TRANSAC.~IONS OF TIE ROYAL SOCIETY OF TROPICAL MEDICIN:~ AND HYGIENE, VOL. 77, No. 6, 763-766 (19831 763

Serological and parasitological survey of blood donors in toxoplasmosis

Kenya for

LESLEY GRIFFIN AND KATHLEEN A. B. WILLIAMS Dept. of Medical Microbiology, University of Nairobi, Box 30588, Nairobi, Kenya; Scottish Toxoplasma

Reference Laboratory, Microbiology Department, Raigmore Hospital, Inverness IV2 3UJ, Scotland.

Summary 322 samples of sera from blood donors in four areas of Kenya were screened for Toxoplasma gondii

antibodies by haemagglutination and 54% proved positive. 299 of these were also tested by dye test and 42% were positive, with 5.9% showing high titres indicating possible active infection. Parasitological examination of the buffy coat from donors was also carried out on 100 samples but no Toxoplasma parasites were seen in spite of high antibody incidence. There appears to be little or no clinical toxoplasmosis in Kenya but serological studies indicate a widespread distribution of the parasite in the human population.

Introduction Serological surveys throughout Africa show varia- Clinical toxoplasmosis appears to be rare in Kenya.

Paediatricians, pathologists, parasitologists and oph- thalmologists who have been working in Kenya for many years are united in regarding this disease as very uncommon, because clinical cases rarely come to the attention of the clinician and few reports occur in the hospital records.

tion in the prevalence of antibodies detected-from 2% in a certain village in the Ivorv Coast to 61% in a , rural area of Somalra. The results of several recent studies have been compiled and are shown in Table I.

Kenya has a large agricultural as well as urban population, however, and most tribes maintain domestic stock, with dogs and cats common every- where as pets and as strays. Moreover Toxoplasma gondii is regarded as a cosmopolitan parasite occurring throughout the world, so it is almost certainly present in Kenya. TSEGA & BELEHU (1980) suggest that T. go&ii may not be rare but may be among the many causes of lymphadenopathy in Ethiopia; however, their study of 61 hospital in-patients with lym- phadenopathy revealed only five with antibodies to the parasite. Unfortunately there are few reports in the literature of cases of toxoplasmosis confirmed by parasitological findings. Most diagnoses are based on clinical or serological findings.

To determine if infection is common in Kenya, serum from blood donors was collected and examined for the presence of antibodies to T. gondii, and the buffy coat from whole blood was examined parasitolo- gically for the presence of Toxoplasma.

Methods 322 serum samples of approximately 0.5 ml fo 1 ml were

collected from blood donors living in four different areas of Kenya, namely Nairobi, Kiambu, Nakuru and Eldoret. Donors were all over 15 years old and biographical information concerning age, sex, tribe and location together with details of the donor’s blood group and rhesus type were obtained from the blood bank records of the National Public Health Laboratories. In addition? sera from 15 cases of suspected ocular toxoplasmosis, wnh uveitis, were studied.

ser010gv The frozen samples were sent to the Scottish Toxoplasma

Reference Laboratory where serological tests for Toxoplasma

Table I-Recent serological surveys for toxoplasmosis and their findings

Country Prevalence

% Hosts Test Used Date Authors

Chile Jordan

45% 37%

Adults Women

? Skin test

1980 TELLO, P. 1980 1980 MORSY &

Somalia Mogadishu Rural Areas

Nigeria

Amazon Basin Bayts Leeward

Algeria

43.6% 61%

20.6%

59% 45.5%

52.2%

Adults Adults Adult blood

donors Man School

children Adults (2)

dye test CFT, IHA

MICHAEL 1980

dye test dye test IFT & Latex agglutination IHA

?

IFT

1980 1980 1979

1980 1980

1977

ZARDI et al., 1980 ZARDI et al., 1980 OGUNBA &

THOMAS, 1979 FERRARONI et al., 1980 DE ROEVER-BONNET

et al., 1980 SCHNEIDER et al., 1979

764 TOXOPLASMOSIS SCREENING OF BLOOD DONORS IN KENYA

Table II-Results of serological screening for toxoplasmosis among Kenyan blood donors

Number of samples screened by haemagglutination 322 Number positive by HA 174 (54%) Number tested by dye test (23 contaminated) 299 Number positive (i.e. >15 International Units) dye tes 126 (42%) Number with high dye test tines (>250 I.U.) with possible active disease 19 (5.9%)

were excluded from the dye test due to contamination and of the remaining 299 tested, 126 (42%) showed greater than or equal to 15 International Units (I.U.) in the dye test. 19 samples (5.9%) had dye test titres of equal to or greater than 250 I.U. which may indicate possible active infection. In some of these the titres exceeded 1000 or 2000 I.U. These results are summa- rized on Table II:

antibodies were carried out. All sera were screened by haemagglutination (THORBURN & WILLIAMS, 1972) and thereafter, where sufficient serum remained, the dye test (SABIN & FELDMAN, 1948) modified for microtitre methods (FELDMAN & LAMB, 1966) and phase contrast microscopy (LELONG & DESMONTS, 1951).

Statistical analysis showed no significant difference at 5% level between positive or negative samples using the haemagglutination test with respect to sex, rhesus factor or blood group in any of the four geographical areas but when the areas were compared with one another, Eldoret showed a higher frequencv of Toxoplasma-positive samples than the remaining areas (x2 = 12.817, p>O.Ol, Table III).

Parasitology Subsequently a further 100 whole blood samples were

collected from blood donor packs approximately one day after donation. The buffy coat was concentrated by centri- fugation in a capillary tube, stained with Giemsa on a slide and examined for the presence of T. go&i parasites. Serum from the same donors was also collected and tested for antibodies as described above.

The age distribution of donors is also shown in Table III. Differences between the various areas cannot be attributed to age rather than increased exposure to infection as the population examined was composed of young adults (15 to 29 years).

Results Of the 322 samples screened, 174 (54%) were

positive by haemagglutination. 23 of the total sample

Meteorological information given on Table IV, indicates very little difference between the four areas studied, except in rainfall. Kenya has a very equable climate with a bimodal rainfall pattern. The long rains usually fall from the end of March through to May, while the short rains occur in October and November. The months from May to September are cool and

Table III-Frequency of Toxoplasma positive sera, tested by haemagglutination, from four areas of Kenya, and age distribution of blood donors

+ve -ve

Total

% +ve

Nakuru

43 56

99

43

Kiambu Nairobi

48 17 35 21

83 38

57.8 44.7 x2 = 12.82 WO.01

Eldoret

E

102

64.7

Total

174 148

322

54.0

Age in years >20 20-29

30-39 >39

Total

28 75 23 90 216 38 8 54 23 :

8 2 1 :, i

66 82 34 99 281

% under 20 years 42.4 91.5 67.6 90.9 76.8

Table IV-Climatic data for four areas of Kenya

Eldoret

Nakuru

Kiambu

Nairobi

Altitude

7050 ft

6141 ft

6095 ft

5600 ft

Mean Temperature

a.m. 16°C p.m. 23°C a.m. 16°C p.m. 24°C a.m. 14°C p.m. 22°C a.m. 16°C

Relative Mean Annual Humidity Rainfall

a.m. 71% p.m. 47% a.m. 75% p.m. 43% a.m. 77% p.m. 45% a.m. 78%

1225 mm

897 mm

1042 mm

973 mm p.m. 22°C p.m. 46%

L. GRIFFIN AND K. A. B. WILLIAMS 765

cloudy while December to March are hot and dry. This pattern applied to all but the desert areas of the country in the north. The mean annual rainfall is higher in Eldoret and Kiambu than in Nairobi and Nakuru although the differences are not marked. Nakuru, situated in the Rift Valley, received less rain than the other centres.

Nairobi and Nakuru are large urban areas with good water supplies and sewage disposal facilities, Eldoret, although a small town, is the centre of an extensive farming region and Kiambu, although less than 15 miles from Nairobi, is a rural area with few piped water facilities.

Parasitological examination of the buffy coat showed no endozoites of T. gondii in any of the samples although malaria parasites were identified in 14 out of 100 samples. Serum from these donors showed a similar frequency of Toxoplasma antibodies to the remaining serum samples, namely 42%.

Of the 15 samples from suspected ocular cases of toxoplasmosis, 41.6% were positive for antibody but as this figure corresponds with that in the normal population no conclusion can be drawn.

Discussion In spite of the paucity of clinical toxoplasmosis in

Kenya the incidence of antibodies among apparently healthy blood donors was high, 54% by haemagglu- tination test and 42% by dye test. These findings agree with those of another study by the author (L.G.), as yet unpublished, which demonstrated, using the ELISA method, that sera from newly delivered mothers of two rural areas of Kenya have antibodies to Toxoplasma in 42.5% and 49.4% of the cases. Other studies from some African countries also show high frequencies of Toxoplasma antibodies as shown on Table I.

However, a similar survey of the incidence of antibodies against T. gondii in the general population of Scotland showed a rate of only 27% using the dye test, and the incidence of congenital toxoplasmosis was estimated to be one in 2000 (WILLIAMS et al., 1981). Congenital toxoplasmosis is very rarely re- corded in Kenya, or other countries of Africa, and a survey of more than 500 neonatal deaths from Kenyan hospitals did not show any cases of the disease (Lucas, personal communication).

The interpretation of the high incidence of Toxo- plasma antibodies in Kenya with so little clinical infection is difficult. It is oossible that most of the population is exposed to the disease during childhood resulting in a mild or asymptomatic infection which produces an antibody response that protects against a severe infection later. If this is the case the high prevalence of antibodies seen in this and other studies in Africa may have a protective role, suggesting that the disease is of minor clinical importance.

Studies currently in progress on the prevalence of Toxoplasma antibodies in young schoolchildren will provide more information on this aspect (Bowry, personal communication) and further data on the prevalence among older people are needed to cover the entire age spectrum before conclusions can be drawn.

The higher frequency of Toxoplasma antibodies in donors from Eldoret compared with the other centres is also difficult to explain. The climate in this area is

very similar to that in the other areas, and since Toxopltzsma occurs widely in many different climatic regions the small differences in rainfall between the areas studied are unlikely to be important. The fact that Eldoret is a farming area may be more important for transmission and exposure to the infection, than small climatic differences.

It has also been suggested that cross reaction with other blood parasites, notably malaria, may account for some false positive readings (Bowry, Wassuna, personal communication) and in order to assess this possibility 102 samples of serum from proven malaria patients were tested for antibody to Toxoplasma.

Only 21 had detectable antibody which lends no support to that contention. Indeed the dye test has always been considered to be absolutely Toxoplasma- specific. The problem of Toxoplasma diagnosis is compounded by the difficulties in detecting an active infection by conventional parasitological methods to confirm the serological findings. In this study no endozoites were identified from buffy coat examined. Ideally inoculation into mice should be used to confirm the presence of Toxoplasma but this is impracticable where large numbers of samples are involved.

The results of this study suggest that though toxoplasmosis may be common in Kenya as a mild infection, severe disease is rare.

Acknowledgements The authors would like to thank the Director and Staff of

the Blood Bank at the National Public Health Laboratories for assistance with the study.

References Feldman, H. A. & Lamb, G. A. (1966). A micromodilica-

tion of the Toxoplasma dye test. Journal of Parasitology, 52, 415.

Ferraroni, J. J., Reed, S. G. & Speer, C. A. (1980). Prevalence of Toxoplasma antibodies in humans and various animals in the Amazon. Proceedings of the Helminthological Society of Washington, 47, 148-150.

Lelong, M. & Desmonts, G. (1951). L’emploi du micro- scoue g contraste de ohase dans la reaction de Sabin- Feldman. Comptes Reidus des Sbances de la Socit% de Biologic Paris, 145, 1660.

Morsey, T. A. & Michael, S. A. (1980). Toxoplasmosis in Jordan. ~oumal of Egyptian Society of Parasitology, 10, 457-470.

Ogunba, E. 0. & Thomas, V. (1979). Antibodies to T. gondii in Ibadan. NigerianJournal of Medical Science, 1, 77-m

de Roever-Bonnet, H., Haverkamp, W., van der Sar, A, Gonzalez, W. & Hovankamn. W. (1980). Serological and clinical evidence of toxopla&osis on the Upper Leeward Islands. Tropical and Geographical Medicine, 32, 53-56.

Sabin, A. B. & Feldman, H. A. (1948). Dyes as Micro- chemical indicators of a new, immunity phenomenon affecting a protozoan parasite (Toxoplasma). Science, 108, 660.

Schneider, R., Tabet-Derraz, O., Dedet, J. P., Belkaid, M. & Lamri, I. (1979). Etude de 2438 serodiagnostics de toxoplasmose par immunofluorescence a L’Institut Pas- teur d’Algerie. Archives de l’lnstitut Pasteur d’Algerie, 52, 95-1n4 ,_ _-..

Tello, P. (1980). Toxoplasmosis y embarazo. Boletin Chileno de Parasitologia, 35, 21-24.

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766 TOXOPLASMOSIS SCREENING OF BLOOD DONORS IN KENYA

Tsega, E. & Belehu, A. (1980). Toxoplasmosis in hospital- ised Ethiopians with Lymphadenopathy. East African Medical Journal, 57, 35-38.

Williams, K. A. B., Scott, J. M., Macfarlane, D. E., Williamson, J. M. W., Elias-Jones, T. F. & Williams, H. (1981). Congenital toxoplasmosis: a prospective survey in the West of Scotland. Journal of Infection, 3, 219-229.

Zardi, O., Adoriosio, E., Harare, 0. & Nuti, M. (1980). Serological survey of toxoplasmosis in Somalia. Trunsac- tions of the Royal Society of Tropical Medicine and Hygiene, 74, 577-581.

Accepted for publication 30th January, 1983.

Elected 20th October, 1983

Abbey, C. D. V., Britain Ahmed, M. N., Bangladesh Alexander, J., Britain Al-Seghayer, S. M., Saudi Arabia Azad, M. A. K., India Banatvala, J. E., Britain Banerjee, U., India Bhattacharya, A. K., India Bhaumik, S. D., India Cantella, R. A., Peru Chatterlee, A., India Chatterjee, S. R., India Connor, R. J., Kenya Datta, S., India Dom, G. M.-H., Belgium Druilhe, I’., France Eslova, A., Britain Fekadu, A., Ethiopia Fison, T. W., Britain Ghanty, S. K., India Ghorai, S. C., India Ghosh, D., India Ghosh, S. K., India Halvorsen-French, C. K. E., Britain Hoover, N. J., USA Hougesen, B., Canada Jana, S. R., India Jha, S. S., India Johnson, L., Uganda Kanoi, I’., India Kaur, T., India Khan, A. R., Libya Khan, A. S., India Koley, B. N., India Kostic-Moreno, A., Yugoslavia Linares, D., Britam Lowa, M. P., Belgium Maizels, R. M., Britain Mallik, A. K., India Massoud, M. M. A., Egypt

New Fellows

Mayilvahanan, N . , India Mazumdar, B., India Mehta, D.. N., India Mensah. B. E.. Nieeria Mishra,‘G., India ” Mitra, S. K., India Mitra, S. K., India Mondal, A., India Mondal, A. B., India Mukherjee, S.,~ India Nardos. W. G.. USA Ofori-Adjei, Ghana Pal, A. D., India Paul, I’. K., India Paul, P. S., India Petrozzi, R. M., Kenya Phillips, J. C., Britain Ranavaya, M. I., German Federal Republic Rangarajan, B., India Ray, R., India Read, D. G., Australia Roy, M. J., India Roy, I’. K., India Sadhukan, N., India Saha, C. K., India Sarangi, A. K., India Sarkar, A., India Sarkar, P., India Sarkar, S. K., India Scott-Taylor, T. H., Britain Sengupta, B. I’., India Sengupta, B. R., India Shepherd, C. A., Australia Sinha, S., India Taha, S. A., Saudi Arabia Teinaz, Y. R., Britain Vanden Eynden, K. N., Belgium Venkataraman, G. V., India Vercruysse, J., Belgium Vickerv. A. C.. USA Viswanath, J . , India Willcox, M. C., Sweden