Impact and operational feasibility of TrueNat™ MTB/Rif under India's RNTCP

BACKGROUND

The Revised National Tuberculosis Control Programme (RNTCP) in Andhra Pradesh, India, introduced TrueNat™ MTB/Rif, a rapid molecular test for detecting Mycobacterium tuberculosis (MTB) and rifampicin (RIF) resistance at 193 TB units (TUs) in October 2018. We evaluated its impact on TB diagnosis and assessed the operational feasibility of its deployment at point-of-care (POC) settings.

METHODS

We compared the number of presumptive TB cases tested and the number (proportion) of microbiologically positive before (January-August 2018) and after (January-August 2019) the deployment of TrueNat. We interviewed laboratory technicians and Senior TB Laboratory Supervisor from 25 randomly selected TUs to assess operational feasibility.

RESULTS

In 2018, 10.5% (range 8.9-13.1) of 245,989 presumptive cases tested were positive. In 2019, of the 185,435 presumptive cases tested, 13.7% (range 9.6-18.9) were positive. The proportion of presumptive TB cases in whom MTB was detected using TrueNat was 14.4% (range 10.0-21.2). TrueNat significantly increased case detection (incidence rate ratio [IRR] 1.30; 95%CI 1.15-1.46), yielding an additional 18 TB cases per 100 000 population. Laboratory technicians became comfortable in performing TrueNat after a median of 10 tests (interquartile range 5-17.5). Invalid reports declined from 6.8% to 3.6%.

CONCLUSION

The deployment of TrueNat as POC diagnostic test improved case detection and was operationally feasible under RNTCP.

Risk factors associated with death among influenza A (H1N1) patients, Tamil Nadu, India, 2010

BACKGROUND

Limited information is available about the risk factors associated with death among patients of influenza A (H1N1) in India.

AIMS

To describe the epidemiology of laboratory-confirmed influenza A (H1N1) patients and identify risk factors associated with death.

SETTINGS AND DESIGN

We reviewed the surveillance data of laboratory-confirmed patients in Tamil Nadu, India, for the year 2010. We conducted a case-control study by comparing 70 laboratory-confirmed A (H1N1) patients who died (cases) with 210 A (H1N1) patients who recovered (controls) to identify the risk factors for deaths.

MATERIALS AND METHODS

We interviewed the controls and immediate care-takers of the influenza patients who died to collect information about socio-demographic details and co-morbid conditions. We used an abstraction form to collect the information about the clinical details from the case records of the hospitals where the cases and controls received treatment.

STATISTICAL ANALYSIS

We analysed the surveillance data by time, place and person. We conducted univariate and multivariate logistic regression analysis for identifying factors associated death.

RESULTS

During 2010, 1302 laboratory-confirmed cases were reported to the Tamil Nadu surveillance unit. Of these, 72 patients died (case fatality=5.5%). About 2/3 of the cases and 40% of the deaths were from three districts. On multivariate analysis, past history of diabetes, treatment in private hospitals, treatment with corticosteroids during illness, visit to >1 healthcare facility before laboratory confirmation and delay of >48 h in starting antivirals were found to be independently associated with the deaths.

CONCLUSIONS

Influenza patients with previous history of diabetes, who had treatment with corticosteroids during illness, and started with antivirals after 48 h of onset of symptoms, were at higher risk of adverse outcome. In order to reduce the risk of death during future waves of influenza in Tamil Nadu, the physicians need to be sensitised regarding (1) higher risk of adverse outcomes among A (H1N1) patients with diabetes; (2) adherence to the national protocol for categorisation of cases; (3) prompt initiation of antivirals for severe cases; and (4) avoidance of systemic corticosteroids during management.

An outbreak of pertussis in Sarli Circle of Kurung-kumey district, Arunachal Pradesh, India

An outbreak of suspected pertussis occurred in Sarli circle of Kurung-kumey district of Arunachal Pradesh in 2007. We investigated this outbreak to confirm the etiology, estimate the magnitude and identify reasons for its occurrence. Twenty-six deaths were reported from the circle. We identified 72 case-patients meeting the case definition of suspected pertussis. The overall attack rate was 30%. None of the under-five children surveyed had received any vaccine in the past. It is essential to establish facilities for conducting routine immunization in Sarli and organizing special campaign in the area to vaccinate all under-fives with full course of vaccines.

Predominance of hepatitis B virus genotype C among Karens, the 'old settlers' of Andaman and Nicobar Islands, India

The Karens, or 'old settlers', migrated from Myanmar to Andaman and Nicobar islands 80 years ago. A high HBV exposure rate among them has been reported. A study of 34 HBsAg carriers was done to investigate the origin of HBV infection among the Karens. RFLP-based genotyping was confirmed by sequencing and phylogenetic analysis. The predominance of HBV/C1/Cs suggests that they carried HBV during their migration, retained it, and in addition, acquired HBV/D2 from the people of mainland India. The reported association of HBV genotype C with disease severity thus warrants further epidemiological investigations among them and on possible spread among neighboring settlers.

Malnutrition and high childhood mortality among the Onge tribe of the Andaman and Nicobar Islands

OBJECTIVES

A study was conducted among the Onge tribe of the Andaman and Nicobar Islands with the objectives of identifying demographic factors responsible for the decline in their population and assessing their nutritional status, which is an important determinant of child survival.

STUDY DESIGN AND SUBJECTS

The study included estimation of indices of fertility and child mortality, and assessment of nutritional status. All individuals of the Onge community settled on Little Andaman Island were included.

RESULTS

The mean total marital fertility rate was estimated to be 5.15 live births per woman and the general fertility rate was 200 live births per 1000 married-woman-years. Although the gross reproduction rate was estimated to be 2.2 female children per married woman, the net reproduction rate was only 0.9 surviving female child per married woman. The mean infant mortality rate during the past 30 years was 192.7 per 1000 live births, and the child survival rate was found to be only 53.2%. A mild to moderate degree of malnutrition was found in 85% of children of pre-school age and severe malnutrition in 10%. The Onges had low intakes of iron, vitamin A and vitamin C. All the screened Onges were found to be infested with one or more intestinal parasites.

CONCLUSIONS

High childhood mortality appears to be the predominant demographic factor responsible for the decline in the Onge population. The high prevalence of undernutrition and micronutrient deficiency disorders could be important factors contributing to the high childhood mortality.

Hepatitis B virus genotypes among the Jarawas: a primitive Negrito tribe of Andaman and Nicobar Islands, India

The Jarawas, a classical hunter-gatherer tribe of Andaman and Nicobar Islands, India, were living in isolation for several centuries. They came into contact with the civilized world recently. Serological studies carried out among them revealed that hepatitis B virus (HBV) infection is hyper-endemic. The present study was carried out to investigate the possible origin of HBV infection in Jarawas. Genotyping, RFLP analysis, sequencing, and sequence analysis revealed the prevalence of HBV genotype C, similar to genotype C detected in Thailand, Vietnam, and Myanmar. In contrast, genotype D was prevalent among other non-Jarawa tribes of the island. These data suggest that HBV infection was transmitted from Indo-China to the Andaman Islands during migration of the Jarawas many centuries ago.

Hepatitis delta virus infection among the tribes of the Andaman and Nicobar Islands, India

Hepatitis B virus infection is highly endemic among the tribes of Andaman and Nicobar Islands, India. We screened 223 hepatitis B surface antigen-positive members of these tribes for hepatitis delta virus infection (HDV). The infection was observed only among the Nicobarese. Considering the serious consequences of HDV infection, we suggest that the tribes of these islands should be monitored for HDV infection.

Assessment of injection-related practices in a tribal community of Andaman and Nicobar Islands, India

A survey to assess injection related practices carried out among the Nicobarese, a mongoloid tribe of Andaman and Nicobar Islands, India. The survey was carried out using the rapid assessment and response guide of Safe Injection Global Network of the World Health Organization and included review of randomly selected prescriptions of patients attending outpatient clinic of district hospital, interview and observation of injection providers in the district hospital and sub-centres and interview of the general population. The findings of the survey showed that 18.8% of prescriptions included at least one injection. The per capita injection rate was 3 per year. Majority of injections were administered with disposable syringe and needle and in hospital setting. All the injection providers were aware about possibility of HIV transmission through unsafe injections. However, the awareness among the general population was low. More than half of the individuals had preference to injections. It is suggested that remedial measures, such as education of prescribers to reduce the number of injections to a bare minimum, maintaining regular supply of disposable injection equipment, provision of adequate sharps containers with safe disposal facilities and community education be undertaken to avoid future spread of blood-borne pathogens.

Hepatitis B vaccination in a hyper-endemic tribal community from India: assessment after three years

Hepatitis B infection is highly endemic among the primitive tribes of Andaman and Nicobar Islands, India and it is necessary to initiate hepatitis B vaccination for control of this infection. A pilot project of mass hepatitis B vaccination using indigenously developed vaccine was initiated among Nicobarese tribe of Car Nicobar Island. Sero-protection rates after second and third year were 89% and 85.5%, respectively. The rate of chronic infection in the vaccinated population after three years was 1.86% compared to the pre-vaccination rate of 20.7%. Considering high sero-protection rates and low cost, the indigenous vaccine could be used for vaccination programme in this tribal community.

Leptospirosis among schoolchildren of the Andaman & Nicobar Islands, India: low levels of morbidity and mortality among pre-exposed children during an epidemic

Leptospirosis is an important public health problem in the Andaman Islands. The disease is being increasingly reported among children and adolescents in recent times. An attempt was made to find out the level of exposure to leptospires, to estimate the incidence of infection and to identity the risk factors for acquiring infection among children. A sample of 1544 schoolchildren was selected. Presence of anti-leptospiral antibodies was tested using the microscopic agglutination test (MAT). Students were interviewed for behavioural factors. In total, 341 (221 seronegative and 120 seropositive) students were followed up clinically and serologically during a subsequent outbreak. An overall seropositivity rate of 23.6% (95% CI 21.54-25.81) was observed. Infection rate was 33.5% among seronegatives whereas re-infection rate was 16.7% among seropositives during the outbreak that occurred 1 month after the first sample collection. Morbidity and mortality were found to be higher among seronegative individuals than seropositives. More than 90% of leptospiral infections were found to be subclinical or unnoticed. The high level of exposure among the children results in high infection rates and because they have less previous exposure than adults, they do not have sufficient protection to resist clinical illness during outbreaks.

Tuberculosis situation among tribal population of Car Nicobar, India, 15 years after intensive tuberculosis control project and implementation of a national tuberculosis programme

OBJECTIVE

To assess the tuberculosis (TB) situation in the tribal community of Car Nicobar island 15 years after the national TB programme was implemented in this area after an intensive phase of TB control in 1986.

METHODS

The entire population of Car Nicobar was enumerated through a house-to-house survey. Children aged <14 years were tuberculin tested and read for reaction sizes. Individuals aged >15 years were asked about the presence of chest symptoms (cough, chest pain, and unexplained fever for two weeks or longer and haemoptysis), and sputum samples were collected from patients with chest symptoms. Sputum samples were examined for presence of acid-fast bacilli.

FINDINGS

Among the 4,543 children enumerated, 4,351 (95.8%) were tuberculin tested and read. Of the 981 children without bacille Calmette-Guerin scars, 161 (16.4%) were infected with TB. A total of 77 cases who were smear-positive for TB were detected from among 10,570 people aged >15 years; the observed smear-positive case prevalence was 728.5 per 100,000. The standardized prevalence of TB infection, annual risk of TB infection, and prevalence of cases smear-positive for TB were 17.0%, 2.5%, and 735.3 per 100,000, respectively.

CONCLUSION

The prevalence of TB infection and smear-positive cases of TB increased significantly between 1986 and 2002. Such escalation took place despite the implementation of the national TB programme on this island, which was preceded by a set of special anti-TB measures that resulted in sputum conversion in a substantially large proportion of the smear-positive cases prevalent in the community. The most likely reason for the increase seems to be the absence of a district TB programme with enough efficiency to sustain the gains made from the one-time initial phase of special anti-TB measures. High risk of transmission of TB infection currently observed on this island calls for a drastic and sustained improvement in TB control measures.

Seroepidemiology of hepatitis B infection among tribal school children in Andaman and Nicobar Islands, India

A sero-survey to assess the prevalence of hepatitis B virus infection was carried out among the Nicobarese children attending different primary schools of Car Nicobar Island. A total of 1574 children were screened for different serological markers of infection. Overall, 44% of the children had evidence of HBV infection with 23% positive for HBsAg. The prevalence rates were found to increase linearly with age. The implications of these findings in relation to control of hepatitis B in the tribal population of these islands are discussed.

Hepatitis B virus: predominance of genotype D in primitive tribes of the Andaman and Nicobar islands, India (1989-1999)

To understand the possible origin of hepatitis B virus (HBV), three of the four hyperendemic, primitive accessible tribes of the Andaman and Nicobar islands, India, were investigated. The Nicobarese tribe was investigated in 1989 and 1999. The S gene from 65 HBV isolates was amplified by PCR and sequenced. Genotyping and serotyping were carried out on the basis of phylogenetic and amino acid analyses of S gene. All 20 Nicobarese-89 isolates, nine Onges-99 isolates and the single Andamanese-99 HBV isolate were classified as genotype D. Of the Nicobarese-99 isolates, 32 (91.4 %) and three (8.6 %) were genotypes D and A, respectively. Per cent nucleotide identity between the S sequences representing different tribes varied from 98.06 to 98.59 % and varied from mainland isolates by 1.6-2.0 %. Although southeast Asian origin is postulated for the Nicobarese tribe, the presence of different genotypes suggests introduction of HBV after migration to these islands, probably from mainland India, 200 years back, when these islands became inhabited as a part of penal settlement during the British regimen.

Alarming prevalence of hepatitis-B infection among the Jarawas--a primitive Negrito tribe of Andaman and Nicobar Islands, India

Jarawas, a classical hunter-gatherer tribe of Andaman and Nicobar islands have lived in isolation for several centuries. It is only recently have they started to come in contact with the outsiders, shedding their hostility. Since then, several disease outbreaks have been reported amongst them. Screening of sera samples collected during one such outbreak showed very high endemicity of hepatitis-B infection with over 60% of the individuals positive for hepatitis B surface antigen (HBsAg). The rates of HBsAg observed among the Jarawas are probably the highest ever reported in the world and warrant immediate control measures which would prevent further spread of this infection in the community.

Immune response to an indigenously developed hepatitis-B (Shanvac-B) vaccine in a tribal community of India

Hepatitis-B infection is highly endemic among the primitive tribes of Andaman and Nicobar Islands, India. A pilot project of hepatitis-B vaccination using indigenously developed (Shanvac-B) was initiated among the Nicobarese tribe in Car Nicobar Island. The 936 individuals negative for HBsAg and anti-HBs were administered three doses of the vaccine at 0, 1 and 6 months. The vaccine was found to be safe and efficacious with sero-protection rates of 49.1, 86.9 and 96.7% after first, second and third dose. Considering the high endemicity of the infection and small number of the tribal population, it is necessary to initiate hepatitis-B vaccination programme for this community. Since the vaccine was found to be cost-effective, it could be adopted for hepatitis-B vaccination in this community.

Prevalence of diurnally subperiodic bancroftian filariasis among the Nicobarese in Andaman and Nicobar Islands, India: effect of age and gender

We conducted a cross-sectional survey to assess the prevalence of disease and microfilaraemia caused by diurnally subperiodic strain of Wuchereria bancrofti transmitted by day biting Aedes niveus in Teressa Island, remotely located in the Nicobar district of Andaman and Nicobar Islands. Lymphatic filariasis is a considerable public health problem on this island with an overall endemicity rate of 16.2%. There was a gradual increase in microfilaraemia prevalence with age, reaching a plateau above 30 years. Both the microfilaraemia and disease rates were significantly higher in males (14.7% and 5.2%) than females (8.6% and 1.5%, P < 0.001). The age and gender specific distribution of chronic manifestations show a gradual increase with age, whereas acute disease started to occur from age 40 in males. Hydrocele (84.6%) was the commonest disease manifestation among males, whereas lymphoedema was the only manifestation encountered among females. As vector control measures are not practicable in this setting, chemotherapy using diethylcarbamazine (DEC) is the only potential option to control this disease.

Changing scenario of hepatitis A virus and hepatitis E virus exposure among the primitive tribes of Andaman and Nicobar Islands, India over the 10-year period 1989-99

The Andaman and Nicobar Islands, Union Territory of India, are home to six primitive tribes. Studies carried out earlier among these tribes revealed very high rates of hepatitis B infection. We have now studied hepatitis A and E infection among them. A total of 951 serum samples were collected from four accessible tribes (Nicobarese, Shompens, Onges and Great Andamanese) and tested for antibodies against hepatitis A and E viruses. In addition, 240 serum samples collected a decade earlier from age-stratified Nicobarese were also screened. Hepatitis A virus (HAV) infection was found to be highly endemic among all the tribes, whereas hepatitis E virus (HEV) infection was common among the Nicobarese and Shompens. The age group-wise prevalence of these infections among the Nicobarese showed different patterns, HAV prevalence rising significantly from those aged 10 years and thereafter reaching a plateau, whereas HEV prevalence was found to be more evenly distributed over all age groups, but rising somewhat after 30 years of age. Over the last decade, the prevalence of HAV among the Nicobarese has declined slightly, particularly in those aged 10 years or less whereas HEV infection has more than doubled over all age ranges. Different HEV prevalence observed among the tribes could not be attributed to differences in sanitation or water supply. This fact and the different age-wise patterns of HAV and HEV prevalences is suggestive of different modes of transmission of HEV that are not shared. The highest rates for HEV were among those tribes which reared pigs suggesting that pigs might serve as reservoir of HEV. Further studies are needed, however, to validate these findings.

Epidemiology of hepatitis B infection among the Nicobarese--a mongoloid tribe of the Andaman and Nicobar Islands, India

Andaman and Nicobar Islands, Union Territory of India, is home to six primitive tribes. Preliminary serological studies carried out earlier among the four accessible tribes revealed that hepatitis B virus (HBV) infection is hyper-endemic among them. The present study was carried out to understand important modes of transmission and to identify possible risk factors associated with HBV infection among the Nicobarese tribe. The epidemiology of HBV infection in these islands appears to be distinct with a high prevalence of the chronic carrier state (22.2%) associated with a comparable proportion of the population being anti-HBs positive (26.3%). More than half of the HBsAg and anti-HBs negative individuals have anti-HBc antibodies. Age, past history of hospital admission, intramuscular injections and number of carriers in the tuhet were found to be significantly associated with exposure to hepatitis B virus. Horizontal transmission through close contact with carriers and perinatal route appears to be an important mode of transmission of HBV in this community. Besides this, use of unsafe injections represents an independent risk factor for acquiring HBV infection in this population. Introducing HBV vaccine in the infant immunization programme and improving injection safety would help to control the infection in the tribal community of these islands.

Red cell genetic abnormalities, beta-globin gene haplotypes, and APOB polymorphism in the Great Andamanese, a primitive Negrito tribe of Andaman and Nicobar Islands, India

The Great Andamanese are a primitive Negrito tribe of the Andaman and Nicobar Islands, India, with a total population of 37. We studied 29 individuals from eight families from this population for abnormal hemoglobins, G6PD deficiency, DNA haplotypes, and apolipoprotein B (APOB, gene) polymorphism. Hb E was detected in five individuals, the prevalence of Hb E heterozygotes being 14.3%. One individual had beta-thalassemia trait. One female was G6PD deficient and showed the G6PD Orissa mutation. Haplotype analysis of the beta-globin gene cluster showed that the betaE chromosomes were linked to two haplotypes (- - - - - + + and + + - + + + +) representing the framework 1 gene, whereas the betaA chromosomes showed eight different haplotypic patterns corresponding to framework 1 and 3 genes. APOB polymorphism analysis showed that the 631-base-pair (bp) allele was the predominant one with a high homozygosity rate, which could be due to the higher rate of inbreeding in this isolated group. The presence of Hb E and our findings on haplotype analysis supports the hypothesis that the Great Andamanese are reasonably believed to be the surviving representatives of the Negrito race that once flourished in the entire Southeast Asian region in ancient times.

Prevalence of hepatitis B infection among the primitive tribes of Andaman & Nicobar Islands

BACKGROUND & OBJECTIVES

Andaman and Nicobar Islands, is the home of six primitive tribes. No information is available on the prevalence of hepatitis B virus (HBV) infection among them. Hence a study was undertaken with the objective of assessing the sero-prevalence of HBV infection among the four accessible tribes of these islands.

METHODS

A total of 1266 serum samples were collected from four tribes i.e., Nicobarese, Shompens, Onges and Great Andamanese and tested for the presence of HBsAg and anti-HBs. Information about different risk factors associated with HBV infection was also collected from the Nicobarese tribe.

RESULTS

The overall seropositivity rate of HBsAg among the Nicobarese was 23.3 per cent (95% C.I. 21.0-25.9). Hepatitis B was also found to be an important health problem among the Shompens and Onges with HBsAg positivity of 37.8 and 31.0 per cent respectively. The age-wise distribution of these serological markers among Nicobarese tribe indicate that the infection is very common in all the age groups. The sero-prevalence was also found to be very high among the children.

CONCLUSIONS & INTERPRETATION

The findings of the present study indicate that hepatitis B infection is hyper endemic among the primitive tribes of these islands. Though none of the risk factors studied in the Nicobarese was found to be significantly associated with HBV infection, the fact that almost 20 per cent of the women in the reproductive age group were positive for HBsAg indicates the possibility of vertical transmission among the Nicobarese. Further studies are required to find out other modes of transmission.

Randomized controlled trial of doxycycline prophylaxis against leptospirosis in an endemic area

Leptospirosis occurs as seasonal outbreaks, lasting for about 3 weeks during October-November in North Andaman. A randomized controlled trial was undertaken to assess the efficacy of doxycycline prophylaxis in the prevention of infection and clinical disease due to leptospires during the outbreak period. A sample population of 782 persons, randomized into two groups was given doxycycline 200 mg/week and a placebo. The microscopic agglutination test was done on blood samples collected on day zero, after 6 weeks and after 12 weeks. Infection rates and attack rates of clinical illness were calculated in the two groups based on the serological results. Statistically there was no difference in the infection rates among the two groups. However, a statistically significant difference was observed in the clinical disease attack rates (3.11 vs. 6.82%) between study group and control group. The results of the study indicate that doxycycline prophylaxis does not prevent leptospiral infection in an endemic area, but has a significant protective effect in reducing the morbidity and mortality during outbreaks.

Leptospiral infection among primitive tribes of Andaman and Nicobar Islands

The Andaman islands were known to be endemic for leptospirosis during the early part of the century. Later, for about six decades no information about the status of the disease in these islands was available. In the late 1980s leptospirosis reappeared among the settler population and several outbreaks have been reported with high case fatality rates. Besides settlers, these islands are the home of six primitive tribes of which two are still hostile. These tribes have ample exposure to environment conducive for transmission of leptospirosis. Since no information about the level of endemicity of the disease among the tribes is available, a seroprevalence study was carried out among all the accessible tribes of the islands. A total of 1557 serum samples from four of the tribes were collected and examined for presence of antileptospiral antibodies using Microscopic Agglutination Test (MAT) employing 10 serogroups as antigens. An overall seropositivity rate of 191% was observed with the highest rate of 53.5% among the Shompens. The seropositivity rates in the other tribes were 16.4% among Nicobarese, 222% among the Onges and 14.8% among the Great Andamanese. All of the tribes except the Onges showed a similar pattern of change in the seroprevalence rates with age. The prevalence rates were rising from low values among children to reach a peak in those aged 2140 years and then declined. Among Onges the seroprevalence rates continued to rise beyond 40 years. In all the tribes, seroprevalence rates were found to be significantly higher among the males. The commonest serogroups encountered were Australis followed by Grippotyphosa, Icterohaemorrhagiae, Pomona and Canicola.

Risk factors in the transmission of leptospiral infection

An unmatched case control study was conducted to study the various risk factors for acquiring leptospiral infection in Diglipur tehsil of North Andaman. A random sample of 1014 persons residing in various villages of Diglipur was inducted into the study. Serum samples were collected from them and tested for anti-leptospiral antibodies using microscopic agglutination test (MAT) using Leptospira grippotyphosa, L. australis, L. canicola and L. icterohaemorrhagiae antigens. Persons with a titre of 1:50 or more were considered as the cases (550) and the seronegatives as controls (464). Information about 30 variables relating to household characteristics, occupation, contact with animals and behavioural factors was collected by interviewing the subjects. The prevalences of these variables in both the groups were calculated and the odds ratio with 95 per cent confidence intervals were computed. The seroprevalence rate was found to increase linearly with age and it was significantly higher in males. None of the risk factors studied had any association with seropositivity to serovar L. icterohaemorrhagiae. For the other serovars, some form of recent exposure to outdoor environment had significant association. Other factors which had association with infection with specific serovars included use of well or stream water and presence of dogs in the house for infection with L. grippotyphosa, farming families and presence of cattle in the houses for infection with L. australis and the habit of bathing in ponds for infection with L. canicola. These observed associations can be taken as clues of the transmission cycles and would help in guiding further investigations for understanding the epidemiology of leptospirosis in these islands.

Intestinal parasitic infestation among different population groups of Andaman and Nicobar islands

A survey was carried out among the rural and urban settlers and two tribal groups viz. Nicobarese and Onges, of Andaman and Nicobar islands. The survey covered preschool school aged children and adults. Out of the total 1,384 stool samples examined, 652 (47.1%) showed ova or cysts of one or more intestinal parasites. Among the preschool children, Nicobarese showed the highest overall prevalence rate (80.5%) followed by urban (46.7%) and rural (38.6%) preschool children. Ascaris lumbricoides was the commonest form of parasite encountered in all the groups of preschool children, followed by Trichuris trichura. While ascariasis and trichuriasis were more common among the urban children than in rural children, giardiasis was more common among the rural preschool children. The school age children among rural settlers showed an overall prevalence rate of 61.1% which was significantly higher than that among the rural preschool children. Among the school age children also, ascariasis was the commonest form of parasitosis followed by trichuriasis. The Nicobarese and Onge adults showed significantly higher overall prevalence rates (72.2%) and 71.1% vs 48.6%) compared to rural adults. In all the groups studied ascariasis was the commonest form of parasitosis except in Onges among whom trichuriasis and giardiasis were more common than ascariasis. Change in prevalence rates over age was studied among the rural settlers. While ascariasis and trichuriasis showed peak prevalence rates in school age children prevalence of giardiasis declined with increase in age from a peak in the preschool age group and prevalence rates of hook worm infestation continued increasing beyond school age.

Little Andaman Island, a new focus of infection with nocturnally periodic Wuchereria bancrofti

A filariasis survey was carried out for the first time in the Little Andaman island, covering a population of 12,247 in 12 of the 13 villages. Infection due to Wuchereria bancrofti was found only in 3 villages with microfilaria (mf) rate ranging from 1.02 to 6.45 per cent. Observations on the appearance of mf in peripheral blood showed that the parasite is nocturnally periodic form with a peak at 2000 h. The infection was prevalent only among the settlers from Bihar and Bangladesh and none of the local tribal population was affected. Carriers included 18 males and 4 females. Their age ranged from 6 to 50 yr. Only one of 2788 individuals examined was found to have clinical manifestation. A total of 442 female mosquitoes belonging to eight species were collected and dissected. Natural infection was found only in Culex quinquefasciatus (0.24%). Epidemiological investigations and vector studies indicates local transmission. Thus, this island appears as a new focus of infection.

Effectiveness of mass neonatal BCG vaccination in the prevention of pulmonary tuberculosis: a case-control study in Nagpur, India

SETTING

Government Medical College, Nagpur, India, a tertiary care hospital.

OBJECTIVE

To estimate the effectiveness of mass neonatal BCG vaccination in the prevention of pulmonary tuberculosis in Nagpur, India.

DESIGN

A hospital-based pair-matched case-control study with a case of 1:3, including 144 cases of pulmonary tuberculosis and 432 controls.

RESULTS

The overall vaccine effectiveness estimated in the present study was 60% (95% Confidence Interval [CI] 43%-72%). The protective effect was more in males in the age group 21-30 years. The prevented fraction was 39% (95% CI 24%-52%).

CONCLUSION

The moderate effectiveness demonstrated in this study needs to be substantiated for other forms of tuberculosis by undertaking community-based case-control studies, before attempting to justify the use of mass neonatal BCG vaccination strategy as a part of the national programme.

Outbreak of leptospirosis with pulmonary involvement in north Andaman

An outbreak of acute febrile illness with haemorrhagic manifestations and pulmonary involvement occurred in Diglipur of North Andaman during October-November 1993. Investigations were carried out to see whether leptospires were responsible for this outbreak. Serum samples were collected from suspected cases and tested for presence of antibodies to leptospires by microscopic agglutination test (MAT) using a battery of 19 antigens representing 16 serogroups. 66.7 per cent of the specimens showed significant titres of antibodies against leptospires, 18 of 23 paired sera (78.3%) showed sero-conversion or four-fold rise in antibody titres. The commonest serovar involved was Leptospira grippotyphosa followed by L. canicola and L. JEZ bratislava. In 7 patients L. grippotyphosa was the sole serovar against which antibodies were detected. Clinical and epidemiological observations of this outbreak were similar with that of earlier seasonal outbreaks of acute febrile illness with haemorrhagic manifestations occurring in the same area, indicating that the past outbreaks may also have been due to leptospires. This is the first report of pulmonary leptospirosis from India.