Survey of the present health & nutritional status of Shompen tribe of Great Nicobar Island

Shompens live on the island of Great Nicobar, the southernmost island of the Andaman and Nicobar archipelago and is one of the two mongoloid tribes of Nicobar district. These are semi-nomadic forest dwellers and depend on wild pigs, monitor lizard, snakes, fishes, crabs, lobsters, megapode bird, monkey, honey, variety of fruits, roots and tubers for sustenance. They cultivate Pandanus plantations on the river banks and valleys. They hunt wild animals using spears/harpoon and negotiate the inland water channels and occasionally coastal waters using outrigger small canoes. The entire island was notified as tribal reserve under Andaman & Nicobar islands (Protection of Aboriginal Tribes) Regulation, 1956, and later, a portion of the island was declared as ‘biosphere reserve’1.

Information about the health status of Shompens is scanty as they keep themselves detached from the mainstream populations and are reluctant to interact with people outside their community1. As per the 2011 census, the population of Shompen was 229. In the 1980s, a health and nutritional study was conducted among the Shompens by a team from the ICMR-National Institute of Nutrition, Hyderabad2, and in the 1990s, a repeat survey was conducted by the ICMR-Regional Medical Research Centre (RMRC), Port Blair3. The important findings of the survey included a poor child survival rate, high prevalence of under nutrition (wasting) among children below five years of age (two-thirds of children had low weight for height), high prevalence of anaemia and Vitamin A deficiency in a small proportion of children. Recommendations were made to address these health issues and these were implemented by the Department of Tribal Welfare (DTW) and Andaman Adim Jan Jati Vikas Samiti (AAJVS). No comprehensive health and nutritional surveys were conducted since, for almost two decades. Hence, a detailed health and nutrition survey of the Shompen community was undertaken in March 2017 to comprehensively assess the current health status of Shompens in terms of nutritional status, disease load, health risks through haematological, biochemical, immunological and behavioural habits such as consumption of alcohol or tobacco.

The survey was carried out by a joint team of various agencies, namely Andaman and Nicobar Tribal Research Institute, Andaman Nicobar Institute of Medical Sciences, ICMR-RMRC, Department of Health Services, DTW and AAJVS. Field team consisting of public health personnel, medical doctors, microbiologists, anthropologists, laboratory technicians and other field staff was constituted, thus drawing personnel from all the participating agencies, to finalize the modalities of the study.

Material & Methods

Enumeration and demographic data: The field research team camped at Great Nicobar Island during March 2017 (one month) and visited various settlements of the Shompen tribe. All persons belonging to the Shompen community present at each settlement were enumerated and their demographic and personal data were recorded with the help of interpreters. The interpreter (government official), who worked with them and knew their language informed them about the benefits of participating in this study. The survey was carried out as a community-based cross-sectional study, and the samples were collected after their oral consent /acceptance.

Nutritional anthropometry: Height, weight, mid-upper arm circumference (MUAC), hip circumference (HC) and waist circumference (WC) were measured in all contacted Shompens using the standard methods. Weight was measured in the standing position using SECA weighing scale with minimal clothing and removing footwear (if any) with accuracy of 100 g and height was measured using calibrated anthropometer rod with an accuracy of 0.1 cm. The weighing machine was checked and validated, using known weights, every day before the start of the survey. WC, HC and MUAC were measured using the measuring tape following standard methods4.

Interview and clinical examination: All the contacted Shompens were clinically examined for signs of micronutrient deficiency disorders, infections and infestations. All were interviewed for the presence of chest symptoms, namely cough, breathlessness, haemoptysis, unexplained fever and weight loss. Identified chest symptomatic individuals were further screened for pulmonary tuberculosis. All persons with fever and/or acute respiratory infection at the time of the survey were identified. All identified fever cases were screened for various aetiological agents of febrile illness. Cases of acute respiratory infection were screened for 12 viral respiratory pathogens. Blood pressure (BP) and pulse rate were measured using electronic BP monitor following standard protocol recommended by the World Health Organization5.

Clinical specimens: Blood and stool samples were obtained from the contacted individuals following standard protocols. Throat swabs were obtained from persons with symptoms/signs of acute respiratory infection or fever. Sputum samples were obtained from all chest symptomatic individuals irrespective of the duration of symptoms. Serum was separated from part of the blood samples. A part of the collected sample was used to separate serum and the remaining whole blood was collected in EDTA & transported. The samples were transported to the laboratory at Port Blair maintaining a cold chain. Stool samples were also transported under cold chain conditions.

Biochemical estimations: Various biochemical parameters were estimated. Random blood glucose level was estimated from the whole blood. Haemoglobin concentration was estimated by the Cyanmethemoglobin method (Span diagnostics Ltd) following the manufacturer’s protocol. Other parameters, namely total cholesterol, triglycerides and high-density lipoprotein cholesterol, urea, creatinine, bilirubin, alanine transaminase, aspartate transaminase, alkaline phosphatase, triiodothyronine (T3), tetraiodothyronine (T4) and thyroid-stimulating hormone, were estimated from the serum samples, following standard protocols6.

Markers of infectious diseases: All the samples were tested for hepatitis B surface antigen and immunoglobulin M (IgM) antibodies to hepatitis C (Monolisa ELISA kits, Biorad, California, USA). IgG antibody levels against measles, rubella, dengue and chikungunya were estimated using quantitative ELISA (enzyme-linked immunosorbent assay). Blood smears were examined for malaria parasite and microfilaria. Serum samples were tested for filarial antigenaemia using immunochromatography test (ICT). Samples were tested for antibodies against Leptospira by microscopic agglutination test using a panel of 12 live Leptospira strains representing circulating serogroups in India, as antigens.

Screening for respiratory pathogens: Throat swabs were tested for a panel of 12 viral respiratory pathogens, namely Inf-A (H1N1pdm09), Inf-A (H3N2), Inf-B, respiratory syncytial virus (RSV) A, RSV B, human metapneumovirus, parainfluenza virus (PIV)-1, PIV-2, PIV-3, PIV-4, rhinovirus and adenovirus using molecular diagnostic tools.

Etiological diagnosis of fever cases: All identified fever cases were investigated for various etiological agents of acute febrile illnesses. Serum samples were tested for IgM antibodies against dengue virus (DENV) and chikungunya virus (CHIKV) using IgM ELISA (NIV kits, Pune). The samples were also tested by reverse transcriptase PCR for DENV, ZIKV and CHIKV-specific RNA. Serum samples were tested for the presence of antibodies against Leptospira by microscopic agglutination test (MAT)7. Throat swabs were screened for viral respiratory pathogens listed above using the molecular diagnostic tools.

Tuberculosis: Smears made from sputum samples obtained from chest symptomatic individuals were stained by the Ziehl−Neelsen technique and were examined microscopically for acid-fast bacilli. Part of the sputum samples was decontaminated and inoculated into Lowenstein Jensen (LJ) medium for the isolation of Mycobacterium tuberculosis.

Haemoglobinopathies and other genetic disorders: All the blood samples were screened for thalassaemia and sickle cell anaemia following standard protocols. The samples were tested for glucose-6-phosphate dehydrogenase (G6PD) deficiency using screening test following standard protocol. Samples positive in screening test were subjected to confirmatory testing.

Data analysis: For constructing the population structure, the demographic data of only three of the four Shompens groups contacted were used. The Shompens whose data were not included in the analysis were a group consisting only of adult males who were encountered on east-west road between 24 and 30 km and were without their families. Including them in analyzing the population structure would have made the population structure highly skewed in favour of adults and males and might not truly represent the population structure of the whole community. The drawback of this decision was that the sample size got limited with a possible higher random error.

Body mass index was calculated using the standard formula8. The proportion of the Shompen adults and children falling into various nutritional categories and micronutrient deficiencies was estimated. The proportion of Shompens with high BP, abnormal lipid fractions, antibodies against various pathogens, haemoglobinopathies and G6PD deficiency were estimated.

Results & Discussion

A total of 69 Shompens (26 Shompens males were excluded from analysis) were contacted in four cluster areas, i.e. Lawful Bay (23), New Chingum (10) and Kokion (10) in Nicobar district. Those identified in the other three areas comprised of males and females across all age groups. Due to the small number of Shompens contacted and the uncertainty around the representation of the sample contacted, it was not possible to make any conclusion about the age and gender structure of the Shompen population. Hence, anthropometric measurements in 43 Shompens were made during this study as against 73 during the 1993 survey.

There are two primary health centres in non-tribal areas of Campbell Bay, the headquarters of Great Nicobar subdivision and at Gandhi Nagar village. One medical subcentre is functional at New Chingam village where a small group of Shompens live. The field officials, i.e. Tribal welfare officer, pharmacist and Janjati sevaks and trekking assistants of AAJVS, an autonomous organization under Tribal Welfare Department of Andaman & Nicobar administration are expected to visit regularly the Shompen camps of accessible areas and persuade the tribals to come to the PHC for medical treatment, whenever they are ill. Shompens of Trinket Bay & Latul Bay visit these units using their small canoes, essentially meant for navigation in inland waters such as streams and rivers. Shompens have their own strong ethnomedicine practices as well.

Nutritional anthropometry of adults: Anthropometric measurements were made on 43 adults (19 males and 24 females; Figure). The mean values of anthropometric indices are presented in Table I. Of the 43 Shompens, 12 and 14 persons were in the age group of 2-10 and 11-20 yr, whereas 5 and 3 individuals in 21-30 and 31-40 yr, respectively. In the two age groups, namely 41-50 and >50 yr, there were six and three individuals, respectively.

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Figure

Shompen adults by gender and nutritional grade. BMI, body mass index.

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Three persons (6.8%) (one male and two females) had a body mass index (BMI) <18.5 indicating undernutrition. Twenty persons each (45%) had a normal BMI (18.5-22.9) and BMI indicative of being over-weight (23-27.4), while one male was obese. The breakup of Shompen adults by gender and nutritional grade is shown in Figure.

A BMI of >23 is considered to be associated with increased cardiovascular risk in Asian adults, and based on this criterion, about half of the surveyed Shompen had increased risk of cardiovascular diseases. It seems that, as in other communities of the islands, cardiovascular risk is starting to emerge in Shompen community as well, despite the fact that these individuals lead a lifestyle much closer to nature than that of other communities. This needs special attention as intervention at this stage might mitigate this emerging health risk.

Nutritional status of under-five age group: The distribution of Shompen under-five children by various nutritional anthropometric parameters is shown in Table II. All the eight children below five years of age were girls.

As per BMI for age, which is the currently accepted index of nutritional status of children, none of the children were undernourished. Weight for height, which is considered a race independent index, also indicated that undernutrition is rare among children below five years of age at present. Chronic undernutrition measured as stunting or height for age analysis showed that 63 per cent of children were stunted. Weight by age also indicated that 33 per cent of children were undernourished.

In earlier surveys, based on height and weight for age analysis, Shompen children were categorized as undernourished23. In ethnic groups such as Shompen that have a shorter stature, BMI for age might be a more appropriate index to assess the nutritional status.

Nutritional status of older children: Anthropometric measurements were available for a total of 17 Shompen children aged 5-17 yr (10 males and 7 females). The distribution of these children by gender and nutritional grades as per BMI for age and height for age is shown in Table III.

The overall shorter stature of the Shompen is evident in the older children as well. As per the standard deviation scores for height for age analysis, 47 per cent were stunted, while as per BMI for age, 12 per cent were undernourished.

Micronutrient deficiency disorders: Conjunctival pallor was observed in eight (18.6%) of the 43 Shompens, angular stomatitis was present in five (11.6%) and carries tooth in two (4.7%). Haemoglobin was tested in 29 Shompens out of which 13 were females. Of these seven (53.9%) had Hb level below cut-off (Table IV). Among the 16 males tested, seven (43.8%) had Hb level below cut-off. Thus, the anaemia prevalence was almost similar among adult females as compared to males. Ten of the Shompens tested were children below the age of 18 yr and six (60%) of these had anaemia. Of these six children, four were girls, two were boys (33.3%).

Morbidities: Fungal infection of the skin was present in six (14%), of the 41 Shompens, while 10 (23.3%) had abdominal pain. There were four cases of cataract and one case of corneal opacity among these contacted (those who were examined). One had complete damage of the right eye due to trachoma and in another due to injury.

Fever survey: The fever survey identified five cases of febrile illness among the 38 Shompens. Blood samples were obtained from four of these cases. DENV, CHIKV and ZIKA viruses was negative in all the four cases. Sample from one of the cases gave a titre of one in 160 in MAT (Microscopic agglutination test) against serogroup Icterohaemorrhagiae. Peripheral smear for malaria parasite, microfilaria and ICT for filarial antigenaemia was negative in all the four samples.

Viral respiratory infections: Throat swabs were obtained from 17 Shompens, who reported respiratory symptoms. None of the samples were positive for the 12 viral respiratory pathogens.

Vector-borne disease: Out of 38 Shompens screened for malaria parasite and 34 individuals screened for microfilaria, none were found to be positive. Serum samples were screened for filarial antigenaemia using ICT kit and none of the sample tested positive confirming that filariasis was not prevalent among Shompens.

Tuberculosis: One female person was on treatment for extrapulmonary tuberculosis. She belonged to a family of multiple cases of tuberculosis. Of the 10 chest symptomatic individuals examined, none were positive for acid-fast bacilli in microscopy.

Antibodies against viral pathogens: Among the 38 Shompens screened, IgG antibodies against measles were detected in 16 (42.1%) and seven (18.4%) against rubella. None of the six children below the age of five yr had antibodies against either of these viruses. In 5-9 yr (n=5), one (20%) had antibodies against measles. The increasing trend in antibody prevalence with age for both the viruses indicates that antibodies are more likely to be induced by natural infection rather than by vaccination. In Dukpa tribe of West Bengal, almost 14 per cent were positive for measles9.

A total of 38 Shompens (88.4%) were tested for the presence of IgG antibodies against dengue and CHIKVs. While none of the tested individuals were positive for anti-DENV IgG antibodies, four (10.5%) individuals in the age group of 10-60 yr were positive for CHIKV, indicating that chikungunya transmission, although at low intensity, must be occurring among the Shompens. In the tribal population of Nilgiris, Tamil Nadu State, dengue infection was observed in 8-10 per cent of the screened population10, while in Mandla district, almost 49 per cent were positive for dengue infection11. Although no attempt was made to study the infestation levels of known vectors of dengue and chikungunya, the existence of antibodies against CHIKV indicates that, probably species of Aedes mosquitoes must be present in their settlement. This is a warning sign, as the mosquitoes capable of transmitting CHIKV are, in general, capable of transmitting DENV also, and as DENV is prevalent in Andamans, the virus can gain access to the Shompen ecology.

Antibodies against Leptospira: A microscopic agglutination test was performed on serum samples obtained from 38 healthy Shompen using a panel of 12 Leptospira strains as antigens. Of these, 16 (42.1%) gave a titre of one in 40 or more, against one or more Leptospira antigens. The common reacting serogroups were Icterohaemorrhagiae and Hebdomedis. Earlier studies in this tribe12 reported a high seropositivity rate of 53±5 per cent. In this study, the values for other tribes in Andaman & Nicobar islands were 16±4 per cent amongst Nicobarese, 22±2 per cent among the Onges and 14±8 per cent among the Great Andamanese, and the most common serogroups encountered were Australis followed by Grippotyphosa, Icterohaemorrhagiae, Pomona and Canicola. Much higher seropositivity (61.1%) was found among the Irula tribes of Tamil Nadu State, India13. In the tribes of Dadra Nagar Haveli, India, 36.5 per cent seropositivity was reported14.

Hypertension: BP was measured in 38 Shompens, and of these, five (13.2%) had systolic BP >140 mmHg or diastolic BP > 90 mmHg but none had systolic BP more than 150 mmHg or diastolic BP more than 100 mmHg, which is defined as severe hypertension. Besides these, another 11 (28.9%) had pre-hypertension as defined as a systolic BP >119 mmHg or diastolic BP > 79 mm of Hg.

Although the prevalence of hypertension appears to be low as compared to the Nicobarese and the rural and urban communities of Andaman and Nicobar Islands, it is still high for a community that live quite close to the nature. In a tribal population in Mizoram15, 27 per cent (n=541) were found to be hypertensive. Laxmaiah et al16 have investigated the tribes from nine States across India and reported varying degrees of hypertensive individuals. Highest was observed from the tribes of Odisha where almost 50-54 per cent were hypertensive and the lowest (7-11%) from Gujarat. Studies outside India17181920 also reported the varying levels of hypertensive individuals (range: 9-45%). Findings of the present study suggest that a large proportion of Shompen adults have BP in the pre-hypertensive or borderline category, which is probably an indication that hypertension is likely to emerge as an important health risk in the near future. If this indication is read along with a similarly large proportion of overweight individuals among them, then there is the reason to be concerned about an impending emergence of a cardiovascular disease epidemic in this population. These warning signals cannot be ignored and intervention, if carried out now may be less costly than resorting to a cardiovascular disease control programme after the effect of these emerging risks manifest in the community.

Biochemical parameters: Serum lipid profile was studied in 31 Shompens. None had serum cholesterol levels above 200 mg/dL, but 10 (32.3%) had cholesterol levels of 150 mg/dL or more. One (6.5%) had triglyceride level above 200 mg/dL. Out of the 31 individuals studied, 30 (96.8%) had HDL levels below 40 mg/dL indicating risk of cardiovascular disease. Only one had LDL (low-density lipoprotein) levels above 129 mg/dL. Except for the low HDL levels, the other parameters of lipid profile indicate a low risk of cardiovascular diseases among them. All those tested (27/43) who were above 14 yr had normal glucose level and none of them had diabetes.

None of the 31 Shompens studied had raised serum bilirubin levels. Two (6.5%) individuals had marginally raised levels of SGOT and SGPT and two (4.9%) had raised levels of alkaline phosphatase and serum albumin levels ≤3.5 gm per cent was observed in four (12.9%). Although marginally raised blood urea levels were observed in five (16.1%), none had raised serum creatinine level. Serum uric acid levels were raised in 17 (54.8%), the significance of which needs to be investigated. None of the Shompens screened had abnormal thyroid hormone levels.

Haemoglobinopathies and G6PD deficiencyi: Among the 39 Shompens tested for β-thalassemia, four were found to have β-thalassemia trait, who were from the same family (husband, wife and their children). There is a need for maintaining a database on the status of each individual of the community with regards to β-thalassemia and other genetic disorders so that pre-marital counselling could be done. Of the 37 Shompens screened for G6PD deficiency, none had the disorder.

Intestinal parasitic infestations: Stool samples from 23 Shompens were tested for ova/cyst of various intestinal parasites and 18(78.3%) were positive for the cyst or ova of one or more parasites. The most common intestinal parasite encountered was Trichuris trichura, which was present in the stool samples of 17(73.9%) Shompens. This was followed by Ascaris lumbricoides, the ova of which was present in stool samples of seven (30.4%) and Giardia lamblia cyst in two (8.7%) Shompens. One individual (4.3%) had infestation with all the three parasites.

Substance use: All the 19 Shompen adults aged 20 yr and above chewed pan, while four (23.5%) consume alcohol. Among the 15 children in the age group of 10-17 yr, eight (57.1%) chewed pan. However, none of the children below the age of 10 yr pan chewing. Shompens above 20 yr of age, irrespective of gender, used tobacco.

Some of the limitations of the study include, the actual population of Shompen tribes could not be estimated and thus could not be covered, as there are restrictions in the entry of any individual to their settlements. They can be contacted mainly in the camps (similar to those where the present survey was conducted), where they gather for ration and also for health check up. Thus, population imbalance, which used to be cited often as the cause as well as the consequence of the decline in population size, could not be verified because of the small number of Shompens who could be contacted and the uncertainty over the representative nature of the sample.

Despite some limitations, the present survey was the first comprehensive health and nutritional survey conducted among the Shompens after a 19 yr gap. Albeit limited, based on the available data, there were apparently no improvements observed in the nutritional status and rates of anaemia since the last survey was carried out during 1990s. At present, a potential for increasing chronic non-communicable diseases among the Shompen community is clearly visible.