidence of infection with *T. trichiura* (43.6%), six months post-treatment with albendazole (400 mg). The most common health complaints following infections with *T. trichiura* include mainly intestinal, such as diarrhoea and abdominal pain [25]. Whilst heavy infections in adults have been found to


*Soil-Transmissible Helminths Infections; Diagnosis, Transmission Dynamics, and Disease… DOI: http://dx.doi.org/10.5772/intechopen.102829*


**Table 1.**

*A summary of STH diagnostic methods, STH detected, usefulness, and disadvantages.*

**284**

#### *Soil-Transmissible Helminths Infections; Diagnosis, Transmission Dynamics, and Disease… DOI: http://dx.doi.org/10.5772/intechopen.102829*

cause iron-deficiency anaemia [26], the light intensity infections recorded among the waste handlers may not result in this health outcome. Nevertheless, waste handlers who were infected with *T. trichiura* may serve as important reservoirs for the continued transmission of the STH among waste handlers, immediate family members and the entire peri-urban community as a whole. The findings from the study also indicated that STH infections were correlated with the type of waste handling activity performed, and that waste handlers who did not use the PPE gloves were about six times more likely to have STH infections compared to those who used gloves. This result has consolidated the knowledge on the importance of hands in the transmission of STH infections and the need to wear PPE to prevent the direct exposure of the bare hand to faecal contaminated soils/environments.

#### **3.4 Public health interventions to reduce the risk of STH in exposed populations**

In endemic populations, the risk of acquiring STH infections could be all year round however, several factors can predispose specific groups of persons to become susceptible. Specific risk factors in pre-school and children of school-going age to STH infections include having long or untrimmed fingernails, failure to wash hands before meals, walking bare-footed, nail-biting, and thumb-sucking habits. School-going children in particular, are more prone to STH infections when playing in unpaved, soil-infested school lawns. In communities, where tube-well rather than treated tap-water is used as the drinking water source, pre-school or non-schoolgoing children become significantly vulnerable, because of the likelihood of faecal contamination from nearby latrines, seepage, or run-off water carrying faecal excrements from open defecation practices [27].

Practicing the appropriate public health intervention measures can reduce the exposure to the risk factors to STH infections in the environment and prevent disease occurrence. These can be achieved by preventive treatment with anti-helminthic drugs, adequate sanitation, and good environmental and personal hygiene practices, and by using appropriate PPE. Health education, change in health behaviour and periodic training among occupational risk groups may also be necessary preventive steps in reducing disease risks among persons living in endemic communities in resource-limited settings of African, Asian, and South American tropical, and subtropical LMICs.

The use of preventive anti-helminthic drugs is the current global strategy in controlling STH infections in at-risk populations [28]. In endemic countries like Ghana, albendazole (400 mg) and mebendazole (500 mg) are the anti-helminthic drugs of choice for the treatment against STH infections [29]. Albendazole and mebendazole have undergone extensive safety and efficacy testing and have been used in millions of people globally with only few and minor side effects [30]. Both drugs are effective broad-spectrum anti-helminthics, inexpensive and are easily administered by trained non-medical personnel. However, unlike mebendazole, albendazole (400 mg) is administered as a single oral dosage, which makes it easier to monitor treatment by direct observation by the researcher [16, 31]. The problem with preventive treatment with anti-helminthic drugs to at-risk populations is the inability to prevent re-infection after a short period of between three and six months [32, 33].

Other measures like proper sanitation and good personal hygiene practices are equally essential to reduce risk factors to STH infections. Good hygiene practices could also reduce the growth of other biological agents, in addition to STHs, on the hands of persons exposed to faecal contaminated soil. Wearing appropriate PPE

during food vending or waste handling, and using footwear in school-going children may serve as barriers to prevent direct physical contact with the infective stages and reduce transmission risks.

Public health education and health promotion activities about keeping healthy behaviours like handwashing with soap after playing in the soil, after engaging in waste handling activities or after defecation and before eating may help to reduce transmission and re-infection rates due to STHs. Receiving periodic training about the use of appropriate PPE may also be necessary preventive steps in reducing disease risks among occupational risk groups like food vendors and waste handlers. These interventions, in addition to the use of anti-helminthic drugs, are necessary steps needed to reduce risk factors to STH infections*.*

It is necessary for the appropriate authorities and policymakers in endemic areas of LMICs including governments, employers, district, and local health authorities to provide appropriate and suitable PPE, replace old and worn out PPE in occupational risk groups, and also provide sufficient sanitation and hygiene facilities, such as toilets, soap, and water, and supervise their use in basic schools and poor settlements. Community members in endemic areas must be encouraged to undergo periodic medical screening and participate in deworming exercises at least once in every six months.

### **4. Conclusion and recommendations**

Vulnerable populations particularly children and occupation risk groups in African, Asian, and South American LMICs, are predominantly faced with the hazards of STH infections. Although the burden of disease is quite high in African LMICs like Ghana and Nigeria, the highest burden of infection from hookworms, *Trichuris trichiura*, and *Ascaris lumbricoides* was reported in Asia. The high endemicity of infection in such settings and populations has huge socio-economic and developmental consequences for those infected. The ability of healthcare systems to promote strategies to block the transmission pathways, prevent infection and reduce complications arising from associated diseases is critical. Stakeholders in government and private agencies, as well as employers of occupation risk groups, need to invest adequate funds, infrastructure, and resources to support efforts in diagnosis, treatment and evaluation of WASH interventions that can mitigate the infection burden in LMICs.

It is important for future surveillance programs in the control of STHs, to consider and adopt more effective interventions that would integrate highly sensitive and specific diagnostic techniques like the polymerase chain reaction rather than microscopy-based methods so that laboratories can detect light-intensity STH infections even in areas of low endemicity. This would enable public health systems to implement appropriate curative or preventive measures against the transmission of STHs, particularly in vulnerable populations.

### **Acknowledgements**

The Public Health (PH) Unit of the School of Medicine and Health Sciences (SMHS), Central University (CU) is greatly appreciated for its support in providing logistics and office space to conduct the narrative review in this chapter.

*Soil-Transmissible Helminths Infections; Diagnosis, Transmission Dynamics, and Disease… DOI: http://dx.doi.org/10.5772/intechopen.102829*
