An atypical Trypanosoma lewisi infection in a 22-day-old neonate from India: An emergent zoonosis

Reports on atypical human trypanosomiasis, caused by Trypanosoma lewisi, are rare and so far a total of 19 reports on human infection with animal trypanosomes, which includes nine cases from Trypanosoma lewisi exist. Trypanosoma lewisi, a Stercorarian trypanosoma of rats, is transmitted by the fecal contamination of the wound or the bite caused by rat flea Ceratophyllus fasciatus. We report here an atypical neonatal infection of T. lewisi in a 22-day-old infant from Agra. The infant presented with a history of high fever, poor appetite, and lethargy for 3 days. The hematological parameters were normal except for a low platelet count. A high C-reactive protein (CRP) concentration of 70.49 mg/L indicated marked inflammation. The Leishman-stained thin blood smears were microscopically positive for the hemoflagellate. Based on the morphological features and further confirmed by polymerase chain reaction (PCR) assay, the hemoflagellate was identified as T. lewisi. Symptomatic treatment and antibiotic therapy helped in an uneventful recovery of the patient.

Keywords: Hemoflagellate, India, infant, Trypanosoma lewisi

How to cite this article:
Jain P, Goyal V, Agrawal R. An atypical Trypanosoma lewisi infection in a 22-day-old neonate from India: An emergent zoonosis. Indian J Pathol Microbiol 2023;66:199-201
How to cite this URL:
Jain P, Goyal V, Agrawal R. An atypical Trypanosoma lewisi infection in a 22-day-old neonate from India: An emergent zoonosis. Indian J Pathol Microbiol [serial online] 2023 [cited 2023 Jan 21];66:199-201. Available from: https://www.ijpmonline.org/text.asp?2023/66/1/199/367961

Introduction

Trypanosomiasis is a complex disease syndrome caused by parasite trypanosomes. Trypanosomes are flagellated protozoans and are mainly hemoparasite causing human and animal trypanosomiasis. Human trypanosomiasis is endemic in Africa and in Latin America. In Africa, it is termed sleeping sickness, caused by T. brucei rhodesiense and T. brucei gambiense. This infection is restricted to the hot and humid regions of Africa that favor the breeding and propagation of the tsetse flies (Glossina spp.), involved in the transmission of the infection. In Latin America, it is termed Chagas disease caused by T. cruzi. These infections are not known to exist in the Indian subcontinent. However, animal trypanosomiasis caused by T. evansi in cattles and horses and by T. lewisi in rats is one of the most important diseases in livestock and wild animals in India. Atypical human infection with T. lewisi is rare and till now nine cases of human infection with this parasite have been reported worldwide of which five of the previous ones have been reported from India.[1] We report here an infection of T. lewisi in a 22-day-old infant, a resident of Agra, Uttar Pradesh, India. This infant is the youngest case to be reported.

Case Report

A 22-day-old female infant, born to a hospital staff member was presented with high fever, inappetence, and lethargy for 3 days. The family was of lower socioeconomic status from Agra, Uttar Pradesh, and had never traveled outside the state or country. A thorough physical examination revealed tiny bite marks on the forehead and chin of the child [Figure 1]. The liver, spleen, and lymph nodes were normal in size. The hematological examinations revealed a hemogram with hemoglobin of 12.6 g/dL, a total leukocyte count of 9400/mm3, and a platelet count of 65,000/μL. The patient was having a low platelet count, which is often seen with this infection. The serum concentration of the C-reactive protein (CRP) was high (70.49 mg/L). The liver function tests revealed raised AST (aspartate aminotransferase) and ALT (alanine aminotransferase) levels of 145.5 and 107 IU/L, respectively. Giemsa-stained thin peripheral blood smears showed a fair number of flagellated parasites. The slender form with tapered ends, large undulating membrane, central nucleus, subterminal kinetoplast, and straight posterior end with free flagellum were characteristic of a Trypanosoma species [Figure 2]. The wet blood smears revealed the characteristic motile trypanosomes. The blood sample was sent to IVRI, Izzatnagar, Bareilly, UP for PCR. A PCR targeting the internal transcribed spacer 1 (ITS1) amplified a 623 bp product, which was specific for T. lewisi. Based on pathological assessment and PCR results, a confirmatory diagnosis of T. lewisi was rendered.

Figure 2: Peripheral smear showing flagellated parasites with subterminal kinetoplast (Leishman ×400)

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The child was hospitalized and treated with intravenous Amikacin, Amoxycillin, and Clavulanic acid for 7 days. The clinical symptoms were eventually subsided and the thoroughly examined posttherapeutic peripheral blood samples were reported to be negative for T. lewisi. The baby was referred to a tertiary care hospital for further consultation, which concurred with the diagnosis and the treatment plan provided. The child was followed up for the next 2 months at clinical outpatient. The blood smears were microscopically negative for the hemoflagellate and PCR was also negative at this stage.

Discussion

Atypical human infections with animal trypanosomes including Trypanosoma evansi and T. lewisi have been previously reported from India.[2] Although T. evansi is widely prevalent in livestock in all agroclimatic zones of India, human infections are rare.[3] The atypical human infection by T. lewisi was first reported in 1933 in a 4-month-old infant in Malaysia.[4] In India, the first two cases of T. lewisi were reported in Raipur.[5] As stated above, 19 cases of atypical human trypanosomiasis caused by animal trypanosomes have been reported so far, Interestingly nine were due to T. lewisi infection, and all nine cases were documented from Asia [Table 1]. The reports on T. evansi infection in humans are reported more than that of the T. lewisi from India.[2]

Trypanosoma lewisi belongs to the Stercorarian group. The infection is quite common in rats and the parasite has a worldwide distribution. It is nonpathogenic, host restricted, and transmitted by the Northern rat flea (Ceratophyllus fasciatus) and the oriental rat flea (Xenopsylla cheopis). The infection is transmitted cyclically in the posterior station of the rat flea. In human beings, it is an opportunistic hemoparasite, and the transmission is postulated through contamination of an open wound with feces of the flea or through a flea bite.[10] However, the exact role of transmission in humans is still unclear. In our case, several flea bite marks were present on the forehead and chin of the infant. Verma et al. have also reported such sting marks in the leg and axilla of the infected child.[9],[10] The infections are mostly reported from people of the low socioeconomic group and in rat-infested surroundings. These factors may weigh in leading to coexistance of diseased individuals in an environment with increased multiplication of fleas in rats eventually leading to the spread of this unusual zoonotic trypanomastigote infection.

T. lewisi infection is usually self-limiting in rodents and humans.[11] Nonetheless, a few fatal cases with central nervous system (CNS) involvement have also been reported in infants as well as in adults.[6] There is no established therapy and treatment protocol with many patients recovering spontaneously without specific treatment with literature suggesting usage of both trypanocide-based therapies and otherwise. A 45-day-old infant who died unfortunately due to the infection in Pune in 2008 was treated with a trypanocide Suramine.[8] However, many cases including the last case (2-month-old infant from Amreli, Gujarat, India) including the current case recovered without specific treatment.[10] It has been suggested that the usage of nontoxic antimicrobials such as those used in the present case report are advisable over the trypanocidals.

T. lewisi infection in the present case had nonspecific symptoms of fever, inappetence, and lassitude, which correspond to the previous reports.[9] Earlier hepatomegaly and splenomegaly have been reported in two individuals.[8],[10] However, the same was not detected in the present case. The microscopy-based examination of the blood smears confirmed Trypanosoma infection and was further confirmed by PCR amplification of a 623 bp fragment specific to ITS1T as T. lewisi. It was hypothesized in the past that infection with animal trypanosomes is rare in humans due to the presence of apolipoprotein L1, a trypanolytic factor in the serum. However, persons with low HDL may be vulnerable to Trypanosoma infection.[3] The serum HDL level of the baby in the present case was normal. It is important to emphasize here that in literature 19 reports exist on atypical human trypanosomiasis caused by the animal trypanosomes and six of them were infants.[9] This could be due to immature immune status, which might make the infants more vulnerable to this infection.[8]

These reports indicate that there may be many more undetected cases of T. lewisi, which may have not been reported from India and therefore, recognition of this parasite among pathologists and clinicians (especially pediatricians) is necessary to create awareness. A thorough surveillance for such atypical human trypanosomiasis is required that further adds the importance of simple peripheral smear examination in this era of automation. Rattus species are reservoirs of many human zoonoses but their role in the transmission of human trypanosomiasis is underrated. Human trypanosomiasis is an emergent rat-borne zoonosis associated with poverty. Further studies on the factors that favor the transmission of atypical human infection with animal trypanosomes may help in preventing the spread of trypanosomiasis.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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