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ORIGINAL ARTICLE
Year : 2017  |  Volume : 20  |  Issue : 1  |  Page : 8-12

Spectrum of tuberculosis in children at Federal Medical Centre, Gusau, Zamfara State, Northwestern Nigeria


1 Department of Paediatrics, ABU/ABUTH, Zaria, Nigeria
2 Department of Paediatrics, Federal Medical Centre, Bida, Nigeria
3 Department of Paediatrics, Federal Medical Centre, Gusau, Zamfara, Nigeria
4 Department of Paediatrics, ABUTH, Zaria, Nigeria

Date of Web Publication11-Apr-2017

Correspondence Address:
Sani Malam Mado
Department of Paediatrics, ABU/ABUTH, Shika, Zaria
Nigeria
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DOI: 10.4103/1118-8561.204330

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  Abstract 


Background: Children contribute a significant proportion of tuberculosis (TB) burden and suffer severe morbidity and mortality, particularly in endemic areas. The diagnosis of TB in children can be challenging because TB can mimic many common childhood diseases, and therefore, high index of suspicion is required to improve detection of cases. Aims: To determine the prevalence and pattern of TB in children at Federal Medical Centre, Gusau. Subjects and Methods: A retrospective study in children aged 4 months to 13 years admitted to the pediatrics medical ward with TB (over a 1 year period) in the year 2008. Results: Of the 1392 children admitted over this period, 67 were suspected cases of TB, giving a prevalence of 4.8%. Six (9%) patients had TB-human immunodeficiency virus co-infection. Only 6 (9%) children received Bacille-Calmette–Guerin (BCG) vaccine. Disseminated TB (DTB) accounted for 34 (50.7%) of the 67 cases, pulmonary TB was present in 26.9% while 9 (13.4%) had spinal TB. Forty (59.7%) patients successfully completed treatment, 15 (22.4%) were lost to follow-up, and 7 (10.4%) died in the course of treatment. Three (4.5%) defaulted and were retreated while 2 (3%) were referred. Conclusion: The prevalence of childhood TB was 4.8% with low BCG vaccine uptake. DTB was the predominant form, followed by pulmonary and spinal TB. Significant proportion of children successfully completed their treatment regimen while case fatality rate was 10.4%.

Keywords: Childhood tuberculosis, disseminated tuberculosis, prevalence of tuberculosis, pulmonary tuberculosis


How to cite this article:
Mado SM, Isa A, Abubakar U, Onazi SO, Gbemiga AO. Spectrum of tuberculosis in children at Federal Medical Centre, Gusau, Zamfara State, Northwestern Nigeria. Sahel Med J 2017;20:8-12

How to cite this URL:
Mado SM, Isa A, Abubakar U, Onazi SO, Gbemiga AO. Spectrum of tuberculosis in children at Federal Medical Centre, Gusau, Zamfara State, Northwestern Nigeria. Sahel Med J [serial online] 2017 [cited 2017 Jun 29];20:8-12. Available from: http://www.smjonline.org/text.asp?2017/20/1/8/204330




  Introduction Top


Tuberculosis (TB) is a chronic infectious disease that can affect any organ of the body. It is among the top ten causes of death among children worldwide.[1] TB is responsible for an estimated 1.7 million deaths each year even after the discovery of anti-TB drugs several decades ago.[2] There is a significant increase in the incidence of TB worldwide attributable to human immunodeficiency virus (HIV) pandemic, deteriorating economic situation and conflicts, particularly in developing countries.[3] Of the approximately 1 million estimated cases of TB in children worldwide, 75% occur in the high-burden countries.[1] The World Health Organization report of 2012 showed that estimated TB incidence in children aged <15 years accounted for 6% of total 8.7 million TB burden in the year 2011.[4] Since majority of cases of childhood TB are smear-negative, data are usually an underestimation of the actual burden of TB in children.[4] The form of TB remains varied even among age groups in children and from one region to another. Almost 2 million people/year die as a result of TB, mostly in developing countries such as Nigeria, but the mortality in children is often underreported.[5] Access to accurate diagnosis and effective treatment in countries with endemic TB is essential to reduce the morbidity and mortality associated with childhood TB.[6] With the advent of GeneXpert test, prompt, easy, and confirmed diagnosis of TB in children appears promising though remains challenging among under-five in Nigeria due to limitations. Generally however, due to inequitable resource spread and limited accessibility, diagnosing confirmed TB cases in children in Nigeria remains difficult and therefore, a high index of suspicion is required.[5]


  Subjects and Methods Top


The study is a descriptive retrospective one carried out in children aged 4 months to 13 years admitted to pediatric medical ward (PMW) with a suspected diagnosis of TB within the study period (January 1, 2008, to December 31, 2008). The records of all children who were diagnosed and treated for TB were retrieved. The approval of Federal Medical Centre, Gusau Ethical Committee, was sought for and obtained before the commencement of the study. The diagnosis of TB was based on WHO criteria for the diagnosis of TB in resource-poor setting.[7] The guideline stipulates that presence of three or more of the following should strongly suggest a diagnosis of TB: (i) Chronic symptoms suggestive of TB (close contact with adult with sputum smear-positive pulmonary TB [PTB], chronic cough: An unremitting cough that is not improving and has been present for >21 days, fever: Body temperature >38°C for 14 days after common causes such as malaria or pneumonia have been excluded, weight loss or failure to thrive not responding to nutritional rehabilitation). (ii) physical signs highly suggestive of TB (physical signs highly suggestive of extrapulmonary TB: Gibbus, especially of recent onset, nonpainful enlarged cervical lymphadenopathy with fistula formation, meningitis not responding to antibiotic treatment and subacute onset or raised intracranial pressure, pleural effusion, pericardial effusion, distended abdomen with ascites, nonpainful enlarged joint). (iii) a positive tuberculin skin test (Mantoux method) (iv) chest radiograph suggestive of TB (persistent opacification in the lung together with enlarged hilar or subcarinal lymph glands, a miliary pattern of opacification in an HIV-uninfected child).[7] Definition of forms of TB: (i) TB involving any specific organ or body system is defined as TB of that organ or body system (ii) disseminated TB (DTB) referred to TB involving 2 or more noncontiguous organ of the body. At discharge, patients were followed up at the pediatric cardiopulmonary clinic. The demographic characteristics, family, social and immunization history, clinical features, results of investigations, and outcome were extracted and analyzed using SPSS version 20.0 (IBM Corporation, Armonk, NY). Results were presented in simple statistical tables and figures. Chi-square test with Yates's correction was used for comparison of proportions. A P value < 0.05 was considered statistically significant.


  Results Top


Sixty-seven children with suspected TB were admitted from January 1, 2008, to December 31, 2008. Over the period, 1392 children were admitted to PMW giving overall prevalence rate of 4.8%. Forty (59.7%) were males and 27 (40.3%) were females with M: F ratio of 1.5:1. The ages ranged from 4 months to 13 years with a mean age of 5.6 ± 3.2 years.

Fifty (74.6%) of the patients were aged 1–<5 years [Table 1] and age under-five years was significantly associated with occurrence of TB P< 0.0001 [Table 2]. Most of the affected patients belong to the lower socioeconomic class.
Table 1: Age distribution of children with tuberculosis infection

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Table 2: Age-specific prevalence of tuberculosis among admitted children

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The predominant symptoms were fever, cough, weight loss, diarrhea, and abdominal distension. Others include lower back swelling and/or pain, lower limbs weakness, regression of previously achieved developmental milestones, and convulsion. All the patients had history of fever while 65 (97%) had cough, 64 (95.5%) weight loss, 33 (49.3%) diarrhea, and 9 (13.4%) low back pain. Common clinical signs were hepatomegaly (53.7%), cervical lymphadenopathy (23.9%), severe wasting and stunting (<−3 z-score) 80.6% and 59.7%, respectively, ascites (11.9%) and 3% presented with jaundice. Nine (13.4%) had gibbus, of which 2 had associated paraplegia. Eight of the nine cases involved thoracic region with marked destruction of the vertebral bodies while one involved the thoracolumbar region. A child had right sided hydronephrosis and positive acid-fast bacilli (AFB) on 3 serial urine specimens. Only 6 (9%) patients had Bacille-Calmette–Guerin (BCG) vaccine. Three (4.5%) patients had positive AFB in their gastric aspirates [Table 3]. Spinal radiographs show marked thoracic vertebral bodies' destruction and collapse in nine patients. [Figure 1] and [Figure 2] show thoracic and chest radiographs of two patients, respectively. Six (9%) patients had HIV/TB co-infection.
Table 3: Results of investigations

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Figure 1: Lateral radiograph showing thoracic vertebral collapse spine T9–T12

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Figure 2: Posterior-anterior view of chest radiograph showing R-sided pleural effusion

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DTB 34 (50.7%) was the most common form of presentation while PTB was second, accounting for 26.9% [Table 4]. Of the 34 patients with DTB, 19 had a combination of PTB and abdominal TB while 15 had both tuberculous adenitis and abdominal TB.
Table 4: Forms of tuberculosis in children with infection

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Outcome

Forty (59.7%) patients were successfully treated as evidenced by the complete resolution of clinical symptoms and signs except for the persistent of thoracic spine deformity in three patients at the end of treatment, 15 (22.4%) were lost to follow-up, and 7 (10.4%) died in the course of treatment. All patients who completed treatment received isoniazid, rifampicin, pyrazinamide, and ethambutol or streptomycin according to Nigerian TB and leprosy treatment guidelines. All the fatal cases were under-five, and 6 of them had DTB while one had PTB complicated by pleural effusion. All the deaths recorded occurred within 3 weeks of commencement of treatment. Three (4.5%) patients defaulted and were later managed as cases of return after default with 3 months intensive phase using streptomycin, rifampicin, isoniazid, pyrazinamide and followed by 4 months course of rifampicin and isoniazid with satisfactory outcome following completion of retreatment while 2 (3%) of the patients were referred.


  Discussion Top


The prevalence of TB among children was 4.8% which is higher than the 1.1% reported by Jiya et al.[8] in 2008 from Sokoto in the same Northwestern Nigeria but lower than that reported from Benin [9] and Abia [10] in Nigeria and India [11] with 11.6%, 21%, and 12% prevalence, respectively. The high prevalence in this study may be attributable to the low BCG vaccine uptake in the population as only 6 (9%) received the vaccine, of whom 2 (33%) showed BCG scar formation. It could also suggest that the burden of disease among adult population, which constitutes the risk to children, is higher than in Sokoto. The highest prevalence of TB was seen in under-five children as 77.6% of TB occurred in this age group in keeping with the findings of Jiya et al. and children below the age of 5 years were statistically more vulnerable to having TB compared to other age groups. This is not surprising as generally the age below 5 years is considered high risk due to the relatively poor and evolving immunity in comparison to older age groups. This was compounded by the poor level of vaccination and high level (81%) of severe malnutrition documented in this study which might have contributed to the development of TB, though the malnutrition could as well be sequelae.

DTB was the predominant form of TB accounting for 50.7% followed by PTB and TB spine in this study in contrast to that reported from Sokoto,[8] India,[11] and Malawi [12] where PTB predominates. Depressed immunity in severely malnourished children may predispose them to have severe forms of TB of which DTB is one. This may explain why DTB was most prevalent in this study as about 81% of the children with TB had severe malnutrition compared to 21% in the Sokoto study. Another possible reason for the predominance of DTB in our study may be due to selection bias as in-patients were more likely to be severely ill and DTB is one of the severe forms of the disease. HIV infection is a known cause of anergy, although the prevalence of HIV/TB co-infection in this study was too low to have significant contribution. Tuberculous meningitis and renal TB were the less common forms of TB encountered in this study. Generally, thoracic spine is the site most commonly affected in TB spine in children [3] as in this study. This is in contrast to a report from Morocco,[13] North Africa, where lumbar spines were the predominant bones affected. The observed difference may be due the origin or focus from where the infection spread to the vertebral bone.

Making a definite diagnosis of TB in children could be challenging, especially in poor-resource setting like ours. The standard methods such as smear microscopy and culture are associated with low sensitivities. Positive yield of AFB in the sputum or gastric aspirate was low in this study as only 3 (4.5%) were positive. This is in tandem with the report where positivity could be as low as 0–21% in children with clinical diagnosis of TB.[14] About 51% of TB cases were extrapulmonary which are known to be paucibacillary and could have contributed to the very low AFB yield in this study. However, the advent of newer, highly sensitive and specific diagnostic methods such as GeneXpert, gas sensor array electronic nose (E-nose), and infrared spectroscopy will inarguably improve the diagnosis of definite TB cases in children when available.[6] Mantoux test was positive in 68.7% of the 67 cases, which is quite low but the presence of severe malnutrition with resultant cutaneous anergy, severe forms of TB, and HIV/TB co-infections might have contributed to the low positivity. Despite its limitation, clinical-based approach with supportive investigations short of smear microscopy and culture may still be invaluable in diagnosing TB in a poor-resource setting. HIV infection and TB may co-exist and that may further compound the difficulty in making the diagnosis of TB. Nine percent of our cases had HIV/TB co-infection while prevalence of 15. 6% and 10% have been reported from Nigeria [15] and other West African countries.[16]

The mortality rate of 10.4% is high but comparable to an earlier study done in Sokoto.[8] Majority of patients 40 (59.7%) completed treatment using isoniazid, rifampicin, pyrazinamide, ethambutol, and streptomycin in different combinations depending on the form of TB according to Nigerian National TB and Leprosy Treatment guideline. This is comparable with successful treatment in Sokoto [8] and Accra, Ghana [17] studies where 53.5% and 58.9% patients completed therapy respectively, but, higher than TB treatment completion rate in Malawi [12] and Ado-Ekiti.[18] The nonavailability of pediatric formulations of these drugs and the required duration of treatment (minimum 6 months) could affect compliance to treatment and hence might explain why 3 (4.5%) patients defaulted, necessitating retreatment.


  Conclusion Top


The prevalence of childhood TB was 4.8% with low BCG vaccine uptake. DTB was the predominant form, followed by pulmonary and spinal TB. A fair proportion of children successfully completed their treatment regimen while case fatality rate was 10.4%.

Acknowledgment

We will like to thank all the Doctors, Nurses, and Nutritionist of Paediatrics Department and Staff of Medical Record Department of FMC, Gusau.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Cadmus SI, Jenkins AO, Godfroide J, Osinusi K, Adewole IF, Murphy RL, et al. Mycobacterium tuberculosis and Mycobacterium africanum in stools from children attending an immunization clinic in Ibadan, Nigeria. Int J Infect Dis 2009;13:740-4.  Back to cited text no. 5
    
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Jai SK, Ordonez A, Kinikar A, Gupte N, Thakar M, Mave V, et al. Pediatric tuberculosis in children in India: A prospective study. Biomed Res Int 2013;2013:783698.  Back to cited text no. 11
    
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Gabriel A, Augustine M, Paul B, Sabrina B, Bhat G, Raziya B, et al. In: Tindyebwa D, Kayila J, Musoke P, Eley B, Coovadia H, Robert R (editors). Handbook on Paediatric AIDS in Africa. 2nd ed. Kampala, Uganda: ANECCA; 2011. p. 138.  Back to cited text no. 16
    
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