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CHAGAS DISEASE, TRIATOMINE BUGS, AND BLOODLOSS
1316 CHAGAS DISEASE, TRIATOMINE BUGS, AND BLOODLOSS
SIR,-Triatomine bugs are the vectors of Chagas disease in Latin ’America. No routine treatment is available and prevention involves in-house spraying of insecticides to reduce vector populations. Even if insect vectors were removed tomorrow Chagas disease would remain a problem for years: the disease is chronic in man and the risk of transfusional and congenital transmission would remain for a time. Furthermore, even if we had a remedy for the disease, triatomine bugs themselves would still represent a serious problem. Domestic infestations can be very stressful. I know of a family in Brazil that split up as a direct result of tension and argument caused by their inability to get rid of the bugs. They even built a new house in an effort to escape the infestation and, though poor, they saved to purchase proprietary insecticides-behaviour in striking contrast to the complacent view of peasants as lacking motivation for betterment and dumbly accepting their lot. The blood-loss caused is of more obvious importance, however. Severe anaemia caused by ticks and insects is rarely considered in man. Some workers have drawn attention to the possibility of iron I deficiency and reduced haemoglobin caused by cimicid bedbugs, yet triatomine bugs are much larger, and may be more numerous. A large triatomine bug such as Panstrongylus megistus may take over 800 mg blood in a single meal.2 Layrisse and Roche3considered the possible contribution of Rhodnius prolixus to chronic blood-loss but, in the absence of data on feeding frequency, they concluded that R. prolixus would cause negligible blood-loss compared with hookworms. Rabinovich et al.4 calculated the feeding frequency of R. prolixus in fourteen houses in Venezuela and estimated a daily blood-loss ranging from <1 to >3 ml per person. Using data of E. Dias and R. Zeledón, Rabinovichs put the blood-loss caused by Triatoma infestans as 17 ml per person per day, although this was undoubtedly an unusual case. My own estimate (table) indicates that ESTIMATED DAILY BLOOD-LOSS PER PERSON IN A HOUSE INFESTED WITH T. INFESTANS IN BRAZIL
anaemia associated with acute Chagas disease is linked to triatomine bugs rather than to Trypanosoma cruzi. In an unpublished report for the World Health Organisation N. M. Prescott has emphasised the need for a realistic appraisal of the economic damage (both to labour output and to health status) of the major tropical diseases. If this is to be done for Chagas disease the impact must be considered in terms not just of clinical manifestations but also of the unknown contribution of chronic blood-loss; and the possible psychological and social damage caused by the vectors and the fear of the disease, which can lead to many workers from endemic regions to be refused employment whether they are disease-positive or not, must also be taken into
account.
Institute of Neurobiology, Serrano 665, Buenos Aires 1414, Argentina
C.J.SCHOFIELD
CYTOTOXIC DRUGS AND STERILITY
SiR,-Dr Glode and his colleagues suggest that cytotoxic chemotherapy causes permanent sterility in the long term survivors of several conditions, including choriocarcinoma. This suggestion is not supported by data from a study of the long term consequences of chemotherapy in patients with invasive mole or choriocarcinoma treated in this unit between 1958 and 1978. We have analysed data on the 611 patients treated with cytotoxic chemotherapy during that 21 year period. 104 patients died from their initial disease; 38 patients from other countries have not been traced; and 83 have not yet returned their questionnaires. There are obstetric data on the remaining 375 women, and by August, 1980, 177 had become pregnant since finishing chemotherapy. There were a total of 315 pregnancies resulting in 245 live births from 167 women and 76 miscarriages or terminations. Only 5 women who wanted to get pregnant have so far failed. All the women received methotrexate, and 40 of those who became pregnant also received cyclophosphamide and actinomycin D. Walden and Bagshawel suggested that patients with trophoblastic tumours may have a poor obstetric history and that this did not appear to be significantly worsened by chemotherapy. The fact that 47% of all women in this series (and 97% of those who wished to) did become pregnant suggests that infertility is rarely a problem in those treated for trophoblastic tumours with the regimen used here.
G. J. S. RUSTIN K. D. BAGSHAWE E. S. NEWLANDS R. H.J. BEGENT
Department of Medical Oncology, Charing Cross Hospital, London W6 8RF
*Assuming
stable age distribution’ with adult
biting frequency
from
Schofield.6
tfrom Szumlewicz,’ but adding 40% $1ml blood =1-054 g.
to
allow for
urine
loss.
daily blood-loss of 2-3 ml would be a more likely average in houses infested with T. infestans. Chronic blood-loss of this nature may be tolerated by healthy adults and children, but what of children burdened with other parasites and on an inadequate diet? Perhaps the iron-deficiency a
1. Venkatachalam PS, Belavady B Loss of haemoglobin iron due to excessive biting by bed bugs. Trans Roy Soc Trop Med Hyg 1962, 56: 218-21. 2 Szumlewicz AP Laboratory colonies of Triatominae, biology and population dynamics. In New approaches in American trypanosomiasis research (PAHO Publ 318). Washington, DC: Pan American Health Organisation, 1976: 63-82. 3 Layrisse M, Roche M. The relationship between anemia and hookworm infection. Am J Hyg 1964; 79: 279-301. 4. Rabinovich JE, Leal JA, Feliciangeli DP Domiciliary biting frequency and blood ingestion of the Chagas’s disease vector Rhodnius prolixus Stahl (Hemiptera: Reduviidae) in Venezuela. Trans Roy Soc Trop Med Hyg 1979; 73: 272-83. 5 Rabinovich JE Vital statistics of Triatominae (Hemiptera: Reduviidae) under laboratory conditions I Triatoma infestans Klug. J Med Entomol 1972; 9: 351-70. 6. Schofield CJ. Nutritional status of domestic populations of Triatoma infestans Trans Roy Soc Trop Med Hyg 1980; 74: 770-78.
ORAL LORAZEPAM TO IMPROVE TOLERANCE OF CYTOTOXIC THERAPY
SIR,-Cytotoxic drug induced emesis is common in cancer patients; as a result, some may refuse further chemotherapy, and a major problem with chemotherapy is the fear of further treatment because of the recollection of unpleasant complications from previous injections. Having read Dr Maher’s letter (Jan. 10, p. 91) investigated the value of oral lorazepam, as an adjunct to standard antiemetics used in patients receiving cis-platin or doxorubicin containing regimens. Results of this pilot study have been encouraging and will be reported elsewhere. 5 patients who would otherwise have refused to continue potentially curative chemotherapy because of distressing cytotoxic drug induced emesis, had a dramatic symptomatic improvement when lorazepam was added to previously ineffective doses of intravenous haloperidol, and they opted to continue with chemotherapy. An hour before chemotherapy, hospital patients were given a single oral dose of 3 mg lorazepam, and 2 - 5 mg haloperidol was administered intravenously at the time of therapy. All patients slept we
1. Walden
PAM, Bagshawe KD. Reproductive performance of
treated for 1108-14.
gestational trophoblastic
tumor.
Am
women successfully J Obstet Gynecol 1976, 125:
SIR,-Triatomine bugs are the vectors of Chagas disease in Latin ’America. No routine treatment is available and prevention involves in-house spraying of insecticides to reduce vector populations. Even if insect vectors were removed tomorrow Chagas disease would remain a problem for years: the disease is chronic in man and the risk of transfusional and congenital transmission would remain for a time. Furthermore, even if we had a remedy for the disease, triatomine bugs themselves would still represent a serious problem. Domestic infestations can be very stressful. I know of a family in Brazil that split up as a direct result of tension and argument caused by their inability to get rid of the bugs. They even built a new house in an effort to escape the infestation and, though poor, they saved to purchase proprietary insecticides-behaviour in striking contrast to the complacent view of peasants as lacking motivation for betterment and dumbly accepting their lot. The blood-loss caused is of more obvious importance, however. Severe anaemia caused by ticks and insects is rarely considered in man. Some workers have drawn attention to the possibility of iron I deficiency and reduced haemoglobin caused by cimicid bedbugs, yet triatomine bugs are much larger, and may be more numerous. A large triatomine bug such as Panstrongylus megistus may take over 800 mg blood in a single meal.2 Layrisse and Roche3considered the possible contribution of Rhodnius prolixus to chronic blood-loss but, in the absence of data on feeding frequency, they concluded that R. prolixus would cause negligible blood-loss compared with hookworms. Rabinovich et al.4 calculated the feeding frequency of R. prolixus in fourteen houses in Venezuela and estimated a daily blood-loss ranging from <1 to >3 ml per person. Using data of E. Dias and R. Zeledón, Rabinovichs put the blood-loss caused by Triatoma infestans as 17 ml per person per day, although this was undoubtedly an unusual case. My own estimate (table) indicates that ESTIMATED DAILY BLOOD-LOSS PER PERSON IN A HOUSE INFESTED WITH T. INFESTANS IN BRAZIL
anaemia associated with acute Chagas disease is linked to triatomine bugs rather than to Trypanosoma cruzi. In an unpublished report for the World Health Organisation N. M. Prescott has emphasised the need for a realistic appraisal of the economic damage (both to labour output and to health status) of the major tropical diseases. If this is to be done for Chagas disease the impact must be considered in terms not just of clinical manifestations but also of the unknown contribution of chronic blood-loss; and the possible psychological and social damage caused by the vectors and the fear of the disease, which can lead to many workers from endemic regions to be refused employment whether they are disease-positive or not, must also be taken into
account.
Institute of Neurobiology, Serrano 665, Buenos Aires 1414, Argentina
C.J.SCHOFIELD
CYTOTOXIC DRUGS AND STERILITY
SiR,-Dr Glode and his colleagues suggest that cytotoxic chemotherapy causes permanent sterility in the long term survivors of several conditions, including choriocarcinoma. This suggestion is not supported by data from a study of the long term consequences of chemotherapy in patients with invasive mole or choriocarcinoma treated in this unit between 1958 and 1978. We have analysed data on the 611 patients treated with cytotoxic chemotherapy during that 21 year period. 104 patients died from their initial disease; 38 patients from other countries have not been traced; and 83 have not yet returned their questionnaires. There are obstetric data on the remaining 375 women, and by August, 1980, 177 had become pregnant since finishing chemotherapy. There were a total of 315 pregnancies resulting in 245 live births from 167 women and 76 miscarriages or terminations. Only 5 women who wanted to get pregnant have so far failed. All the women received methotrexate, and 40 of those who became pregnant also received cyclophosphamide and actinomycin D. Walden and Bagshawel suggested that patients with trophoblastic tumours may have a poor obstetric history and that this did not appear to be significantly worsened by chemotherapy. The fact that 47% of all women in this series (and 97% of those who wished to) did become pregnant suggests that infertility is rarely a problem in those treated for trophoblastic tumours with the regimen used here.
G. J. S. RUSTIN K. D. BAGSHAWE E. S. NEWLANDS R. H.J. BEGENT
Department of Medical Oncology, Charing Cross Hospital, London W6 8RF
*Assuming
stable age distribution’ with adult
biting frequency
from
Schofield.6
tfrom Szumlewicz,’ but adding 40% $1ml blood =1-054 g.
to
allow for
urine
loss.
daily blood-loss of 2-3 ml would be a more likely average in houses infested with T. infestans. Chronic blood-loss of this nature may be tolerated by healthy adults and children, but what of children burdened with other parasites and on an inadequate diet? Perhaps the iron-deficiency a
1. Venkatachalam PS, Belavady B Loss of haemoglobin iron due to excessive biting by bed bugs. Trans Roy Soc Trop Med Hyg 1962, 56: 218-21. 2 Szumlewicz AP Laboratory colonies of Triatominae, biology and population dynamics. In New approaches in American trypanosomiasis research (PAHO Publ 318). Washington, DC: Pan American Health Organisation, 1976: 63-82. 3 Layrisse M, Roche M. The relationship between anemia and hookworm infection. Am J Hyg 1964; 79: 279-301. 4. Rabinovich JE, Leal JA, Feliciangeli DP Domiciliary biting frequency and blood ingestion of the Chagas’s disease vector Rhodnius prolixus Stahl (Hemiptera: Reduviidae) in Venezuela. Trans Roy Soc Trop Med Hyg 1979; 73: 272-83. 5 Rabinovich JE Vital statistics of Triatominae (Hemiptera: Reduviidae) under laboratory conditions I Triatoma infestans Klug. J Med Entomol 1972; 9: 351-70. 6. Schofield CJ. Nutritional status of domestic populations of Triatoma infestans Trans Roy Soc Trop Med Hyg 1980; 74: 770-78.
ORAL LORAZEPAM TO IMPROVE TOLERANCE OF CYTOTOXIC THERAPY
SIR,-Cytotoxic drug induced emesis is common in cancer patients; as a result, some may refuse further chemotherapy, and a major problem with chemotherapy is the fear of further treatment because of the recollection of unpleasant complications from previous injections. Having read Dr Maher’s letter (Jan. 10, p. 91) investigated the value of oral lorazepam, as an adjunct to standard antiemetics used in patients receiving cis-platin or doxorubicin containing regimens. Results of this pilot study have been encouraging and will be reported elsewhere. 5 patients who would otherwise have refused to continue potentially curative chemotherapy because of distressing cytotoxic drug induced emesis, had a dramatic symptomatic improvement when lorazepam was added to previously ineffective doses of intravenous haloperidol, and they opted to continue with chemotherapy. An hour before chemotherapy, hospital patients were given a single oral dose of 3 mg lorazepam, and 2 - 5 mg haloperidol was administered intravenously at the time of therapy. All patients slept we
1. Walden
PAM, Bagshawe KD. Reproductive performance of
treated for 1108-14.
gestational trophoblastic
tumor.
Am
women successfully J Obstet Gynecol 1976, 125: