Prevalence of Pediculus humunus capitis, Pediculus humanus corporis, and Pthirus pubis in Al-Kut, Iraq

1. Introduction

Human lice, including Pediculus humunus capitis, Pediculus humanus corporis, and Pediculus Pthirus pubis, are important medical arthropods in human life. These arthropods caused medical problems that are called pediculosis and sometimes lead to serious diseases with mortality ( 1 ). The lice are transmitted from place to host or host to host and adapt to live on the human body ( 2 ). Pediculus humanus capitis is detected on human head hair since it is a suitable environment for its nourishment and reproduction.

The length of an adult Pediculus humanus capitis is estimated at 2-3 mm, and it feeds on the blood present in the blood vessels extending in the scalp causing itching in this area. An adult Pediculus humanus capitis lives for 3-4 weeks, during which it lays about 300 eggs with the size of 0.3×0.8 mm (Figure 1). After mating, the eggs are attached to the hair near the scalp through the gelatinous substance secreted by the mother during spawning. The eggs hatch and become nymphs after 6-9 days, the nymph goes through three steps to reach adulthood ( 3 - 5 ).

Figure 1. Types of human lice (9)

Body lice (i.e., Pediculus humanus corporis) are bigger than head lice (4-5 mm) and resemble a sesame seed. They adhere to the body clothes, especially under the armpits and around the waist, and often move on the surface of the skin to feed, causing itching and rashes that develop skin ulcers that are a place for the growth of bacteria and fungi (Figure 2). The life cycle of body lice is 5-7 days, and they are found in abundance among people who live in unsanitary areas. Pediculus humanus corporis lays about 50 eggs on a person’s clothes that hatch after about 9 days. The nymphs go through three steps to reach adulthood ( 6 - 8 ).

Figure 2. Body lice infestation with rash (10)

Figure 3. Eyelashes infested with lice (16)

Pubic lice (Pthirus pubis) are found in the pubic hair, and in rare cases, around human eye eyelashes (Figure 3) ( 11 , 12 ). Their size is approximately 1.5-0.2 mm (Figure 3). Pthirus pubis lays approximately 30 eggs within 3 weeks that hatch after 6-10 days into nymphs, which stay 2-3 weeks in this stage, leading to adults. Routh, Mirensky ( 13 ) showed that human lice are transmitted from one person to another by having contact with or wearing the clothes of the infected person, which is dependent on personal hygiene. The results of a different study in Iraqi provinces, such as Baghdad, Basra, and Kirkuk, showed high rates of infection with these

ectoparasites, especially in poor health conditions ( 14 ). Mahmood ( 15 ) conducted a study on public primary school students (boys and girls) aging 6-12 years old and found that the overall prevalence rate of Pediculus humanus capitis was higher in girls than in boys. The present study mainly aimed to determine the prevalence of Pediculus humunus capitis, Pediculus humanus corporis, and Pediculus Pthirus pubis among the inhabitants of a different area of Al-Kut city in Iraq.

2. Material and Methods

2.1. Sampling

This study was conducted on 1,632 individuals from 225 families in different zones of Al-Kut city (urban, rural, and slum areas) within March-October 2020 to determine the distribution and prevalence of Pediculus humunus capitis, Pediculus humanus corporis, and Pthirus pubis (Figure 4).

Figure 4. Study area, Al-Kut city, Iraq

This study was based on the visual examination of the hair and scalp (especially behind the ears and above the neck), in a special form with 225 families. The collection of nymphs and lice after the examination of front temporal, parietal, occipital, retro auricular, and nape was accomplished by combing wet hair (14). Data collection on pubic lice infestation was performed on volunteer families by completing survey forms and interviews.

This project was approved by the Ethics Committee of the Agriculture College, Sumer University, Rifai, Iraq. Parents of the families were informed of the research objectives. The authorization of the Ethics Committee was obtained to carry out experiments on humans.

2.2. Statistical Analysis

The gathered data were analyzed in SPSS software (version 20). The significant differences between mean scores were assessed using a t-test, and the correlations between parameters, such as area, age, and gender, were estimated by Pearson correlation coefficient. A p-value of < 0.05 was considered significant.

3. Results and Discussion

A total of 1,632 individuals completed the questionnaires, among whom 315 cases were infected with Pediculus humunus capitis, Pediculus humanus corporis, and Pthirus pubis. The overall infection rate with head lice was obtained at 19.3%. Table 1 presents the relationship of head lice infection with the number of family members and type of living zone. The results of the study showed that the highest infection rates were observed in families with 10-15 members, whether in the urban, rural, or slum areas, accounting for 4.1%, 12.0%, and 8.1%, respectively. However, the lowest infection rates were obtained at 1.8%, 4.7%, and 2.1% for families having 2-3 members in the urban, rural, and slum areas, respectively. Based on the findings of the study, the gender and age of the person were important factors in influencing the infection rate, as it was reported that 234 (22.8%) females suffered, while 81 (13.3%) males were infected (Table 2). Furthermore, the results of the study showed that 249 (79.3%) males and females were infected at the age range of 3-17 years old, while 66 (20.9%) males and females aged 18-40 years old suffered from these infections (Table 3). In a study conducted by Amin and D Mahmood ( 17 ), 1,277 (14.43%) out of 8,847 cases were infected with Pediculus humanus capitis aging 6-11 years old from Kalar district, Kurdistan region, Iraq. According to the findings of the mentioned study, the rate of infection was higher in girls than in boys.

The data collected from healthcare centers and clinics for dermatology in those regions showed varying numbers regarding the infected cases, as the average infection with Pthirus pubis was 11 person per 100 people visiting these centers during the aforementioned study period. The ages of the infected individuals ranged from 4 to 32 years old who lived in various regions (Table 4). Based on the findings of the study, the infectious rate was various, as the average infection with Pediculus humanus corporis was obtained at 3 people per 100 people visiting these centers during the aforementioned study period.

Lice feed several times a day, and heavy infestations can cause intense irritation and severe itching. Toxic reactions to the saliva injected into the skin may lead to weariness and a general feeling of illness, ( 18 ). Pediculus humanus corporis and Pthirus pubis feed on blood and cause itching, which leads to ulceration, and vectors of pathogens, such as Rickettsia prowazekii, Borrelia recurrentis, and Bartonella quintana, cause the transmission of epidemic typhus, relapsing fever, and trench fever among humans. A more general reaction of fever, headaches, a diffuse rash, fatigue, and myalgias may appear a few weeks or months after the beginning of the parasitism ( 8 , 19 , 20 ). Pediculus humanus capitis feeds on blood and causes itching, which leads to ulcers; however, it is not a vector for any disease ( 21 , 22 ). As with other lice infestations, intense itching leads to scratching, which can cause sores and secondary bacterial infection of the skin. Individuals infected with pubic lice should be evaluated for other sexually transmitted diseases. Due to the fact that infection with Pediculus humunus capitis, Pediculus humanus corporis, and Pthirus pubis is common in densely populated areas with low public health and hygiene, giving information is highly important in reducing the pollution of these insects.

Authors' Contribution

Study concept and design: A. K. M. L.

Acquisition of data: A. K. M. L.

Analysis and interpretation of data: M. M. R.

Drafting of the manuscript: M. M. R.

Critical revision of the manuscript for important intellectual content: A. K. M. L.

Statistical analysis: A. K. M. L.

Administrative, technical, and material support: A. K. M. L.

Ethics

All the procedures were approved by the ethics committee of Sumer University, Rifai, Iraq under the project number 62835-29647.

Conflict of Interest

The authors declare that they have no conflict of interest.

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