S.Q. Nizami ( Departments of Pediatrics, The Aga Khan University Hospital, Stadium Road, Karachi. )
B.J. Farooqui ( Departments of Microbiology, The Aga Khan University Hospital, Stadium Road, Karachi. )
Although cholera is an endemic disease in Bangladesh, India and other countries, it was never a significant cause of gastroenteritis in Pakistan before 1988. Since then, cases of cholera are identified each year, both in adults and children in Pakistan. In order to see the contribution of Vibrio cholerae as a cause of gastroenteritis in children, we reviewed the cases of cholera admitted in the pediatric ward of the Aga Khan University Hospital, Karachi, Pakistan. Of 4346 children hospitalized with gastroenteritis during 1990 through 1995, 348 children (8%) were confirmed to have cholera. The youngest child with cholera was seven days old. The mean age was 31±34 months. The cases of cholera were received from all over the city.Most cases were due to Vibrio cholerae Ogawa biotype ELTOR but the new strain, i.e., Vibrio cholerae 0139 was isolated in 14% cases in 1994. The sensitivity of Vibrio cholerae has also changed. In 1994, the organisms were resistant to commonly recommended antibiotics, i.e., tetracycline, ampicillin and erythroan but sensitive to ceftrioxone, cefixime, ofloxacin and nalidixic acid. Adequate measures to improve hygiene and sanitation and supply of safe potable water is needed to prevent any future epidemic of cholera in the city (JPMA 48:171,1998).
Cholera is an endemic disease in many parts of the developing world including India, Bangladesh and other Asian countries1-4. The International Center for Control of Diarrhoeal Disease Research Bangladesh (ICDDRB) treats 10000 to 12000 cases of diarrhoea each year, of which 12-14% are due to cholera1. Imported cases of cholera occur in developed countries sporadically. In 1988, 14 cases of cholera were reported from four European countries1. In addition to endemic cholera, epidemics and pandemics also occur periodically leading to high morbidity and mortality. Epidemics of cholera occurred in 1991 and 1992 in Latin America including Peru, Brazil and Equador5,6. The causative organsim for the disease is Vibno cholerae which was first isolated in 1883. In 1905, another biotype called ELTOR was isolated which was responsible for the major epidemic of 1961-62. in South East Asia. The ELTOR variety is equally pathogenic and the disease caused by it is also as severe as by classical Vibrio choleare7,8. The ELTOR variety entered India in 1964 and appeared in Chittagong in 1963 and in Dhaka in 1964 where it completely replaced classical type in 19739. Serologically, two types of \\\\/ibrio choleme are common i.e., Ogawa and Inaba. However, in 1991 a new serological variety was isolated in Bangladesh whichwas not typable with10 sera and was called as Vibrio cholerae Non 01 sera and was named as Vibrio cholerae Non 01, 0139, Bengal2,10 Clinically, this variety is also similar to Ogawa and Inaba in its severity11.
Later it was reported from India12,13 and Thailand14. Vibrio choleme 0139 was also isolated in Pakistan in 1994 at our hospital15. In Pakistancholera has been suspected as one of the major causes of outbreaks of gastroenteritis each year during the monsoon seasonbut never confinned bacteriologically. In 1988 only two cases of cholera were reported in adults from Mansehra16. Since, 1988, cases of cholera are encountered each year during and after the monsoon season and have been reported mostly in adults. We have encountered cholera not only in children but also in newborns and infants, which is rather uncommon. Although there have been a few rts15,17 about cholera in adults from Pakistan, there is hardly any report published about cholera in children, At the Aga Khan University we are encountering cases of cholera in children since 1989, when only ten children were admitted with the diagnosis of cholera. The number of cases increased subsequently each year. Hence, we reviewed the cases of cholera in children admitted to the pediatric ward of the Aga Khan University Hospital in order to see: the trend of prevalence of cholera in this group over the years, the prevalence of various types ofvibrio cholera and its sensitivity to the antibiotics and if the cholera was confined to any specific area of Karachi.
Subjects and Methods
All the children admitted to the pediatric ward with the diagnosis of gastroenteritis during 1990 through 1995 were included in the study. The stool samples of these children had been sent to the microbiology laboratory in Cary-Blair medium to isolate Vibrio cholerae in addition to the routine stool cultures. These stool samples were inoculated on Thiosuiphate Citrate Bile Sucrose (TCBS) medium and inçubatedat37°Cfor24 hours. Any growthofflatcolonies 2-3 mm in diameter were further subcultured on nutrient agar slope medium for oxidase test and alkaline peptone water media for motility. The suspected colonies on TCBS medium were confirmed using AP120E (Analytical Profile Index) strips. Agglutination tests were performed on all strains with standard Vibno cholerae antisera ZM 05-07 prepared by Murex Diagnostics Limited Dartford England DAI 5LR.
The charts of the children admitted with cholera confirmed by stool culture during 1990 and 1994 were selected for detailed evaluation. These years were selected because in 1990 a good numberofchildren were admitted with cholera for the first time at the Aga Khan University Hospital and 1994 was selected because of highest number of children admitted with cholera in 1994 during the past six years. Age, sex, date of admission, residences, degree of dehydration at admission, initial laboratory findings including hemoglobin, leucocyte count, platelet count and electrolytes were recorded. Type of Vibrio cholerae isolated and their sensitivity was also noted. The data so obtained was entered in the computer and analyzed using computer program EPI-Info version 6.02 WHOICDD October 1994.
From January 1990 through December 1995, 4346 children were admitted with the diagnosis of gastroenteritis, of i.e., 145 (17% of children admitted with gastroenteritis) were admitted with cholera in 1994 (Figure 1).
This seasonal variations ofadmissions is shown in figure 2
(highest number being in August followed by July). The mean ages (±SD) of these children were 29±35 months in 1990 and 27±29 months in 1994. The minimum age was seven days in 1990 and was 27 days in 1994. Males were slightly higher in number than female in 1994 (Table I).
There was no significant difference in hemoglobin, leucocyte count, platelet count, serum sodium, potassium and bicarbonate level in children admitted during 1990 and 1994 (Table II).
The children came from all over Karachi including slum areas with poor hygiene such as Azam Basti and Korangi and highly developed areas like Clifton and Defence society. The number of cases admitted from different areas of Karachi is shown in Figure 3.
In 1990 all the isolates from stools were Vibrio cholerae biotype ELTOR but in 1994, 14% isoaltes were Vibrio cholerac 0139 type. Sensitivity of the organisms has also changed over the years. In 1990 all the isolates were sensitive to tetracycline, ampicillin and erythrocin but resistant to co-trimoxazole. In 1994, only 17% of all isolates were sensitive to tetracycline and 33% were . However, all the isolates in 1994 were sensitive to cefotaxime, ceftrioxone, cefixime, ofloxacin and nalidixic acid.
Diarrhoea in children is still a major cause of morbidity and mortality in Pakistan. The common causes of childhood diarrhoea are viruses, various species of Shigella, Salmonella, E. coli and Campylobacter. We could not find any report of Vibrio cholerae from Pakistan in literature before 1988. The situation has however, changed and cholera has become a major cause of diarrhoea specially during the monsoon season. We are not getting as many cases of cholera as in Bangladesh, where cholera is an endemic disease but an annual prevalence of 8%inour study is enough to qualify it for labelling as an endemic disease. As diarrhoea is more common in children less than five years of age, same trend was seen in cholera as well. However, it was unusual to see cholera in an infant as young as a seven days. Since a significant mortality can be expected in cases of cholera in a country where adequate health facilities are not available to the general population, preventive steps are more important. Hence adequate precautions in terms of improved hygiene and sanitation and supply of clean potable water is very important to prevent gastroenieritis and avoid cholera. Another significant cause of worry is that even the new strain, i.e., V. cholcrae 0139 Bengal was isolated here. This shows a rapid transmission of the Vibrio cholerae from one country to another. Since the cases of cholera were received from different areas of Karachi including well developed localities such as Clifton and Defence society, it cannot be attributed only to poor hygiene. Perhaps the water delivery system of the whole city is contaminated with the organisms. Vibno cholerae has the nature of disappearing during non-epidemic seasons and reappearing during the monsoon season. Thus, it remains dormant during non-rainy season of the year18. We have also noted the same periodicity in our study as most of the cases were identified during May to October each year.
Treatment of cholera is mainly prompt rehydration and not antibiotic therapy. Antibiotics may reduce the transmission of the organisms from patient to contacts. The antibiotics which are recommended for use in cholera include tetracycline and furazolidone19. However, the sensitivity of organisms has changed over time. The organisms are now resistant to tetracycline, co- trimoxazole and ampicillin and sensitive to third generation cephalosporins, ofloxacin and nalidixic acid. Hence if any antibiotic is to be used then nalidixic acid seems to be the antibiotic of choice at present for children in Karachi.
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