ORIGINAL RESEARCH

First report of Neospora caninum infection in cattle in Sudan

Amira Mohamed Elhassan Ibrahim &

Abdelghafar Mohamed Elfahal &Abdel Rahim Mohamed El Hussein

Accepted: 18 August 2011 /Published online: 7 September 2011# Springer Science+Business Media B.V. 2011

Abstract A cross-sectional survey was conducted inSudan to determine sero-prevalence and risk factorsassociated with Neospora caninum infection in non-vaccinated dairy herds and to assess importance of thedisease. Blood samples were collected from a total of 262animals from 25 herds. Sera were tested for antibodiesagainst N. caninum using ELISA test. The prevalencerates of N. caninum antibodies in cattle were high both atherd level (44%) and at individual animal level (10.7%).Herd level infection rates were similar in Khartoum State(43.7%) and at Gazira States (44.4%). The overallprevalence rates were higher (16.1%) in Gazira State thanin Khartoum State (9%) but with no significant variation.The sero-prevalence at individual animal level wassignificantly higher (p<0.05) in animals with history ofabortion (12.8%) than in apparently healthy animal(11.3%), animal with history of infertility (8.1%), orneonatal death of calves (4.3%). In addition, significantlyhigher (P<0.05) sero-prevalence was observed in samplescollected during the rainy season (6.87%) than winter(3.05%) or summer (0.76%). However, no significantdifferences in sero-prevalence due to locality, animalbreed, sex, and age were observed (p>0.05). Thispreliminary study reveals for the first time the existenceof natural N. caninum infection in Sudan. Also, the

findings of the present study indicated that this disease ishighly prevalent in two major areas of dairy production inthe country, and this calls for control strategy to beimplemented.

Keywords Neospora caninum . Dairy cattle . Abortion .

cELISA . Sudan

Introduction

Neospora caninum is a protozoan parasite closely related toToxoplasma gondii, although they are genetically andantigenically distinct (Holmdahl et al. 1994). N. caninuminfects a wide range of domestic and wild animals, amongwhich cattle seem to be the most important. The infectioncauses pregnancy failures, such as repeated abortions andstillbirths resulting in enormous economic losses throughoutthe world (Barling et al. 2000). Recently, dogs and coyoteshave been established as the definitive hosts of N. caninum(McAllister et al. 1998; Gondim et al. 2004).

N. caninum can be transmitted postnatally (horizontally,laterally) by ingestion of tissues infected with tachyzoites ortissue cysts or by ingestion of food or drinking watercontaminated by sporulated oocysts, or it can be transmittedtrans-placentally (vertically, congenitally) from an infecteddam to her fetus during pregnancy (Dubey et al. 2007).

Since the first isolation of N. caninum, a range ofserological assays has been developed for detectinginfections in dogs, cattle, and a variety of other potentialhost species. The serological assays include the indirectfluorescent antibody test, several enzyme-linked immuno-sorbent assays (ELISAs), Neospora agglutination test, andimmunoblotting. All the serological assays are based ontachyzoite antigens (Dubey and Schares 2006).

A. M. E. Ibrahim (*) :A. R. M. El HusseinCentral Veterinary Research Laboratories,Animal Resources Research Corporation (ARRC),P.O. Box 8067, El Amarat,Khartoum, Sudane-mail: amirahassan98@hotmail.com

A. M. ElfahalCentral Laboratory, Ministry of Science and Technology,P.O. Box 7099, Khartoum, Sudan

Trop Anim Health Prod (2012) 44:769–772DOI 10.1007/s11250-011-9963-5

In Sudan, there is meager information about thefrequency and etiological factors of abortion in dairy cattle,and none is known about N. caninum infection.

The present study aimed to investigate N. caninuminfection among Sudanese dairy cattle, particularly thosesuffering from reproductive problems.

Materials and methods

Blood samples were collected from 25 herds with history ofreproductive problems in two geographic areas (16 herds inKhartoum State and 9 herds in Gazira State) in Sudan(Table 1). Animals sampled in these herds includedindividuals with history of abortion, infertility, and neonatalcalf death or animals with no such history. Animals of bothsexes and various age groups (1, 2, 3 years and above) werebled at different seasons: winter (November–February),summer (March–June), and rainy season (July–October).Blood samples were collected from 262 local and crossbredanimals. Sera were extracted by centrifugation at 1,500 rpmfor 10 min and kept at −20°C until they were tested for thepresence of antibodies against N. caninum using ELISAassay.

A herd was considered positive for N. caninum infectionwhen at least one animal with positive antibody reactionwas detected.

ELISA for detection N. caninum antibodies in sera

Commercial competitive ELISA kits (Investcare Vet Com-pany (VMRD), UK) were used to detect antibodies againstthe N. caninum antibodies (IgG, IgM) according tomanufacturer’s instructions.

Statistical analysis

The serological results and other information gatheredduring this investigation such as locality, sex, and breed(indigenous and crossbred) of the sampled animals wereedited and analyzed statistically using statistical package(SPSS version 13). To identify the association of the riskfactors with the specific sero-prevalence, the Chi-square (χ2

test) and one-way ANOVA was used. The statisticalsignificance level used was p≤0.05.

Results

Infection at herd level

Out of 25 herds tested at both states, 11 (44%) proved to bepositive for N. caninum antibodies. Of these, seven (43.7%)out of the 16 herds in Khartoum State and four (44.4%) outof nine herds in Gazira State were positive. The highest

Table 2 Seropositivity toNeospora caninum in cattlefrom different locations inKhartoum and Gazira States

State Location Sample Numberspositive

Percentagepositive

Khartoum Khartoum 90 6 6.6

Khartoum North 67 10 14.9

Omdurman 43 2 4.7

Subtotal 200 18 9

Gazira Alkamleen 10 0 <1

Wad Madani 52 10 19.2

Subtotal 62 10 16.1

Total 262 28 10.7

Table 1 Herds levels of infectionwith Neospora caninum in cattlein Sudan

States Location Number ofherds

Total numberof animals

Number ofpositive herds

Percentagepositive

Khartoum Khartoum 5 284 1 20

Khartoum North 7 1135 5 71

Omdurman 4 164 1 25

Gazira Alkamleen 1 10 0 <1

Wad Madani 8 430 4 50

Total 25 2024 11 44

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infection rate (71%) was observed in Khartoum North inKhartoum State (Table 1).

Individual infection level

The overall prevalence of N. caninum antibodies in bothstates was 10.7% (28/262). Prevalence rates of 6.6%,14.9%, and 4.7% were recorded from Khartoum, KhartoumNorth, and Omdurman Districts, respectively. In GaziraState, prevalence rates of <1% and 19.2% were recorded forAlkamleen and Wad Madani Districts, respectively (Table 2).

Collectively, the prevalence of N. caninum infection wassignificantly (p<0.05) higher (12.8%) in animals withhistory of abortion than in apparently healthy (11.3%),infertility cases (8.1%), or in animals with history ofneonatal calf mortality (4.3%) (Table 3).

Moreover, the highest sero-prevalence of N. caninumwas found in samples collected during the rainy season(6.87%, p<0.05), but there were no statistically significantrelationship between antibodies prevalence and breed,animal sex, age, or locality (Table 4).

Discussion

This study represents the first serological evidence forpresence of N. caninum infection in Sudan. N. caninumantibodies were prevalent both at herd and at individualanimal level. Out of the 16 herds tested in Khartoum State,seven (43.7%) herds proved to be positive for N. caninumantibodies; similarly, four (44.4%) of nine herds in GaziraState were positive. The highest infection rate (71%) amongherds was observed in Khartoum North in Khartoum State;this high prevalence rate (five herds out of seven wereinfected) is in concordance with high abortion ratesreported from farms in this particular area (Elhassan,unpublished data). Atkinson et al. (2000) recorded thatabortions were associated with N caninum infection, andassociation between seropositivity in dams and daughterswas highly significant.

At individual animal level, the overall sero-prevalence ofneosporosis in dairy cattle herds in Sudan was found to be10.7%. Positive cases were more frequent among abortedanimals (12.8%) than in animals without history ofreproductive problems. This finding is in full agreementwith those of Dubey (2003) and Moore et al. (2009) whomentioned that aborted animals were more likely to bepositive to N. caninum than those without signs of abortion.

Romero-Salas et al. (2010) reported that N. caninumantibodies prevalence increases with age, a matter thatsuggests horizontal and trans-placental transmission of theparasite. However, in the present study, no significantassociation between age and sero-prevalence was foundsuggesting an effective trans-placental transmission frominfected dams to their calves (Sevgili and Aktas 2005).

The prevalence was also observed to be high in thecrossbred females, but with no significant difference (p≥0.05) from local breeds similar to the findings of Sevgiliand Aktas (2005). This may be explained by the fact thatcrossbred cattle were the predominant type in all herds

Table 4 Influence of some riskfactors on sero-prevalence ofNeospora caninum in cattlefrom different locations inKhartoum and Gazira States

aAge was in years

Variable Group Number ofsamples

Percentagepositive

P value

Breed Local 8 0 (0) >0.05Cross 254 28 (10.7)

Sex Female 244 24 (9.2) >0.05Male 18 4 (1.5)

Season Winter 100 8 (3.05) <0.05Dry 45 2 (0.76)

Rainy 117 18 (6.87)

Agea 1 26 5 (1.9) >0.052 19 2 (0.7)

3 and above 217 21 (8.1)

Locality Khartoum State 200 18 (6.9) >0.05Gazira State 62 10 (3.4)

Table 3 Association between seropositive results to Neosporacaninum and signs of reproductive problem in cattle detected bycELISA from different locations in Khartoum and Gazira States

Signs Numbers ofnegativesample

Numberspositiveand percents

Total P value

Abortion 68 10 (12.8) 78 <0.05Infertility 34 3 (8.1) 37

Death after birth 22 1 (4.3) 23

Apparentlyhealthy

110 14 (11.3) 124

Total 234 28 (10.7) 262

Only the aborted group showed significant association with N.caninum antibodies

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included in the present study. Management systems are alsonoted to affect breed sero-prevalence more than breedrelated susceptibility to infection (Dubey et al. 2007).

The effect of the seasonal variations in climate duringthis study was found to be significant (P<0.05), and highsero-prevalence was observed during the rainy seasonwhich is often hot and humid.

Similar results were found by Thurmond et al. (1995)who recorded a highly significant seasonal pattern regard-ing the submission of N. caninum-positive aborted fetusesin California. The highest number of positive cases wassubmitted during winter, which in California is mild andhumid in contrast to summer, which is hot and dry(Thurmond et al. 1995). Moreover, risk factor analysis ofabortion risk in N. caninum-seropositive dams in twoSpanish dairy herds suggested that there was a significantrelationship between rainfall and abortion (Lo’pez-Gatius etal. 2005). It was suspected that increased rainfall may posedirect and indirect stresses to cattle by elevated heatproduction in response to cold temperatures, behavioralstress, impaired food quality, and diminished hygiene thatcould trigger N. caninum-associated abortion in latentlyinfected cattle (Lo’pez-Gatius et al. 2005).

Climatological differences between geographical areasmay also affect oocyst survival and subsequently the diseaseprevalence (Sanderson et al. 2000). These differences mayalso affect the density distribution of other unrecognizeddefinitive hosts. There was no significant relationshipbetween sero-prevalence and cow origin in the present study.This may have resulted from similar climatologic andmanagement factors in the two areas examined.

In conclusion, the present study reports the first serologicalevidence of natural N. caninum infection in dairy cattle inSudan. The study showed high and significant prevalence ofantibodies to the parasite in animals with history of abortion;however, further country-wide investigations are required tofully evaluate the epidemiology of this parasite and itseconomic impact in Sudan.

Acknowledgment The authors would like to thanks Miss AzaaBabiker Musa. Central Laboratory, Ministry of Science and Technol-ogy, for helping in statistical analysis.

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