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Zoonotic infections in Nigeria: overview from a medical perspective
Acta Tropica 76 (2000) 59 – 63 www.elsevier.com/locate/actatropica
Zoonotic infections in Nigeria: overview from a medical perspective A.O. Coker a,*, R.D. Isokpehi a, B.N. Thomas b, A.F. Fagbenro-Beyioku b, S.A. Omilabu c a
Campylobacter Research Laboratory, Department of Medical Microbiology and Parasitology, College of Medicine, Uni6ersity of Lagos, Idiaraba, Lagos, Nigeria b Tropical Diseases Research Laboratory, Department of Medical Microbiology and Parasitology, College of Medicine, Uni6ersity of Lagos, Idiaraba, Lagos, Nigeria c Virology Research Unit, Department of Medical Microbiology and Parasitology, College of Medicine, Uni6ersity of Lagos, Idiaraba, Lagos, Nigeria
Abstract Infections of domestic and wild animals that are transmitted directly or by an arthropod vector to humans are a major cause of morbidity and mortality worldwide and particularly in Nigeria. With a population of over 100 million and the need for improved health care delivery, Nigerians are at considerable risk considering the seriousness of these infections. Zoonotic infections that are endemic in Nigeria include tuberculosis, trypanosomiasis, toxoplasmosis, taeniasis, rabies, lassa fever and yellow fever. Zoonotic food-borne infections (caused by Campylobacter, Salmonella and Escherichia coli O157:H7) and cryptosporidiosis are emerging. Sporadic cases such as strongyloidiasis, ascariasis, leptospirosis, scabies, pentastomiasis and African histoplasmosis have been reported. There is a need to determine the prevalence of tick-borne zoonoses. Prevention and control of zoonoses in humans is by vaccination, treatment and health education. As a first measure to improve control, the link between veterinary and medical officers, which is presently very weak, needs to be strengthened. Furthermore, regional multidisciplinary approaches to the control of zoonotic infections should be adopted in West Africa, which take into consideration the huge inter-border traffic. © 2000 Elsevier Science B.V. All rights reserved. Keywords: Zoonoses; Emerging; Sporadic; Nigeria; Endemic; Public health
1. Introduction Zoonoses are infections involving in the transmission of the aetiologic agent to humans from an * Corresponding author. Tel.: + 234-1-5453760-74, ext. 2138; fax: + 234-1-5851432. E-mail address: [email protected] (A.O. Coker).
ongoing reservoir in animals or arthropods, without the permanent establishment of a new life cycle in humans (Murphy, 1998). The following zoonoses are notifiable in Nigeria, anthrax, brucellosis, lassa fever, rabies, sleeping sickness, typhoid fever (salmonellosis), tuberculosis, and yellow fever. Infections such as tuberculosis, rabies, toxoplasmosis, taeniasis and yellow fever
0001-706X/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved. PII: S 0 0 0 1 - 7 0 6 X ( 0 0 ) 0 0 0 9 1 - 7
A.O. Coker et al. / Acta Tropica 76 (2000) 59–63
60
Table 1 Endemic, emerging and sporadic zoonoses in Nigeria Zoonotic infection Endemic zoonoses Lassa fever Rabies Toxoplasmosis Trypanosomiasis Tuberculosis Yellow fever Emerging zoonoses Campylobacteriosis Enterohaemorrahagic Escherichia coli Cryptosporidiosis Salmonellosis
ment, hunting, farming, cultural beliefs and poor or completely absent animal inspection by health officers have exposed man and his domestic animals to zoonotic disease. In this paper, we discuss the prevalence of some selected zoonotic infections encountered in Nigeria. Data on prevalence were summarised from publications of the Federal Ministry of Health (FMH, 1996) and the Federal Office of Statistics (FOS, 1993) and other previously published reports. Zoonotic infections in Nigeria will be discussed under three categories, endemic, emerging and sporadic (Table 1).
2. Endemic zoonoses in Nigeria
Sporadic zoonoses African histoplasmosis Ascariasis Brucellosis Clostridium perfringens infection Leptospirosis Pentastomiasis Scabies Strongyloidiasis
2.1. Tuberculosis
are well documented (FMH, 1996; Kalu et al., 1996; Adeiga and Audu, 1998) while new ones such as campylobacteriosis and Escherichia coli O157:H7 infections are apparently emerging (Coker and Adefeso, 1994; Ogunsanya et al., 1994). A combination of climatic, ecological, agricultural and socio-economic factors has led to a hazardous veterinary public health situation in Nigeria. The claiming of forests for urban develop-
Tuberculosis is a disease of global importance and could be either anthropozoonotic or zooanthroponotic (Awofeso, 1998). Data from the Federal Ministry of Health reveals the incidence of tuberculosis (Tables 2 and 3). The public health effect remains alarming, especially with the recent association of psychiatric morbidity with tuberculosis, the low educational status in the South, and the inseparable association of human life with animal husbandry in the North (Aghanwa and Erhabor, 1998). However, with the re-launch of the National Programme on Immunisation and the establishment of the National Control Programme on Tuberculosis and Leprosy, a reduction in incidence of TB is anticipated.
Table 2 Reported cases of some notifiable zoonotic infections in Nigeriaa Infection
1987
1988
1989
1990
1991
1992
1993
1994/95
Anthrax Brucellosis Rabies Sleeping sickness Tuberculosis Typhoid fever Yellow fever
192 – 4 1757 19 723 2179 1510
170 – 7 326 16 980 3436 1945
45 – 12 880 12 232 3502 2105
8 12 341 1061 20 122 4772 3528
– 4 1055 1024 19 100 8101 2568
– 69 92 1660 14 802 19 003 149
9 9 106 834 11 601 11 893 152
1 – 19 231 10 040 26 729 25
a
Sources, Federal Office of Statistics (FOS, 1993); Federal Ministry of Health (FMH, 1996).
A.O. Coker et al. / Acta Tropica 76 (2000) 59–63
61
Table 3 Reported deaths from notifiable zoonotic infections in Nigeriaa Infection
1987
1988
1989
1990
1991
1992
1993
1994/95
Anthrax Brucellosis Rabies Sleeping sickness Tuberculosis Typhoid fever Yellow fever
– – 4 40 422 34 599
1 – 7 31 423 237 1531
– – 12 3 300 84 412
– – 27 13 213 92 13
– – 11 9 471 259 661
0 0 0 2 16 21 0
0 0 0 1 12 13 0
1 – 6 2 407 707 1
a
Sources, Federal Office of Statistics (FOS, 1993); Federal Ministry of Health (FMH, 1996).
2.2. Yellow fe6er Yellow fever is the most important viral zoonoses in Nigeria. The infection is known to be transmitted by the mosquito, Aedes aegypti and to have a 10-year cycle (Wagbatsoma and Ogbeide, 1999). A recent study in our laboratory, supported by results from other workers indicated that 66.1% of patients presenting with pyrexia of unknown origin (PUO) were positive for the yellow fever complement fixing antibody (Baba et al., 1999).
2.3. Rabies Rabies is endemic in Nigeria and dogs are the major reservoirs (Adeiga and Audu, 1998). Status of the disease in the country between 1988 and 1995 is presented in Tables 2 and 3. The public health significance of the infection has been highlighted, considering the economic situation, which makes it almost impossible for dog owners to have their pets vaccinated (Adeiga and Audu, 1998). Prophylaxis is based on vaccination with the anti-rabies vaccine, while treatment involves the use of suckling mouse brain vaccine (SMBV) which is effective and well tolerated (Harry et al., 1985). Recently, two outbreaks of rabies were recorded in Benin-city and Ondo located in the mid-west and southwest Nigeria, respectively.
2.4. Lassa fe6er Lassa fever was first reported in Nigeria among the patients and staff of an American missionary
hospital (Ayele, 1992). It is a disease in which nosocomial transmission is a high possibility and its public health significance can be viewed from this standpoint. In a recent survey among 552 health workers from six different health facilities in Nigeria, Lassa virus immunoglobulin G (IgG) was detected in 12.3% of the study group, with prevalence ranging from 1.2 to 27.3% (Bajani et al., 1997).
2.5. Trypanosomiasis African trypanosomiasis (sleeping sickness) is an important zoonotic infection in West Africa, especially in parts of the region where livestock are reared and in the forest areas where animal reservoirs are found (Kalu et al., 1996; Molyneux, 1998). Trypanosoma brucei gambiense is the most common species found in Nigeria (Smith et al., 1998) but data on human infection is limited (Table 2). The apparently low figures might be due to the poor and uncoordinated manner by which data are compiled. Anecdotal evidence suggests that an endemic situation probably exist in the northern part of Nigeria.
2.6. Toxoplasmosis Toxoplasmosis is a protozoan infection caused by the parasite Toxoplasma gondii and its distribution is global (Dubey et al., 1998). With the increase in the number of immuno-deficient individuals in Nigeria as a result of AIDS, T. gondii is emerging as one of the most common infections in these individuals (Olusi et al., 1994; Onadeko et
A.O. Coker et al. / Acta Tropica 76 (2000) 59–63
62
Table 4 Toxoplasmosis in Nigeria based on measurement of anti-Toxoplasma antibodies References
State
Locality
Positive (%)
Emejuaiwe et al. (1976) Okoh et al. (1981) Megafu and Ugwuegbulam (1981) Jaji and Acholonu (1985) Olusi et al. (1994) Onadeko et al. (1996)
Anambra and Imo Kano Anambra Lagos Benue Oyo
Enugu Kano Enugu Lagos Makurdi Ibadan
77.3 32.1 15.0 59.0, 60.2a, 63.2b 57.0 75.4a, 80.4b
a b
Pregnant women. Non-pregnant women.
al., 1996). The infection is endemic in Nigeria with anti-Toxoplasma antibodies ranging between 15 and 88% (Table 4). Present data shows a prevalence of 75.4 and 80.5% among pregnant and post-partum women, respectively (Onadeko et al., 1996).
(Ezeh et al., 1991). Other zoonotic infections occurring sporadically in Nigeria include scabies (Olasode and Onayemi, 1998) pentastomiasis (Nzeh et al., 1996) ascariasis (Agi, 1997) African histoplasmosis (Khalil et al., 1998; Onwuasoigwe and Gugnami, 1998) strongyloidiasis (Arije et al., 1992) and brucellosis (Corbel, 1997).
3. Emerging zoonoses
3.1. Campylobacter species Over the past decade, Campylobacter jejuni/coli has emerged from obscurity as veterinary pathogen to recognition as a leading cause of enteritis in humans in Nigeria (Coker and DosunmuOgunbi, 1983; Coker and Adefeso, 1994; Smith et al., 1999). Studies by Adegbola et al. (1990) revealed that C. jejuni biotypes 1 were the most common while serogroups 2, 4, 29 and 36 were also seen. This distribution pattern suggests that these serogroups are involved in the zooanthroponotic route of transmission in Nigeria. Other emerging zoonotic infections include enterohaemorrhagic E. coli, salmonellosis, cryptosporidiosis and Clostridum perfringens infection. However, data on these infections are extremely limited.
4. Sporadic zoonoses Leptospirosis has been found to have very high prevalence in Northern Nigeria where animal husbandry remains the main occupation of the people
5. Links between medical and veterinary officers in Nigeria Links between these two groups of professionals can be said to be non-existent or at best very weak. Research is needed to gather more basic information on the prevalence of zoonotic infections in Nigeria and in this regard both medical and veterinary personnel have important roles to play. There is an urgent need to establish a regional animal health information system which should make use of computer technology and electronic information so that recent data can be made readily available to the appropriate personnel.
References Adegbola, R.A., Alabi, S.A., Akinkuede, F.O., Coker, A.O., Odugbemi, T., 1990. Correlation between human and animal bio-serogroups of Camylobacter isolates in Nigeria. J. Trop. Med. Hyg. 93, 280 – 283. Adeiga, A., Audu, R.A., 1998. Detection of rabies virus in saliva of apparently healthy dogs. Biomed. Lett. 54, 207 – 212.
A.O. Coker et al. / Acta Tropica 76 (2000) 59–63 Aghanwa, H.S., Erhabor, G.E., 1998. Demographic/socioeconomic factors in mental disorders associated with tuberculosis in southwest Nigeria. J. Psychosom. Res. 45, 353 – 360. Agi, P.I., 1997. Comparative helminth infections of man in two rural communities of the Niger Delta Nigeria. West Afr. J. Med. 16, 232 –236. Arije, A., Kadiri, S., Osobamiro, O.A., Akinkugbe, O.O., 1992. Chronic diarrhoea due to strongyloidiasis in a Nigerian with chronic renal failure: a case report. J. Trop. Med. Hyg. 95, 354 – 355. Awofeso, N., 1998. Implementing tuberculosis control programmes in Kaduna State Nigeria. Int. J. Tuberculosis Lung Dis. 2, 336 – 337. Ayele, T., 1992. Disease Prevention and Control in Nigeria. Annual Report, World Health Organisation, Geneva, Switzerland. Baba, S.S., Fagbami, A.H., Ojeh, C.K., 1999. Preliminary studies on the use of solid-phase immunosorbent techniques for the rapid detection of Wesselsbron virus (WSLV) IgM by haemagglutination-inhibition. Comp. Immunol. Microbiol. Infect. Dis. 22, 71–79. Bajani, M.D., Tomori, O., Rollin, P.E., Harry, T.O., Bukbuk, N.D., Wilson, L., Childs, J.E., Peters, C.J., Ksiazek, T.G., 1997. A survey for antibodies to Lassa virus among health workers in Nigeria. Trans. R. Soc. Trop. Med. Hyg. 91, 379 – 381. Coker, A.O., Dosunmu-Ogunbi, O., 1983. Biotypes among Campylobacter jejuni strains isolated in Lagos. Int. J. Microbiol. 1, 77 – 79. Coker, A.O., Adefeso, A.O., 1994. The changing pattern of Campylobacter jejuni/coli in Lagos, Nigeria. East Afr. J. Med. 71, 437 – 440. Corbel, M.J., 1997. Brucellosis: an overview. Emerg. Infect. Dis. 3, 213 – 221. Dubey, J.P., Lindsay, D.S., Speer, C.A., 1998. Structures of Toxoplasma gondii tachyzoites, bradyzoites and sporozoites and biology and development of tissue cysts. Clin. Microbiol. Rev. 11, 267–299. Emejuaiwe, S.O., Njoku-Obi, A.N.U., Talwar, R.S., Kodiliaye, N.C., 1976. Serological reactions in possible human toxoplasmosis in most parts of East Central State of Nigeria. Bull. Anim. Health Prod. Afr. 24, 271–285. Ezeh, A.O., Adesiyun, A.A., Addo, P.B., Ellis, W.A., Makinde, A.A., Bello, C.S.S., 1991. Serological and cultural examination for human leptospirosis in Plateau State Nigeria. Cent. Afr. J. Med. 37, 11–15. FMH, 1996. Health in Nigeria 1994–1995. National Health Management Information System, Federal Ministry of Health, Nigeria. FOS, 1993. Annual Abstracts of Statistics. Federal Office of Statistics, Nigeria.
.
63
Harry, T.O., Adeiga, A., Nasidi, A., 1985. Rabies in Nigeria. Lancet 2, 601 – 602. Jaji, B.E., Acholonu, A.D.W., 1985. Toxoplasmosis in Lagos: antibodies determination and age distribution. Niger. J. Microbiol. 5, 36 – 40. Kalu, A.U., Uzoukwu, M., Ikeme, M., 1996. Prevalence of tsetse fly and ruminant trypanosomiasis in Katsina-Ala Local Government Area Nigeria. Roum. Arch. Microbiol. Immunol. 55, 341 – 352. Khalil, M.A., Hassan, A.W., Gugnami, H.C., 1998. African histoplasmosis: report of four cases from north-eastern Nigeria. Mycoses 41, 293 – 295. Megafu, U., Ugwuegbulam, I., 1981. Incidence of positive toxoplasmosis haemagglutination test in the Nigerian (Ibo) women with recurrent abortions. Int. J. Fertil. 26, 132 – 134. Molyneux, D.H., 1998. Vector-borne parasitic diseases — an overview of recent changes. Int. J. Parasitol. 28, 927 – 934. Murphy, F.A., 1998. Emerging zoonoses. Emerg. Infect. Dis. 4, 429 – 435. Nzeh, D.A., Akinlemibola, J.K., Nzeh, G.C., 1996. Incidence of Armillifer armillatus (Pentastome) calcification in the abdomen. Cent. Afr. J. Med. 42, 29 – 31. Ogunsanya, T.I., Rotimi, V.O., Adenuga, A., 1994. A study of the aetiological agents of childhood diarrhoea in Lagos, Nigeria. J. Med. Microbiol. 40, 10 – 14. Okoh, A.E.J., Agbonlahor, D.E., Momoh, M., 1981. Toxoplasmosis in Nigeria — a serological survey. Trop. Anim. Health Prod. 13, 137 – 143. Olasode, O.A., Onayemi, O., 1998. Scabies revisited in a depressed economy. Cent. Afr. J. Med. 44, 18 – 21. Olusi, T.A., Ajayi, J.A., Makinde, A.A., 1994. Antibodies to Toxoplasma gondii in a rat-eating population of Benue State Nigeria. Ann. Trop. Med. Parasitol. 88, 217 – 218. Onadeko, M.O., Johnson, D.H., Payne, R.A., Francis, J., 1996. The prevalence of Toxoplasma antibodies in pregnant women and the occurrence of stillbirth and congenital malformation. Afr. J. Med. Sci. 25, 331 – 334. Onwuasoigwe, O., Gugnami, H.C., 1998. African histoplasmosis: osteomyelitis of the radius. Mycoses 41, 105 – 107. Smith, D.H., Pepin, J., Stich, A.H.R., 1998. Human African trypanosomiasis: an emerging public health crisis. Br. Med. Bull. 54, 341 – 355. Smith, S.I., Sansa, T.I., Coker, A.O., 1999. Antibiotic susceptibility patterns and b-lactamase production of animal and human isolates of Campylobacter in Lagos, Nigeria. Z. Naturforsch. 54, 583 – 586. Wagbatsoma, V.A., Ogbeide, O., 1999. Towards malaria control: the knowledge of health care providers about mosquito and malaria transmission. Cent. Afr. J. Med. 45, 4 – 6.
Zoonotic infections in Nigeria: overview from a medical perspective A.O. Coker a,*, R.D. Isokpehi a, B.N. Thomas b, A.F. Fagbenro-Beyioku b, S.A. Omilabu c a
Campylobacter Research Laboratory, Department of Medical Microbiology and Parasitology, College of Medicine, Uni6ersity of Lagos, Idiaraba, Lagos, Nigeria b Tropical Diseases Research Laboratory, Department of Medical Microbiology and Parasitology, College of Medicine, Uni6ersity of Lagos, Idiaraba, Lagos, Nigeria c Virology Research Unit, Department of Medical Microbiology and Parasitology, College of Medicine, Uni6ersity of Lagos, Idiaraba, Lagos, Nigeria
Abstract Infections of domestic and wild animals that are transmitted directly or by an arthropod vector to humans are a major cause of morbidity and mortality worldwide and particularly in Nigeria. With a population of over 100 million and the need for improved health care delivery, Nigerians are at considerable risk considering the seriousness of these infections. Zoonotic infections that are endemic in Nigeria include tuberculosis, trypanosomiasis, toxoplasmosis, taeniasis, rabies, lassa fever and yellow fever. Zoonotic food-borne infections (caused by Campylobacter, Salmonella and Escherichia coli O157:H7) and cryptosporidiosis are emerging. Sporadic cases such as strongyloidiasis, ascariasis, leptospirosis, scabies, pentastomiasis and African histoplasmosis have been reported. There is a need to determine the prevalence of tick-borne zoonoses. Prevention and control of zoonoses in humans is by vaccination, treatment and health education. As a first measure to improve control, the link between veterinary and medical officers, which is presently very weak, needs to be strengthened. Furthermore, regional multidisciplinary approaches to the control of zoonotic infections should be adopted in West Africa, which take into consideration the huge inter-border traffic. © 2000 Elsevier Science B.V. All rights reserved. Keywords: Zoonoses; Emerging; Sporadic; Nigeria; Endemic; Public health
1. Introduction Zoonoses are infections involving in the transmission of the aetiologic agent to humans from an * Corresponding author. Tel.: + 234-1-5453760-74, ext. 2138; fax: + 234-1-5851432. E-mail address: [email protected] (A.O. Coker).
ongoing reservoir in animals or arthropods, without the permanent establishment of a new life cycle in humans (Murphy, 1998). The following zoonoses are notifiable in Nigeria, anthrax, brucellosis, lassa fever, rabies, sleeping sickness, typhoid fever (salmonellosis), tuberculosis, and yellow fever. Infections such as tuberculosis, rabies, toxoplasmosis, taeniasis and yellow fever
0001-706X/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved. PII: S 0 0 0 1 - 7 0 6 X ( 0 0 ) 0 0 0 9 1 - 7
A.O. Coker et al. / Acta Tropica 76 (2000) 59–63
60
Table 1 Endemic, emerging and sporadic zoonoses in Nigeria Zoonotic infection Endemic zoonoses Lassa fever Rabies Toxoplasmosis Trypanosomiasis Tuberculosis Yellow fever Emerging zoonoses Campylobacteriosis Enterohaemorrahagic Escherichia coli Cryptosporidiosis Salmonellosis
ment, hunting, farming, cultural beliefs and poor or completely absent animal inspection by health officers have exposed man and his domestic animals to zoonotic disease. In this paper, we discuss the prevalence of some selected zoonotic infections encountered in Nigeria. Data on prevalence were summarised from publications of the Federal Ministry of Health (FMH, 1996) and the Federal Office of Statistics (FOS, 1993) and other previously published reports. Zoonotic infections in Nigeria will be discussed under three categories, endemic, emerging and sporadic (Table 1).
2. Endemic zoonoses in Nigeria
Sporadic zoonoses African histoplasmosis Ascariasis Brucellosis Clostridium perfringens infection Leptospirosis Pentastomiasis Scabies Strongyloidiasis
2.1. Tuberculosis
are well documented (FMH, 1996; Kalu et al., 1996; Adeiga and Audu, 1998) while new ones such as campylobacteriosis and Escherichia coli O157:H7 infections are apparently emerging (Coker and Adefeso, 1994; Ogunsanya et al., 1994). A combination of climatic, ecological, agricultural and socio-economic factors has led to a hazardous veterinary public health situation in Nigeria. The claiming of forests for urban develop-
Tuberculosis is a disease of global importance and could be either anthropozoonotic or zooanthroponotic (Awofeso, 1998). Data from the Federal Ministry of Health reveals the incidence of tuberculosis (Tables 2 and 3). The public health effect remains alarming, especially with the recent association of psychiatric morbidity with tuberculosis, the low educational status in the South, and the inseparable association of human life with animal husbandry in the North (Aghanwa and Erhabor, 1998). However, with the re-launch of the National Programme on Immunisation and the establishment of the National Control Programme on Tuberculosis and Leprosy, a reduction in incidence of TB is anticipated.
Table 2 Reported cases of some notifiable zoonotic infections in Nigeriaa Infection
1987
1988
1989
1990
1991
1992
1993
1994/95
Anthrax Brucellosis Rabies Sleeping sickness Tuberculosis Typhoid fever Yellow fever
192 – 4 1757 19 723 2179 1510
170 – 7 326 16 980 3436 1945
45 – 12 880 12 232 3502 2105
8 12 341 1061 20 122 4772 3528
– 4 1055 1024 19 100 8101 2568
– 69 92 1660 14 802 19 003 149
9 9 106 834 11 601 11 893 152
1 – 19 231 10 040 26 729 25
a
Sources, Federal Office of Statistics (FOS, 1993); Federal Ministry of Health (FMH, 1996).
A.O. Coker et al. / Acta Tropica 76 (2000) 59–63
61
Table 3 Reported deaths from notifiable zoonotic infections in Nigeriaa Infection
1987
1988
1989
1990
1991
1992
1993
1994/95
Anthrax Brucellosis Rabies Sleeping sickness Tuberculosis Typhoid fever Yellow fever
– – 4 40 422 34 599
1 – 7 31 423 237 1531
– – 12 3 300 84 412
– – 27 13 213 92 13
– – 11 9 471 259 661
0 0 0 2 16 21 0
0 0 0 1 12 13 0
1 – 6 2 407 707 1
a
Sources, Federal Office of Statistics (FOS, 1993); Federal Ministry of Health (FMH, 1996).
2.2. Yellow fe6er Yellow fever is the most important viral zoonoses in Nigeria. The infection is known to be transmitted by the mosquito, Aedes aegypti and to have a 10-year cycle (Wagbatsoma and Ogbeide, 1999). A recent study in our laboratory, supported by results from other workers indicated that 66.1% of patients presenting with pyrexia of unknown origin (PUO) were positive for the yellow fever complement fixing antibody (Baba et al., 1999).
2.3. Rabies Rabies is endemic in Nigeria and dogs are the major reservoirs (Adeiga and Audu, 1998). Status of the disease in the country between 1988 and 1995 is presented in Tables 2 and 3. The public health significance of the infection has been highlighted, considering the economic situation, which makes it almost impossible for dog owners to have their pets vaccinated (Adeiga and Audu, 1998). Prophylaxis is based on vaccination with the anti-rabies vaccine, while treatment involves the use of suckling mouse brain vaccine (SMBV) which is effective and well tolerated (Harry et al., 1985). Recently, two outbreaks of rabies were recorded in Benin-city and Ondo located in the mid-west and southwest Nigeria, respectively.
2.4. Lassa fe6er Lassa fever was first reported in Nigeria among the patients and staff of an American missionary
hospital (Ayele, 1992). It is a disease in which nosocomial transmission is a high possibility and its public health significance can be viewed from this standpoint. In a recent survey among 552 health workers from six different health facilities in Nigeria, Lassa virus immunoglobulin G (IgG) was detected in 12.3% of the study group, with prevalence ranging from 1.2 to 27.3% (Bajani et al., 1997).
2.5. Trypanosomiasis African trypanosomiasis (sleeping sickness) is an important zoonotic infection in West Africa, especially in parts of the region where livestock are reared and in the forest areas where animal reservoirs are found (Kalu et al., 1996; Molyneux, 1998). Trypanosoma brucei gambiense is the most common species found in Nigeria (Smith et al., 1998) but data on human infection is limited (Table 2). The apparently low figures might be due to the poor and uncoordinated manner by which data are compiled. Anecdotal evidence suggests that an endemic situation probably exist in the northern part of Nigeria.
2.6. Toxoplasmosis Toxoplasmosis is a protozoan infection caused by the parasite Toxoplasma gondii and its distribution is global (Dubey et al., 1998). With the increase in the number of immuno-deficient individuals in Nigeria as a result of AIDS, T. gondii is emerging as one of the most common infections in these individuals (Olusi et al., 1994; Onadeko et
A.O. Coker et al. / Acta Tropica 76 (2000) 59–63
62
Table 4 Toxoplasmosis in Nigeria based on measurement of anti-Toxoplasma antibodies References
State
Locality
Positive (%)
Emejuaiwe et al. (1976) Okoh et al. (1981) Megafu and Ugwuegbulam (1981) Jaji and Acholonu (1985) Olusi et al. (1994) Onadeko et al. (1996)
Anambra and Imo Kano Anambra Lagos Benue Oyo
Enugu Kano Enugu Lagos Makurdi Ibadan
77.3 32.1 15.0 59.0, 60.2a, 63.2b 57.0 75.4a, 80.4b
a b
Pregnant women. Non-pregnant women.
al., 1996). The infection is endemic in Nigeria with anti-Toxoplasma antibodies ranging between 15 and 88% (Table 4). Present data shows a prevalence of 75.4 and 80.5% among pregnant and post-partum women, respectively (Onadeko et al., 1996).
(Ezeh et al., 1991). Other zoonotic infections occurring sporadically in Nigeria include scabies (Olasode and Onayemi, 1998) pentastomiasis (Nzeh et al., 1996) ascariasis (Agi, 1997) African histoplasmosis (Khalil et al., 1998; Onwuasoigwe and Gugnami, 1998) strongyloidiasis (Arije et al., 1992) and brucellosis (Corbel, 1997).
3. Emerging zoonoses
3.1. Campylobacter species Over the past decade, Campylobacter jejuni/coli has emerged from obscurity as veterinary pathogen to recognition as a leading cause of enteritis in humans in Nigeria (Coker and DosunmuOgunbi, 1983; Coker and Adefeso, 1994; Smith et al., 1999). Studies by Adegbola et al. (1990) revealed that C. jejuni biotypes 1 were the most common while serogroups 2, 4, 29 and 36 were also seen. This distribution pattern suggests that these serogroups are involved in the zooanthroponotic route of transmission in Nigeria. Other emerging zoonotic infections include enterohaemorrhagic E. coli, salmonellosis, cryptosporidiosis and Clostridum perfringens infection. However, data on these infections are extremely limited.
4. Sporadic zoonoses Leptospirosis has been found to have very high prevalence in Northern Nigeria where animal husbandry remains the main occupation of the people
5. Links between medical and veterinary officers in Nigeria Links between these two groups of professionals can be said to be non-existent or at best very weak. Research is needed to gather more basic information on the prevalence of zoonotic infections in Nigeria and in this regard both medical and veterinary personnel have important roles to play. There is an urgent need to establish a regional animal health information system which should make use of computer technology and electronic information so that recent data can be made readily available to the appropriate personnel.
References Adegbola, R.A., Alabi, S.A., Akinkuede, F.O., Coker, A.O., Odugbemi, T., 1990. Correlation between human and animal bio-serogroups of Camylobacter isolates in Nigeria. J. Trop. Med. Hyg. 93, 280 – 283. Adeiga, A., Audu, R.A., 1998. Detection of rabies virus in saliva of apparently healthy dogs. Biomed. Lett. 54, 207 – 212.
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