The Serological Survey for Human Cysticercosis Prevalence in Mbulu District, Tanzania

doi:10.4236/aid.2012.23009

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Advances in Infectious Diseases, 2012, 2, 62-66

http://dx.doi.org/10.4236/aid.2012.23009 Published Online September 2012 (http://www.SciRP.org/journal/aid)

The Serological Survey for Human Cysticercosis

Prevalence in Mbulu District, Tanzania

Beda J. Mwang’onde1,2*, Gamb a Nkwengulila1, Mwita Chacha1

1Department of Zoology and Wildlife Conservation, University of Dar es Salaam, Dar es Salaam, Tanzania; 2Division of Livestock

and Human Disease Vector Control, Tropical Pesticides Research Institute, Arusha, Tanzania.

Email: *[email protected]

Received July 4th, 2012; revised August 2nd, 2012; accepted September 3rd, 2012

ABSTRACT

Human cysticercosis, a zoonotic disease due to Taeniasolium, is of the highly debilitating and stigmatizing neglected

tropical diseases due to epilepsy, ophthalmia and dermatological disorders in endemic developing countries. Tanzania is

among the sub-Saharan African countries with an average prevalence of porcine cysticercosis 17.2% [1], which in-

creases the risk of human cysticercosis infection. Studies on people with epilepsy in northern zone of Tanzania show a

16.2% [2] to be suffering from neurocysticercosis. While this was the case, there were no single report on the preva-

lence of human cysticercosis neither to regu lar hospital visitors, admissions, and nor general public that result to insuf-

ficient deployment of intervention strategies. Study was performed to assess the prevalence of human cysticercosis in

general public in Mbulu district. The cephalic venous blood was collected from assorted community members. Serum

was extracted and then subj ected to Cysticercus IgG Western Blot Assay for human cysticercosis sero-screening. It was

found that about 16.3% of the community members had antibodies signifying infection by human cysticercosis. This is

the first ever study to assess the prevalence of human cysticercosis in the country and it has revealed the problem to be

very high. This study can be valuable for deployment of appropriate intervention measures on human cysticercosis in

the study area and extend to the entire country.

Keywords: Human Cysticercosis; Taeniasolium; Mbulu-Tanzania; Prevalence

1. Introduction

Human cysticercosis is a zoonotic disease which is ca us ed

by the larval stage of pork tapeworm (Taeniasolium cys-

ticercosis) and poses serious public health co ns e qu e n ce s i n

developing countries [3]. The disease affects no less than

20 million people with an annual fatality rate of ap-

proximately 50,000 people worldwide [4]. Human cysti-

cercosis accounts for about 10% of all acute neurological

admissions and a main cause of late onset epilepsy in

endemic areas [5] with about 20% - 50% of all late-onset

epilepsy cases globally [6]. Human cysticercosis infec-

tion can go unnoticed therefore, its public health conse-

quence may be grave than it is estimated. Recent trends

due to international tourism into remote or rural areas,

expansion of global business and increase of the number

of trans-migrants from rural to urban areas as well as in-

crease of immigrants and refugees, have drastically in-

creased the cases of taeniasis and cysticercosis in devel-

oped countries, Orthodox Jewish [7] and Muslim com-

munities [8,9].

Human cysticercosis is highly reported in Latin Amer-

ica, Asia and Africa. Studies in some regions of Mexico

show a prevalence of 3.6% of the general population [4];

in Asia 3.2% [10]; in Caribbean particularly in Haiti

2.8%, [11] and; in western Africa the prevalence of hu-

man cysticercosis range from 1.3% - 2.4% [12]. On the

other hand, in sub-Saharan Africa about 30% of people

with epilepsy have been diagnosed with neurocysticerco-

sis [13]. Neurocysticercosis due to Taeniasolium cysti-

cercosis is reported to be a disease of poverty and under

development as to why being one of the main causes of

epilepsy in developing countries [14]. Nevertheless, the

importation T. solium by tourism, migration of tapeworm

carriers or indirectly by importations of infected pigs, or

pig meat poses risks of the disease in Europe [15]. Be-

cause of globalization, human cysticercosis begins to

appear in industrialized countries particularly Portugal

and Northern Spain [16] and in North America[17]; and

in Islamic [18] and Orthodox Jewish [17] communities.

That is to say that the epidemiology of human cysticer-

cosis spares no community in the world because of glob-

alization.

The risk of human cysticercosis in Tanzania is very high

because the average prevalence of Taenia cellulosa e was

*Corresponding a uthor.

The Serological Survey for Human Cysticercosis Prevalence in Mbulu District, Tanzania 63

reported to be 17.2% [1]. On the other hand, piggery in-

dustry has significantly grown in the country due to rapid

economic turnover and a drastic rise in pork consumption

in many rural and urban areas [19]. In urban communi-

ties, pork is a delicacy that goes together with alcohol

consumption [20]. The free range system of keeping pigs,

lack and or improper use of latrines, clandestine slaugh-

tering and marketing of pork, absence of pork inspection

and barbecuing [21-23], further increase the risk of hu-

man cysticercosis infection in Tanzania populations’. With

the reported high risks of human cysticercosis, studies

mainly have been reporting porcine cysticercosis [1,6,21,

24]. The few studies that report cysticercosis infections

in human are based on neuro cysticercosis particularly to

people with epilepsy [2,25]. Hospital based studies in

people with epilepsy in northern Tanzania report an av-

erage neurocysticercosis prevalence of 16.2% [2,25]. Be-

cause human cysticercosis can go unnoticed for quite long,

these reported studies in human do not adequately pro-

vide with the cysticercosis prevalence picture in the Tan-

zania’s population.

This study reports a serological survey of human cys-

ticercosis based on antibodies determination in the gen-

eral community from Mbulu district, in the northern part

of Tanzania.

2. Materials and Methods

2.1. Study Area and Ethical Clearance

The study was carried out in Mbulu District (3.80˚S -

4.50˚S, 35.00˚E - 36.00˚E). Mbulu district has a popula-

tion of 321,359 (DED, 2011). The area lies at an esti-

mated altitude of 1000 - 2400 m above sea level. Climate

ranges from semi-arid to sub-humid with an annual rain-

fall of <400 and >1200 mm, respectively. There are two

rainy seasons with two peaks of maximum rains. The

long rainy season extends from about March to mid- May

and the short rainy period from November to December.

In between (January through February) is a dry season.

Relative humidity ranges from 55% to 75% and mean

annual temperatures range from 15˚C to 24˚C. The ethi-

cal clearance and approval of the study was sought from

the National Institute for Medical Research (NIMR) (ref.

NIMR/HQ/R.8a/Vol. IX/1297). NIMR is one of the United

Republic of Tanzania research organs responsible for

health research and the key board that oversees all regu-

latory issues of health research in the country.

2.2. Data Collection for Serological Survey of

Human Cysticercosis

The goal of this survey was to assess the proportion of

people in the study area carrying Abs of T. solium cysti-

cercosis as an indication of infection by the cestode.

Blood samples from randomly selected and consented

community members were collected.

About 544 individuals of different age groups and sex

from general community participated in the study. About

3 mls of cephalic venous blood was collected from each

of the consented participants by the use of evacuated

collection tubes. The samples were centrifuged at 3500

rpm at Mbulu District Hospital for serum extraction, ali-

quoted and stored in cryogenic vials in freezers before

they were transported to the University of Dar es Salaam

for further storage at –20˚C. The determination of anti-

bodies for human cysticercosis infection was carried out

by using Cysticercus IgG Western Blot Assay (LDBIO

Diagnostics 69009 Lyon-France) at Biotechnology La-

boratory, Department of Molecular Biology and Bio-

technology, University of Dar es Salaam.

Cysticercus IgG Western Blot Assay detects the pres-

ence of cysticercosis antibodies. However, the test may

be cross-reactive with other parasites. The principle of

the test is based on Cysticercus antigens from a crude

larval extract which have been resolved by electrophore-

sis into bands and transferred by electroblotting onto a

nitrocellulose membrane which is readly cut into testing

str ips. The presence on the strip of a minimum of 2 well-

defined bands among the 6 (i.e. 6 - 8; 12; 23 - 26; 39; 45;

50 - 55 kDa) described bands were considered as an in-

dication of human cysticercosis. However, the presence

of the lower molecular weight band (6 - 8 kDa) was also

described as an indication of active cysticercosis [26].

2.3. Statistical Analysis

Data entry and validation was carried ou t using ms-excel

2010 version (Ms Corp., Redmond, WA, USA). Data on

human cysticercosis seroprevalencewas analyzed using

the Statistical Package for Social Sciences version 19.0

(SPSS Statistic 19, 2010 IBM). Descriptive statistics

were used to obtain the percentage prevalence of both

human cysticercosis and other helminthes infections that

were able to be detected by the kit in differen t age groups

of the sampled population. The unequal variance t-test

(Welch’s t-test) was used to test for the variations of in-

fection between different age groups and gender,



.

3. Results

3.1. Prevalence Rate of Human Cysticercosis and

other Helminthes

The mean age of respondents was 34.49 ± 18.44 with a

range of 92. The female to male ratio was 0.64. The

prevalence of human cysticercosis for circulating cysti-

cercal antibodies in Mbulu general community was

16.3% (n = 544). The infection rate was found to in-

crease with age and the male participants were more

The Serological Survey for Human Cysticercosis Prevalence in Mbulu District, Tanzania

positive to human cysticercosis than female participants.

Based on age cohorts, the prevalence rates were 2% (0 -

10 years); 8% (11 - 15 years); and 52% (16 - 45 years).

Then the prevalence rate decreased to 19% (45 - 60

years); 5% (61 - 75 years); and 1% in above 76 years of

age. About 75% of the positive cases were males with

56.3% of all positive cases in both female and males

suggesting neurocysticercosis infection. The frequencies

of other parasitic infections were echinococcosis 12.1%,

schistosomiasis 6.8%, toxocariasis 14.1%, and toxoplas-

mosis 1.7%. The age cohort between 16 - 45 years was

significantly more infected with human cysticercosis than

cohorts between 0 - 10 years (p < 0.00015, df = 46); 11 -

15 years (p < 0.0065 , df = 51); 46 - 60 year s (p < 0.0062,

df = 61); 61 - 75 years (p < 0.0004, df = 48) ; and 76 and

above (p < 0.0001, df = 45).

4. Discussions

Human cysticercosis infections are one of the major

causes of epilepsy and other neurological syndromes

which are highly debilitating and thus resulting into so-

cial stigmatization in developing endemic countries. Based

on the findings from this study, the disease is highly

prevalent in Mbulu. Because Mbulu district is one of the

main sources of pork in urban, the risk of human infec-

tion in Tanzania mighty be very high as under cooked

pork consumption increase chances of pork tapeworm

infestation. The fact that the epidemiology of human cys-

ticercosis is favoured by food, water or environmental

contamination by pork tapeworm eggs from tapeworm

carriers, the threat of the disease in the country might be

holistic.

The study found anticysticercal antibodies for human

cysticercosis in eighty eigh t participan ts correspond ing to

16.3% of all tested community members from the general

public in Mbulu, a district in the northern zone of Tanza-

nia. These findings correspond to the 16.7% (by Ag-

ELISA) of active human cysticercosis which was re-

ported from Mbozidistrict [27], a district in a southern

zone of Tanzania, again one of the main sources of pork

in both rural and urban areas. Elsewhere, in Rwanda and

Mozambique, the seroprevalence of human cysticercosis

was found to be 2.8% and 12.1% [28,29], respectively.

While all human cysticercosis results contrasted in here

are from Africa south of Sahara, the observed differences

might have been contributed by target groups for study,

method of testing and risk factors for the disease. The

risk of human cysticercosis in Mbulu is very high be-

cause of traditional behaviour of keeping pigs under free

range system.

On the other hand, the observed prevalence is signifi-

cantly less to that reported byNsengunya et al. [30]

which was 31.5% (n = 648) of the health individuals

positive to an ticysticercal antibodies in Burundi. The hu-

man cysticercosis prevalence reported by this study had

the highest frequency in ages between 16 - 45 years. This

is in complement with that reported by Samir et al. [31],

however, under the reported study the higher frequency

is attributed by high return of the participants for the re-

ported age range than other cohorts. Males were detected

more positive (75%) to human cysticercosis than females

(p = 0.0099, df = 86). The differences in human cysti-

cercosis seropositivity rates between sexes and age groups

possibly reflect levels of exposure by gender to risk fac-

tors. Males and the reported productive age group (16 -

45) might be spending more time in local brews clubs

where they are subjected to eating undercooked pork and

or contaminated food or drinks by tapeworm eggs. How-

ever, further studies need to be done to find out whether

there is any genetic, sexual or senility relations hip for hu-

man cysticercosis infections. The prevalence rate of hu-

man cysticercosis was also found to decrease with the

increasing age particularly at ages above 50 years old.

This may have been also contributed by the low return

rate to participating to the study because of decreased

chances of being picked for sampling as the life expec-

tancy in Tanzania is 48 years due to HIV/AIDS pan-

demic and the leading cause of death, and malaria, the

number one killer of children under five [32]. High pre-

valence of human cysticercosis in the study region is

contributed by the free range system of keeping pigs and

the indiscriminate disposal of human faeces that are later

easily picked by pigs and thus enhance the parasite life-

cycle. The best intervention measure for this highly de-

bilitating and stigmatizing disease is education to deny

human faeces-pig contact followed by mass che mot herapy

by physician prescribed anthelmintic drug of choice to

humans.

Based on these findings, human cysticercosis is a big

problem in the country that requires an in-depth review

and serological survey all over the country, mapping and

then development of a logical framework for interv entio n

strategies of the disease.

5. Acknowledgements

The research for this paper was carried out within the

framework of the consortium Afrique One “Ecosystem

and Population Health: Expanding Frontiers in Health”.

Afrique One is funded by the Wellcome Trust (WT-

087535MA) and the University of Dar es Salaam for

hosting and experimental facilitation of the project.

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